Ecopetrol (EC) 20-F/A 26 Apr 18 2017 FY Annual report (foreign) (amended) Financial data

Document And Entity Information

Document And Entity Information	12 Months Ended
	Dec. 31, 2017shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Entity Registrant Name	ECOPETROL S.A.
Entity Central Index Key	1,444,406
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Trading Symbol	EC
Entity Common Stock, Shares Outstanding	41,116,694,690

Consolidated statement of finan

Consolidated statement of financial position - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents		$ 7,945,885	$ 8,410,467
Trade and other receivables, net		6,098,918	4,212,701
Inventories, net		4,601,396	3,841,901
Other financial assets		2,967,878	5,315,537
Current tax assets		625,374	1,129,098
Equity instruments measured at fair value		0	51,610
Other assets		880,425	1,035,632
Current assets other than non-current assets or disposal groups classified as held for sale or as held for distribution to owners		23,119,876	23,996,946
Assets held for sale		104,140	132,216
Total current assets		23,224,016	24,129,162
Non-current assets
Investment in associates and joint ventures		1,330,460	1,552,694
Trade and other receivables, net		777,132	729,410
Property, plant and equipment		61,404,374	62,328,502
Natural and environmental resources		21,308,265	22,341,047
Intangible assets		380,226	272,132
Deferred tax assets		4,016,161	4,248,014
Other financial assets		3,565,847	1,371,358
Goodwill		1,159,922	1,159,922
Other assets		681,009	826,736
Total non-current assets		94,623,396	94,829,815
Total assets		117,847,412	118,958,977
Current Liabilities
Loans and borrowings	[1]	5,144,504	4,126,203
Trade and other payables		6,968,207	6,854,363
Provisions for employee benefits		1,829,819	1,974,496
Current tax liabilities		2,005,688	2,130,940
Accrued liabilities and provisions		558,828	821,954
Other liabilities		339,565	439,274
Current liabilities other than liabilities included in disposal groups classified as held for sale		16,846,611	16,347,230
Liabilities related to assets held for sale		0	40,128
Total current liabilities		16,846,611	16,387,358
Non-current liabilities
Loans and borrowings		38,403,331	48,095,824
Trade and other payables		29,469	23,893
Provisions for employee benefits		6,502,475	3,901,082
Deferred tax liabilities		1,333,280	1,639,703
Accrued liabilities and provisions		5,978,621	5,095,916
Other liabilities		537,926	254,700
Total non-current liabilities		52,785,102	59,011,118
Total liabilities		69,631,713	75,398,476
Equity
Subscribed and paid in capital		25,040,067	25,040,067
Reserves		2,177,869	1,558,844
Retained earnings		5,210,302	(402,462)
Other equity items		14,006,715	15,830,409
Equity attributable to owners of parent		46,434,953	42,026,858
Non-controlling interest		1,780,746	1,533,643
Total equity		48,215,699	43,560,501
Total liabilities and equity		$ 117,847,412	$ 118,958,977
[1]	The increase in the current portion is mainly due to the expiration of: i) the first tranche of local bonds issued by Ecopetrol S.A. in 2013, and ii) the 5-year series of international bonds issued in 2013 by Ecopetrol S.A.. These bonds mature in August and September 2018, respectively.

Consolidated statement of profi

Consolidated statement of profit or loss - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Profit or loss [abstract]
Sales revenue	$ 55,954,228	$ 48,485,561	$ 52,347,271
Cost of sales	(36,908,325)	(34,251,423)	(36,994,516)
Gross profit	19,045,903	14,234,138	15,352,755
Administrative expenses	(1,764,524)	(1,923,268)	(1,700,985)
Operations and project expenses	(2,926,065)	(2,751,687)	(4,034,268)
Recovery of (expense for) impairment of long-term assets, net	1,311,138	(928,747)	(7,864,875)
Other operating income, net	505,403	274,112	378,538
Operating income	16,171,855	8,904,548	2,131,165
Financial results, net
Finance income	1,159,356	1,311,743	621,924
Finance expenses	(3,660,601)	(3,463,540)	(2,718,414)
Foreign exchange gain (loss)	5,514	976,430	(5,566,614)
Financial result, net	(2,495,731)	(1,175,367)	(7,663,104)
Share of profits (losses) of associates and joint ventures	93,538	61,345	(46,687)
Profit (loss) before income tax expense	13,769,662	7,790,526	(5,578,626)
Income tax expense	(5,800,268)	(4,543,046)	(710,353)
Net profit (loss) for the period	7,969,394	3,247,480	(6,288,979)
Net profit (loss) attributable to:
Owners of parent	7,178,539	2,447,881	(7,193,859)
Non-controlling interest	790,855	799,599	904,880
Net profit (loss) for the period	$ 7,969,394	$ 3,247,480	$ (6,288,979)
Basic and diluted earnings (loss) per share	$ 174.6	$ 59.5	$ (175)

Consolidated statement of other

Consolidated statement of other comprehensive income - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Profit or loss [abstract]
Net profit (loss) for the period	$ 7,969,394	$ 3,247,480	$ (6,288,979)
Unrealized gain (loss) on hedges:
Cash flow hedge for future exports	(84,837)	461,424	(217,291)
Hedge of a net investment in a foreign operation	57,997	(155,359)	0
Cash flow hedge with derivative instruments	35,768	33,869	(60,083)
Equity instruments measured at fair value:
Unrealized (loss) gain	(7,828)	126,205	(106,911)
Realized (loss) gain	0	(68,497)	(19,405)
Foreign currency translation	(257,147)	(925,981)	5,979,644
Other comprehensive income that will be reclassified to profit or loss, net of tax	(256,047)	(528,339)	5,575,954
Other comprehensive income not to be reclassified to profit or loss in subsequent periods (net of taxes):
Remeasurement (loss) gain on defined benefit plans	(1,548,043)	(1,153,442)	1,404,602
Others (losses) gains	(11,817)	(46,826)	58,643
Other comprehensive income that will not be reclassified to profit or loss, net of tax	(1,559,860)	(1,200,268)	1,463,245
Other comprehensive income for the year, net of tax	(1,815,907)	(1,728,607)	7,039,199
Total comprehensive income for the year, net of tax	6,153,487	1,518,873	750,220
Comprehensive results attributable to:
Owners of parent	5,353,778	784,658	(328,604)
Non-controlling interest	799,709	734,215	1,078,824
Comprehensive income	$ 6,153,487	$ 1,518,873	$ 750,220

Consolidated statement of chang

Consolidated statement of changes in equity - COP ($) $ in Millions	Total	Subscribed and paid-in capital	Additional paid-in capital	Reserves	Other comprehensive income		Retained earnings	Total	Non-controlling interest
Opening balance at Dec. 31, 2014	$ 48,534,228	$ 10,279,175	$ 6,607,612	$ 17,963,370	$ 3,980,749		$ 8,192,040	$ 47,022,946	$ 1,511,282
Net income	(6,288,979)	0	0	0	0		(7,193,859)	(7,193,859)	904,880
Dividends declared	(6,183,572)	0	0	0	0		(5,468,521)	(5,468,521)	(715,051)
Release\Appropriation of reserves, net	0	0	0	2,344,095	0		(2,344,095)	0	0
Capitalization of reserves	0	14,760,895	0	(14,760,895)	0		0	0	0
Other movements	87	(3)	87	0	0		3	87	0
Gain (loss) on hedging instruments:
Cash flow hedge for future exports	(217,291)	0	0	0	(217,291)		0	(217,291)	0
Hedge of a net investment in a foreign operation	0
Cash flow hedge with derivative instruments	(60,083)	0	0	0	(43,590)		0	(43,590)	(16,493)
Net fair value gain (loss) on equity instruments measured at fair value	(126,316)	0	0	0	(126,316)		0	(126,316)	0
Foreign currency translation	5,979,644	0	0	0	5,789,207		0	5,789,207	190,437
Actuarial valuation losses	1,404,602	0	0	0	1,404,602		0	1,404,602	0
Other movements	58,643	0	0	0	58,643		0	58,643	0
Closing balance at Dec. 31, 2015	43,100,963	25,040,067	6,607,699	5,546,570	10,846,004		(6,814,432)	41,225,908	1,875,055
Net income	3,247,480	0	0	0	0		2,447,881	2,447,881	799,599
Dividends declared	(1,029,612)	0	0	0	0		0	0	(1,029,612)
Legal reserve used to offset previous year loss	0	0	0	(3,869,907)	0		3,869,907	0	0
Release\Appropriation of reserves, net	0	0	0	(117,819)	0		117,819	0	0
Other movements	(29,723)	0	0	0	0		(23,637)	(23,637)	(6,086)
Gain (loss) on hedging instruments:
Cash flow hedge for future exports	461,424	0	0	0	461,424		0	461,424	0
Hedge of a net investment in a foreign operation	(155,359)	0	0	0	(155,359)		0	(155,359)	0
Cash flow hedge with derivative instruments	33,869	0	0	0	24,546		0	24,546	9,323
Net fair value gain (loss) on equity instruments measured at fair value	57,708	0	0	0	57,708		0	57,708	0
Foreign currency translation	(925,981)	0	0	0	(811,345)		0	(811,345)	(114,636)
Actuarial valuation losses	(1,153,442)	0	0	0	(1,153,442)		0	(1,153,442)	0
Other movements	(46,826)	0	0	0	(46,826)		0	(46,826)	0
Closing balance at Dec. 31, 2016	43,560,501	25,040,067	6,607,699	1,558,844	9,222,710	[1]	(402,462)	42,026,858	1,533,643
Net income	7,969,394	0	0	0	0		7,178,539	7,178,539	790,855
Dividends declared	(1,497,178)	0	0	0	0		(945,684)	(945,684)	(551,494)
Release\Appropriation of reserves, net	0	0	0	619,025	0		(619,025)	0	0
Other movements	(1,111)	0	1	0	2		(1,066)	(1,063)	(48)
Gain (loss) on hedging instruments:
Cash flow hedge for future exports	(84,837)	0	0	0	(84,837)		0	(84,837)	0
Hedge of a net investment in a foreign operation	57,997	0	0	0	57,997		0	57,997	0
Cash flow hedge with derivative instruments	35,768	0	0	0	25,984		0	25,984	9,784
Net fair value gain (loss) on equity instruments measured at fair value	(7,828)	0	0	0	(7,828)		0	(7,828)	0
Foreign currency translation	(257,147)	0	0	0	(255,153)		0	(255,153)	(1,994)
Actuarial valuation losses	(1,548,043)	0	0	0	(1,548,043)		0	(1,548,043)	0
Other movements	(11,817)	0	0	0	(11,817)		0	(11,817)	0
Closing balance at Dec. 31, 2017	$ 48,215,699	$ 25,040,067	$ 6,607,700	$ 2,177,869	$ 7,399,015	[1]	$ 5,210,302	$ 46,434,953	$ 1,780,746
[1]	During 2016 the Group reclassified to the statement of profit or loss COP$68,497 (2015 - COP$19,405) arising from the realization of accumulated fair value gains on equity of assets available for sale - Empresa de Energía de Bogotá and Interconexión Eléctrica S.A.

Consolidated statement of cash

Consolidated statement of cash flows - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flow provided by operating activities:
Net profit (loss) for the period	$ 7,969,394	$ 3,247,480	$ (6,288,979)
Adjustments to reconcile the net profit (loss) to net cash provided by operating activities:
Income tax expense	5,800,268	4,543,046	710,353
Depreciation, depletion and amortization	8,281,347	7,607,000	6,770,358
Foreign exchange loss	(5,514)	(976,430)	5,566,614
Finance cost of loans and borrowings	2,385,994	2,765,024	1,768,618
Finance cost of post-employment benefits and abandonment costs	753,047	580,491	627,827
Dry wells	898,264	342,691	1,266,440
Loss on disposal of non-current assets	26,686	78,990	59,932
Gain in acquisition of interests in joint operations	(451,095)	0	0
Loss on (recovery of) impairment of short term assets	30,600	74,393	(8,698)
(Recovery of) loss on impairment of long term assets	(1,311,138)	928,747	7,864,875
Gain on fair value adjustment of financial assets	(104,706)	(59,593)	(109,673)
Share of profit (loss) of associates and joint ventures	(93,538)	(61,345)	46,687
Net gain on the sale of assets held for sale	(166,389)	0	0
Gain on sale of equity instruments measured at fair value	(13,236)	(47,129)	(72,339)
Hedge ineffectiveness	8,918	0	0
Realized foreign exchange cash flow hedges	(160,772)	(33,074)	(7,646)
Income tax paid	(4,217,303)	(4,347,364)	(3,148,028)
Net change in operational assets and liabilities:
Trade and other receivables	(2,189,473)	(1,400,583)	751,031
Inventories	(323,626)	(217,198)	(183,231)
Trade and other payables	21,417	(619,131)	(2,202,808)
Tax assets and liabilities	(493,533)	2,547,232	(1,964,995)
Provisions for employee benefits	(227,384)	(11,677)	(206,444)
Provisions and contingencies	104,135	(827,153)	(216,939)
Other assets and liabilities	451,263	118,523	654,960
Net cash generated by operating activities	16,973,626	14,232,940	11,677,915
Cash flow from investing activities:
Investment in property, plant and equipment	(2,363,283)	(3,646,929)	(8,548,933)
Investment in natural and environmental resources	(3,426,405)	(2,121,295)	(6,856,761)
Acquisition of interests in joint operations	(141,950)	0	0
Acquisitions of intangibles	(175,868)	(69,253)	(112,255)
Sales (purchases) of other financial asset	564,754	(5,446,507)	1,208,898
Interests received	405,562	386,001	293,507
Dividends received	270,136	437,803	423,856
Proceeds from sales of assets held for sale	159,041	0	0
Proceeds from sales of equity instruments measured at fair value	56,930	966,715	613,998
Proceeds from sales of property, plant and equipment	267,324	109,896	166,211
Net cash used in investment activities	(4,383,759)	(9,383,569)	(12,811,479)
Cash flow used in financing activities:
Proceeds from borrowings	444,827	4,594,640	10,985,933
Repayment of borrowings	(9,007,340)	(3,149,917)	(4,903,592)
Interest payments	(2,696,979)	(2,495,446)	(1,981,127)
Capitalizations	0	0	3
Dividends paid	(1,504,647)	(1,712,298)	(5,493,400)
Net cash used in financing activities	(12,764,139)	(2,763,021)	(1,392,183)
Exchange difference in cash and cash equivalents	(290,310)	(226,333)	1,458,019
Net (decrease) increase in cash and cash equivalents	(464,582)	1,860,017	(1,067,728)
Cash and cash equivalents at the beginning of the year	8,410,467	6,550,450	7,618,178
Cash and cash equivalent at the end of the year	7,945,885	8,410,467	6,550,450
Non-cash transactions
Capitalization of reserves	0	0	14,760,895
Payment of income tax through the offset of balances in favor	$ 0	$ 656,121	$ 894,451

Reporting entity

Reporting entity	12 Months Ended
	Dec. 31, 2017
Disclosure of reporting entity [Abstract]
Disclosure of reporting entity [text block]	1. Reporting entity Ecopetrol S.A. (“Ecopetrol”) is a mixed economy company, of a commercial nature, incorporated in 1948 in Bogotá - Colombia, parent company of the Ecopetrol Business Group. Its corporate purpose is to conduct commercial or industrial activities related to the exploration, exploitation, production, refining, transportation, storage, distribution and commercialization of hydrocarbons and their derivatives and products, directly or through its subsidiaries (collectively referred to as "Ecopetrol Business Group"). 11.51 88.49 The address of the main office of Ecopetrol is Bogotá - Colombia, Carrera 13 No. 36 - 24.

Basis for presentation

Basis for presentation	12 Months Ended
	Dec. 31, 2017
Disclosure of basis of presentation [Abstract]
Disclosure of reclassifications or changes in presentation [text block]	2. Basis for presentation 2.1 Statement of compliance and authorization of financial statements These consolidated financial statements of Ecopetrol and its subsidiaries as of December 31, 2017 and 2016 and for the years ended December 31, 2017, 2016 and 2015 have been prepared in accordance with International Financial Reporting Standards (IFRS), issued by the International Accounting Standards Board (IASB). Accounting policies described in Note 4 have been applied consistently in all periods. These consolidated financial statements were approved and authorized for issuance by the Board of Directors of Ecopetrol on April 19, 2018. 2.2 Basis for consolidation The consolidated financial statements were prepared by consolidating all companies set out in Exhibit 1, which are those over which Ecopetrol exercises direct or indirect control. Control is achieved when the Group: § Has power over the investee (including rights to manage relevant activities); § Is exposed, or has the rights, to variable returns from its involvement with the investee; and § Has the ability to use its power to affect its operational returns. This instance occurs when the Group has less than a majority of the voting rights of an investee, and it still has the power over the investee to provide it with the practical ability to direct the relevant activities of the investee unilaterally. The Group considers all relevant facts and circumstances in assessing whether or not the Company’s voting rights in an investee are sufficient or not to give it power, including: a) The percentage of the Group's voting rights relative to the size and apportionment of the shares of other vote holders; b) Potential voting rights held by the Group, other vote holders or other parties; c) Rights arising from other contractual arrangements; and d) Any additional facts and circumstances that indicate that the Group has, or does not have, the current ability to direct the relevant activities, at the time that decisions need to be made, including voting patterns at previous shareholders´ meetings. Subsidiaries are consolidated from the date on which control is obtained until the date that such control ceases. All inter-company assets and liabilities, equity, income, expenses and cash flows relating to transactions between entities of the Ecopetrol Business Group were eliminated on consolidation. Unrealized losses are also eliminated. Non-controlling interest represents the proportion of profit, other comprehensive income and net assets in subsidiaries that are not attributable to Ecopetrol shareholders. The following subsidiaries were incorporated in 2017: a) Esenttia Resinas del Perú SAC: b) ECP Hidrocarburos México S.A. de CV 2.3 Measurement basis The consolidated financial statements have been prepared on a historical cost basis, except for financial assets and liabilities that are measured at fair value through profit or loss and/or changes in other comprehensive income at the end of each reporting period, as explained in the accounting policies included below. Historical cost is generally based on fair value of the consideration given in exchange for goods and services. The fair value is the price that would be received from selling an asset or that would be paid for transferring a liability among market participants, in an orderly transaction, on the date of measurement. When estimating the fair value, the Ecopetrol Business Group uses assumptions that market participants would use for pricing an asset or liability at current market conditions, including risk assumptions. 2.4 Functional and presentation currency The consolidated financial statements are presented in Colombian Pesos, which is the Ecopetrol’s functional currency. For each Group entity its functional currency is determined based of the main economic environment where it operates. The statements of profit or loss and cash flows of subsidiaries with functional currencies different from Ecopetrol S.A.’s functional currency are translated at the exchange rates on the dates of the transaction or based on the monthly average exchange rate. Assets and liabilities are translated at the closing rate and other equity items are translated at exchange rates at the time of the transaction. All resulting exchange differences are recognized in other comprehensive income. On disposal of all or significant part of a foreign operation, the cumulative translation adjustment related to the particular foreign operation is reclassified to profit or loss. The financial statements are presented in Colombian pesos rounded up to the closest million unit (COP 000,000) except when otherwise indicated. 2.5 Foreign currency Transactions in foreign currencies are initially recorded by the Group’s entities at their respective functional currency spot rates at the transactions date. Monetary items denominated in foreign currencies are translated at the functional currency spot rates prevailing at the reporting date. Differences arising on settlement or translation or monetary items are recognized in profit or loss, in financial results, net, except those resulting from the conversion of loans and borrowings designated as cash flow hedges or net investment in a foreign operation hedge, which are recognized in other comprehensive income within equity. When the hedged item affects the financial results, exchange differences accumulated in equity are reclassified to profit or loss as part of operating results. Non-monetary items measured at fair value that are denominated in a foreign currency are translated using the exchange rates prevailing on the date when the fair value is determined. The gain or loss arising on translation of non-monetary items measured at fair value is treated in line with the recognition of the gain or loss on the change in fair value of the item. 2.6 Classification of assets and liabilities as current and non-current The Ecopetrol Business Group presents assets and liabilities in the consolidated statement of financial position based on whether assets are classified as current or non-current. An asset or liability is classified as current when: § It is expected to be sold or consumed in the ordinary course of business; § Held mainly for the purpose of trading; § Expected to mature in twelve months or less; and, § Cash or a cash equivalent, unless the exchange of such asset or liability is restricted or to be used to settle a liability more than twelve months after the reporting period; or § In the case of a liability, there is no unconditional right to defer settlement of the liability until at least twelve months after the reporting period. Other assets and liabilities are classified as non-current. Deferred tax assets and liabilities are classified as non-current assets and liabilities. 2.7 Earnings (loss) per share (basic and diluted) Basic earnings (loss) per share is calculated by dividing the profit for the year attributable to equity holders of Ecopetrol S.A., the parent company, by the weighted average number of ordinary shares outstanding during the year. There is no potential dilution of shares. 2.8 Reclassifications As of December 31, 2017, the Group changed the presentation of deferred tax assets and liabilities balances by offsetting deferred tax balances levied by the same taxation authority. As a result, the Group reclassified the corresponding amounts as of December 31, 2016 to conform them to the current year's presentation, which had an immaterial impact in the deferred tax assets and deferred tax liabilities line items as of December 31, 2016. In addition, such reclassifications did not have an impact in the statements of cash flows, profit or loss and changes in equity for the year ended December 31, 2016. See additional details in Note 10 - Taxes.

Significant estimates and accou

Significant estimates and accounting judgments	12 Months Ended
	Dec. 31, 2017
Disclosure of significant estimates and accounting judgments [Abstract]
Disclosure of accounting judgements and estimates [text block]	3. Significant estimates and accounting judgments The preparation of the consolidated financial statements requires management to make judgements, estimates and assumptions that affect the reported amounts of assets, liabilities, sales revenues, costs and commitments recognized in the financial statements and the accompanying disclosures. The Group based its assumptions and estimates on parameters available when the consolidated financial statements were prepared. Uncertainty about these assumptions and estimates could result in outcomes that required a material adjustment to the carrying amount of assets or liabilities affected in future periods. Changes in estimates are adjusted prospectively in the period in which the estimate is revised. In the process of applying the Group’s accounting policies, management has made the following judgments and estimates which have the most significant impact on the amounts recognized in the consolidated financial statements: 3.1 Oil and gas reserves Hydrocarbon reserves are estimates of the amount of hydrocarbons that can be economically and legally extracted from the Group’s oil and gas properties. The reserves estimation is conducted annually as of December 31 in accordance with the United States Securities and Exchange Commission (SEC) definitions and rules set forth in Rule 4-10(a) of SEC Regulation S-X and the disclosure guidelines contained in the SEC final rule - Modernization of Oil and Gas Reporting. As required by current regulations, the future estimated date on which a field will no longer produce for economic reasons, is based on actual costs and average of crude prices (calculated as the arithmetical average of prices on the first day of the past 12 months). The estimated date for end of production will affect the amount of reserves, unless the prices have been defined by contractual agreements; therefore, if the prices and costs change from one year to the other, the proved reserves estimate also changes. Generally, our proved reserves decrease as prices go down and increase when prices go up. Reserves estimation is an inherently complex process and it involves professional judgments. Reserves estimations are prepared using geological, technical and economic factors, including projections of future production rates, oil prices, engineering data and duration and amount of future investments, and they imply a certain degree of uncertainty. These estimations reflect the regulatory and market conditions existing on the date of reporting, which could significantly differ from other conditions during the year or in future periods. Any changes in regulatory and/or market conditions and assumptions could materially affect the reserves estimation. Impact of oil reserves and natural gas in depreciation and depletion Changes to estimations for proven developed reserves may affect the carrying amounts of exploration and production assets, natural resources and environment, goodwill, liabilities for dismantling and depreciation, depletion and amortization. With all other variables remaining unchanged, a decrease in estimated proven reserves would increase, prospectively, depreciation, depletion and amortization costs, while an increase in reserves would reduce depreciation and amortization expenses, as depreciation, depletion and amortization charges are calculated using the units of production method. Information about the carrying amounts of exploration and production assets and the amounts charged to income, including depreciation, depletion and amortization, is presented in Notes 15 and 16. 3.2 Asset impairment (recovery) Management uses its professional judgment in assessing the existence of evidence of an expense for (recovery of) impairment, based on internal and external factors. When an indicator of impairment or reversal of a prior periods impairment exists, the Group estimates the recoverable amount of the cash generating units (CGU), which is considered the greater of fair value less costs of disposal and the value in use. The assessments require the use of estimates and assumptions, such as, among other factors: (1) estimation of the volumes and market value of oil and natural gas reserves; (2) production profiles for oilfields and the future production of refined and chemical products; (3) investments, taxes and future costs; (4) useful life of assets; (5) long-term prices; (6) the discount rate, which is revised annually and determined as the weighted average cost of capital (WACC); and (7) changes in environmental regulation. The recoverable amount is compared to the carrying amount of the asset, thus determining whether the asset is impaired or if the impairment recognized in prior periods should be reversed. A previously recognized impairment loss is reversed only if there has been a change in the assumptions used to determine the assets or in the CGU’s recoverable amount since the last impairment loss was recognized. The reversal is limited so that the carrying amount of an asset or CGU, other than goodwill, does not exceed either its recoverable amount, or the carrying amount that would have been determined (net of amortization or depreciation) had no impairment loss been recognized for the asset or CGU in prior periods. Future oil price assumptions are estimated at current market conditions. Expected production volumes, which comprise proven and unproved reserves, are used for impairment testing because management believes this to be the most appropriate indicator of expected future cash flows, which would also be considered by market participants. Reserves estimates are inherently imprecise and subject to risk and uncertainty. Furthermore, projections about unproved volumes are based on information that is necessarily less robust than what is available for mature reservoirs. These estimates and assumptions are subject to risk and uncertainty. Therefore, there is a possibility that changes in circumstances will impact these projections, which may also impact the recoverable amount of assets and/or CGUs, hence, may also affect the recognition of an impairment loss or the reversal of prior period impairment amounts. 3.3 Exploration and evaluation costs The application of the Group’s accounting policy for exploration and evaluation costs requires judgment in order to determine whether future economic benefits are likely, either from future exploitation or sale, or whether activities have not reached a stage which permits a reasonable assessment of the existence of reserves. Certain exploration and evaluation costs are initially capitalized when it is expected that commercially viable reserves will result. The Group uses its professional judgment of future events and circumstances and makes estimates in order to annually assess the generation of future economic benefits for extracting oil resources, as well as technical and commercial analyses to confirm its intention of continuing their development. Changes regarding available information such as drilling success level or changes in the project's economics, production costs, and investment levels, as well as other factors, may result in capitalized exploration drilling costs being recognized in profit or loss for the period. The expenses for dry wells is included in operating activities in the consolidated statement of cash flows. 3.4 Determination of cash generating units (CGU) The allocation of assets in cash generating units requires significant judgment, as well as assessments regarding integration among assets, the existence of active markets, and similar exposure to market risk, shared infrastructure, and the way in which management monitors the operations. See Note 4.12 - Impairment of non-financial assets for more information. 3.5 Abandonment and dismantling costs of fields and other facilities According to environmental and oil regulations, the Group is required to bear the costs for the abandonment of oil extraction and transportation facilities, which include the cost of plugging and abandoning wells, dismantling facilities, and environmental remediation in the affected areas. Estimated abandonment and dismantling costs are recorded at the time of the installation of the assets and are reviewed annually. The calculations for these estimations are complex and involve significant judgments by Management. The ultimate decommissioning costs are uncertain and cost estimates can vary in response to many factors, including changes to relevant legal requirements, the emergence of new restoration techniques or experience at other production sites. The expected timing, extent and amount of expenditure may also change, for example, in response to changes in internal cost projections, changes in reserve estimates, future inflation rates and discount rates. The Group considers that the abandonment and dismantling costs are reasonable, based on the experience of the Group and market conditions; nevertheless, significant variations in external factors used for the calculation of the estimation could significantly impact the amounts recorded in the financial statements. 3.6 Pension plan and other benefits The determination of expenses, liabilities and adjustments relating to pension plans and other defined retirement benefits makes it necessary for management to use its judgment in the application of actuarial assumptions made in the actuarial calculation. The actuarial assumptions include estimates regarding future mortality, retirement, changes in compensation and discount rate in order to reflect the time value of money, in addition to the rate of return on the plan's assets. Due to the complexity in the valuation of these variables, as well as their long term nature, the estimated amounts are quite sensitive to any change in these assumptions. These assumptions are reviewed on an annual basis and may differ materially from actual results due to changes in economic and market conditions, regulatory changes, judicial rulings, higher or lower retirement rates, or longer or shorter life expectancies among employees. 3.7 Goodwill impairment In December of each year, the Group performs an annual impairment test on goodwill to assess if its carrying amount may be impaired. The determination of the recoverable amount is described in note 4.12 and its calculation requires assumptions and estimates. The Group considers that the assumptions and estimations used are reasonable and supportable based on the current market conditions and are aligned to the risk profile of the related assets. However, if different assumptions and estimations are used, they could lead to different results. Valuation models used to determine fair value are sensitive to changes in the underlying assumptions. For example, sales volumes and prices that will be paid for the purchase of raw materials are assumptions that may vary in the future. Adverse changes in any of these assumptions could lead to the recognition of goodwill impairment. 3.8 Litigation The Group is subject to claims relating to regulatory and arbitration proceedings, tax assessments and other claims arising in the normal course of business. Management evaluates these claims based on their nature, the likelihood that they materialize and the amounts involved, to decide on the amounts recognized and/or disclosed in the financial statements. This analysis, which may require considerable judgment, includes the assessment of current legal proceedings brought against the Group and claims not yet initiated. A provision is recognized when the Group has a present obligation derived from a past event, it is likely that an outflow of resources of economic benefits will be required to settle the obligation, and a reliable estimate of the amount of such obligation can be made. 3.9 Taxes Calculation of the income tax provision requires interpretation of tax law in the jurisdictions where the Ecopetrol Business Group operates. Significant judgment is required to determine estimates for income tax on taxable profits and to evaluate the recoverability of deferred tax assets, which are based on the ability to generate sufficient taxable income during the periods in which such deferred taxes could be used or deduct. To the extent that future cash flows and taxable income differ significantly from the estimates, the Group's ability to realize the deferred tax assets recorded could be affected. Furthermore, changes in tax rules could limit the capacity of the Group to obtain tax deductions in future years, as well as the recognition of new tax liabilities resulting from auditing conducted by the tax authorities. Tax positions taken involve a thorough assessment by Management, and are reviewed and adjusted in response to situations such as expiration in the applicability of laws, closing of tax audits, additional disclosures caused by any legal issue or a court decision relevant to a particular tax issue. The Group records provisions based on estimated potential liabilities that could be derived from a tax audit. The amount of these provisions depends on factors such as previous experience in tax audits and different interpretations of tax legislation. The actual results may differ from the estimates recorded. 3.10 Hedge accounting The process of identifying hedging relationships between hedged items and the underlying instruments (derivative and non-derivative such as long-term foreign currency-denominated debt), and their corresponding effectiveness, requires the use of judgment by management. The Group periodically monitors the alignment between its hedge instruments and its risk management policy.

Accounting policies

Accounting policies	12 Months Ended
	Dec. 31, 2017
Disclosure of accounting policies [Abstract]
Disclosure of significant accounting policies [text block]	4. Accounting policies The accounting policies indicated below have been applied consistently for all the periods presented. 4.1 Financial instruments The classification of financial instruments depends on the nature and purpose for which the financial assets or liabilities were acquired and is determined at the time of initial recognition. Financial assets and financial liabilities are initially measured at their fair value. Transaction costs that are directly attributable to the acquisition or issue of financial assets and financial liabilities (other than financial assets and financial liabilities at fair value through profit or loss) are added to or deducted from the fair value of the financial assets or financial liabilities, as appropriate, on initial recognition. Transaction costs directly attributable to the acquisition of financial assets or financial liabilities at fair value through profit or loss are recognized immediately in profit or loss. All financial assets are initially recorded at fair value. Loans and trade receivables, other receivables and financial assets held-to-maturity are measured subsequently measured at amortized cost using the effective interest method. Equity investments available for sale that do not have a market quotation price and for which fair value cannot be reliably measured are measured at cost less any impairment identified at the end of each reporting period. Measurements at fair value Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value measurement is based on the presumption that the transaction to sell the asset or transfer the liability takes place in the principal market of the asset or liability or in the absence of a principal market in the most advantageous market for the asset or liability. All assets and liabilities for which fair value is measured or disclosed in the financial statements are classified within the following scale based on the lowest level input that is significant to the fair value measurement as a whole, as follows: § Level 1: Quoted (unadjusted) market prices in active markets for identical assets or liabilities. The fair value of the Group’s marketable securities that a quoted market price is based on Level 1 inputs. § Level 2: Valuation techniques for which the lowest level input that is significant to the fair value measurement is directly or indirectly observed. Level 2 inputs include prices of similar assets, prices obtained through quotations made by stockbrokers, and prices that can be substantially corroborated with other observable data with the same contractual terms. For derivative contracts for which a quoted market price is not available, fair value estimations are generally determined using models and other valuation methods, the key inputs for which include future prices, volatility estimates, price correlation, counterparty credit risk and market liquidity, as appropriate. For other assets and liabilities, fair value estimations are generally based on the net present value of expected future cash. § Level 3: Valuation techniques for which the lowest level input that is significant to the fair value measurement is unobservable. The Group does not use Level-3 inputs for the measurement of financial assets and liabilities. The Group may use Level-3 inputs for the calculation the recoverable amount of certain non-financial assets for the purpose of impairment testing. Effective interest rate method The effective interest rate method is a method of calculating the amortized cost of a financial instrument and accounting of income or financial cost over the relevant period. The effective interest rate is the discount rate that exactly discounts estimated future cash receipts or payments (including all fees, transaction costs and other premiums or discounts) through the expected life of the financial instrument (or, when appropriate, at a shorter period), to the net carrying amount on initial recognition. Impairment The Group evaluates, on each reporting date, if there is objective evidence that a financial asset or group of financial assets are impaired. Financial assets are evaluated for the impairment indicators at the end of each reporting period. Financial assets are considered to be impaired when there is objective evidence that, as a result of one or more events that occurred after initial recognition, the estimated future cash flows of the asset have been affected. For financial assets measured at amortized cost, the amount of the impairment loss recognized is the difference between the asset’s carrying amount and the present value of estimated future cash flows, discounted at the financial asset’s original effective interest rate. De-recognition of financial assets Ecopetrol derecognizes a financial asset only upon the expiration of the contractual rights to the cash flows of the asset or, when it has transferred its rights to receive such cash flows or has assumed the obligation to pay the cash flows received in full without material delay to a third party and (a) it has transferred substantially all the risks and benefits inherent in the ownership of the financial asset or (b) it has neither transferred nor retained substantially all the risks and benefits of the asset, but has transferred control of the asset. When the Group does neither transfer nor retain substantially all the risks and benefits of the asset or transfer control of the asset, the Group continues to recognize the transferred asset, to the extent of its continuing participation, and it also recognizes the associated liability. 4.1.1 Cash and cash equivalents Cash and cash equivalents include cash on hand, financial investments that are highly liquid, bank deposits and special funds with original maturity dates of ninety days or less which are subject to an insignificant risk of changes in value. 4.1.2 Financial assets The Group classifies its financial assets in the following categories: a) Financial assets measured at fair value through profit or loss Financial assets at fair value through profit or loss are financial assets held for trading and financial assets designated at the time of the initial recognition at fair value through profit or loss. Financial assets are classified as held for trading if they are acquired to be sold or repurchased in the short term. They are recognized at their fair value and losses or profits arising at the time of re-measurement are recognized in the statement of profit or loss. b) Financial assets measured at fair value with changes in other comprehensive income These are equity instruments of other non-controlled and non-strategic companies not allowing for any type of control or significant influence thereon and where the Group’s management does not intend to negotiate with them in the short-term. These investments are recorded at their fair value and unrealized gains or losses are recognized in other comprehensive income and credited to the available for sale reserve until the investment is derecognized, at which time, the cumulative gain or loss is recognized in other operating income, or the investment is determined to be impaired, when the cumulative loss is reclassified from the available to sale reserve to the statement of profit or loss. c) Loans and receivables Loans to employees are initially recorded using the present value of the future cash flows, discounted at the current market rate for similar loans. If the interest rate is less than the current market rate, fair value will be less than the amount of the loan. This difference is recorded as a benefit to employees. 4.1.3 Financial liabilities Financial liabilities correspond to the financing obtained by the Group through bank credit facilities and bonds, accounts payable to suppliers and creditors. Bank credit facilities and bonds are initially recognized at their fair value, net of transactions cost. After initial recognition, interest-bearing credit facilities and bonds are subsequently measured at amortized cost, using the effective interest rate method. The effective interest method amortization is included as a financial expense in the statement of profit or loss. Accounts payable to suppliers and creditors are short-term financial liabilities recorded at nominal value, since it does not significantly differ from fair value. A financial liability is derecognized when the obligation specified in the corresponding contract is paid or expired. When an existing financial liability has been replaced by another from the same lender, under substantially different terms, or the terms of an existing liability are substantially modified, such modification is treated as the de-recognition of the original liability and recognized as a new liability. The difference between the respective carrying amounts is recognized in the statement of profit or loss. 4.1.4 Derivative financial instruments and hedging activities Financial derivative instruments are initially recognized in the statement of financial position as assets or liabilities and are measured at fair value on the date on which the derivative is recorded and subsequently measured at fair value. Changes in the fair value of derivatives are recognized as gains or losses in the statement of profit or loss, except for the effective portion of cash flow hedges, which is recognized in other comprehensive income and later reclassified to profit or loss when the hedge item affects profit or loss. Changes in fair value of derivative contracts, which do not qualify or are not designated as hedges, including forward contracts for the purchase and sale of commodities under negotiation for physical delivery or receipt of the commodity are recorded in profit or loss. Derivatives embedded in the host contract are accounted for as separate derivatives at fair value if their economic characteristics and risks are not closely related to those of the host contracts and the and the host contracts are not held for trading or designated at fair value through profit or loss. These embedded derivatives are measured at fair value with changes in fair value recognized in profit or loss. 4.1.5 Hedging operations For purposes of hedge accounting, hedges are classified as: § Fair value hedges, when hedging the exposure to changes in fair value of a recognized asset or liability, or unrecognized firm commitment, or an identifiable portion of such asset, liability or firm commitment. § Cash flow hedges when hedging the exposure to variability in cash flows that is either attributable to a particular risk associated with a recognized asset or liability or a highly probable forecast transaction. § Hedges of a net investment in a foreign operation. At the inception of the hedging relationship, the Group formally designates and documents the hedge relationship between the hedging instrument and the hedged item, together with its risk management objectives and strategy to perform hedging transactions. Such hedges are expected to be highly effective in achieving offsetting changes in fair value or cash flows and are; assessed on an ongoing basis to determine that they have been highly effective throughout the financial reporting periods for which they were designated. The effective portion of the gain or loss of the hedging instrument is recognized in other comprehensive income, while any ineffective portion is recognized in the consolidated statement of profit or loss, in the net financial results line item. The amounts previously recognized in other comprehensive income are transferred to profit or loss, when the hedged transaction affects profit or loss. When the hedged item is the cost of a non-financial asset or liability, the amounts previously recognized in other comprehensive income are transferred to the initial carrying amount of the non-financial asset or liability. If the hedging instrument expires or is sold, terminated or exercised without replacement or rollover, or if its designation as a hedge is revoked or when the hedge no longer meets the criteria for hedge accounting, any cumulative gain or loss previously recognized in other comprehensive income remains separately in equity until the forecast transaction occurs is recognized in the consolidated statement of profit or loss. When it is no longer expected that the initially hedged transaction will occur. Ecopetrol designates long-term loans as hedging instruments for its exposure to the exchange risk in future oil exports. See Note 30 for further information. Hedges of net investment in a foreign operation are accounted in a way similar to the cash flow hedges. Gains or losses on of the hedging instrument related to the effective portion of the hedge are recognized in other comprehensive income, while any gains or losses relating to the ineffective portion are recognized in the statement profit or loss. Cumulative gains or losses recorded in equity is transferred to the consolidated statement of profit or loss when the foreign operation is partially or totally disposed of. Ecopetrol allocates long-term loans as hedging instruments for its exposure to foreign exchange risk on its investment in subsidiaries whose functional currency is the U.S. dollar. See Note 30 for further information. 4.2 Inventories Inventories are stated at the lower of cost and net realizable value. Inventories mainly comprise crude oil, fuels and petrochemicals and consumable inventories (spares and supplies). The cost of crude oil is the production costs, including transportation costs. The cost required to bring the pipeline into working order, is treated as part of the related pipeline. The cost of other inventories is determined based on the weighted average cost method, which includes acquisition costs (deducting commercial discounts, rebates and other similar items), transformation, and other costs incurred to bring inventory to their current location and condition, such as transportation costs. Consumable inventories (spares and supplies) are recognized as inventory and then charged to expense, maintenance or project to the extent that such items are consumed. Ecopetrol estimates the net realizable value of inventories at the end of the period. When the circumstances that previously caused inventories to be written down below cost no longer exist, or when there is clear evidence of an increase in the net realizable value because of a change in economic circumstances, the amount of the write-down is reversed. The reversal cannot be greater than the amount of the original write-down, so that the new carrying amount will always be the lower of the cost and the revised net realizable value. 4.3 Related parties Related parties are considered those in which one party has the ability to control, or has joint control of the other, or exercises significant influence over the other party in making financial or operational decisions, or is a member of key management personnel (or close relative of a member). The Group considers related parties to be associates, joint ventures, key management executives, entities managing resources for payment of employee post-employment benefit plans and Colombian government entities for the purposes of certain relevant transactions, such as the purchase of hydrocarbons and the fuel price stabilization fund (see Note 4.16). 4.3.1 Investments in associates An associate is an entity over which the Ecopetrol Business Group has significant influence but not control. Significant influence is the power to participate in the financial and operational policy decisions of the investee, but it is not control or joint control over those policies. Generally, these entities are those in which the Group holds an equity interest with voting rights of 20 50 Investments in associates are accounted for using the equity method. Under this method, the investment in an associate is initially recognized at cost. The carrying amount of the investment is adjusted to recognize changes in the Group’s share of net assets of the associate since the acquisition date. Goodwill related to the associate is included in the carrying amount of the investment and is not tested for impairment separately. The Group's share of the results of operations of the associate is recognized in the consolidated statement of profit or loss. Any change in other comprehensive income is recognized in other comprehensive income of the Group. After application of the equity method, the Group determines if it is necessary to recognize an impairment on its investment in its associate. At each reporting date, the Group determines whether there is objective evidence that the investment is impaired. If there is such evidence, the amount of the impairment is calculated as the difference between the recoverable amount and its carrying value, and then the impairment is recognized in the consolidated statement of profit or loss. When necessary, the Group makes adjustments to the accounting policies of associates to ensure consistency with the policies adopted by the Group. Additionally, the equity method of these companies is measured on their most recent financial statements. 4.3.2 Joint ventures A joint venture is a type of joint arrangement whereby the parties that have joint control of the arrangement have rights to the net assets of the joint arrangement. Joint control exists only when decisions about the relevant activities require unanimous consent of the parties sharing such control. The accounting treatment for the recognition of joint ventures is the same as investments in associates. 4.4 Joint operations A joint operation is a type of joint arrangement whereby the parties that have joint control of the arrangement have rights to the assets and obligations for the liabilities, relating to the arrangement. Joint operation contracts are entered into between Ecopetrol and third parties to share risk, secure capital, maximize operating efficiency and optimize the recovery of reserves. In these joint operations, one party is designated as the operator to execute the operations and report to partners according to their participating interests. Likewise, each party takes its share of the produced hydrocarbons (crude oil or gas) according to their share in production. When Ecopetrol participates as a non-operator partner, it records the assets, liabilities, sales revenues, cost of sales and expenses based on the operator’s report. When Ecopetrol is the direct operator of joint venture contracts, it records its percentage of assets, liabilities, sales revenues, costs and expenses, based on the participation of each partner in the items corresponding to assets, liabilities, sales revenues, costs and expenses. When the Group acquires or increases its participation in a joint operation in which the activity constitutes a business combination, such transaction is recorded applying the acquisition method in accordance with IFRS 3 - Business combination. The acquisition cost is the sum of the consideration transferred, which corresponds to the fair value, on the date of acquisition of the assets transferred and the liabilities incurred. Any transaction cost related to the acquisition or increased share in the joint operation that constitutes a business combination is recognized in the consolidated statement of profit or loss. The excess of the sum of the consideration transferred and the amount paid in the operation is recognized as goodwill. If the result is in an excess value of the net assets acquired over the amount paid in the operation, the difference is recognized as income in the consolidated statement of profit or loss on the date of recognition of the transaction. 4.5 Non-current assets held for sale Non-current assets are classified as held for sale if their carrying values will be recovered principally through a sale transaction rather than through continued use. Non-current assets are classified as held for sale only when the sale is highly probable within one year from the classification date and the asset (or group of assets) is available for immediate sale in its present condition. These assets are measured at the lower of their carrying amount and fair value less related costs of disposal. See Note 13 for further information. 4.6 Property, plant and equipment Recognition and measurement Property, plant and equipment are stated at cost less accumulated depreciation and accumulated impairment losses. Tangible components related to natural and environmental resources are part of property, plant and equipment. The initial cost of an assets comprises its purchase price or construction cost, including import duties and non-refundable purchase taxes, any costs directly attributable to bringing the asset into operation, costs of employee benefits arising directly from the construction or acquisition, borrowing costs incurred that are attributable to the acquisition and construction of qualifying assets and the initial estimate of the costs of dismantling and abandonment of the item. Spare parts and servicing equipment are recorded as inventories and recognized as an expense as they are used. Major spare parts and stand-by equipment that the entity expects to use during more than one period are recognized as property, plant and equipment. Any gain or loss arising from the disposal of a property, plant and equipment is recognized in profit or loss of the period. Subsequent disbursements Subsequent disbursements correspond to all payments to be made on existing assets in order to increase or extend the initial expected useful life, increase productivity or productive efficiency, allow for significant reduction of operating costs, increase the level of reserves in exploration or production areas or replace a part or component of an asset that is considered critical for the operation. The costs of repair, conservation and maintenance of a day to day nature are expensed as incurred. However, disbursements related to major maintenance are capitalized. Depreciation Property, plant and equipment is depreciated using the straight-line method, except for those associated with exploration and production activities which are depreciated using the units-of-production method. Technical useful lives are updated annually considering factors such as: additions or improvements (due to parts replacement or critical components for the asset’s operation), technological advances, obsolescence and other factors; the effect of this change is recognized from the period in which it was executed. Depreciation of an asset starts when it is ready to be used. Useful lives are determined based on the period over which an asset is expected to be available for use, physical exhaustion, technical or commercial obsolescence and legal limits or restrictions over the use of the asset. The estimated useful life of assets fluctuates in the following ranges: Plant and equipment 15 - 65 years Pipelines, networks and lines 10 - 59 years Buildings 12 - 80 years Other 5 - 33 years Land is recorded separately from buildings and facilities and is not subject to depreciation. Depreciation methods and useful lives are reviewed annually and adjusted if appropriate Natural and environmental resources Recognition and measurement Ecopetrol uses the successful efforts method to account for exploration and production of crude oil and gas activities, following the provisions of IFRS 6 – Exploration for the evaluation of mineral resources. Exploration costs Acquisition and exploration costs are recorded as exploration and evaluation assets until the determination of whether the exploration drilling is successful or not; if determined to be unsuccessful, all costs incurred are recognized as expenses in the consolidated statement of profit or loss. Exploration costs are those incurred with the objective of identifying areas that are considered to have prospects of containing oil and gas reserves, including geological and geophysical, seismic costs, viability, and others, which are recognized as expenses when incurred. Furthermore, disbursements associated with the drilling of exploratory wells and those related to stratigraphic wells of an exploratory nature are charged as assets until it is determined if they are commercially viable; otherwise, they are expensed in the consolidated statement of profit or loss as dry wells expense. Other expenditures are recognized as expenses when incurred. An exploration and evaluation asset is no longer classified as such when the technical feasibility and commercial viability of extracting a mineral resource are demonstrable. Exploration and evaluation assets are reclassified to the natural and environmental resources account after being assessed for impairment. All capitalized costs are subjected to technical and commercial revisions at least once a year to confirm the evaluation and exploration efforts continue on the fields; otherwise, these costs are written off through to profit or loss. Exploration costs are net of the revenues obtained from the sale of crude oil during the extensive testing period, net of cost of sales, since they are considered necessary to complete the asset. Development costs Development costs correspond to those costs incurred to obtain access to proved reserves and to provide facilities for extracting, treating, gathering and storing. When a project is approved for development, the corresponding capitalized acquisition and exploration costs are classified as natural and environmental resources and costs subsequent to the exploration phase are capitalized as development costs of the properties that contain such natural resources. All development costs are capitalized, including drilling costs of unsuccessful development wells. Production costs Production costs are those incurred to operate and maintain productive wells, and are part of the corresponding equipment and facilities. Production activity includes extraction of oil and gas to the surface, its gathering, treatment and processing as well as storage in the field. Production costs are expenses recorded in the consolidated statement of profit or loss as incurred unless they add oil and gas reserves, in which case they are capitalized. Production and support equipment is recognized at cost and is part of property, plant and equipment subject to depreciation. Capitalized costs also include decommissioning, dismantling, retiring and restoration costs, as well as the estimated cost of future environmental obligations. The estimation includes plugging and abandonment costs, facility dismantling and environmental recovery of areas and wells. Changes arising in new abandonment liability estimations and environmental remediation are capitalized in the carrying amount of the related asset. Depletion Depletion of natural and environmental resources is determined using the unit-of-production method per field, using proved developed reserves as a base, except in limited exceptional cases that require greater judgment by Management to determine a better amortization factor of future economic benefits over the useful life of the asset. Depreciation rates are reviewed annually, based on reserves reports and the impact of any changes is recognized prospectively in the financial statements. Reserves are audited by internationally recognized external consultants and approved by the Company’s Board of Directors. Proved reserves consist of the estimated quantities of crude oil and natural gas demonstrated with reasonable certainty by geological and engineering data to be recoverable in future years from known reserves under existing economic and operating conditions, that is, at the prices and costs that apply at the date of the estimation. Impairment Assets associated to exploration, evaluation and production are subject to review for possible impairment in their carrying amount. See notes 3.2 – Asset impairment (recovery) and 4.12 - Impairment of non-financial assets. 4.8 Capitalization of borrowing costs Borrowing costs related to the acquisition, construction or production of a qualifying asset that requires a substantial period of time to get ready for its intended use are capitalized as part of the cost of such asset when it is probable that future economic benefits associated with the item will flow to the Group and costs can be measured reliably. Other borrowing costs are recognized as finance costs. Projects that have been suspended but that the Group intends to continue to pursue their development in the future, are not considered qualifying assets for the purpose of capitalization of borrowing costs. 4.9 Intangible assets Intangible assets with a defined useful life, are stated at cost less accumulated amortization and any impairment loss. Intangible assets are amortized under the straight-line method, over their estimated useful lives. The estimated useful lives and amortization method are revised at the end of each reporting period; any change in estimates is recognized on a prospective basis. The disbursements in relation to research activities are expensed as incurred. 4.10 Goodwill Goodwill is initially measured at cost (being the excess of the aggregate of the consideration transferred and the amount recognized for non-controlling interest and any previous interest held over the net identifiable assets acquired and liabilities assumed). After initial recognition goodwill is measured at cost less any accumulated impairment loss. Goodwill is not amortized but tested for impairment annually. 4.11 Leases Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards of ownership. All other leases are classified as operating leases. Assets held under finance leases, when Ecopetrol is the lessee, are recognized in the consolidated statement of financial position at an amount equal to the fair value of the leased asset or, if lower, the present value of the minimum lease payment. These assets are depreciated over the asset's useful life. When there is no reasonable certainty that the company will obtain ownership of the asset at the end of the contract, the leased assets are depreciated in the shortest period between the asset estimated useful life and the lease term. The corresponding liability to the lessor is included in the consolidated statement of financial position as a finance lease obligation, in the loans and financing line item. Lease payments are apportioned between financial charges and reduction of lease liabilities in order to achieve a constant rate of interest on the liability remaining balance. Interest expense is recognized in profit or loss. Operating lease payments are recognized as an expense on a straight-line basis over the lease term, except where another systematic prorating basis is more representative of the time pattern of economic benefits from the lease. Contingent rentals arising under operating leases are recognized as an expense in the period in which they are incurred. 4.12 Impairment of non-financial assets In order to evaluate if any tangible or intangible assets are impaired, Ecopetrol compares its carrying amount with its recoverable amount at the end of each reporting period or earlier, if there is any indicator that an asset may be impaired. For purposes of impairment testing, the assets are grouped into cash generating units (CGU), provided that those assets individually considered do not generate cash inflows that, to a greater extent, are independent from those generated by other assets or CGUs. The group of assets in different CGUs requires the exercise of professional judgment and the consideration, among other parameters, of the business segments. In this sense, in the Exploration and Production segment, each CGU corresponds to each one of the different contractual areas commonly called “fields”; by exception, in those cases where the cash inflows generated by several fields are interdependent from each other, those fields are grouped into a single CGU. In the case of the Refining and Petrochemicals segment, each CGUs corresponds to each one of the refineries of the Ecopetrol Business Group and for the Transportation segment; each pipeline is taken as an independent CGU. The recoverable amount of the asset is the higher amount of the fair value less costs of disposal or its value in use. If the recoverable amount of an asset (or of a CGU) is lower than its net carrying amount, such amount (or that of the CGU) is reduced to its recoverable amount, recognizing

New accounting standards and re

New accounting standards and regulatory changes	12 Months Ended
	Dec. 31, 2017
Disclosure of new standards issued by the IASB [Abstract]
Disclosure of expected impact of initial application of new standards or interpretations [text block]	5. New accounting standards and regulatory changes Ecopetrol adopted for the first time the following amendments to the IFRS issued by the IASB, applicable for the period covered by this report: § Amendments to IAS 7 statement of cash flows - Disclosure initiative: requires entities to disclose changes in their liabilities arising from financing activities, including those arising from cash and non-cash flows (including, among others, the effect of fluctuations in the Colombian peso-U.S. dollar exchange rate). The adoption of the amendments to IAS 7 had no impact on the amounts recognized in the financial statements. The Group provides the information for the current period and the comparative period, required by this standard in Note 20 - Loans and borrowings. The following accounting standards will become effective in future periods and are being implemented and /or assessed: § IFRS 9 "Financial instruments" replaced IAS 39 "Financial Instruments: Recognition and Measurement" and entered into force for annual periods beginning on January 1, 2018. IFRS 9 includes standards on: 1) the classification and measurement of financial assets and liabilities, 2) impairment of financial assets, and 3) hedge accounting. Ecopetrol will apply In relation to classification and measurement, the Group made and assessment on its financial assets and liabilities and concluded that: a) the valuation of financial assets and liabilities measured at amortized cost is consistent with the Group’s business model, which seeks to pay or receive cash flows at a certain moment; b) the amortized cost valuation method does not apply to short-term accounts payable and receivables, as they do not have an associated interest rate and their settlement is less than one year; and c) investment portfolios and financial derivatives continue to be measured at fair value with changes in fair value through profit or loss, in compliance with their function within the Group’s business model. Based on the aforementioned evaluations, the current classification of the Group's financial instruments is consistent with its business model and no significant change to the current accounting is expected. With respect to the impairment assessment model applied to financial assets valued at amortized cost, Management believes that the adoption of IFRS 9 will not result in any impact, taking into account processes executed to monitor credit risk, knowledge prior to the financial situation of the counterparties with which transactions are made, and the quality of the portfolio. Finally, with respect to the hedging accounting model, as an accounting policy, the Group decided to continue applying the guidance of IAS 39 for existing operations. Should Ecopetrol decide to establish new hedges, the requirements of IFRS 9 will be assessed to establish the relationship of those hedges to and their alignment with risk management objectives, as well as the qualitative and quantitative components to be considered for effectiveness of the assessment. § IFRS 15 "Revenue from ordinary activities in contracts with customers" provides a five-step model to account revenue arising from contracts with customers, focusing on the identification and fulfillment of performance obligations. IFRS 15 replaces IAS 18 "Revenue" and is effective for annual periods beginning on or after January 1, 2018. According to the new standard, revenues are recognized when performance obligations are satisfied and there is no indication that the price or variable consideration are not measurable or realizable. Likewise, the recognition of revenue is observed when the client obtains control of the goods or services offered in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. The standard also contains presentation and disclosure requirements that are more detailed than those defined by IAS 18, which represents an increase in the volume of disclosures required in the financial statements. The Ecopetrol Business Group will apply this standard on January 1, 2018, using the modified retrospective method, which allows adjusting the calculated impacts within equity, at the date of initial application, without adjusting the comparative years. Management estimates that the adoption of the new standard will not have a material effect; nevertheless, the adoption will required the implementation of new internal controls, changes in accounting procedures and policies to allow documentation on the adoption of the standard and its future application. During the process of implementing IFRS 15, sources of ordinary income were assessed, considering the identification of contracts with customers, performance obligations, the determination of transaction prices, the association of prices with performance obligations, and the recognition of income when such obligations are fulfilled. The analysis included the following aspects by segment: Exploration and production : Revenues in this segment correspond to the sale of oil and natural gas. The Group assessed the following: agreements with partners in joint operations, long-term contracts, over and underlifting, production, royalties, role of principal and agent, purchase and sale agreements, take-or-pay agreements and variable price components. No significant impacts were identified for the recognition, measurement or presentation of revenue in this segment. The Group assessed whether the operating partner in a joint operation can have a contract with another non-operator partner to market and sell the non-operator product to a third party. The analysis included whether one of the parties acts as principal or agent in the agreement. The operator evaluates whether it records gross income based on total production or net income based on its net operating interest. The non-operator evaluates the moment of revenue recognition. The Ecopetrol Business Group does not maintain significant agreements with non-operating partners whereby it assumes the role of agent. Transport and Logistics : Revenues in this segment correspond to the income from transport, storage and wholesale commercialization of crude or refined products derived from petroleum either by pipeline, rail, barge or truck. Pipelines and other transportation systems can be used to move crude oil from production sites to refineries and deliver the various refined products to fuel distributors. The main aspects evaluated are ship or pay and ship and pay contracts, variable price components and deposit agreements. The Ecopetrol Business Group has evaluated the performance obligations established in the provision of service, noting that there are no conditions with effects on the variable price related to volumetric adjustments or other contractual conditions that prevent recognition of income. Take-or-pay contracts No significant impacts were identified for recognition, measurement or reporting of revenue for this segment. Refining, Petrochemicals and Biofuels For each of these segments, income is recognized when the goods or services have been delivered to customers at the established delivery points (when the performance obligation is fulfilled), whereby the transfer of the goods takes place and the risks associated with the products have been accepted by customers. Regarding the agent and principal structure, as part of the process of selling products or services, the Ecopetrol Business Group enters into contracts to acquire, on behalf of the customer, other products or provide services. Under these contracts, the Ecopetrol Business Group is considered as the entity responsible for fulfilling the specific performance obligation. In some cases an inventory risk is not maintained before or after having sold the good or rendered the service. The Ecopetrol Business Group has assessed the impact on recognition in both cases and does not expect significant effects in the adoption of the new standard. As a result of the analysis of these segments, it was concluded that: a) for contracts with several performance obligations, the Group concluded that such contracts are interdependent; therefore, the prices assigned are not independent and the application of a pricing methodology was not required; b) the Ecopetrol Business Group acts as principal in its transactions where it controls assets before transferring them to a client; c) the Group recognizes variable considerations in transaction prices unless they cannot be reliably measured, in which case the recognition is deferred until the uncertainty is resolved; d) the product's method is used by the Group to recognize income from long-term contracts with partial deliveries of goods; e) no effects associated with contract costs were identified when they were recognized in the accounting period and capitalization of the costs is not required; and, f) non-monetary agreements are recognized at fair value. § IFRS 16 "Leases" provides a new model for a lessee's accounting, according to which all leases, other than those of short-term and with small amounts, will be recognized in the balance sheet, as an asset (right of use) and a liability (financial lease) and in the statement of profit or loss, the respective amortization of the right of use during the term of the lease. IFRS 16 will be effective for annual periods beginning on or after January 1, 2019, with limited possibilities for early implementation. IFRS 16 replaces the current IAS 17 "Leases" and IFRIC 4 "Determination of whether an agreement contains a lease". IFRS 16 "Leases" contains a new model for the identification of leases and their treatment in the financial statements for lessees. As a result of its implementation, oil and gas companies could recognize more assets and liabilities, mainly derived from the rental of drilling equipment and offices. Ecopetrol has completed its initial assessment and started an action plan for its implementation. The Group will continue to perform a more detailed analysis of the potential impact on the financial statements from the adoption of IFRS 16 and does not expect to adopt it in advance. § Amendments to IFRS 10 and IAS 28: Asset sale or contribution between an investor and its associate or joint venture. The amendments address the conflict between IFRS 10 and IAS 28 as to the treatment of control loss of a subsidiary that is sold or contributed to an associate or joint venture. The amendments clarify that the gain or loss resulting from the asset sale or contribution that constitutes a business, as defined in IFRS 3, between the investor and its associate or joint venture, is recognized in its entirety. However, any gain or loss resulting from an asset sale or contribution that is not a business, is recognized only up to the interests of investors who are not related to the associate or joint venture. The IASB has deferred the effective date of these amendments indefinitely, but an entity that early adopts it must apply them prospectively. § Annual Improvements to IFRS Standards 2014-2016 cycle: Modifications to the following standards: - IFRS 12: The interpretation clarifies the scope of the standard by specifying that disclosure requirements in the standard, except those listed in paragraphs B10 to B16, apply to the interests of an entity listed in paragraph 5 (subsidiaries, joint arrangements, associates and non-consolidated structured entities), which are classified as held for sale or discontinued operations in accordance with IFRS 5. - IFRIC 22 Transactions in foreign currency and early consideration: The interpretation deals with transactions in foreign currency where: § There is a consideration that is denominated in foreign currency; § The entity recognizes an asset for early payment or a deferred tax liability with respect to such consideration, before the recognition of the related asset, expense or income; and § The asset for said advance or deferred tax liability is not monetary. The Interpretations Committee reached the following conclusions: § The date of the transaction, in order to determine the exchange rate, is the date of the initial recognition of the non-monetary advance or deferred tax liability. § If there are several payments received in advance, a transaction date is established for each payment. These new accounting policies are subject to change until the Group presents its first financial statements on the initial application date.

Cash and cash equivalents

Cash and cash equivalents	12 Months Ended
	Dec. 31, 2017
Disclosure of cash and cash equivalents [Abstract]
Disclosure of cash and cash equivalents [text block]	6. Cash and cash equivalents 2017 2016 Banks 5,484,981 3,319,465 Short-term investments 2,459,438 5,090,048 Cash 1,466 954 7,945,885 8,410,467 As of December 31, 2017, cash and cash equivalents balance included COP $ 96,758 114,206 The fair value of cash and cash equivalents approximates their book value due to their short-term nature. The return on cash and cash equivalents for the year ended December 31, 2017 was approximately 4.2 3.5 Rating 2017 2016 AAA 2,807,170 3,198,394 A1 2,922,714 1,466,015 BRC1 + 1,152,593 312,290 F1 896,231 545,872 Aa3 99,029 - Aa2 27,868 - A-2 27,350 - No rating available 12,750 67,185 F2 180 409,717 A1+ - 73,470 F1+ - 2,188,471 Prime-2 - 78,989 F3 - 37,172 Prime-3 - 32,748 B - 144 7,945,885 8,410,467 See credit risk policy in Note 30.3.

Trade and other receivables, ne

Trade and other receivables, net	12 Months Ended
	Dec. 31, 2017
Disclosure of trade and other receivables, net [Abstract]
Disclosure of trade and other receivables [text block]	7. Trade and other receivables, net 2017 2016 Current Customers Foreign 2,052,829 1,366,322 Domestic 1,533,058 1,180,577 Fuel price stabilization fund (1) 2,256,312 1,203,811 Related parties (Note 31) 23,013 97,730 Industrial services 26,223 60,025 Accounts receivable from employees (2) 34,461 42,407 Other 173,022 261,829 6,098,918 4,212,701 Non-current Accounts receivable from employees (2) 484,504 425,468 Related parties (Note 31) 154,810 170,121 Fuel price stabilization fund (1) 77,510 77,510 Other 60,308 56,311 777,132 729,410 (1) Accounts receivable from the Ministry of Finance and Public Credit, arising from the differences between the international parity price of regular motor gasoline and diesel and the prices charged by the Group, in accordance with Resolution 180522 issued on March 29, 2010, as amended. The Ministry of Finance and Public Credit actually settles the payments. (2) Ecopetrol transferred the administration, management and control of loans granted to employees to Cavipetrol (“Corporación de los trabajadores de la Empresa Colombiana de Petróleos Ecopetrol S.A.”). 2017 2016 Opening balance 144,329 160,406 Additions of allowances, net 35,229 19,438 Accounts receivable write-off and uses (9,542) (35,515) Closing balance 170,016 144,329

Inventories, net

Inventories, net	12 Months Ended
	Dec. 31, 2017
Disclosure of Inventories, net [Abstract]
Disclosure of inventories [text block]	8. Inventories, net 2017 2016 Crude oil 1,836,363 1,557,267 Fuels and petrochemicals 1,481,777 1,270,870 Materials for the production of goods 1,283,256 1,013,764 4,601,396 3,841,901 2017 2016 Opening balance 265,435 198,539 Additions 9,134 41,957 Foreign currency translation (4,266) 50,053 Uses (75,796) (25,114) Closing balance 194,507 265,435

Other financial assets

Other financial assets	12 Months Ended
	Dec. 31, 2017
Disclosure of Other financial assets [Abstract]
Disclosure of financial assets [text block]	9. Other financial assets 2017 2016 Assets measured at fair value through profit or loss Investment Portfolio - Local currency 3,310,338 2,519,311 Investment Portfolio - Foreign currency 3,194,287 4,116,987 6,504,625 6,636,298 Assets measured at amortized cost 3,636 4,152 Hedging instruments 25,464 46,445 Total 6,533,725 6,686,895 Current 2,967,878 5,315,537 Non-current 3,565,847 1,371,358 6,533,725 6,686,895 The average return of the investment portfolio in Colombian pesos and U.S. dollars was 7.4 8.1 1.1 0.8 Changes in fair value are recognized in financial result (Note 29). 9.1 Restrictions As of December 31, 2017 and 2016, there were no investment with a restricted use. On November 6, 2016, through the Ministries of Mines and Energy and Finance and Public Credit, the termination of Ecopetrol's sequester status in the process of nullity and re-establishment of rights filed against the Comuneros de Santiago de las Atalayas was confirmed. In view of the foregoing, the restricted assets related to this case were released Ecopetrol (see Note 23.3 – Comuneros – Santiago de las Atalayas provisions, for further information). 9.2 Maturity 2017 2016 Up to 1 year 2,967,878 5,315,537 1-2 years 1,588,145 838,786 2-5 years 1,817,558 497,204 > 5 years 160,144 35,368 6,533,725 6,686,895 9.3 Fair value 2017 2016 Level 1 317,912 25,066 Level 2 6,186,713 6,611,232 6,504,625 6,636,298 There were no transfers between hierarchy levels for the years ended December 31, 2017 and 2016. The securities comprising Ecopetrol's portfolio are valued on a daily basis according to the instructions issued by the Financial Superintendence of Colombia. To this end, the information provided by authorized entities is used, which includes data from active markets. For cases in which market data is not available, other directly or indirectly observable data is used. For U.S. dollar-denominated investments, fair value is based on information released by Bloomberg while for investments denominated in Colombian pesos, fair value is provided by Infovalmer, an entity authorized by the Financial Superintendence of Colombia to provide this service. Within the investment hierarchy process, in addition to the information used for the valuation, other relevant aspects are taken into account, such as the issuer’s rating, investment rating, and the risk analysis of the issuer performed by Ecopetrol, which makes it possible to establish the appropriate hierarchy level for investments. 9.4 Credit rating Rating 2017 2016 AAA 3,175,727 1,858,665 A1 1,149,606 3,060,660 AA+ 1,067,989 50,192 BBB- 378,939 - A 300,179 - AA- 233,668 3,730 A+ 175,767 - BBB 21,835 - AA - 5,289 F1+ - 1,636,039 No rating available 915 21,723 6,504,625 6,636,298 See credit risk policy in Note 30.3

Taxes

Taxes	12 Months Ended
	Dec. 31, 2017
Disclosure Of Taxes [Abstract]
Disclosure of income tax [text block]	10. Taxes 10.1 Current tax assets and liabilities 2017 2016 Current tax assets Income tax (1) 165,437 308,868 Credit tax balance (2) 234,410 598,140 Other taxes 225,527 222,090 Total 625,374 1,129,098 Current tax liabilities Income tax (1) 1,305,011 1,478,294 National tax and surcharge on gasoline 136,706 324,402 Carbon tax 51,383 - Other taxes (3) 512,588 328,244 Total 2,005,688 2,130,940 (1) Corresponds to the resulting value after subtracting advanced tax payments, favorable balances and advance payments settled in the previous year's statement. The main variation compared to the previous period corresponds to the decrease in non-deductible expenses, and the effects of the tax reform on issues such as depreciation and exchange difference. (2) Includes mainly the value added tax (VAT) receivable balance. (3) Mainly includes VAT payable balances and industry and commerce tax. 10.2 Income tax a) The income tax rate will be 34 33 b) A surtax was established on income tax for 2017 and 2018, of 6 4 c) Companies located in a free trade zone are taxed at a rate of 20 15 d) Presumptive income will be calculated by applying a 3.5 stabilized rate for the calculation of presumptive income will continue to 3 e) For fiscal year 2017, the Ecopetrol Business Group has companies that are subject to a 40 15 20 f) Aligns the tax depreciation systems to accounting depreciation and establishes a limit to the annual depreciation deductible amount based on the table established in the tax reform. Tax amortization of oil and gas investments is calculated based on the technical production unit method which is aligned with accounting amortization. g) The cost of acquisition of exploration rights, G &; G, exploratory drilling, etc., is capitalized for tax purposes until the technical and commercial feasibility of extracting the resource is achieved. h) Accumulated tax loss balance generated starting January 1, 2017 can be offset with the liquid income generated over the following 12 years (unlimited for those with CEJ). i) For the period January 1, 2013 through December 31, 2016, taxable income in Colombia was subject to a 25 9 10 15 3 On December 23, 2014, through Law 1739, a surtax on income for equality - CREE was established for the years 2015, 2016, 2017 and 2018, which is applicable entities with taxable income above COP$ 800 5 6 8 9 For taxable year 2016, the Ecopetrol Business Group had companies subject to a 40 15 j) As of December 31, 2017 and 2016, Refinería de Cartagena, Bioenergy, and Ecopetrol Costa Afuera S.A.S., subsidiaries, have accrued accumulated tax losses that can be offset with future taxable income of COP$4,288,957 and COP$ 3,352,216, respectively, originated between 2009 and 2017. As per current tax legislation, accumulated tax losses accrued starting fiscal year 2007 can be offset, or tax adjusted, at any time, against taxable income without prejudice of the periods in which the entity was subject to the presumptive income regime. Accumulated tax losses cannot be transferred to its shareholders. However, in accordance with Article 290 of Law 1819 of 2016, the unused accumulated tax losses through December 31, 2016, can be offset based on a formula contained in that article. As of December 31, 2017, deferred tax assets related to unused accumulated tax losses, which do not expire, amounted to COP$ 611,766 The assessment of the accumulated tax losses related to companies Ecopetrol Costa Afuera S.A.S., Bioenergy and Bioenergy Zona Franca with respect to deferred tax is mentioned in this note under the chapter titled "Deferred Income Tax". In accordance with Article 290 of Law 1819 of 2016, the unused presumptive income surplus and minimal base surplus generated before 2017 on income tax and CREE can be used based on a formula contained in said Article and subject to the terms established in Article 189 of the Tax Code. Statute of limitations of review for tax returns Tax returns may be reviewed by the tax authorities within 5 years following the filing date and/or amendment, if the returns reflected tax losses. As of the year 2017, the statute of limitations covering tax returns will be 3 years as of the date of expiration or as of the filing date, when these have been filed extemporaneously. With respect to transfer pricing, the statute of limitations will be 6 years. With respect to tax returns with favorable balances, the statute of limitations will be 3 years as of the filing date of the request for devolution or offsetting. With regard to tax returns in which tax losses are offset, these will be considered determined after 6 years counted as of their filing date. With respect to tax returns where tax losses are calculated, the statute of limitations will be 12 years and if the losses are offset within the last 2 years of the 12-year period, the statute of limitations will be extended up to 3 additional years from the year of offsetting. Income tax expense 2017 2016 2015 Current income tax 5,144,962 4,517,336 3,510,546 Adjustments to prior years’ tax (68,270) - - Deferred income tax 723,576 25,710 (2,800,193) Income tax expenses 5,800,268 4,543,046 710,353 Reconciliation of the income tax expenses 2017 2016 2015 Net income (loss) before income tax 13,769,662 7,790,526 (5,578,626) Statutory rate 40 % 40 % 39 % Income tax at statutory rate 5,507,865 3,116,210 (2,175,664) ETR reconciliation items: Effect in changes in tax rates and tax base (CREE tax) 910 807,989 2,063,782 Non-deductible wealth tax 85,872 229,375 253,422 Foreign currency translation and exchange difference (186,787) (234,316) 310,657 Prior year taxes 274,777 140,630 (21,233) Non-deductible expenses 129,531 486,300 251,246 Valuation of investments - - 48,129 Non-taxable income (11,900) (3,142) (19,986) Income tax calculated 5,800,268 4,543,046 710,353 Current 5,076,692 4,517,336 3,510,546 Deferred 723,576 25,710 (2,800,193) 5,800,268 4,543,046 710,353 The effective tax rate (ETR) as of December 31, 2017 was 42.1 58.3 Income and supplementary tax returns for taxable years 2011, 2012, 2014, 2015 and 2016, and CREE returns for taxable years 2014, 2015 and 2016 of the Ecopetrol Business Group are subject to acceptance and review by the tax authorities. Management of the Ecopetrol Business Group companies considers that the amounts accounted as liability for payable taxes are sufficient and are supported by current regulations, doctrine and case law applicable to any claim that could be eventually filed with respect to such years. The Group's strategy is not making tax decisions based on aggressive or less-assured positions that could put into question its tax returns. Deferred income tax 2017 2016 Deferred tax assets 4,016,161 4,248,014 Deferred tax liabilities (1,333,280) (1,639,703) Net deferred income tax 2,682,881 2,608,311 2017 2016 Deferred tax assets (liabilities) Provisions (3) 1,840,988 1,875,965 Employee benefits (2) 1,373,561 656,997 Loss carry forwards 611,766 477,808 Accounts payable 208,618 311,607 Accounts receivable 94,864 133,840 Property plant and equipment and Natural and environmental resources (1) (1,006,299) (220,315) Goodwill (408,932) (345,288) Borrowings and other financial liabilities - (113,497) Others (31,685) (168,806) 2,682,881 2,608,311 Deferred tax assets 4,016,161 4,248,014 Deferred tax liabilities (1,333,280) (1,639,703) 2,682,881 2,608,311 (1) For tax purposes, natural and environmental resources and property, plant and equipment have a useful life and a depreciation and amortization calculation methodology different from those determined as per international accounting standards. (2) Actuarial calculations for health, retirement pensions, education, pension bonds and other benefits to long-term employees. (3) The most representative item corresponds to the provision for well abandonment. The table above takes into consideration the offsetting of deferred tax assets and deferred tax liabilities within the same tax jurisdiction. The overall deferred tax position in a particular tax jurisdiction determines if a deferred tax balance is presented within deferred tax assets or deferred tax liabilities. Accordingly, certain deferred tax assets are presented within deferred tax liabilities, and certain deferred tax liabilities within deferred tax assets. Property Provisions Employee Loss Accounts As of December 31, 2015 205,499 1,824,844 - 238,193 726,256 Recognized in profit or loss (425,814) 51,121 40,300 239,615 (414,649) Recognized in OCI - 0 616,697 - - As of December 31, 2016 (220,315) 1,875,965 656,997 477,808 311,607 Recognized in profit or loss (785,984) (34,977) (22,818) 133,958 (102,989) Recognized in OCI - - 739,382 - - As of December 31, 2017 (1,006,299) 1,840,988 1,373,561 611,766 208,618 Goodwill Borrowings Accounts Others Total As of December 31, 2015 (262,290) (540,811) 17,927 3,804 2,213,422 Recognized in profit or loss (82,998) 427,314 115,913 23,488 (25,710) Recognized in OCI - - - (196,098) 420,599 As of December 31, 2016 (345,288) (113,497) 133,840 (168,806) 2,608,311 Recognized in profit or loss (63,644) 113,497 (38,976) 78,357 (723,576) Recognized in OCI - - - 58,764 798,146 As of December 31, 2017 (408,932) - 94,864 (31,685) 2,682,881 The Ecopetrol Business Group offsets assets and liabilities for deferred taxes only if it has a legally enforceable right to offset current tax liabilities and assets; and in the case of deferred tax on assets and liabilities, to the extent that they also correspond to income taxes required by the same tax jurisdiction and the same tax authority. Pursuant to current tax law, losses generated in income and supplementary taxes and/or income tax for equality - CREE before 2017, must be offset with the net income obtained in 2017 and subsequent periods, taking into account the formula set forth in Section 5, Article 290 of Law 1819 of 2016. Tax losses determined must not be tax readjusted. As of the tax year 2017, companies can offset tax losses obtained in the current period defined, with taxable income generated through the next 12 taxable periods, following the attainment of said tax losses, without prejudice of the period's presumptive income. Deferred tax assets related to tax losses generated by Bioenergy S.A. and Bioenergy Zona Franca in the amount of COP$( 53,328 44,475 If the Group would have recognized the deferred tax assets that were not recognized, the income for the period ended on December 31, 2017, would have increased by COP$ 97,803 In accordance with tax provisions applicable until December 31, 2016, the surplus of presumptive income and the minimum base generated before 2017 in income and supplementary taxes and in the income tax for equality - CREE, respectively, can be offset with ordinary net income obtained by the Group in the next five years, using for such purpose the formula set forth in Section 6, Article 290 of Law 1819 of 2016. 2017 2016 Opening balance 2,608,311 2,213,422 Deferred tax recognized in profit or loss (723,576) (25,710) Deferred tax recognized in other comprehensive income (a) 798,146 420,599 Closing balance 2,682,881 2,608,311 (a) December 31, 2017 Pre-tax Deferred After tax Actuarial valuation gains (losses) 2,251,656 (739,382) 1,512,274 Cash flow coverage for crude exports 80,896 (54,056) 26,840 Other 12,119 (4,708) 7,411 2,344,671 (798,146) 1,546,525 December 31, 2016 Pre-tax Deferred After tax Actuarial valuation gains (losses) 1,770,139 (616,697) 1,153,442 Cash flow hedging for future crude oil exports (537,353) 220,596 (316,757) Derivative financial instruments (56,804) 22,722 (34,082) Other - (47,220) (47,220) 1,175,982 (420,599) 755,383 Deferred tax assets (liabilities) not recognized As of December 31, 2017, deferred tax assets (liabilities) are not recognized in the difference between the accounting and tax bases related to investments in companies of the Ecopetrol Business Group, as there is no intention to sell any of these investments in the foreseeable future. 10.3 Other taxes 10.3.1 Tax on dividends The new tax on dividends will be applicable to foreign companies and entities on profits generated starting 2017. The rate of this tax will be 5%. Furthermore, the tax rate for dividends will be 35%. In this scenario, the 5% tax on dividends will apply to the amount of the tax distribution, once it has been reduced with the 35% income tax. For taxed individuals residing in Colombia, the tax on dividends will have a maximum 10% rate that will be applied on non-taxed dividends, and 35% with respect to taxed dividends distributed. There are no effects on income tax related to dividend payments made by the Group to its shareholders during 2017 and 2016. 10.3.2 Transfer prices Income tax payers carrying out operations with related parties abroad or located in free trade zones or companies located in countries considered tax havens, must determine their ordinary and extraordinary revenues, costs and deductions, considering the arm's length principle for such transactions. Such companies submitted their transfer-pricing information statement for the 2016 tax year and their respective supporting documents. For the 2017 tax year, the transactions performed with related parties abroad, as well as the business conditions for such operations and their general structure, did not vary significantly as compared with the previous year. Therefore, it can be inferred that said transactions were performed in accordance with the arm's length principle. It is estimated that no adjustments will be required from the analysis of transfer prices in 2017, which entail amendments of the income provision of taxable year 2017. 10.3.3 Value added tax (VAT) As of tax year 2017, the general sales tax rate is 19 5 As of tax year 2017, the VAT was extended to the sale of goods at large, the sale or concession of intangibles related to industrial property and to the provision of services in Colombia, or from services abroad, except for express exclusions of the norm, pursuant to Article 173 of Law 1819 of 2016. Likewise, Article 194 of this Law stipulated that the term for filing requests for VAT deductions will be 3 bimonthly periods immediately following the period of causation. 10.3.4 Wealth tax Law 1739 of 2014 established the wealth tax for natural and juridical persons whose possession of wealth at January 1, 2015 exceeds COP$ 1,000 The applicable rate will depend on the taxable base of each taxpayer and the paid value will not be deductible or discountable on income and supplementary taxes or income tax for equality - CREE, nor can they be offset by these, or any other taxes. In 2017, the wealth tax paid by the Group amounted to COP$ 226,778 569,756

Equity instruments measured at

Equity instruments measured at fair value	12 Months Ended
	Dec. 31, 2017
Disclosure of equity instruments measured at fair value [Abstract]
Disclosure of fair value measurement of equity [text block]	11. Equity instruments measured at fair value As of December 31, 2016, Equity instruments measured at fair value mainly included the shares that Ecopetrol owned in Empresa de Energía de Bogotá S.A.E.S.P, which were sold as part of the shareholding sales plan, authorized by the National Government through Decree 2305 of November 13, 2014. During the 2017, Ecopetrol completed the sales of shares under the sales plan with the following: - On July 29, 2017, the sale of 10,999,163 2,000 21,998 - On October 19, 2017, the shareholding sales plan was completed, with the sale of the remaining 17,465,872 2,000 34,932 2017 2016 Opening balance 51,610 913,488 Fair value adjustments (7,828) 126,205 Proceeds from sale of shares (56,930) (966,715) Profit (loss) on sale of shares 13,236 (21,368) Transfers (88) - Closing balance - 51,610

Other assets

Other assets	12 Months Ended
	Dec. 31, 2017
Disclosure of other assets [Abstract]
Disclosure of other assets [text block]	12. Other assets 2017 2016 Current Partners in joint operations (1) 583,656 735,032 Prepaid expenses 115,866 140,606 Advanced payments to contractors and suppliers 103,762 151,871 Related parties (Note 31) 7,716 7,135 Other assets 69,425 988 880,425 1,035,632 Non-current Abandonment and pension funds (2) 323,621 312,423 Employee benefits 202,012 187,969 Advanced payments and deposits 74,225 63,402 Judicial deposits and attachments 43,248 140,338 Trust funds 32,748 87,602 Other assets 5,155 35,002 681,009 826,736 (1) Corresponds to the net value of cash calls and cutbacks generated in relation to the operations carried out with partners through Exploration and Production (E&;P) contracts, Technical Evaluations (TEA) contracts and agreements entered in to with the National Hydrocarbons Agency (ANH), as well as through association contracts and other types of contracts. (2) Corresponds to Ecopetrol’s share in trusts established to support costs of abandonment of wells and dismantling of facilities as well as the payment of future retirement pensions in some association contracts.

Assets held for sale and their

Assets held for sale and their related liabilities	12 Months Ended
	Dec. 31, 2017
Disclosure of assets held for sale and their related liabilities [Abstract]
Disclosure of assets held for sale and their related liabilities [text block]	13. Assets held for sale and their related liabilities 2017 2016 Assets held for sale Surplus project materials (1) 56,049 65,703 Property, plant and equipment (2) 48,091 36,902 Oil fields (3) - 29,611 104,140 132,216 Liabilities related to assets held for sale Oil fields (3) - 40,128 - 40,128 (1) Mainly includes assets remaining from the expansion project of the oil pipeline for transport of extra heavy crude conducted by Oleoducto Central SA - Ocensa. In 2017, the Group sold part of these assets, generating a loss of COP$ 2,337 (2) Includes buildings and land belonging to Ecopetrol and Andean Chemicals Ltd., the latter related to Louisiana Green Fuels (ethanol plant, water plant and harvesters). The Group recorded an impairment loss on these assets of COP$ 11,292 (3) Corresponds mainly to the Sogamoso, Rio Zulia, Rio de Oro and Puerto Barco, Santana, Nancy Maxine Burdine and Valdivia Almagro oil fields, awarded through an auction in November 2016. During the second and third quarter of 2017, Ecopetrol obtained the approval of the assignment of rights of these areas by the ANH, with the transfer of the assets and the corresponding sale being formalized. These operations generated a net profit of COP $ 168,726

Investments in associates and j

Investments in associates and joint ventures	12 Months Ended
	Dec. 31, 2017
Disclosure of Investments in associates and joint ventures [Abstract]
Disclosure of investments accounted for using equity method [text block]	14. Investments in associates and joint ventures The details on the participations, economic activity, address, area of operations and financial information of the investments in joint ventures and associates can be found in Exhibit 1. 14.1 Composition and movements 2017 2016 Investment in joint ventures Equion Energy Limited 1,057,466 1,156,430 Offshore International Group 845,325 937,938 Ecodiesel Colombia SA 38,383 39,525 1,941,174 2,133,893 Less impairment: Equion Energy Limited (296,427) (253,683) Offshore International Group (539,465) (577,053) 1,105,282 1,303,157 Investments in associates Invercolsa SA 223,963 243,156 Serviport SA 9,905 5,255 Olefinas Port Society 1,214 1,126 235,082 249,537 Less impairment: Serviport SA (9,904) - 225,178 249,537 1,330,460 1,552,694 The following is the movement of investments in companies: Associates Joint Total Opening balance 249,537 1,303,157 1,552,694 Effects of equity method through: Profit or loss 46,669 46,869 93,538 Other comprehensive income - (14,752) (14,752) Dividends declared (61,124) (224,837) (285,961) Impairment (Note 18.1.2) (9,904) (5,155) (15,059) Closing balance 225,178 1,105,282 1,330,460 For the year ended December 31, 2016: Associates Joint Total Opening balance 69,516 1,862,418 1,931,934 Effects of equity method through: Profit or loss 48,299 13,046 61,345 Other comprehensive income 173,772 (49,127) 124,645 Dividends declared (42,050) (384,787) (426,837) Impairment (Note 18.1.2) - (127,858) (127,858) Reclassifications - (10,535) (10,535) Closing balance 249,537 1,303,157 1,552,694 14.2 Restrictions on investments The number of shares held by Ecopetrol in Invercolsa S.A. has been subject to a legal dispute with another shareholder of this company. The courts decided in favor of Ecopetrol through a ruling IN 2011, whereby it was determined that 324 11.58 43.35 14.3 Additional information about associates and joint ventures 2017 2016 Equion Offshore Equion Offshore Energy International Energy International Limited Group Limited Group Statement of financial position Current assets 909,927 289,618 712,078 317,700 Non-current assets 955,849 1,568,395 1,406,510 1,693,947 Total assets 1,865,776 1,858,013 2,118,588 2,011,647 Current liabilities 430,130 192,513 417,203 147,090 Non-current liabilities 98,835 657,746 170,527 671,577 Total liabilities 528,965 850,259 587,730 818,667 Equity 1,336,811 1,007,754 1,530,858 1,192,980 Other complementary information Cash and cash equivalents 170,618 32,490 300,689 22,224 Current financial liabilities 336,352 97,960 328,497 21,408 Non-current financial liabilities 2,921 214,259 309 356,353 2017 2016 2015 Equion Offshore Equion Offshore Equion Offshore Energy International Energy International Energy International Limited Group Limited Group Limited Group Statement of profit or loss Sales revenue 1,213,692 393,210 1,204,301 379,811 1,218,796 463,660 Costs (793,999) (508,461) (969,318) (502,107) (958,467) (654,095) Administrative expenses and others 12,188 (103,340) (44,810) (221,238) (74,258) (128,895) Financial income (expenses) 2,373 (20,264) 59,143 (12,010) 37,970 (8,528) Income tax (180,546) 60,575 30,199 107,507 (209,221) 90,294 Financial year results 253,708 (178,280) 279,515 (248,037) 14,820 (237,564) Other comprehensive results 913,728 - 935,847 - 1,024,423 - Other complementary information Dividends paid to the Ecopetrol 217,075 - 375,035 - 284,984 - Depreciation and amortization 557,970 232,953 678,488 228,250 642,369 229,317 2017 2016 Equion Offshore Equion Offshore Energy International Energy International Limited Group Limited Group Equity of the associate 1,336,811 1,007,754 1,530,858 1,192,980 % of Ecopetrol’s ownership 51 % 50 % 51 % 50 % Ecopetrol’s ownership 681,773 503,877 780,738 596,490 Additional value of the investment 375,693 341,448 375,693 341,448 Impairment (296,427) (539,465) (253,684) (577,053) Carrying amount of the investment 761,039 305,860 902,747 360,885

Property, plant and equipment

Property, plant and equipment	12 Months Ended
	Dec. 31, 2017
Disclosure of property plant and equipment explanatory [Abstract]
Disclosure of property, plant and equipment [text block]	Property, plant and equipment The following shows a breakdown of the changes in property, plant and equipment and depreciation and impairment for the years ended December 31, 2017 and 2016: Plant and Pipelines, Work in Buildings Lands Other Total Cost Balance as of December 31, 2016 42,608,276 29,087,782 4,874,406 6,911,757 3,894,220 3,482,439 90,858,880 Additions/capitalizations 904,854 876,940 (102) 363,836 14,631 203,124 2,363,283 Increase in abandonment costs 51,619 105,097 - - - - 156,716 Capitalized financial interests 38,847 33,875 8,501 6,941 1,027 20,113 109,304 Exchange differences capitalized 2,636 2,299 577 471 70 672 6,725 Disposals (67,326) (56,147) (26,991) (6,539) (23) (2,727) (159,753) Foreign currency translation (136,501) (49,800) (13,302) (4,904) (7,850) (3,394) (215,751) Transfers (2) (840,511) 2,000,003 (976,771) 347,024 (62,720) (893,531) (426,506) Balance as of December 31, 2017 42,561,894 32,000,049 3,866,318 7,618,586 3,839,355 2,806,696 92,692,898 Accumulated depreciation and impairment losses Balance as of December 31, 2016 (15,511,995) (9,965,554) (262,597) (2,088,478) (26,852) (674,902) (28,530,378) Depreciation expense (1,996,614) (1,479,792) - (416,698) - (106,878) (3,999,982) Recovery (losses) for impairment (Note 18) 1,014,613 316,360 (372,804) 11,538 (7,794) 16,006 977,919 Disposals 54,244 13,464 - 807 - 2,583 71,098 Foreign currency translation 15,166 32,729 - 3,929 - 3,802 55,626 Transfers (2) 1,644,613 (1,378,833) 81,981 (179,660) (4,876) (26,032) 137,193 Balance as of December 31, 2017 (14,779,973) (12,461,626) (553,420) (2,668,562) (39,522) (785,421) (31,288,524) Net balance as of December 31, 2016 27,096,281 19,122,228 4,611,809 4,823,279 3,867,368 2,807,537 62,328,502 Net balance as of December 31, 2017 27,781,921 19,538,423 3,312,898 4,950,024 3,799,833 2,021,275 61,404,374 (1) The balance of work in progress as of December 31, 2017, mainly includes investments in production at the Castilla field, the integral plan of electrical energy and secondary recovery of Yarigui and the modernization project of the Barrancabermeja refinery. (2) Transfers correspond mainly to transfers to: a) inventory of project materials for use in the operation for COP$ 250,239 7,222 31,852 Plant and Pipelines, Work in Buildings Lands Other Total Cost Balance as of December 31, 2015 37,360,222 26,856,085 11,015,010 6,479,356 4,068,951 3,653,798 89,433,422 Additions/capitalizations 1,457,547 1,383,352 (107,181) 360,596 41,202 511,413 3,646,929 (Decrease) increase in abandonment costs (84,780) (78,712) - - - 6,137 (157,355) Capitalized interest - - 205,662 - - 37,116 242,778 Exchange differences capitalized - - 8,639 - - - 8,639 Disposals (158,193) (21,814) (16,031) (12,540) 713 (15,455) (223,320) Foreign currency translation (42,870) (298,750) (1,629,613) (9,832) (69,878) 12,416 (2,038,527) Other (reclassifications) (2) 4,076,350 1,247,621 (4,602,080) 94,177 (146,768) (722,986) (53,686) Balance as of December 31, 2016 42,608,276 29,087,782 4,874,406 6,911,757 3,894,220 3,482,439 90,858,880 Accumulated depreciation and impairment Balance as of December 31, 2015 (13,469,749) (8,572,373) (19,566) (1,698,791) (13,689) (554,181) (24,328,349) Depreciation expense (1,869,604) (1,426,659) - (392,294) - (102,621) (3,791,178) Impairment (Note 17) (659,223) 33,048 (3,270) 57,157 24,067 (13,517) (561,738) Disposals 121,382 14,022 - 7,021 15 11,524 153,964 Foreign currency translation 272,582 138,611 38,904 12,658 - 8,007 470,762 Other (reclassifications) (2) 92,617 (152,203) (278,665) (74,229) (37,245) (24,114) (473,839) Balance as of December 31, 2016 (15,511,995) (9,965,554) (262,597) (2,088,478) (26,852) (674,902) (28,530,378) Net balance as of December 31, 2016 27,096,281 19,122,228 4,611,809 4,823,279 3,867,368 2,807,537 62,328,502 (1) The balance of work in progress as of December 31, 2016, mainly includes investments made in the development projects of the Castilla y Chichimene fields, integral energy plan (PIEEL for its acronym in Spanish), primary and secondary development of the Tibú-Socuabo project and modernization of the Refinería de Barrancabermeja. (2) Corresponds mainly to transfers to: a) inventory of project materials for use in the operation for COP$ (712,967) 68,750 116,692

Natural and environmental resou

Natural and environmental resources	12 Months Ended
	Dec. 31, 2017
Disclosure of Natural and environmental resources [Abstract]
Disclosure of natural and environmental resources explanatory [text Block]	16. Natural and environmental resources Oil Asset Exploration and Total Cost Balance as of December 31, 2016 47,079,096 2,304,915 4,818,124 54,202,135 Additions/capitalizations 2,422,203 59,345 944,857 3,426,405 Acquisition of interests in joint operations (Note 32.3) 141,950 - - 141,950 Adjustment to fair value of participation in joint operations (Note 32.3) 451,095 - - 451,095 Increase (decrease) in abandonment costs 224 (143,241) 25,935 (117,082) Disposals (38,072) (629) (214,850) (253,551) Dry wells (2) - - (898,264) (898,264) Capitalized financial interests 72,395 - 9,952 82,347 Exchange differences capitalized 4,913 - 675 5,588 Foreign currency translation (62,446) (573) (14,504) (77,523) Transfers (3) 112,500 (4,554) (163,117) (55,171) Balance as of December 31, 2017 50,183,858 2,215,263 4,508,808 56,907,929 Accumulated amortization and impairment losses Balance as of December 31, 2016 (30,470,415) (1,390,673) - (31,861,088) Depletion expense (3,979,179) (194,140) - (4,173,319) Recovery (losses) for impairment (Note 18) 376,934 - - 376,934 Disposals 37,808 290 - 38,098 Foreign currency translation 42,114 245 - 42,359 Transfers (3) (22,225) (423) - (22,648) Balance as of December 31, 2017 (34,014,963) (1,584,701) - (35,599,664) Net balance as of December 31, 2016 16,608,681 914,242 4,818,124 22,341,047 Net balance as of December 31, 2017 16,168,895 630,562 4,508,808 21,308,265 (1) The balance of exploration and evaluation includes mainly investments made in the Purple Angel, Tayrona and unconventional hydrocarbons projects and in the developing fields, Piedemonte, Castilla y Tibú. (2) Includes mainly dry wells in operation of: 1) Ecopetrol S.A. for (COP$ 450,524 312,684 57,877 (3) Corresponds mainly to transfers to property, plant and Oil investments Asset retirement Exploration and Total Cost Balance as of December 31, 2015 44,148,353 1,762,374 6,189,142 52,099,869 Additions/capitalizations 3,045,474 10,391 (934,570) 2,121,295 Increase (decrease) in abandonment costs - 566,213 (4,062) 562,151 Disposals (26,548) (37,942) (121,032) (185,522) Dry wells (2) - - (342,691) (342,691) Capitalized financial interests - - 98,431 98,431 Exchange differences capitalized - - 7,259 7,259 Foreign currency translation (352,766) (8,049) (103,728) (464,543) Other 264,583 11,928 29,375 305,886 Balance as of December 31, 2016 47,079,096 2,304,915 4,818,124 54,202,135 Accumulated depreciation and impairment loss Balance as of December 31, 2015 (26,874,774) (1,181,798) - (28,056,572) Depletion expense (3,496,998) (208,769) - (3,705,767) Impairment (Note 18) (239,151) - - (239,151) Disposals 26,320 37,942 - 64,262 Foreign currency translation 218,898 5,171 - 224,069 Other (104,710) (43,219) - (147,929) Balance as of December 31, 2016 (30,470,415) (1,390,673) - (31,861,088) Net balance as of December 31, 2015 17,273,579 580,576 6,189,142 24,043,297 Net balance as of December 31, 2016 16,608,681 914,242 4,818,124 22,341,047 (1) The balance of exploration and evaluation mainly includes investments in production projects of direct operation in Castilla, Chichimene and Piedemonte. Additionally, it includes offshore exploration projects: Fuerte Sur, Kronos and Tayrona and Onshore: Caño Sur block, CPO 10 and non-conventional hydrocarbons program. (2) Includes dry wells in operation of: 1) Ecopetrol for COP$ 302,965 26,273 5,032 5,049 3,372 (3) Corresponds mainly of transfers to: a) non-current assets held for sale for COP$ 244,387 (68,898) (17,532) Accounting for suspended exploratory wells 2017 2016 2015 Between 1 and 3 years (a) 600,767 1,300,874 490,184 Between 3 and 5 years (b) 791,261 197,997 100,316 More than 5 years (c) 250,219 153,552 161,392 Total suspended exploratory wells 1,642,247 1,652,423 751,892 No. of projects exceeding 1 year 24 24 59 Wells under 1 year of suspended 2,480 528,313 280,801 (a) Corresponds mainly to discovery wells of Ecopetrol America Inc: Leon 2 and Warrior # 1, which are under evaluation. (b) The balance corresponds mainly to discovery wells of Ecopetrol America Inc: Leon 1, which are under evaluation and Rydberg which is currently working on the development plan and feasibility (c) Corresponds mainly to wells of Offshore International Group, which are temporarily abandoned.

Intangible assets

Intangible assets	12 Months Ended
	Dec. 31, 2017
Disclosure of detailed information about intangible assets [abstract]
Disclosure of intangible assets [text block]	17. Intangible assets Licenses and Other Total Cost Balance as of December 31, 2016 784,320 138,982 923,302 Acquisitions 169,545 6,323 175,868 Disposals (9,469) - (9,469) Foreign currency translation (1,414) (92) (1,506) Transfers 17,574 23,339 40,913 Balance as of December 31, 2017 960,556 168,552 1,129,108 Accumulated amortization Balance as of December 31, 2016 (583,680) (67,490) (651,170) Amortization of the period (89,216) (18,830) (108,046) Disposals 8,744 - 8,744 Foreign currency translation 979 - 979 Transfers (2,242) 2,853 611 Balance as of December 31, 2017 (665,415) (83,467) (748,882) Net balance as of December 31, 2016 200,640 71,492 272,132 Net balance as of December 31, 2017 295,141 85,085 380,226 Useful life < 5 years < 7 years Licenses Other Total Cost Balance as of December 31, 2015 733,115 244,063 977,178 Additions 63,560 5,693 69,253 Disposals (29,099) - (29,099) Foreign currency translation (9,359) (149) (9,508) Reclassifications 26,103 (110,625) (84,522) Balance as of December 31, 2016 784,320 138,982 923,302 Accumulated amortization Balance as of December 31, 2015 (533,784) (55,343) (589,127) Amortization expense (81,913) (28,142) (110,055) Disposals 29,097 - 29,097 Foreign currency translation 8,527 1 8,528 Reclassifications (5,607) 15,994 10,387 Balance as of December 31, 2016 (583,680) (67,490) (651,170) Balance as of December 31, 2015 199,331 188,720 388,051 Balance as of December 31, 2016 200,640 71,492 272,132 Useful life < 5 years < 7 years (1) Corresponds mainly to easements.

Impairment of long-term assets

Impairment of long-term assets	12 Months Ended
	Dec. 31, 2017
Disclosure of Impairment on long term assets [Abstract]
Disclosure of impairment of assets [text block]	18. Impairment of long-term assets As mentioned in Note 4.12, each year the Group assesses whether there are indications of impairment of its assets or cash-generating units or whether an impairment loss recognized in previous periods may be reversed. The impairment of our non-current assets includes expenses (or recovery) of impairment of property, plant and equipment and natural resources, investments in companies, goodwill and other non-current assets. The Group is exposed to future risks derived mainly from variations in: (i) the oil prices outlook, (ii) refining margins and profitability, (iii) cost profile, (iv) investments and maintenance expenses, (v) amounts of recoverable reserves, (vi) market and country risk assessments reflected in the discount rate, and (vii) changes in domestic and international regulations, among others. Any change in the foregoing variables used to calculate the recoverable amount of a non-current asset can have a material effect on the recognition or either losses or recovery of impairment charges in the profit or loss statement. In our business segments highly sensitive variables can include, among others: (i) in the exploration and production segment, variations of the hydrocarbon prices outlook; (ii) in the refining segment, changes in product and crude oil prices, discount rate, refining margins, changes in environmental regulations, cost structure and the level of capital expenditures; and (iii) in the transport and logistics segment, changes in tariffs regulation and volumes transported. Expense (recovery) for impairment Expense (recovery of) impairment by segment 2017 2016 2015 Production and exploration (183,718) 196,448 4,504,495 Refining and Petrochemicals (1,067,965) 773,361 3,278,993 Transport and Logistics (59,455) (41,062) 81,387 (1,311,138) 928,747 7,864,875 Recognized in: Property, plant and equipment (Note 15) (977,919) 561,738 4,144,754 Natural resources (Note 16) (376,934) 239,151 2,865,076 Investment in joint ventures and associates (Note 14) 15,059 127,858 588,144 Other non-current assets 28,656 - - Goodwill - - 266,901 (1,311,138) 928,747 7,864,875 18.1 Exploration and production segment The expenses for (recovery of) asset impairment of the Exploration and Production segment for the years ended December 31 of 2017, 2016 and 2015 is as follows: 2017 2016 2015 Oilfields (188,873) 68,590 3,649,451 Investment in joint ventures and associates (Note 14) 5,155 127,858 588,144 Goodwill - - 266,900 (183,718) 196,448 4,504,495 18.1.1 Oilfields In 2017, based on new market variables, incorporation of new reserves, Ecopetrol’s crude oil basket price discounts as compared to the ICE Brent crude price, available technical and operational information, there was a partial reversal of an impairment recognized in previous years for the oil fields that operate in Colombia CPO09, Casabe and Oripaya and in fields operated abroad Gunflint Dalmatian and K2, and an impairment in the Tibú, Underriver, Provincia and Orito fields . In 2016, as a result of the revision of prospective oil prices in the long term, it was identified that some impairments recognized in previous years for oil fields could be recovered due to an improved future price scenarios. The main fields on which there was a recovery of impairment were Chichimene, Caño Sur, Apiay and Llanito. Similarly, the new technical information and operational aspects that gave rise to changes in investment levels caused an impairment in the Casabe, Tibú, Gunflint and Niscota fields. 2017 Cash generating units Carrying amount Recoverable Expense for Oil fields in Colombia Expense 2,172,747 1,588,207 584,540 Recovery 13,229,212 23,906,828 (298,210) Fields operated abroad Recovery 748,510 1,324,010 (475,203) (188,873) 2016 Cash generating units Carrying amount Recoverable Expense for Oil fields in Colombia Expense 5,258,265 4,902,943 1,117,020 Recovery 17,502,391 36,704,807 (1,090,434) Fields operated abroad Expense 688,895 647,272 42,004 68,590 2015 Cash generating units Carrying amount Recoverable Expense for Oil fields in Colombia 10,323,500 7,645,665 2,430,923 Fields operated abroad 1,242,979 24,451 1,218,528 3,649,451 The assumptions used in the model to determine the recoverable amount include: - The fair value less costs of disposal of the Exploration and Production segment assets was determined based on cash flows after tax derived from the business plans approved by Group's management, which are developed based on long-term macroeconomic policies and fundamental assumptions of supply and demand. The fair value category is level 3. - Balance of oil and gas reserves, in addition to proven reserves included in Note 34; probable and possible reserves were also considered, adjusted by different risk factors. - The real discount rate determined as the average weighted cost of capital of market participants (WACC) established for each company in the segment with rates ranging between 7.9 8.9 7.9 8.9 - Oil price - Brent: The forecasts include US$52.9/barrel for 2018, US$72.5/barrel average for the next six years and US$81.9/barrel as of 2030. In 2016, the assumptions made used a price of US$56.8/ barrel in 2017, US $67.9/barrel average for the medium term and US$80/ barrel in the long term. The aggregation of assets to identify the CGUs is consistent as compared to the previous period. 18.1.2 Investment in associates and joint ventures from Exploration and Production segment Investments in associated companies and joint ventures in the segment are recorded through the equity method. Ecopetrol evaluates if there is any objective evidence to determine if the value of such investments has deteriorated in the period, especially those Companies that were acquired with goodwill. 2017 2016 2015 Equion Energy Limited 42,744 81,155 172,528 Offshore International Group (37,589) 46,703 415,616 Total 5,155 127,858 588,144 The assumptions used to determine the recoverable amount of the companies assessed are those described in Note 18.1.1, except for the use of a discount rate in real terms in 2017 for Equion Energía Limited of 8.2 8.9 8.6 8.0 In 2017, because of new market variables, new reserves, price differentials against reference indicators, and available technical and operational information, there was a recovery of an impairment recognized in previous years for Offshore International Group and Equion Energy. For 2016, in spite of better forecasts of oil prices in the long term, there was an additional impairment in the investment in the Offshore International Group for the reversion to local authorities of some low-prospective success exploration blocks, high geological risk, and low economic viability with respect to a new price scenario. 18.2 Refining and Petrochemical segment 2017 Cash generating units Carrying amount Recoverable (Recovery) Refinería de Cartagena 20,578,412 22,012,710 (1,434,298) Refinería de Barrancabermeja (projects) 1,172,773 898,786 273,987 Bioenergy 757,741 665,395 92,346 22,508,926 23,576,891 (1,067,965) 2016 Cash generating units Carrying amount Recoverable Expenses for Refinería de Cartagena 21,672,367 21,206,515 465,852 Bioenergy 925,955 618,446 307,509 22,598,322 21,824,961 773,361 2015 Cash generating units Carrying amount Recoverable Expenses for Refinería de Cartagena 26,561,335 23,335,096 3,226,240 Bioenergy 642,139 589,386 52,753 27,203,474 23,924,482 3,278,993 The aggregation of assets for identifying the CGUs is consistent across these periods. 18.2.1 Refinería de Cartagena The recoverable amount of the Refinería de Cartagena was calculated based on the fair value less costs of disposal, which is higher than its value in continued use. The fair value less costs of disposal of the Refinería de Cartagena was determined based on cash flows after taxes that are derived from business plans approved by the Group's management, which are developed based on market prices provided by a third party expert, which considers long-term macroeconomic variables and fundamental supply and demand assumptions for crude and refined products. The fair value category is level 3. The assumptions to determine the recoverable amount included: a) a gross refining margin determined by crude oil feedstock and products price outlook provided by an independent third party expert; b) an actual discount rate of 6.0% (2016 - 6.3%) determined under WACC methodology; c) current conditions or benefits, or similar, as an industrial user of goods and services of the free trade zone and during the validity of the license; d) level of costs and long-term operating expenses in line with international refinery standards of similar configuration and conversion capacity, e) refinery throughput and production, and f) level of continued investment. In 2017, we recorded a partial reversal of the impairment recorded in previous periods primarily as a result of: a) an improved outlook in refining margins due to the ratification of the implementation of the International Convention for the Prevention of Pollution from Ships (Marpol) starting in 2020; b) a lower discount rate resulting from the application of WACC methodology; and c) operational and financial optimizations identified as part of the stabilization of the refinery. In 2016, we recorded an impairment caused mostly by adjustment of operational variables based on what was that observed during the stabilization period, offset by a lower discount rate and better refining margins. 18.2.2 Refinería de Barrancabermeja In compliance with the provisions of IAS 36 - Impairment of the value of assets, during 2017 the Refinería de Barrancabermeja recognized COP$ 273,987 18.2.3 Bioenergy The recoverable amount of Bioenergy was calculated based on the fair value less the costs of disposal level with value hierarchy 3, which is greater than the value in continued The assumptions used in the model to determine the recoverable amount included: a) forecast of ethanol prices based on projections made by Ecopetrol specialists based on independent third party sources; and b) a 6.2 6.7 In 2017 and 2016, we recorded an impairment mainly due to updating of the dates of entry into operation of the project, the stabilization process of the industrial plant, and the updating of operational variables. 18.3 Transport and Logistics segment In 2017, there was a recovery of an impairment for the Transportation and Logistics segment for COP$ 59,455 The recovery of COP$ 41,062 The recoverable amount of these assets was determined based on its fair value with costs of disposal with value hierarchy 3, which corresponds to discounted cash flows based on the hydrocarbon production curves and tariffs regulated by the Ministry of Mines and Energy and the Energy and Gas Regulating Commission - CREG. The real discount rate used in the valuation was 5.0% (2016 -4.98%).

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2017
Disclosure of Goodwill [Abstract]
Disclosure of goodwill [text block]	19. Goodwill The balance as of December 31, 2017 and 2016 of goodwill in acquisitions of subsidiaries is as follows: 2017 2016 Transport and Logistics Oleoducto Central S.A. 683,496 683,496 Exploration and Production Hocol Petroleum Ltd. 537,598 537,598 Refining and Petrochemicals Andean Chemical Ltd 127,812 127,812 Propilco S.A 108,137 108,137 1,457,043 1,457,043 Less impairment Hocol Petroleum Ltd. (297,121) (297,121) 1,159,922 1,159,922 As of December 31, 2017 and 2016, the Group assessed the recoverability of the carrying value of goodwill generated in the acquisition of subsidiaries. The recoverable amount was determined based on the realization value less costs of disposal using the present value of future cash flows for each of the companies acquired with goodwill. The source of information used the financial projections of each company derived from the business plans approved by management, which were developed based on long term macro-economic factors such as price curves and margins and fundamental assumptions of supply and demand. As a result of the analysis, the Group did not recognize any goodwill impairment.

Loans and borrowings

Loans and borrowings	12 Months Ended
	Dec. 31, 2017
Disclosure of loans and borrowings [Abstract]
Disclosure of borrowings [text block]	20. Loans and borrowings Exhibit 2 details the main conditions of the most significant loans of the Business Group. 20.1 Composition of loans and borrowings Weighted average effective interest rate as of December 31 2017 2016 2017 2016 Local currency Bonds 8.9 % 8.6 % 1,692,471 2,008,203 Syndicated loan 8.7 % 9.5 % 3,307,950 3,828,329 Other (1) 7.7 % 9.1 % 978,795 905,266 5,979,216 6,741,798 Foreign currency Bonds 6.1 % 6.1 % 29,166,594 29,310,165 Commercial loans – Refinería de Cartagena 4.3 % 4.1 % 7,401,781 7,988,678 Commercial loans 4.3 % 2.9 % 528,815 7,945,693 Other (1) 471,429 235,693 37,568,619 45,480,229 43,547,835 52,222,027 Current (2) 5,144,504 4,126,203 Non-current 38,403,331 48,095,824 43,547,835 52,222,027 (1) Includes financial leasing and debt in connection with build, operate, maintenance and transfer (BOMT) contracts. (2) The increase in the current portion is mainly due to the expiration of: i) the first tranche of local bonds issued by Ecopetrol S.A. in 2013, and ii) the 5-year series of international bonds issued in 2013 by Ecopetrol S.A.. These bonds mature in August and September 2018, respectively. 20.2 Main movements of loans and borrowings Bonds - foreign currency § On June 8, 2016 500 5.875 current 1,800 Foreign currency commercial loans § On June 30, 2017, Ecopetrol prepaid all of its international syndicated loan, whose nominal value was US$ 1,925 § On December 15, 2017, Ecopetrol prepaid the loan entered into 175 § On December 15, 2017, Ecopetrol prepaid 300 Local currency commercial loans § On February 23, 2016, Ecopetrol entered into a bilateral commercial credit agreement with Bancolombia SA for COP$990,000, which was prepaid in October 2016. This loan had a term of 8 years, amortizable with 2 years of grace on principal repayments, with interest payable semiannually at a DTF TA + 560 basis points. § On August 14, 2017, Ecopetrol entered into an agreement for a committed credit line with Bancolombia S.A. for COP$ 990,000 20.3 Maturity of loans and borrowings Up to 1 1-5 years 5-10 years > 10 years Total Local Currency Bonds 253,172 742,512 322,956 373,831 1,692,471 Syndicated loan 739,348 2,009,420 559,182 - 3,307,950 Other 98,729 415,599 308,121 156,346 978,795 1,091,249 3,167,531 1,190,259 530,177 5,979,216 Foreign currency Bonds 2,651,174 9,948,238 12,018,813 4,548,369 29,166,594 Commercial loans – Refinería de Cartagena 958,918 3,635,848 2,807,015 - 7,401,781 Commercial loans 153,873 315,849 59,093 - 528,815 Other 289,290 119,014 63,125 - 471,429 4,053,255 14,018,949 14,948,046 4,548,369 37,568,619 5,144,504 17,186,480 16,138,305 5,078,546 43,547,835 (1) Includes short-term credit and the current portion of long-term debt, as applicable. The following are the maturities of loans and borrowing as of December 31, 2016: Up to 1 1 - 5 years 5-10 years > 10 years Total Local currency Bonds 312,207 955,204 357,015 383,777 2,008,203 Commercial loans 793,743 2,375,023 659,563 - 3,828,329 Others 58,952 333,372 339,009 173,933 905,266 Total local currency 1,164,902 3,663,599 1,355,587 557,710 6,741,798 Foreign currency Bonds 1,648,707 10,956,507 12,133,576 4,571,375 29,310,165 Commercial loan Refinería de Cartagena 875,734 3,549,216 3,472,379 91,349 7,988,678 Other commercial loans 371,804 7,450,587 123,302 - 7,945,693 Other 65,056 114,226 56,411 - 235,693 Total foreign currency 2,961,301 22,070,536 15,785,668 4,662,724 45,480,229 4,126,203 25,734,135 17,141,255 5,220,434 52,222,027 (1) Includes short-term credit and the current portion of long-term debt, as applicable. 20.4 Breakdown by type of interest rate and currency The following is the breakdown of loans and borrowing by type of interest rate as of December 31, 2017 and 2016: 2017 2016 Local currency Fixed rate 143,156 299,472 Floating rate 5,836,060 6,442,326 5,979,216 6,741,798 Foreign currency Fixed rate 35,062,742 35,719,486 Floating rate 2,505,877 9,760,743 37,568,619 45,480,229 43,547,835 52,222,027 The floating rate loans in local currency are indexed mainly to the CPI (Consumer Price Index) and the DTF (Fixed Term Deposits); and those in foreign currency loans at LIBOR plus a spread. 20.5 Loans designated as hedging instrument As of December 31, 2017, the Group designated US$ 8,532 10,512 5,200 million is used to hedge the net investment in foreign operations with the US dollar as their functional currency and 3,332 20.6 Guarantees and covenants Financing obtained directly by Ecopetrol S.A. in capital markets has no guarantees granted or financial covenant restrictions, due to the support of the Colombian Government through the Ministry of Finance and Public Credit. Until December 13, 2017, when Ecopetrol voluntarily assumed the international loan held by Reficar, in its capacity as sponsor, the following restrictions applied to Reficar: maintain a minimum debt service coverage ratio of 1.35:1; obligation to maintain a commercial trust and a depositary agreement for receiving resources of the new refinery to fulfill specific purposes such as operating expenses, interest and others. The following is a summary of certain restrictions contained in certain loan instruments of Ecopetrol’s subsidiaries: - The loan entered into by Oleoducto de los Llanos is guaranteed with the economic rights of the ship-or-pay transportation agreements with Meta Petroleum Corp and also includes certain restrictions regarding capital contributions and asset disposal. - The syndicated loan entered into by Oleoducto Bicentenario requires that this subsidiary maintain an established relationship of leverage and solvency and cash flow / service to the debt. - The loan entered into by Bioenergy with Bancolombia is guaranteed with the La Esperanza 1 and 2 fields in the amount of COP$6,343 and there are certain restrictions on the variation of direct or indirect ownership by Ecopetrol S.A. in this subsidiary. Ecopetrol and its subsidiaries were in compliance with these restrictions as of December 31, 2017 and 2016. 20.7 Fair value of loans The fair value of loans and borrowings is COP$ 45,781,317 52,109,438 For fair value measurement, local currency bonds were valued using Infovalmer reference prices, while bonds in U.S. dollars, were valued using Bloomberg. With regard to the other financial obligations for which there is no market benchmark, a discount to present value technique was used. These rates incorporate market risk through some benchmarks (Libor, DTF) and the Group’s credit risk (spread). 20.8 Movement of net financial debt Cash and Other financial Loans and Net financial equivalents assets (1) borrowings debt Balance as of December 31, 2015 6,550,450 1,585,379 (53,223,338) (45,087,509) Cash flow 2,086,350 5,446,507 1,050,723 8,583,580 Exchange difference: Recognized in profit or loss (226,333) (12,837) 1,252,420 1,013,250 Recognized in other comprehensive income - - 612,983 612,983 Financial cost registered to projects - - (357,107) (357,107) Financial income (expense) recognized in profit or loss - 59,593 (2,765,024) (2,705,431) Foreign currency translation - (6,462) 593,384 586,922 Other movements not generating cash flow (2) - (385,285) 613,932 228,647 Balance as of December 31, 2016 8,410,467 6,686,895 (52,222,027) (37,124,665) Cash flow (174,272) (564,755) 11,259,492 10,520,465 Exchange difference: Recognized in profit or loss (290,310) 208,394 147,993 66,077 Recognized in other comprehensive income - - 70,958 70,958 Financial cost registered to projects - - (203,964) (203,964) Financial income (expense) recognized in profit or loss - 104,706 (2,385,994) (2,281,288) Foreign currency translation - 39,628 (76,171) (36,543) Other movements that do not generate cash flow - 58,857 (138,122) (79,265) Balance as of December 31, 2017 7,945,885 6,533,725 (43,547,835) (29,068,225) (1) The balance of other financial assets as of December 31, 2015 includes the value of the securities related to Santiago de las Atalayas for COP$ 699,832 (2) Corresponds to operations with remittances financed in dollars with domestic banks for the payment of imports.

Trade and other payables

Trade and other payables	12 Months Ended
	Dec. 31, 2017
Disclosure Of Trade and other payables [Abstract]
Disclosure of trade and other payables [text block]	21. Trade and other payables 2017 2016 Suppliers 5,088,957 4,687,353 Partners’ advances 880,420 864,971 Withholding tax 376,169 379,194 Related parties 129,520 114,420 Insurance and reinsurance 121,555 110,530 Agreements in transport contracts (1) 91,324 111,899 Deposits received from third parties 25,523 209,570 Dividends payable (2) 3,723 11,193 Various creditors 280,485 389,126 6,997,676 6,878,256 Current 6,968,207 6,854,363 Non-current 29,469 23,893 6,997,676 6,878,256 (1) Corresponds to the value of debt from agreements in transport contracts of oil pipelines and poliducts, impacted by volumetric adjustments, compensation for quality and other inventory management agreements. (2) Dividends declared at the General Shareholders' Meeting on 2016 profits, amounting to 945,684 The carrying amount of trade accounts and other accounts payable approximates their fair value due to their short-term nature.

Provisions for employees benefi

Provisions for employees benefits	12 Months Ended
	Dec. 31, 2017
Disclosure of defined benefit plans [abstract]
Disclosure of employee benefits [text block]	22. Provisions for employees benefits 2017 2016 Post-employment benefits Healthcare 5,367,005 4,475,540 Pension 1,327,859 76,695 Education 502,260 333,379 Bonds 348,442 263,563 Other plans 77,636 67,945 Termination benefits - Voluntary retirement plan 155,286 161,796 7,778,488 5,378,918 Social benefits and salaries 485,939 423,360 Other employee benefits 67,867 73,300 8,332,294 5,875,578 Current 1,829,819 1,974,496 Non-current 6,502,475 3,901,082 8,332,294 5,875,578 22.1 Post-employment benefits liability (asset) Pension and bonds (1) Other Total 2017 2016 2017 2016 2017 2016 Liabilities for employee benefits Opening balance 12,463,433 10,435,546 5,041,133 4,170,047 17,504,566 14,605,593 Current service cost - - 52,164 53,771 52,164 53,771 Past service cost - - - 164,271 - 164,271 Interest expense 872,524 876,076 350,060 333,894 1,222,584 1,209,970 Actuarial losses (gains) 1,621,184 1,915,767 1,012,205 616,834 2,633,389 2,532,601 Benefits paid (809,677) (763,956) (350,130) (297,684) (1,159,807) (1,061,640) Closing balance 14,147,464 12,463,433 6,105,432 5,041,133 20,252,896 17,504,566 Plan assets Opening balance 12,123,175 11,181,604 2,473 - 12,125,648 11,181,604 Return on assets 848,677 950,704 385 - 849,062 950,704 Contributions to funds - - 22,465 - 22,465 - Variation in the ceiling of assets - 379,884 - - - 379,884 Benefits paid (809,677) (771,528) (22,078) 2,406 (831,755) (769,122) Actuarial gains (losses) 308,988 382,511 - 67 308,988 382,578 Closing balance 12,471,163 12,123,175 3,245 2,473 12,474,408 12,125,648 Net post-employment benefits liability 1,676,301 340,258 6,102,187 5,038,660 7,778,488 5,378,918 (1) There is no cost for the pension and pension plans service, due to the fact that the beneficiaries were retired as of July 31, 2010. The following table shows the movement in profit and loss and in other comprehensive income as of December 31, 2017 and 2016: 2017 2016 Recognized in profit or loss Current service cost 52,164 53,771 Past service cost - 164,271 Interest expense, net 373,522 259,266 Remedies 13,889 - 439,575 477,308 Recognized in other comprehensive income Healthcare (794,535) (792,093) Pension and pension bonds (1,312,195) (1,533,256) Education and severance (203,779) 175,259 Termination benefits - Voluntary retirement plan (3) 67 Change in the effect of the asset ceiling - 379,884 (2,310,512) (1,770,139) Deferred tax 762,469 616,697 Other comprehensive income, net of taxes (1,548,043) (1,153,442) 22.2 Plan assets Plan assets are resources held by pension trusts, for payment of pension obligations. Payments for health and education post-employment benefits is Ecopetrol’s responsibility. The destination of trust resources and its yields cannot be changed or returned to the Group until all pension obligations have been fulfilled. The following is the composition of the plan assets of pension and pension bonds by type of investment as of December 31, 2017 and 2016: 2017 2016 Bonds issued by the national government 4,349,400 4,410,326 Bonds of private entities 2,967,030 2,880,958 Other local currency 2,337,580 2,910,083 Other public bonds 1,149,200 693,061 Variable yield 605,380 305,052 Bonds of foreign entities 558,920 622,817 Other foreign currency 503,653 300,878 12,471,163 12,123,175 46.0 54.0 The fair value of level 2 plan assets is calculated using prices quoted in the assets’ market. The Group obtains these prices through reliable financial data providers recognized in Colombia or abroad depending on the investment. For the securities issued in local currency, the fair value of plan assets is calculated using information published by Infovalmer, a price supplier authorized by the Financial Superintendence of Colombia. According to its methodology, prices are calculated based on market information on the valuation date or estimated from historical inputs according to the criteria established for the calculation of each of the prices. The average price is calculated based on the most representative market of the transactions carried out through electronic platforms approved and supervised by the regulator. On the other hand, the estimated price is calculated for investments that do not reflect enough information to estimate an average market price, replicating the quoted prices for similar assets or prices obtained through quotes from brokers. This estimated price is also given by Infovalmer as a result of the application of robust methodologies approved by the financial regulator and widely used by the financial sector. Rating 2017 2016 AAA 4,870,932 4,467,642 Nation 4,471,274 4,610,251 AA+ 690,391 470,944 BAA2 371,972 141,940 BBB 246,795 150,808 F1+ 230,321 416,439 BBB- 192,636 23,237 BBB+ 159,103 193,835 BRC 1+ 118,008 309,282 AA 58,234 79,750 BAA3 45,699 131,993 A 39,048 4,175 A3 29,098 61,325 AA3 27,051 14,385 AA- 18,770 34,197 VRR1 + 14,112 55,821 BAA1 5,296 5,274 Other qualifications 9,621 66,470 No rating available 872,802 885,407 12,471,163 12,123,175 See credit risk policy in Note 30.3. 22.3 Actuarial assumptions 2017 Pension Bonds Health Education Other benefits Discount rate 6.50 % 6.25 % 6.50 % 5.50 % 5.51% Salary growth rate N/A N/A N/A N/A 4.75% / 4.25% Expected inflation rate 3.00 % 3.00 % 3.00 % 3.00 % 3.00% Pension growth rate 3.00 % N/A N/A N/A N/A Cost trend Short-term rate N/A N/A 6.00 % 4.00 % N/A Long-term rate N/A N/A 4.00 % 4.00 % N/A 2016 Pension Bonds Health Education Other benefits Discount rate 7.25 % 7.00 % 7.25 % 6.50 % 6.67% Salary growth rate N/A N/A N/A N/A 4.25% Expected inflation rate 3.00 % 3.00 % 3.00 % 3.00 % 3.00% Pension growth rate 3.00 % N/A N/A N/A N/A Cost trend Short-term rate N/A N/A 3.00 % 4.00 % N/A Long term rate N/A N/A 4.00 % 4.00 % N/A N/A: Not applicable for this benefit. (1) Weighted average discount rate. The cost trend is the projected increase for the initial year , which The mortality table used for the calculations was that of ‘Valid Annuitant’ for men and women based on the experience gained for the period 2005-2008 of the Colombian Social Security Institute. 22.4 Maturity of benefit obligation Period Pension Other Total 2018 880,298 374,315 1,254,613 2019 877,165 355,241 1,232,406 2020 899,128 358,292 1,257,420 2021 921,333 361,655 1,282,988 2022 952,531 362,998 1,315,529 2023-2026 5,201,619 1,824,756 7,026,375 22.5 Sensitivity analysis Pension Bonds Health Education Other Discount rate -50 basis points 13,948,863 1,032,967 5,775,492 527,839 242,117 +50 basis points 12,440,607 948,129 4,962,688 480,224 230,501 Inflation rate -50 basis points 12,386,975 946,675 N/A N/A 156,021 +50 basis points 14,003,214 1,033,715 N/A N/A 161,094 Salary growth rate -50 basis points N/A N/A N/A N/A 76,336 +50 basis points N/A N/A N/A N/A 79,150 Cost trend -50 basis points N/A N/A 4,982,874 479,829 N/A +50 basis points N/A N/A 5,797,753 528,104 N/A 22.6 Voluntary retirement plan In August 2016, the Group offered a voluntary retirement plan to 200 employees who met certain criteria. As of December 31, 2017 and 2016, 137 employees were part of plan, with a corresponding cost of COP$ 155,286 161,796

Accrued liabilities and provisi

Accrued liabilities and provisions	12 Months Ended
	Dec. 31, 2017
Disclosure of accrued liabilities and provisions [Abstract]
Disclosure of accrued expenses and other liabilities [text block]	23. Accrued liabilities and provisions Below is the breakdown of the changes in the different categories of provisions and contingencies as of December 31, 2017 and 2016: Asset Environmental retirement contingencies obligation Litigation and others Total Balance as of December 31, 2016 5,064,660 209,932 643,278 5,917,870 Increase in abandonment costs 39,634 - - 39,634 Additions (recoveries) 110,587 (19,185) 106,532 197,934 Uses (66,469) (7,742) (19,613) (93,824) Financial costs 379,891 - (367) 379,524 Foreign currency translation (979) (39) 718 (300) Transfers (1) - - 96,611 96,611 Balance as of December 31, 2017 5,527,324 182,966 827,159 6,537,449 Current 199,824 159,881 199,123 558,828 Non-current 5,327,500 23,085 628,036 5,978,621 5,527,324 182,966 827,159 6,537,449 Asset Environmental retirement Comuneros contingencies obligation Litigation provision and others Total Balance as of December 31, 2015 4,452,369 99,798 702,486 822,694 6,077,347 Increase in abandonment costs 404,797 - - - 404,797 Additions (recoveries) 18,285 44,120 (702,486) (74,312) (714,393) Uses (68,460) (4,585) - (31,218) (104,263) Financial costs 317,448 - - (173) 317,275 Foreign currency translation (14,703) (355) - (2,759) (17,817) Transfers (1) (45,076) 70,954 - (70,954) (45,076) Balance as of December 31, 2016 5,064,660 209,932 - 643,278 5,917,870 Current 330,057 146,767 - 345,130 821,954 Non-current 4,734,603 63,165 - 298,148 5,095,916 5,064,660 209,932 - 643,278 5,917,870 (1) Mainly includes transfers to liabilities associated with assets held for sale. 23.1 Asset retirement obligation The estimated liability for asset retirement obligation costs corresponds to the future obligation to restore environmental conditions to a level similar to that existing before the start of projects or activities, as described in Note 3.5 - Abandonment and dismantling costs of fields and other facilities. As these relate to long-term obligations, this liability is estimated by projecting the expected future payments and discounting at present value with a rate indexed to the Group's financial obligations, taking into account the temporality and risks of this obligation. The discount rates used in the estimate of the obligation as of December 31, 2017 were: Exploration and Production 6.93 7.93 7.02 8.20 7.37 8.99 23.2 Litigation The following is a summary of the main legal proceedings recognized in the statement of financial position whose amount exceeds COP$13,000 million, where the expectation of loss is probable Proceeding 2017 2016 Provision for the payment of the 2016 legal stability contract premium with the Ministry of Finance and Public Credit regarding investment in Reficar 64,104 59,528 Litigation with Schrader Camargo, supplier of Reficar 17,003 17,003 Settlement before the Procuraduría General de la Nación with the firms Acciona Infraestructura S.A. and Mantenimiento y Montajes S.A., August 18, 2016. In 2017, it was ruled in favor of the Group and the provision was reversed. - 44,986 23.3 Comuneros - Santiago de las Atalayas provisions On November 8, 2016, the Ministry of Mines and Energy concluded that the resources that were restricted in relation to this process were not royalties and, therefore, were not due to the Comuneros. In accordance with the foregoing, the resources held by Ecopetrol are its property, without any claim or discussion to date regarding ownership title thereof. On November 8, 2016, the amount claimed reached COP$ 688,664 23.4 Environmental contingencies and others These corresponds to contingencies for environmental incidents and obligations related to environmental compensation and mandatory investment of 1% for the use of, exploitation of or effect on natural resources imposed by national, regional and local environmental authorities. Mandatory investment of 1 The Colombian Government through the Ministry of Environment and Sustainable Development, issued in December 2016 and in January 2017 the Decrees 2099 and 075, which modify the Single Regulatory Decree of the environment and sustainable development sector, Decree 1076 of 2015, related to the mandatory investment for the use of water taken directly from natural sources. The main changes established by these decrees were related to the areas and lines of investment and the basis for settlement of the obligations. Similarly, June 30, 2018 was declared the maximum date to modify investment plans that were underway. On June 30, 2017, Ecopetrol filed with the National Environmental Licensing Authority (ANLA) certain investment plans to meet the 1% mandatory investment based on the new decrees, relative to investment lines, maintaining the settlement base of Decree 1900. As of December 31, 2017, the provision for the 1% mandatory investment for the use of water was estimated based on the parameters established in Decree 1076 of 2015. The Group is in the process of analyzing the impact of the applicability of the changes set out in the aforementioned decrees. Ocensa Some requests for arbitration were filed by some of Ocensa’s shippers in connection with the tariff and monetary conditions established in the transportation contracts for the use of the increased capacity of the pipeline resulting from the P-135 project. Similar claims could be brought by other shippers of the aforementioned project. Frontera Energy Colombia Corp. Sucursal Colombia entered into a memorandum of understanding for a comprehensive settlement agreement that is pending the approval by Frontera’s arbitration panel. If the arbitration panel approves the settlement agreement, it will resolve any pending proceedings and controversies among the parties, and both parties will execute the amendments to the Agreements. The recognized provision is based on the risk assessment carried out by Ocensa and its advisors, without implying the recognition of the validity of the claims of the shippers. 23.5 Legal proceedings not provided for The following is a summary of the main contingent liabilities that have not been recognized in the statement of financial position as, according to the evaluations made by internal and external advisors of the Group, the expectation of loss is not probable as at December 31, 2017 and 2016: Proceedings 2017 2016 Environmental damage caused by a terrorist attack in 2015 against the Transandino pipeline. 209,220 - Breaking of the economic and financial balance with contractor for the construction of the transport system. 110,266 - On March 14, 2016, a lawsuit was filed for default settling the contract between Konidol and Ecopetrol, which caused Ecopetrol incurred excess costs in the maintenance contract in 2016. 62,131 62,131 Salary readjustments to the amounts established by Ecopetrol for personnel, related to a contract with a third party for the commissioning and construction of surface facilities for production and exploration projects. 60,313 - Compensation to third parties for damage caused by hydrocarbon spills during a tanker truck accident on the Villeta - Guaduas road oil spills. 43,333 43,333 Contractual imbalance with a third party in relation to road connection works. 31,679 - Settlement of differences with a supplier under a contract whose purpose was the engineering, procurement and construction management of project P135. Although the parties reached a preliminary settlement agreement, the Comptroller General's Office did not approve it and the process continues in the evidentiary stage. The result of these processes is subject to the decision of the arbitrator. 30,027 - Contractual controversy with a third party in relation with seismic acquisition services and seismic program processing. 30,000 - Recalculation of legal and non-legal social benefits on sums paid for the benefit of saving incentives. 16,562 16,562 Controversy regarding income tax returns for taxable years 2010 and 2011 of Hocol, related to deductions in exploration fixed assets. In September 2017, Hocol paid taxes on the tax revenue processes of taxable years 2010 and 2011 of $ 89,271 - 344,915 23.6 Details of contingent assets The following is a breakdown of the Group’s principal contingent assets, where the associated contingent gain is likely, but not certain as of December 31, 2017 and 2016: Proceedings 2017 2016 Ocensa claim that seeks the payment of the negative balance by Equion Energia Limited and Santiago Oil Group, which are reflected in Ocensa's volumetric balances. 112,735 - Claim for reimbursement based on a disagreement with Ecopetrol corresponding to investment in facilities in the Guaduas field of the "Rio Seco" association contract. 40,711 40,746 Environmental incident in 2011, in the Caño Limón Coveñas Pipeline. 35,000 - Criminal claim filed by Ecopetrol against the administrator of agreements with a corporation for alleged document falsification. 32,000 - Breach of a pipe purchase order because the physical characteristics of the coating do not match what was contracted. 21,232 21,232 Nullity of administrative act issued by the DIAN, which ordered a special contribution for public works contracts. 13,214 13,214 Claim against Metapetroleum for damage suffered due to the late delivery of crude volumes under the Quifa association contract. - 25,421 Refinería de Cartagena On March 8, 2016, Reficar presented a request for Arbitration before the International Chamber of Commerce against Chicago Bridge &; Iron Group NV, CB&;I (UK) Limited and CBI Colombiana S.A. (collectively, "CB&;I") related to the contract for the construction, procurement and engineering entered into by Reficar and CB&;I for the expansion of Refinería de Cartagena, in Cartagena, Colombia. Reficar is the claimant in the arbitration process of the CCIO and requests at least US$ 2 213 In relation to this matter, as of December 31, 2017, there is an amount of approximately US$ 122 proof of the sources for these invoices, delivered by CB&;I, have not been accepted by of AMEC Foster Wheeler - PCIB. 23.7 Investigations of control entities As part of the investigations carried out by various control entities of the modernization and expansion project (the “Project”) of Refinería de Cartagena, Reficar has been officially informed of the following investigations and proceedings: a) Office of the Comptroller General (Contraloría General de la República) Because of the modifications of the schedule and budget related to the Project, the Office of the Comptroller General initiated a special audit investigation of the Project in 2016 and delivered a final report to Reficar on December 5, 2016. The report made 36 findings most of which were related to increased costs compared to budget for services, labor and materials. As a result of the findings described above, the Office of the Comptroller General opened actions for financial responsibility (proceso de responsabilidad fiscal) against 36 individuals and the six companies involved in the Project, including current and former members of Ecopetrol’s Board of Directors; former members of Reficar’s Board of Directors; current and former employees of Ecopetrol; and former employees of Reficar, as well as Chicago Bridge &; Iron Group N.V., CBI - Chicago Bridge &; Iron company (CB&;I) Americas Ltd., Chicago Bridge &; Iron Group CB&;I UK Limited, CBI Colombiana S.A., Foster Wheeler USA Corporation and Process Consultants Inc. One current member of Ecopetrol’s Board of Directors being investigated in these proceedings. In January 2017, the Office of the Comptroller General initiated another special audit in Reficar and delivered a final report to Reficar on July 12, 2017. In this report the Office of the Comptroller General concluded that, in their opinion, Reficar’s 2016 Financial Statements do not reasonably represent, in all material aspects, the entity’s financial position as of December 31, 2016. b) Attorney General’s Office (Procuraduría General de la Nación) Reficar has been officially informed that the Attorney General’s Office currently has one ongoing investigation relating to the Project. The investigation initiated in 2012 against members of Reficar’s Board of Directors at the time, as well as certain current and former officers of Reficar. On September 12, 2017 the Attorney General’s Office issued a list of charges related to the failure to fulfill some of their duties as administrators and/or for acting “ultra vires” in the exercise of their functions against: (i) Javier Genaro Gutiérrez (Ecopetrol CEO, 2007-2015), (ii) Felipe Laverde (Reficar General Counsel, 2009-March 2017), (iii) Pedro Rosales (Ecopetrol Downstream Executive Vice President, 2008-2015), (iv) Diana Constanza Calixto (Ecopetrol Head of the Corporate Finance Unit, 2009-2014) and (vi) Reyes Reinoso Yañez (Reficar CEO, 2012-2016) The Attorney General’s Office closed the case against the rest of the members of Reficar’s Board of Directors and the rest of the current and former officers of Reficar. c) Prosecutor’s Office (Fiscalía General de la Nación) The Prosecutor’s Office is conducting an investigation. In connection therewith, between July 25 and August 2, 2017 the Prosecutor’s Office indicted the following individuals with charges, the majority of which are related to offenses against the public administration and illegal interest in the execution of agreements: (i) Orlando José Cabrales Martínez (Reficar CEO, 2009-2012); (ii) Reyes Reinoso Yañez (Reficar CEO, 2012-2016); (iii) Felipe Laverde Concha (Reficar General Counsel, 2009-March 2017); (iv) Pedro Alfonso Rosales Navarro (Ecopetrol Downstream Executive Vice President, 2008-2015); (v) Masoud Deidehban (CBI Executive Project Director); (vi) Phillip Asherman (CBI CEO) and (vii) Carlos Lloreda (Reficar’s statutory auditor from 2013-2015). The arraignment hearing is scheduled to take place on May 30, 2018. Ecopetrol is not in a position to forecast the results of these investigations; nor is it possible to evaluate the probability of any consequence that may impact the financial statements, such as additional provisions, fines or ignorance of tax deductions that affect the amounts of deferred tax assets. As of the date of this report, the financial statements continue to adequately disclose the financial and operational situation of Ecopetrol in all material aspects and its internal controls remain in force.

Equity

Equity	12 Months Ended
	Dec. 31, 2017
Disclosure of equity [Abstract]
Disclosure of share capital, reserves and other equity interest [text block]	24. Equity The main components of equity are detailed below: 24.1 Subscribed and paid-in capital Ecopetrol’s authorized capital amounts to $ 36,540,000 60,000,000,000 41,116,694,690 11.51 4,731,905,873 88.49 36,384,788,817 the Colombian 11,499,933 18,883,305,310 25,040,067 24.2 Additional paid-in capital Additional paid-in capital mainly corresponds to: (i) share premium from the Group’s capitalization in 2007, for 4,457,997 31,377 2,118,468 receivables (142) 24.3 Equity reserves 2017 2016 Legal reserve 1,426,151 1,269,680 Fiscal and statutory reserves 512,632 289,164 Occasional reserves 239,086 - Total 2,177,869 1,558,844 2017 2016 Opening balance 1,558,844 5,546,570 Release of reserves (289,164) (406,983) Allocation to reserves 908,189 289,164 Legal reserve used to offset previous year loss (Note 24.4) - (3,869,907) Closing balance 2,177,869 1,558,844 Legal reserve The Colombian Code of Commerce establishes that 10 50 Occasional reserves Occasional reserves correspond to allocation of net income as approved at the shareholders at the Stockholders’ meeting to carry out new explorations. On March 31, 2017, the Stockholders’ Meeting approved the appropriation of occasional reserves for the establishment of a reserve for new explorations for the amount of COP $ 239,086 Tax and mandatory reserves The Colombian tax regime allows for the allocation of up to 70 In addition, Decree 2336 of 1995 set out the obligation to establish a reserve for the changes in valuation of investments. Unrealized fair value gains are allocated to a reserve. 24.4 Retained earnings and dividends balance 2017 2016 Opening balance (402,462) (6,814,432) Profit attributable to owners of Ecopetrol’s shareholders 7,178,539 2,447,881 Release of reserves 289,164 406,983 Allocation to reserves (908,189) (289,164) Dividends declared (1) (945,684) - Legal reserve used to offset previous year loss (2) - 3,869,907 Other movements (1,066) (23,637) Closing balance 5,210,302 (402,462) (1) The Company distributes dividends based on its separate annual financial statements, prepared under International Financial Reporting Standards accepted in Colombia (NCIF, by its acronym in Spanish). The Ordinary General Shareholders' Meeting, held on March 31, 2017, approved the proposal for profit distribution proposal for 2016 and set the distribution of dividends of COP$ 945,684 Dividends paid in 2017 attributable to the shareholders of Ecopetrol S.A. amounted to COP$ 945,661 690,177 558,986 1,022,121 (2) The Ordinary General Meeting of Shareholders, held on March 31, 2016, approved the proposal for profit distribution, which established that there would be no distribution for the year 2015, given the net loss occurred in that year; in addition, the shareholders voted to use the legal reserve to offset this loss, as permitted by the Article 456 of the Colombian Code of Commerce. The amount of losses offset by releases from the legal reserve after tax and mandatory allocations amounted to COP$ 3,869,907 24.5 Other comprehensive income attributable to owners of parent The following is the composition of the other comprehensive income attributable to the shareholders of the parent company, Ecopetrol S.A., net tax as of December 31, 2017 and 2016 2017 2016 Actuarial gain on defined benefit plans (553,091) 994,953 Gain (loss) on equity instruments measured at fair value (1) - 7,828 Cash flow hedges for future exports (Note 30.2.2) 159,295 244,131 Hedge of a net investment in a foreign operation (Note 30.2.3) (97,362) (155,359) Cash flow hedge with derivative instruments 6,942 (19,042) Others - 11,817 Foreign currency translation 7,883,231 8,138,382 7,399,015 9,222,710 (1) During 2016 the Group reclassified to the statement of profit or loss COP$ 68,497 19,405 24.6 Earnings (loss) per share 2017 2016 2015 Profit (loss) attributable to Ecopetrol’s shareholders 7,178,539 2,447,881 (7,193,859) Weighted average number of outstanding shares 41,116,694,690 41,116,694,690 41,116,694,690 Net basic earnings (loss) per share (Colombian pesos) 174.6 59.5 (175.0)

Sales revenue

Sales revenue	12 Months Ended
	Dec. 31, 2017
Disclosure of Sales revenue [Abstract]
Disclosure of revenue [text block]	Sales revenue 2017 2016 2015 National sales Mid-distillates 9,590,326 8,553,503 10,215,224 Gasoline 6,990,187 6,092,739 6,128,208 Services 3,873,352 4,043,284 4,435,274 Natural gas 1,815,754 1,988,336 1,845,345 Crude oil 909,871 553,666 491,279 Plastic and rubber 833,982 724,708 724,392 LPG and propane 509,619 405,869 335,494 Asphalts 275,803 340,400 461,188 Other products 1,207,245 994,645 988,346 26,006,139 23,697,150 25,624,750 Recognition of price differential (1) 2,229,953 1,048,022 441,871 28,236,092 24,745,172 26,066,621 Foreign sales Crude oil 21,479,063 17,278,579 21,181,265 Fuel oil 1,982,408 2,158,539 2,166,469 Gasoline and turbo fuels 1,223,994 1,046,758 93,125 Diesel 1,213,740 1,604,498 81,982 Plastic and rubber 1,169,101 1,171,342 1,096,730 Natural gas 32,303 58,809 182,950 LPG and propane 15,631 8,568 - Trading of crude - - 1,309,196 Cash flow hedge for future exports – Reclassification to profit or loss (Note 30.2.2) 160,772 33,074 7,646 Other 441,124 380,222 161,287 27,718,136 23,740,389 26,280,650 55,954,228 48,485,561 52,347,271 (1) Corresponds to the application of Decree 1880 of September 2014 and Resolution 180522 of 2010, which defined the procedure for price differentials (value generated by the difference between the parity price and the regulated price, which can be positive or negative). See Note 4.16 – Sales revenue recognition, for more details. Sales by geographic areas 2017 % 2016 % 2015 % Colombia 28,236,092 50.5 % 24,745,172 51.0 % 26,066,621 49.8 % United States 12,532,932 22.4 % 11,956,967 24.7 % 11,921,720 22.8 % Asia 6,136,796 11.0 % 2,717,414 5.6 % 6,123,593 11.7 % Central America and the Caribbean 6,070,565 10.8 % 3,551,894 7.3 % 3,366,978 6.4 % South America and others 1,947,226 3.5 % 2,568,163 5.3 % 886,433 1.7 % Europe 1,030,617 1.8 % 2,945,951 6.1 % 3,981,926 7.6 % 55,954,228 100 % 48,485,561 100 % 52,347,271 100 % Concentration of customers During 2017, Organización Terpel S.A. represented 14.3 14.4 14.4 10 segments

Cost of sales

Cost of sales	12 Months Ended
	Dec. 31, 2017
Disclosure of cost of sales before impairment of non-current assets [Abstract]
Disclosure of cost of sales [text block]	26. Cost of sales 2017 2016 2015 Variable costs Imported products (1) 11,637,419 12,049,477 12,935,878 Depreciation, amortization and depletion 5,765,186 5,333,245 5,166,455 Purchases of hydrocarbons - ANH (2) 4,338,576 3,178,199 3,741,010 Purchases of crude in association and concession 2,240,704 1,517,829 1,928,938 Process materials 889,122 608,535 366,454 Hydrocarbon transport services 665,714 783,307 1,380,733 Electric energy 561,424 618,675 424,920 Purchases of other products and gas 488,056 519,884 703,163 Taxes and contributions (3) 449,959 478,332 481,029 Services contracted in associations 195,689 305,326 563,032 Others (4) (663,916) (432,694) (322,547) 26,567,933 24,960,115 27,369,065 Fixed costs Depreciation and amortization 2,366,849 2,050,739 1,433,263 Maintenance 2,038,970 1,998,128 2,334,130 Labor costs 1,815,213 1,571,511 1,542,701 Services contracted 1,414,056 1,083,176 1,301,094 Services contracted in associations 1,008,336 1,260,470 1,415,422 General costs 510,128 383,842 461,994 Materials and operating supplies 468,205 333,258 435,238 Taxes and contributions 343,505 391,032 461,624 Hydrocarbon transport services 333,671 157,463 147,733 Non-capitalized costs of projects 41,459 61,689 92,252 10,340,392 9,291,308 9,625,451 36,908,325 34,251,423 36,994,516 (1) Imported products correspond mainly to diesel fuel and diluent to facilitate the transport of heavy crude oil. (2) Corresponds to purchases of crude oil by Ecopetrol from the National Hydrocarbons Agency (ANH) derived from national production, both of the Group in direct operation and of third parties. (3) Includes gas royalties paid and carbon tax. (4) Corresponds to the capitalization of production costs to inventory.

Administrative, operations and

Administrative, operations and project expenses	12 Months Ended
	Dec. 31, 2017
Disclosure of Administration, operation and project expenses [Abstract]
Disclosure of general and administrative expense [text block]	27. Administrative, operations and project expenses 2017 2016 2015 Administrative expenses General expenses 723,341 556,563 393,971 Labor expenses 624,424 657,051 491,748 Taxes (1) 362,963 663,889 730,841 Depreciation and amortization 53,796 45,765 84,425 1,764,524 1,923,268 1,700,985 Operations and project expenses Exploration costs 1,341,940 728,590 1,584,249 Commissions, fees, freights and services 471,657 568,513 878,259 Taxes 324,223 286,331 348,871 Labor expenses 310,947 278,383 309,021 Maintenance 122,273 147,197 181,630 Depreciation and amortization 95,516 177,252 86,215 Fee for regulatory entities 63,470 87,325 77,909 Corporate projects 29,702 301,854 456,159 Others 166,337 176,242 111,955 2,926,065 2,751,687 4,034,268 (1) Mainly corresponds to the recognition of the wealth tax. See Note 10 - Taxes.

Other operating income net

Other operating income net	12 Months Ended
	Dec. 31, 2017
Disclosure of Other operating income and expenses, net [Abstract]
Disclosure of other operating income expense [text block]	28. Other operating income net 2017 2016 2015 (Expense) recovery of provisions for litigations (72,408) 112,999 205,879 Expense for gas pipeline availability BOMT contracts (1) (72,318) (125,077) (124,957) Impairment expense of short-term assets (68,800) (98,739) (2,858) Profit (loss) on sale of assets 40,227 (82,200) 6,744 Gain on acquisition of interests in joint operation (Note 32.3) 451,095 - - Compensation received - 17,790 29,848 Deferred income BOMT contract’s (2) - 211,768 193,197 Other income 227,607 237,571 70,685 505,403 274,112 378,538 (1) Corresponds to the services rendered in connection with the BOMT contracts for the construction, operation, maintenance and transfer of gas pipelines with Transgas. This contract terminated in August 2017. (2) Corresponds to the amortization of the deferred income recognized by Ecopetrol in 2007 for the advance payment made by the Ministry of Finance and Public Credit of the obligations by Ecogas, in relation to the BOMT contracts for the construction, operation, maintenance and transfer of gas pipelines, signed between Ecopetrol and Transgas de Occidente, Centragas and Gases de Boyacá and Santander S.A. in 1997. The amortization of this deferred income ended in December 2016.

Financial result, net

Financial result, net	12 Months Ended
	Dec. 31, 2017
Disclosure of financial result, net [Abstract]
Disclosure of finance income (cost) [text block]	Financial result, net 2017 2016 2015 Finance income Results from financial assets and others 739,148 136,715 164,615 Yields and interests 405,562 386,001 293,506 Gain on sale of equity instruments 13,236 47,129 72,339 Resources from Santiago de las Atalayas (1) - 688,664 - Other financial income 1,410 53,234 91,464 1,159,356 1,311,743 621,924 Finance expenses Interest (2) (2,385,994) (2,765,024) (1,768,618) Financial cost of other liabilities (3) (753,047) (580,491) (627,827) Results from financial assets (481,308) (48,997) (167,869) Other financial expenses (40,252) (69,028) (154,100) (3,660,601) (3,463,540) (2,718,414) Foreign exchange gain (loss), net 5,514 976,430 (5,566,614) Financial result, net (2,495,731) (1,175,367) (7,663,104) (1) Corresponds to the recovery of the provision “Comuneros – Santiago de las Atalayas”. Its balance consisted mainly from the valuation and financial gains generated while the cash that was subject to the reserve (see Note 23.3 for more information). (2) As of December 31, 2017, borrowing costs for the financing of developing natural resources and property, plant and equipment of COP$ 191,651 341,209 744,426 (3) Includes

Risk management

Risk management	12 Months Ended
	Dec. 31, 2017
Disclosure of financial risk management [Abstract]
Disclosure of financial risk management [text block]	30. Risk management 30.1 Commodity price risk Ecopetrol’s business is significantly impacted by international prices for crude oil and refined products. The prices for these products are volatile and drastic changes could adversely affect the Group business prospects and results of operations. A large proportion of Ecopetrol’s sales revenues come from sales of crude oil, natural gas and refined products. These products are indexed to international reference prices such as the Brent index. Consequently, fluctuations in those international indexes have a direct effect on the financial condition and Group’s results of operations. Prices of crude oil, natural gas and refined products have historically fluctuated as a result of a variety of factors including, among others, competition within the oil and natural gas industry; changes in international prices of natural gas and refined products; long-term changes in the demand for crude oil, natural gas and refined products; regulatory changes; changes in the cost of capital; adverse economic conditions; transactions in derivative financial instruments related to oil and gas and development or availability of alternative fuels. The Ecopetrol Business Group has a policy approved by the Board of Directors that allows it to use derivative financial instruments in the organized over the counter (OTC) market to cover itself from the risk of price fluctuations of crude oil and refined products associated with physical transactions. The Group has established appropriate processes to handle risk which include constant monitoring of physical and financial markets to identify risks in order to subsequently prepare and execute hedging strategies. Ecopetrol does not regularly use derivative instruments to hedge exposures to sales or purchase price risks. The impact of the settlement of the price hedges made in 2016 and 2015 was not material and was made as hedging instruments to mitigate risk at different price indices to the benchmark of the Group's international trade strategy on exports of crude and imports of products. In 2017, hedging transactions were not carried out with derivative instruments. In 2016 and 2015, then outstanding price hedges were settled in full, with an impact on the result of the period of COP$ 3,181 4,141 30.2 Exchange rate risk The Ecopetrol Business Group operates mainly in Colombia makes sales in the local and international markets. It is exposed to exchange rate risk, which arises from various foreign currency exposures due to commercial transactions and assets and liabilities denominated in foreign currency. The impact of exchange rate fluctuations, especially the Colombian peso/U.S. dollar exchange rate, has been material in previous years. To mitigate this risk, the Group's risk management strategy involves the use of non-derivative financial instruments related to cash flow hedges for future exports and net investment of foreign operations to minimize exchange rate risk exposure. The U.S. dollar/Colombian peso exchange rate has fluctuated over the last few years. The Colombian peso appreciated on average by 3.3 11.2 37.3 3,000.71 3,149.47 When the Colombian peso appreciates in relation to the U.S. dollar, export sales revenue decreases when converted to Colombian pesos; however, imported goods, oil services and interest on foreign debt denominated in U.S. dollars become less expensive. Conversely, when the Colombian peso depreciates, export revenues, when translated to Colombian pesos, increases, and imports and servicing of the external debt become more expensive. (in US$ Million) 2017 2016 Cash and cash equivalents 1,203 1,916 Other financial assets 1,072 1,367 Trade receivables and payables, net (7) (282) Loans and borrowings (12,590) (15,172) Net liability position (10,322) (12,171) Of the total net liability position, US$ 8,532 1,699 91 30.2.1 Sensitivity analysis for exchange rate risk The Group’s risk management strategy involves the use of non-derivative financial instruments related to cash flow hedges for future exports and hedges of a net investment in a foreign operation in order to minimize exposure to currency rate risk, which is detailed below. Scenario / Variation in Effect on income Effect on other 1 % 2,715 305,293 5 % 13,577 1,526,465 The sensitivity analysis only includes financial assets and liabilities in foreign currency at the closing date. 30.2.2 Cash flow hedge for future exports Ecopetrol is exposed to foreign exchange risk given that a significant percentage of its income from crude oil exports is denominated in U.S. dollars. In recent years, the Group has acquired long-term debt for investment activities in the same currency in which it expects to receive the cash flow of its export sales revenues. This situation creates a natural hedge relationship due to the fact that the risks generated by the foreign exchange difference of export sales revenues when booked in Ecopetrol’s functional currency (Colombian pesos) are naturally hedged with the foreign exchange variances of the long-term debt, in line with the Group's risk management strategy. With the objective of presenting in the financial statements the effect of the existing natural hedge between exports and debt, understanding that the exchange rate risk materializes when the exports are made, on October 1, 2015, the Board of Directors designated the sum of US$5,440 million of Ecopetrol's foreign currency debt as a hedge instrument of future revenue from crude oil exports, for the period 2015-2023, in accordance with IAS 39 - Financial instruments: Recognition and Measurement. Hedge accounting records the impact on the statement of profit or loss at the time of realization of the hedged risk. For this to happen, every month when foreign currency debt is converted to Colombian pesos based on the closing rate for the period, the effects for exchange difference are recognized in other comprehensive income, within equity and, as crude oil exports take place and the hedge occurs and sales revenue is recognized, cumulative exchange differences held within other comprehensive income are reclassified to profit or loss statement, impacting operating income. (US$ Million) 2017 2016 Hedging instrument at the beginning of the period 5,312 5,376 Reassignment of hedging instruments 1,803 870 Realization of exports (1,803) (870) Capital payments (1) (1,980) (64) Hedging instrument at the end of the period 3,332 5,312 (1) On June 30, 2017, Ecopetrol prepaid the entire outstanding balance of the international syndicated loan whose nominal value was US$ 1,925 2017 2016 Opening balance (244,131) 217,291 Exchange difference 15,934 (724,395) Reclassification to profit or loss 160,772 (33,074) Ineffectiveness (9,247) - Deferred income tax (82,622) 296,047 Closing balance (159,294) (244,131) Year Before Taxes After taxes 2018 95,462 (33,439) 62,023 2019 66,039 (23,132) 42,907 2020 23,804 (8,338) 15,466 2021 21,541 (7,545) 13,996 2022 21,541 (7,545) 13,996 2023 16,786 (5,880) 10,906 245,173 (85,879) 159,294 30.2.3 Hedge of a net investment in a foreign operation The Board of Directors approved the application of net investment hedge accounting from June 8, 2016. The measure is intended to reduce the volatility of non-operating income due to exchange rate variations. The net investment hedge will be applied on a portion of Group’s investments in foreign operations, in this case on investments in subsidiaries which have the US dollar as their functional currency, using a portion of the Group’s US dollar denominated debt as the hedging instrument. Ecopetrol designated the net investments in Ocensa, Ecopetrol America Inc., Hocol Petroleum Ltd. (HPL) and Reficar and as hedged items and as a hedging instrument and US$ 5,200 2016 2017 2016 Opening balance 155,359 - Exchange difference (86,892) 231,879 Ineffectiveness 329 - Deferred income tax 28,566 (76,520) Closing balance 97,362 155,359 30.2.4 Hedging with derivatives to minimize currency risk The Group carries out forwards hedging operations using the Non-Delivery modality, for mitigating the volatility of the exchange rate in the cash flow required for operations of its subsidiary, Ocensa, whose functional currency is the US dollar. The forward hedging instruments used enable setting sales prices in US dollars, mitigating the foreign exchange variation given Ocensa’s obligations relative to operational cost and tax payments are payable in Colombian pesos. The accounting policy applicable to this operation is described in the Note 4.1.5.1. As of December 31, 2017, there are forward contracts with a net short position for US$ 325 323 The impact on the statement of profit or loss for the settlement of these hedges amounted to COP$ 99,971 42,865 35,769 33,869 30.3 Credit risk Credit risk is the risk that the Group may suffer financial losses as a consequence of default of: a) payments by its clients for the sale of crude oil, gas, products or services; b) financial institutions in which it keeps investments, or c) by counterparties with which it has contracted financial instruments. 30.3.1 Credit risk for customers In the selling process of crude oil, gas, refined products and petrochemicals, and transport services, the Group may be exposed to credit risk in the event that customers fail to fulfill their payment obligations. The Group’s risk management strategy has designed mechanisms and procedures that aim to minimize such events, thus safeguarding the Group's cash flow. The Group performs a continuous analysis of the financial strength of its counterparties, by classifying them according to their risk level and financial guarantees in the event of a default of payments. Similarly, the Group continuously monitors national and international market conditions for early alerts of major changes that may have an impact on the timely payment of obligations from customers of the Group. Allowances for loan losses are set by individual analysis of each customer’s situation. The Group performs administrative and legal actions required to recover amounts past due and charges interest from customers that fail to comply with payment policies. 2017 2016 Less than 3-month overdue 65,354 179,008 Between 3- and 6-month overdue 1,131 14,275 More than 6-month overdue 79,688 103,574 146,173 296,857 30.3.2 Credit quality of resources in financial assets Following the promulgation of Decree 1525 of 2008, which provides general rules on investments for public entities, Ecopetrol’s management established guidelines for our investment portfolios. These guidelines determine that investments in Ecopetrol’s U.S. dollar portfolio are generally limited to investments of our excess cash in fixed-income securities issued by entities rated A or higher in the long term and A1/P1/F1 or higher in the short term (international scale) by Standard &; Poor’s Ratings Services, Moody’s Investors Service or Fitch Ratings. In addition, Ecopetrol S.A. may also invest in securities issued or guaranteed by the U.S. government or Colombian government, without regard to the ratings assigned to such securities. In Ecopetrol’s Colombian Peso portfolio, it must invest our excess cash in fixed-income securities of issuers rated AAA in the long term, and F1+/BRC1+ in the short term (local scale) by Fitch Ratings Colombia or BRC Standard &; Poor’s. In addition, Ecopetrol may also invest in securities issued or guaranteed by the Colombian government without rating restrictions. In order to diversify risk in our Colombian Peso portfolio, Ecopetrol does not invest more than 10 5 1 Ecopetrol’s investment portfolio in U.S. dollars is segmented into four tranches, each one matching our liquidity needs. The working capital tranche is calculated taking into account our cash flow needs for the next 60 days. The liquidity tranche is calculated as the contingent cash flow needs over the working capital, taking into account the development of capital expenditures related to projects. The asset liability tranche is built to match our long-term debt. The investment tranche includes the remaining amount of the total portfolio after deducting the amounts pertaining to the above mentioned tranches and after subtracting the Colombian Peso portfolio. Ecopetrol’s investment portfolio in Colombian Pesos is segmented in two tranches, each one matching our liquidity needs. The first tranche is calculated taking into account our cash flow needs for the next 30 days, and the second tranche is built for investment purposes. The credit rating of issuers and counterparties in transactions involving financial instruments is disclosed in Note 6 - Cash and cash equivalents, Note 7 - Other financial assets and Note 21 - Provisions for employee benefits. 30.4 Interest rate risk Interest rate risk arises from Ecopetrol’s exposure to changes in interest rates because the Ecopetrol Business Group has investments in fixed and floating-rate instruments and has issued floating rate debt linked to LIBOR, DTF and IPC interest rates. Thus, interest rate volatility may affect the fair value and cash flows of the Group's investments and the financial expense of floating rate loans and financing. As of December 31, 2017, 19 31 Ecopetrol controls the exposure to interest rate risk by establishing limits to exposure duration, Value at Risk - VAR and tracking error. Autonomous equities linked to Ecopetrol’s pension obligations are also exposed to changes in interest rates, as they include fixed and floating rate instruments that are marked to market. Colombian regulation for pension funds, as stipulated in the Decree 941 of 2002 and Decree 1861 of 2012, indicates that they have to follow the same regime as the regular obligatory pension funds in their moderate portfolio. Effect on profit or loss (+/-) Effect on Other Financial Financial Plan assets +100 basis points (66,120) 112,383 (171,031) -100 basis points 66,120 (112,282) 183,988 A sensitivity analysis of discount rates on pension plan assets and liabilities is disclosed in Note 22 – Provisions for employee benefits. 30.5 Liquidity risk The ability to access capital necessary to finance the Group’s investment plans on acceptable terms can be limited due to deterioration in market conditions. A new financial crisis could worsen risk perception in emerging markets. Events impacting the political and regional environment of Colombia, could make it difficult for our subsidiaries to access capital markets. These conditions, together with potential significant losses in the financial services sector and changes in credit risk assessments, may make it difficult to obtain financing on favorable terms. As a result, the Group may be forced to review the opportunity and scope of its investment plans as necessary, or access financial markets under less favorable terms, thereby negatively affecting the Group’s results of operations and financial position. Liquidity risk is managed in accordance with the Group’s policies aimed at ensuring that there are sufficient net funds to meet the Group's financial commitments within its maturity schedules with no additional costs. The main method for the measurement and monitoring of liquidity is cash flow forecasting. During 2017, the Group used US$ 2,400 Up to 1 year 1-5 years 5-10 years > 10 years Total Loans (payment of principal and interest) 5,040,130 28,151,892 18,873,280 15,484,650 67,549,952 Trade and other payables 6,968,207 134,815 - - 7,103,022 Total 12,008,337 28,286,707 18,873,280 15,484,650 74,652,974 30.6 Capital management The main objective of the capital management of the Ecopetrol Business Group is to ensure a financial structure that optimizes the cost of capital, maximizes the rate of return to its shareholders and allows access to financial markets at a competitive cost to cover financing needs that support an investment grade credit rating profile. 2017 2016 Loans and borrowings (Note 20) 43,547,835 52,222,027 Cash and cash equivalents (Note 6) (7,945,885) (8,410,467) Other financial assets (Note 9) (6,533,725) (6,686,895) Net financial debt 29,068,225 37,124,665 Equity (Note 24) 48,215,699 43,560,501 Leverage 37.61 % 46.01 % The movement of the net financial debt is detailed in Note 20.8.

Related parties

Related parties	12 Months Ended
	Dec. 31, 2017
Disclosure of transactions between related parties [abstract]
Disclosure of related party [text block]	Related parties associates Accounts Accounts Other Accounts Loans Other Joint Ventures Equion Energy Limited (1) 4,010 - 7,716 101,472 259,760 7 Ecodiesel Colombia S.A. 362 - - 22,228 - - Associates Invercolsa S.A. 18,641 - - - - - Offshore International Group Inc. (2) - 154,810 - - - - Serviport S.A. - - - 5,820 - - Balance as of December 31, 2017 23,013 154,810 7,716 129,520 259,760 7 Current 23,013 - 7,716 129,520 259,760 7 Non-current - 154,810 - - - - 23,013 154,810 7,716 129,520 259,760 7 Accounts Accounts Other assets Accounts Loans Joint Ventures Equion Energy Limited 97,601 - 7,135 89,666 30,644 Ecodiesel Colombia SA 129 - - 20,765 - Offshore International Group (2) - 170,121 - - - Associates Serviport SA - - - 3,989 - Balance as of December 31, 2016 97,730 170,121 7,135 114,420 30,644 Current 97,730 - 7,135 114,420 30,644 Non-current - 170,121 - - - 97,730 170,121 7,135 114,420 30,644 Loans with related parties: (1) Deposits held by Equion in Capital AG for a nominal value of US$ 77 1.44 (2) Loan granted by Ecopetrol SA to Savia Perú SA (subsidiary of Offshore International Group) for US$ 57 4.99 49 The amounts outstanding are not guaranteed and will be settled in cash. No expense has been recognized in the current period or in previous periods with respect to uncollectible or doubtful accounts related to the amounts owed by related parties. 2017 2016 2015 Sales and Purchases Sales and Purchases Sales and Purchases Joint Ventures Equion Energy Limited 425,881 598,636 491,698 418,618 515,968 190,158 Ecodiesel Colombia SA 6,583 259,269 5,744 265,584 7,245 267,647 Offshore International Group 15,188 - 6,285 - - - Associates Serviport SA - - - 24,572 - - Total 447,652 857,905 503,727 708,774 523,213 457,805 The dividends received from these Companies are related in note 14 - Investments in associates and joint ventures. 31.1 Key executives management In accordance with the approval given by the shareholders’ meeting in 2012, compensation paid to committees 4,426,000 4,140,000 3,870,000 50 compensation 1,877 1,253 The total compensation paid to Directors as of December 31, 2017 amounted to COP$ 20,669 13,901 5,401 4,674 Key management personnel % Shares Felipe Bayón <1% outstanding shares Mauricio Cárdenas Santamaría <1% outstanding shares Héctor Manosalva Rojas <1% outstanding shares Rafael Espinosa Rozo <1% outstanding shares 31.2 Post-employment benefit plans The administration and management of resources for payment of Ecopetrol's pension obligations are managed by autonomous pension funds As of December 31, 2017 and 2016, the entities managing these resources were: Fiduciaria Bancolombia, Fiduciaria de Occidente and Consorcio Ecopetrol PAAC (comprised of Fiduciaria La Previsora, Fiduciaria Bancoldex, Fiduciaria Agraria and Fiduciaria Central). These entities will manage pension resources for a five-year term (2016 - 2021) 31.3 Government related parties The Colombian Government controls 88.49 a) Purchase of oil from the National Hydrocarbons Agency - ANH The Group has a direct relationship with ANH, an entity which operates under the rules of the Ministry of Mines and Energy, whose objective is to manage the oil and gas reserves and resources owned by the Colombian Nation. Ecopetrol purchases the crude oil that the ANH receives from all producers in Colombia at the prices set in accordance with a jointly established formula, which reflects the export sale prices (crude oils and products), adjusted for API gravity quality, sulfur content, transportation rates from the wellhead to the ports of Coveñas and Tumaco, refining process cost and a commercialization rate. This contract was extended to June 30, 2018. From December 2013 the Group commercialized, on behalf of the ANH, the natural gas received by the latter in kind from producers. Since January 2014, ANH has received royalties in cash for the production of natural gas. The purchase value of oil and gas from ANH is detailed in Note 26 - Cost of sales. Additionally Ecopetrol, like other oil companies, takes part in "rounds" for the allocation of exploration blocks in Colombia without implying special treatment for Ecopetrol on account of it being an entity whose majority shareholder is the Colombian Government. b) Price differential Regular gasoline and diesel sale prices are regulated by the National Government. In this case, there are differentials between the volume reported by the Colombian companies at the time of the sale and the difference between the international parity price and the regulated price actually charged, where the parity price is the daily price of gasoline and diesel oil of the respective month in Colombian pesos, indexed to the United States of America Gulf market, calculated in accordance with Resolution 18 0522 of 2010 and the Producer Price reference defined by the Ministry of Mines and Energy. These differentials may be in favor or against the producers. The value of this differential is detailed in Note 25 - Sales revenue and 7 – Trade and other receivables, net. c) National Tax and Customs Direction Ecopetrol, just like any other company in Colombia, has tax obligations that it must comply with and does not have any other kind of association or commercial relationship with the National Tax and Customs Direction. For more information see Note 10 – Taxes. d) Comptroller General of the Republic Ecopetrol, just like any other state entity in Colombia, is obliged to comply with the requirements set out by the Comptroller General of the Republic and make an annual payment to this entity on account of a maintenance fee. Ecopetrol does not have any other kind of association or commercial relationship with this entity.

Joint operations

Joint operations	12 Months Ended
	Dec. 31, 2017
Disclosure of joint operations [abstract]
Disclosure of joint operations [text block]	32. Joint operations The Group 32.1 Partners Contract Type % Geographic area of Chipirón 30-40% Harvest 30% Occidental Andina LLC Cravo Norte Production 50% Colombia Rondón 50% Chevron Petroleum Group Guajira Production 57% Colombia Mansarovar Energy Colombia Ltd Nare Production 50% Colombia Meta Petroleum Corp Quifa Production 40% Colombia Equion Energy Limited Piedemonte Production 50% Colombia Casanare 64% Corocora 56% Perenco Colombia Limited Estero Production 89% Colombia Garcero 76% Orocúe 63% ONGC Videsh Limited RC-10 Caribbean Round Exploration 50% North Caribbean Offshore Petrobras, Repsol &; Statoil Tayrona Exploration 30% North Caribbean Offshore Repsol &; Statoil TEA GUA OFF-1 Exploration 50% North Caribbean Offshore Anadarko Fuerte Norte Exploration 50% North Caribbean Offshore Shell Deep Rydberg/Aleatico Exploration 29% Gulf of Mexico Repsol - Leon Lion Exploration 40% Gulf of Mexico Noble Energy Gunflint Production 32% Gulf of Mexico Murphy Oil Dalmatian Production 30% Gulf of Mexico Anadarko K2 Production 21% Gulf of Mexico Equion Energia Limited Niscota Production 20% Brazil Chevron CE-M-715_R11 Exploration 50% Brazil 32.2 Partners Contract Type % Geographic VMM29 ExxonMobil Exploration Colombia CR2 Exploration 50% Colombia C62 Talisman Colombia Oil CPO9 Exploration 55% Colombia ONGC Videsh Limited Colombia Branch RC9 Exploration 50% Colombia CPVEN Sucursal Colombia VMM32 Exploration 51% Colombia Shell Exploration and Production CR4 Exploration 50% Colombia Hocol S.A. AMA4 Exploration 100% Colombia SK Innovation Co Ltd. San Jacinto Exploration 70% Colombia Repsol Exploración Colombia S.A. Catleya Exploration 50% Colombia Emerald Energy PLC Suc. Colombia Cardon Exploration 50% Colombia Gas Ltd. CPO9 - Akacias Production 55% Colombia Occidental Andina LLC La Cira Infantas Production 58% Colombia Teca 86% Colombia Ramshorn International Limited Guariquies I Production 50% Colombia Equion Energy Limited Cusiana Production 98% Colombia Perenco Oil And Gas San Jacinto Rio Paez Production 18% Colombia Cepsa Colombia San Jacinto Rio Paez Production 18% Colombia Total Colombia Mundo Nuevo Exploration 15% Colombia Talisman Oil &; Gas Mundo Nuevo Exploration 15% Colombia Lewis Clarinero Exploration 50% Colombia Maurel &; Prom Suramerica CPO17 Exploration 50% Colombia Equion Energia Limited Alto Magdalena Pipeline OAM 45% Colombia Emerald Energy Alto Magdalena Pipeline OAM 45% Colombia Frontera Energy Alto Magdalena Pipeline OAM 45% Colombia ONGC Videsh Limited Block RC-9 Contract- Caribbean Round No. 37-2007 Exploration 50% Gulf of Mexico JX Nippon FAZ-M-320_R11 Exploration 70% Brazil JX Nippon POT-M-567_R11 Exploration 100% Brazil 32.3 Relevant operations during the period During 2017 and 2016, the following significant events occurred in respect of our a) Acquisition of interests in joint operations On December 11, 2017, Ecopetrol América Inc. acquired the 11.6 9.2 20.8 The acquisition of MCX’s interest was recognized in accordance with policy 4.4 Joint Operations. To determine the fair value of the assets acquired and liabilities assumed, the income approach model was used, using the discounted cash flow and market data to determine the fair values of oil and gas properties. This model incorporated future commodity prices, estimated volumes of oil and gas reserves, future developments, operating costs, future abandonment and packing costs and a risk adjusted discount rate. The fair value of the consideration transferred 47.6 141,950 198.4 146 recognition a gain of 150.8 98 451,095 Transaction costs incurred in the operation amounted to US $ 0.2 b) Termination of the Rubiales and Pirirí field contracts On and Pirirí fields gained control over 46 c) Termination of the Tauramena association agreement On July 3, 2016, the Tauramena Association Agreement was terminated and for this reason, Ecopetrol began to operate directly the Cusiana field, Casanare. Since its commercialization in 1993, it was operated first by BP and then by Equion. Cusiana represents for Ecopetrol a 98 2

Information by segments

Information by segments	12 Months Ended
	Dec. 31, 2017
Disclosure of operating segments [abstract]
Disclosure of entity's operating segments [text block]	33. Information by segments A description of the Group’s business segments is in Note 4.19 – Information by business segment. 33.1 Statement of profit or loss The following segment information is reported based on the information used by the Board of Directors as the top body to make strategic and operational decisions of these business segments. The performance of the segments are based primarily on an analysis of income, costs, expenses and results for the period generated by each segment which are regularly monitored. The information disclosed in each segment is presented net of transactions between the Ecopetrol Business by segment For the year ended on December 31, 2017 Exploration Refining and Transport Eliminations Total Third-party sales 25,004,320 27,343,359 3,606,549 - 55,954,228 Inter-segment sales 11,490,614 1,300,657 6,991,515 (19,782,786) - Total sales revenue 36,494,934 28,644,016 10,598,064 (19,782,786) 55,954,228 Fixed costs 8,055,925 2,886,745 2,637,604 (3,239,880) 10,340,394 Variable costs 18,254,159 23,968,650 634,231 (16,289,109) 26,567,931 Cost of sales 26,310,084 26,855,395 3,271,835 (19,528,989) 36,908,325 Gross profit 10,184,850 1,788,621 7,326,229 (253,797) 19,045,903 Administrative expenses 781,386 516,501 466,669 (32) 1,764,524 Operation and project expenses 2,070,916 965,457 142,847 (253,155) 2,926,065 Impairment of non-current assets (183,718) (1,067,965) (59,455) - (1,311,138) Other operating income and expenses, net (545,218) 11,694 28,121 - (505,403) Operating income 8,061,484 1,362,934 6,748,047 (610) 16,171,855 Financial result, net Financial income 1,062,393 164,006 106,659 (173,702) 1,159,356 Financial expenses (2,288,576) (1,110,874) (434,664) 173,513 (3,660,601) Foreign exchange gain (loss), net (101,030) 163,992 (57,448) - 5,514 (1,327,213) (782,876) (385,453) (189) (2,495,731) Share of profits of associates 120,786 15,245 (42,493) - 93,538 Income before tax 6,855,057 595,303 6,320,101 (799) 13,769,662 Income tax (3,034,556) (238,625) (2,527,087) - (5,800,268) Net profit (loss) for the period 3,820,501 356,678 3,793,014 (799) 7,969,394 Profit (loss) attributable to: Group owners of parent 3,820,501 358,859 2,999,978 (799) 7,178,539 Non-controlling interest - (2,181) 793,036 - 790,855 3,820,501 356,678 3,793,014 (799) 7,969,394 Supplementary information Depreciation, depletion and amortization 5,981,294 1,188,871 1,111,182 - 8,281,347 For the year ended December 31, 2016 Exploration and Refining and Transportation Eliminations Total Third-party sales 20,527,332 24,194,024 3,764,205 - 48,485,561 Inter-segment sales 7,693,878 629,690 6,884,571 (15,208,139) - Total sales revenue 28,221,210 24,823,714 10,648,776 (15,208,139) 48,485,561 Fixed cost 6,940,074 2,458,745 2,861,269 (2,968,780) 9,291,308 Variable cost 16,032,574 20,385,242 488,522 (11,946,223) 24,960,115 Cost of sales 22,972,648 22,843,987 3,349,791 (14,915,003) 34,251,423 Gross profit 5,248,562 1,979,727 7,298,985 (293,136) 14,234,138 Administrative expenses 832,266 574,413 516,884 (295) 1,923,268 Operation and projects expenses 1,656,960 1,206,718 180,353 (292,344) 2,751,687 Impairment of non-current assets 196,448 773,361 (41,062) - 928,747 Other operating income and expenses, net (349,419) 20,947 53,559 801 (274,112) Operating income 2,912,307 (595,712) 6,589,251 (1,298) 8,904,548 Financial result, net Financial income 983,472 46,469 61,373 220,429 1,311,743 Financial expenses (2,017,641) (952,006) (262,844) (231,049) (3,463,540) Foreign exchange gain (loss), net 923,573 94,715 (41,858) - 976,430 (110,596) (810,822) (243,329) (10,620) (1,175,367) Share of profit of associates 39,397 22,785 (837) - 61,345 Income before tax 2,841,108 (1,383,749) 6,345,085 (11,918) 7,790,526 Income tax (1,518,738) (446,595) (2,577,713) - (4,543,046) Net income for the period 1,322,370 (1,830,344) 3,767,372 (11,918) 3,247,480 Income attributable to: Group owners of parent 1,322,370 (1,823,020) 2,960,449 (11,918) 2,447,881 Non-controlling interest - (7,324) 806,923 - 799,599 1,322,370 (1,830,344) 3,767,372 (11,918) 3,247,480 Supplementary information Depreciation, depletion and amortization 5,482,827 1,145,780 978,394 - 7,607,001 For the year ended December 31, 2015 Exploration and Refining and Transportation Eliminations Total Third-party sales 25,669,213 22,456,866 4,221,192 - 52,347,271 Inter-segment sales 6,063,398 788,810 6,623,358 (13,475,566) - Total Revenue 31,732,611 23,245,676 10,844,550 (13,475,566) 52,347,271 Fixed costs 7,208,632 1,902,797 3,304,815 (2,790,793) 9,625,451 Variable costs 18,500,240 18,856,011 439,607 (10,426,793) 27,369,065 Cost of sales 25,708,872 20,758,808 3,744,422 (13,217,586) 36,994,516 Gross income 6,023,739 2,486,868 7,100,128 (257,980) 15,352,755 Administrative expenses 731,626 451,250 518,109 - 1,700,985 Operation and projects expenses 2,969,723 1,155,301 157,596 (248,352) 4,034,268 Impairment of non-current assets 4,504,497 3,278,993 81,388 - 7,864,878 Other operating income and expenses, net (399,954) 122,595 (101,182) - (378,541) Operating income (1,782,153) (2,521,271) 6,444,217 (9,628) 2,131,165 Finance results, net Financial income 536,121 135,622 86,568 (136,387) 621,924 Financial expenses (1,774,090) (451,906) (492,485) 67 (2,718,414) Foreign exchange gain (loss), net (4,798,741) (949,176) 181,303 - (5,566,614) (6,036,710) (1,265,460) (224,614) (136,320) (7,663,104) Share of profit of companies (70,407) 23,187 533 - (46,687) Income before tax (7,889,270) (3,763,544) 6,220,136 (145,948) (5,578,626) Income tax 2,037,650 (257,256) (2,490,747) - (710,353) Net income (loss) for the period (5,851,620) (4,020,800) 3,729,389 (145,948) (6,288,979) Income attributable to: Group owners of parent (5,851,620) (4,016,050) 2,819,759 (145,948) (7,193,859) Non-controlling interest - (4,750) 909,630 - 904,880 (5,851,620) (4,020,800) 3,729,389 (145,948) (6,288,979) Supplementary information Depreciation, depletion and amortization 5,318,587 570,033 881,738 - 6,770,358 33.2 Sales by product For the year ended on December 31, 2017 Exploration Refining and Transport and Eliminations Total Local sales Mid-distillates 1,334 9,588,992 - - 9,590,326 Gasoline - 8,052,289 - (1,062,102) 6,990,187 Services 181,384 221,910 10,597,698 (7,127,640) 3,873,352 Natural gas 2,540,233 4 - (724,483) 1,815,754 Crude oil 11,668,529 - - (10,758,658) 909,871 Plastic and rubber - 833,982 - - 833,982 LPG and propane 199,796 309,823 - - 509,619 Asphalts 34,834 240,969 - - 275,803 Other products 214,059 1,103,089 - (109,903) 1,207,245 14,840,169 20,351,058 10,597,698 (19,782,786) 26,006,139 Recognition of price differential - 2,229,953 - - 2,229,953 14,840,169 22,581,011 10,597,698 (19,782,786) 28,236,092 Foreign sales Crude oil 21,426,665 52,398 - - 21,479,063 Fuel oil - 1,982,408 - - 1,982,408 Gasoline and turbo fuels - 1,223,994 - - 1,223,994 Diesel - 1,213,740 - - 1,213,740 Plastic and rubber - 1,169,101 - - 1,169,101 Natural gas 32,303 - - - 32,303 LPG and propane 15,631 - - - 15,631 Cash flow hedge for future exports – Reclassification to profit or loss 160,772 - - - 160,772 Other 19,393 421,364 367 - 441,124 21,654,764 6,063,005 367 - 27,718,136 36,494,933 28,644,016 10,598,065 (19,782,786) 55,954,228 For the year ended December 31, 2016 Exploration Refining and Transportation Eliminations Total Local sales Med-distillates - 8,553,503 - - 8,553,503 Gasoline and turbo fuel - 6,465,939 - (373,200) 6,092,739 Services 73,247 41,736 10,572,170 (6,643,869) 4,043,284 Natural gas 2,383,323 11,763 - (406,750) 1,988,336 Plastic and rubber - 724,708 - - 724,708 L.P.G. and propane 90,783 319,644 - (4,558) 405,869 Crude oil 5,284,554 - - (4,730,888) 553,666 Asphalts 31,277 309,123 - - 340,400 Aromatics - 186,228 - - 186,228 Oil fuel 1,382 146,866 - - 148,248 Other products 424,952 669,568 75,793 (510,144) 660,169 8,289,518 17,429,078 10,647,963 (12,669,409) 23,697,150 Recognition of price differential - 1,048,022 - - 1,048,022 8,289,518 18,477,100 10,647,963 (12,669,409) 24,745,172 Foreign sales Crude 19,516,197 - - (2,237,618) 17,278,579 Oil fuel - 2,158,539 - - 2,158,539 Med-distillates 1,594,945 - - 1,594,945 Plastic and rubber - 1,171,342 - - 1,171,342 Gasoline and turbo fuel 1,046,758 - - 1,046,758 Natural gas 350,685 - - (291,875) 58,810 L.P.G. and propane 6,342 2,225 - - 8,567 Cash flow hedging – Reclassification 33,074 - - - 33,074 Other products 25,395 363,250 814 316 389,775 19,931,693 6,337,059 814 (2,529,177) 23,740,389 Total sales revenue 28,221,211 24,814,159 10,648,777 (15,198,586) 48,485,561 For the year ended December 31, 2015 Exploration and Refining and Transportation Eliminations Total Local sales Med-distillates 25,782 10,206,599 - (17,157) 10,215,224 Gasoline - 6,464,661 - (336,453) 6,128,208 Services 118,812 198,369 10,822,078 (6,703,985) 4,435,274 Natural gas 2,198,284 - - (352,939) 1,845,345 Crude oil 5,847,368 - - (5,356,089) 491,279 Diesel and asphalts 49,583 411,605 - - 461,188 Plastic and rubber - 724,392 - - 724,392 L.P.G. and propane 154,201 190,346 - (9,053) 335,494 Other products 262,906 1,070,725 22,472 (367,757) 988,346 8,656,936 19,266,697 10,844,550 (13,143,433) 25,624,750 Recognition of price differential - 441,871 - - 441,871 8,656,936 19,708,568 10,844,550 (13,143,433) 26,066,621 Foreign sales Crude 21,495,762 - - (314,497) 21,181,265 Fuel oil - 2,166,469 - - 2,166,469 Trading of crude 1,309,196 1,309,196 Natural gas 233,500 - - (50,550) 182,950 Gasoline and turbo fuel 27,756 65,369 - - 93,125 Diesel - 81,982 - - 81,982 Plastic and rubber - 1,096,730 - - 1,096,730 Cash flow hedging – Reclassification to profit or loss 7,646 - - - 7,646 Other products and services 1,815 126,558 - 32,914 161,287 23,075,675 3,537,108 - (332,133) 26,280,650 Total revenue 31,732,611 23,245,676 10,844,550 (13,475,566) 52,347,271 33.3 Capital expenditures by segments 2017 Exploration Refining and Transport and Total Property, plant and equipment 927,282 606,749 829,252 2,363,283 Natural and environmental resources 3,568,355 - - 3,568,355 Intangibles 154,155 4,941 16,772 175,868 4,649,792 611,690 846,024 6,107,506 2016 Exploration Refining and Transport and Total Property, plant and equipment 1,208,464 1,099,850 1,338,615 3,646,929 Natural and environmental resources 2,121,295 - - 2,121,295 Intangibles 53,774 10,274 5,205 69,253 3,383,533 1,110,124 1,343,820 5,837,477 2015 Exploration Refining and Transport and Total Property, plant and equipment 2,460,975 3,590,279 2,497,679 8,548,933 Natural and environmental resources 6,856,761 - - 6,856,761 Intangibles 69,126 18,494 24,635 112,255 9,386,862 3,608,773 2,522,314 15,517,949

Contractual obligations

Contractual obligations	12 Months Ended
	Dec. 31, 2017
Disclosure of Contractual obligations [Abstract]
Disclosure of commitments [text block]	Contractual obligations The Group has several commitments and contractual obligations that may require future disbursement of funds. The main commitments are related to a) payments of loans and borrowings, which are disclosed in Note 30.5, b) payment of benefits post-employment, the amounts of which in the next 5 years are disclosed in Note 22.4 c) future payment commitments in service contracts, operational leasing, gas and energy supplies, purchase of assets and others, and d) commitments of exploration activities and others with the National Hydrocarbons Agency in current contracts. The details of the commitments and contractual obligations can be found in section 4.8 Financial Review - Financial Indebtedness and Other Contractual Obligations.

Subsequent events

Subsequent events	12 Months Ended
	Dec. 31, 2017
Events after reporting period [Abstract]
Disclosure of events after reporting period [text block]	35. Subsequent events - On April 13, 2018, Ecopetrol redeemed all of its outstanding 4.250 September 18, 2018 350 - On March 14, 2018, Ecopetrol formed the subsidiary Ecopetrol Energía SAS E.S.P., domiciled 99 capitalization 1 - On March 2, 2018, a seepage of water and traces of crude oil occurred near the Lisama 158 well, located in the village of La Fortuna, in the Middle Magdalena Valley of Colombia. Ecopetrol activated its contingency plan to contain the spill. It is estimated that 550 barrels of crude, mixed with mud and rainwater, seeped into the streams of La Lisama and Caño Muerto. As of March 30, 2018, the Lisama 158 well was sealed and stopped flowing. Ecopetrol has ordered an investigation to determine the cause of the seepage. As of the date of this annual report, the National Environmental Licenses Agency (ANLA) has opened an investigation into the incident and the Prosecutor’s Office and other control entities may also open investigations. Besides the notice of seven constitutional actions for protection of fundamental rights. Ecopetrol is not aware of any other third party claims in connection with this incident, it cannot offer any assurance as to whether or not there will be third party actions in the future. - As part of the investigations carried out by various control entities of the modernization and expansion project of Reficar the following developments in the investigations and proceedings have occurred: Office of the Comptroller General (Contraloría General de la República): On February 2, 2018, the Legal Accounts Commission of the National House of Representatives of the Republic of Colombia informed Reficar that the House of Representatives decided, through Resolution No. 2713, that it would not close the General Budget, Treasury Account or the National Balance Sheet for the 2016 fiscal year, since the 2016 Financial Statements of several state entities, among them Reficar, had received a negative opinion from the Office of the Comptroller General. Pursuant to Resolution No. 2713, Colombian control entities have been ordered to initiate disciplinary, fiscal and/or penal investigations. Ecopetrol is not in a position to forecast the results of these investigations; nor is it possible to evaluate the probability of any consequence that may impact the financial statements, such as additional provisions, fines or ignorance of tax deductions that affect the amounts of deferred tax assets.

Supplemental information on oil

Supplemental information on oil and gas producing activities	12 Months Ended
	Dec. 31, 2017
Exploration for and evaluation of mineral resources [Abstract]
Disclosure of exploration and evaluation assets [text block]	Supplemental information on oil and gas producing activities (unaudited) The information in this note is referred to as “unaudited” as a means of clarifying that it is not covered by the audit opinion of the independent registered public accounting firm that has audited and reported on the “Consolidated Financial Statements”. In accordance with the requirements of the United States Securities and Exchange Commission (SEC), Rule 4-10(a) of Regulation S-X, Release 33-8879, Accounting Standards Codification 932 and the ASU- 2010-03 “Oil and Gas reserve Estimation and Disclosures” rule, this section provides supplemental information on oil and gas exploration and producing activities of the Group. The information included in sections a) to c) provides historical cost information pertaining to costs incurred in exploration, property acquisitions and development, capitalized costs and results of operations. The information included in sections d) and e) presents information on Ecopetrol’s estimated net proved reserve quantities, standardized measure of estimated discounted future net cash flows related to proved reserves and changes in estimated discounted future net cash flows. The following information corresponds to Ecopetrol’s oil and gas producing activities as of December 31 2017, 2016 and 2015, and includes information related to the Group’s consolidated subsidiaries as well as its investments the joint ventures Equion Energía Limited and Offshore International Group. The oil and gas exploration and production activities of these two joint ventures are immaterial, as such the corresponding information has not been disclosed separately. Under the SEC final rule optional disclosure of possible and probable reserves is allowed but, the Group opted not to do so. Ecopetrol estimated its reserves without considering non-traditional resources. (a) Capitalized costs relating to oil and gas exploration and production activities 2017 2016 2015 Natural and environmental properties 48,129,595 47,097,475 45,789,713 Wells, equipment and facilities - property, plant and equipment 30,405,565 29,931,039 21,822,897 Exploration and production projects 6,632,812 6,855,832 9,145,198 Accumulated depreciation, depletion and amortization (51,791,897) (49,714,944) (39,743,147) Net capitalized cost 33,376,075 34,169,402 37,014,661 It includes information of the Exploration and Production segment subsidiaries. In accordance with IAS 37, costs capitalized to provisions for obligations of 598,125 766,909 580,575 (b) Costs incurred in oil and gas exploration and developed activities Costs incurred are summarized below and include both amounts expensed and capitalized in the corresponding period. 2017 2016 2015 Acquisition of proved properties (1) 591,875 - - Acquisition of unproved properties (2) 164,180 - 357,772 Exploration costs 1,095,588 852,097 1,012,264 Development costs 3,599,385 2,190,426 8,018,131 5,451,028 3,042,523 9,388,167 (1) On December 11, 2017, Ecopetrol América Inc. acquired the 11.6 share 9.2 20.8 (2) Corresponds mainly to investments made by Ecopetrol América Inc in offshore exploration projects of the Warrior and Rydberg wells. For 2015, relates to drilling for the Leon 2 exploratory project, operated by Repsol as well as acquisition of the lease sales 235 and 246 (unproven lands). (c) Results of operations for oil and gas exploration and production activities The Group’s results of operations from oil and gas exploration and production activities for the years ended December 31, 2017, 2016 and 2015 are as follows: 2017 2016 2015 Net revenues Sales 29,823,565 21,322,662 26,039,708 Transfers 7,518,216 7,734,195 5,692,902 37,341,781 29,056,857 31,732,610 Production costs (1) 6,535,794 5,785,950 6,006,563 Depreciation, depletion and amortization (2) 6,349,382 5,927,466 6,234,190 Other production costs (3) 14,066,593 12,370,540 14,457,836 Exploration expenses (4) 1,342,952 730,393 1,586,940 Other expenses (5) 882,743 1,684,590 6,364,414 29,177,464 26,498,939 34,649,943 Income before income tax expense 8,164,317 2,557,918 (2,917,333) Income tax expense (3,678,955) (1,367,357) (371,376) Results of operations for exploration and production activities 4,485,362 1,190,561 (3,288,709) (1) Production costs are lifting costs incurred to operate and maintain productive wells and related equipment and facilities including costs such as operating labor, materials, supplies, and fuel consumed in operations and the costs of operating natural gas liquids plants. In addition, they include expenses 380,810 305,653 206,570 (2) In accordance with IAS 37 the expense related to asset retirement obligations were 179,601 188,370 294,849 (3) Corresponds to transportation costs and naphtha that are not part of the Group’s (4) Exploration expenses include the costs of geological and geophysical activities as well as the non-productive exploratory wells. (5) Corresponds to administration and marketing expenses. During 2017, 2016 and 2015, the Group transferred approximately 20.1 17.7 17.9 Those 48.4 46.1 37.4 of crude oil and gas production volume The intercompany transfers were realized (d) Reserve information Ecopetrol follows international standards for estimating, classifying and reporting reserves framed under SEC definitions. The process is led by the Reserves Department which submits the report to the Board of Directors for approval. The reserves were audited at a level of 99% by 2 specialized auditing companies: DeGolyer and MacNaughton and Ryder Scott Group. According to these certifications the reserves report complies with the content and guidelines set forth in Rule 4-10 of Regulation S-X issued by the United States SEC. The following information relates to the net proven reserves owned by the Ecopetrol Business Group in 2017, 2016 and 2015, and corresponds to the official reserves statements prepared by the Group: 2017 2016 2015 Oil Gas Total Oil Gas Total Oil Gas Total (Mbls) (Gpc) (Mbe) (Mbls) (Gpc) (Mbe) (Mbls) (Gpc) (Mbe) Proved reserves: Opening balance 1,033 3,218 1,598 1,239 3,479 1,849 1,465 3,529 2,084 Revisions of previous estimates (1) 124 294 175 (50) (23) (54) (64) 225 (25) Improved recovery 72 4 73 11 1 11 16 3 17 Purchases 3 2 4 - - - - - - Extensions and discoveries 44 - 43 22 25 27 24 - 24 Production (188) (264) (234) (189) (264) (235) (202) (278) (251) Closing balance 1,088 3,254 1,659 1,033 3,218 1,598 1,239 3,479 1,849 Proved developed reserves: Opening balance 779 3,131 1,329 913 3,176 1,470 1,042 3,284 1,618 Closing balance 818 3,158 1,372 779 3,131 1,329 913 3,176 1,470 Proved undeveloped reserves: Opening balance 254 87 269 326 303 379 423 245 466 Closing balance 270 96 287 254 87 269 326 303 379 (1) Represents changes in previous proved reserves, upward or downward, resulting from new information (except for an increase in proved area), usually obtained from development drilling and production history or result from changes in economic factors. For additional information about the changes in Proved Reserves and the process for estimating reserves, see section 3.4.3 - Business Overview - Exploration and Production - Reserves. (e) Standardized measure of discounted future net cash flows relating to proved oil and gas quantities and changes therein 2017 2016 2015 Future cash inflows 182,114,282 140,458,230 176,865,586 Future costs Production (70,159,534) (60,705,779) (76,363,169) Development (14,860,992) (12,005,835) (16,498,118) Income taxes (23,660,328) (15,400,000) (30,052,830) Future net cash flow 73,433,428 52,346,616 53,951,469 10% discount factor (22,216,583) (18,221,004) (19,117,422) Standardized measure of discounted net cash flows 51,216,845 34,125,612 34,834,047 2017 2016 2015 Net change in sales and transfer prices and in production cost (lifting) related to future production 26,918,170 3,603,876 (50,472,025) Changes in estimated future development costs (1,978,913) (4,767,340) 592,529 Sales and transfer of oil and gas produced, net of production costs (30,805,987) (23,270,907) (25,726,047) Net change due to extension discoveries 284,374 154,352 (93,190) Net change due to purchase and sales of minerals in place 211,777 (83,450) - Net change due to revisions in quantity estimates 9,090,882 (2,570,103) (985,217) Previously estimated development costs incurred during the period 3,482,570 5,042,697 10,769,369 Accretion of discount 4,416,512 5,423,781 11,321,221 Timing and other 11,934,458 6,394,404 (4,381,037) Net change in income taxes (6,462,611) 9,364,255 18,775,304 Aggregate change in the standardized measure of discounted future net cash flows for the year 17,091,232 (708,435) (40,199,093)

Exhibit 1. Consolidated subsidi

Exhibit 1. Consolidated subsidiaries, associates and joint ventures	12 Months Ended
	Dec. 31, 2017
Disclosure of consolidated subsidiaries, associates and joint ventures [Abstract]
Disclosure of interests in subsidiaries, associates and joint ventures [text block]	Exhibit 1. Consolidated subsidiaries, associates and joint ventures Group Functional Ownership Activity Country/Domicile Geographic Equity, net Profit Total Total Ecopetrol Global Energy SLU U.S. Dollar 100 % Investment vehicle Spain Spain 3,056,580 102,120 3,056,719 139 Ecopetrol Oleo é Gas do Brasil Ltda. Real 100 % Exploration and exploitation of hydrocarbons Brazil Brazil 36,385 (54,591) 50,933 14,548 Ecopetrol del Perú S.A. U.S. Dollar 100 % Exploration and exploitation of hydrocarbons Peru Peru 48,969 (2,271) 51,792 2,823 Ecopetrol America Inc. U.S. Dollar 100 % Exploration and exploitation of hydrocarbons United States United States 2,964,718 163,529 3,368,997 404,279 Black Gold Re Ltd. U.S. Dollar 100 % Reinsurer of Ecopetrol and its subordinates Bermuda Bermuda 607,199 28,135 729,125 121,926 Ecopetrol Germany Gmbh U.S. Dollar 100 % Exploration and exploitation of hydrocarbons Germany Angola 2,345 (118) 2,773 428 Hocol Petroleum Limited U.S. Dollar 100 % Investment vehicle Bermuda Bermuda 2,223,406 (135,261) 2,223,464 58 Hocol S.A. U.S. Dollar 100 % Exploration, exploitation and production of hydrocarbons Cayman Islands Colombia 1,529,052 (60,103) 2,747,950 1,218,898 Andean Chemicals Ltd. U.S. Dollar 100 % Investment vehicle Bermuda Bermuda 5,168,133 (526,869) 5,169,911 1,778 Refinería de Cartagena S.A * U.S. Dollar 100 % Refining, commercialization and distribution of hydrocarbons Colombia Colombia 17,008,913 39,195 25,805,231 8,796,318 Propileno del Caribe Propilco S.A. U.S. Dollar 100 % Production and commercialization of polypropylene resin Colombia Colombia 1,414,530 225,175 1,927,883 513,353 COMAI - Compounding and Masterbatching Industry Colombian Peso 100 % Manufacture of polypropylene compounds and masterbatches Colombia Colombia 141,580 114,241 202,879 61,299 * Information taken from the audited financial statements. Consolidated subsidiaries (2/2) Group Functional Ownership Activity Country/Domicile Geographic Equity, net Profit (loss) Total Total Bioenergy S.A. Colombian Peso 99.04 % Production of biofuels Colombia Colombia 335,858 (237,846) 433,582 97,724 Bioenergy Zona Franca SAS Colombian Peso 99.04 % Production of biofuels Colombia Colombia 246,866 (197,949) 702,627 455,761 Amandine Holdings Corp. Colombian Peso 99.04 % On sale Panama Panama 6,657 - 6,657 - The Arces Group Corp. Colombian Peso 99.04 % On sale Panama Panama 5,100 - 5,100 - Cenit SAS Colombian Peso 100 % Storage and transportation by hydrocarbon pipelines Colombia Colombia 13,801,943 3,014,820 15,243,690 1,441,747 Oleoducto Central SA - Ocensa U.S. Dollar 72.65 % Transportation by crude oil pipelines Colombia Colombia 3,014,831 1,667,219 6,205,436 3,190,605 Oleoducto de los Llanos Colombian Peso 65 % Transportation by crude oil pipelines Panama Colombia 1,106,571 321,792 1,919,509 812,938 Oleoducto de Colombia SA - ODC Colombian Peso 73 % Transportation by crude oil pipelines Colombia Colombia 351,308 202,432 555,250 203,942 Bicentenario de Colombia SAS Colombian Peso 55.97 % Transportation activity by crude oil pipelines Colombia Colombia 1,069,490 385,500 3,205,369 2,135,879 Ecopetrol Capital AG U.S. Dollar 100 % Financing, liquidation of financing of group companies or any type of company Switzerland Switzerland 1,240,473 145,970 5,806,746 4,566,273 Ecopetrol Global Capital SLU Euro 100 % Investment vehicle Spain Spain 20 (51) 39 19 Esenttia Resinas del Perú U.S. Dollar 100 % Marketing polypropylene resins and masterbatches Peru Peru 3,866 (84) 15,981 12,115 Ecopetrol Costa Afuera SAS Colombian Peso 100 % Offshore Caribbean exploration Colombia Colombia 15,671 (69,242) 139,192 123,521 ECP Hidrocarburos de México SA de CV U.S. Dollar 100 % Offshore Caribbean exploration Mexico Mexico 4,100 (3,653) 5,851 1,751 Associated companies and joint ventures Group Functional Ownership Activity Country/Domicile Geographic Equity, Profit Total Total Associates Invercolsa SA (*) Colombian Peso 43 % Holding with investments in transport and distribution of natural gas and LPG Colombia Colombia 516,640 84,628 560,368 43,728 Serviport SA (*) Colombian Peso 49 % Services for the support of loading and unloading of oil ships, supply of equipment, technical inspections and load measurements Colombia Colombia 20,212 2,031 70,966 50,754 Sociedad Portuaria Olefinas y Derivados S.A. (*) Colombian Peso 50 % Construction, use, maintenance and administration of port facilities, ports, private docks. Colombia Colombia 2,847 178 3,189 342 Joint Ventures Equion Energy Limited U.S. Dollar 51 % Exploration, exploitation and production of hydrocarbons United Kingdom Colombia 1,336,811 253,709 1,865,776 528,965 Ecodiesel Colombia SA (*) Colombian Peso 50 % Production, marketing and distribution of biofuels and oleo chemicals Colombia Colombia 76,766 13,236 128,420 51,654 Offshore International Group (*) U.S. Dollar 50 % Exploration, development, production and processing of hydrocarbons United States Peru 1,007,754 (178,280) 1,858,013 850,259 (*) Information available as of November 30, 2017

Accounting policies (Policies)

Accounting policies (Policies)	12 Months Ended
	Dec. 31, 2017
Disclosure of accounting policies [Abstract]
Description of accounting policy for financial instruments [text block]	4.1 Financial instruments The classification of financial instruments depends on the nature and purpose for which the financial assets or liabilities were acquired and is determined at the time of initial recognition. Financial assets and financial liabilities are initially measured at their fair value. Transaction costs that are directly attributable to the acquisition or issue of financial assets and financial liabilities (other than financial assets and financial liabilities at fair value through profit or loss) are added to or deducted from the fair value of the financial assets or financial liabilities, as appropriate, on initial recognition. Transaction costs directly attributable to the acquisition of financial assets or financial liabilities at fair value through profit or loss are recognized immediately in profit or loss. All financial assets are initially recorded at fair value. Loans and trade receivables, other receivables and financial assets held-to-maturity are measured subsequently measured at amortized cost using the effective interest method. Equity investments available for sale that do not have a market quotation price and for which fair value cannot be reliably measured are measured at cost less any impairment identified at the end of each reporting period. Measurements at fair value Fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value measurement is based on the presumption that the transaction to sell the asset or transfer the liability takes place in the principal market of the asset or liability or in the absence of a principal market in the most advantageous market for the asset or liability. All assets and liabilities for which fair value is measured or disclosed in the financial statements are classified within the following scale based on the lowest level input that is significant to the fair value measurement as a whole, as follows: § Level 1: Quoted (unadjusted) market prices in active markets for identical assets or liabilities. The fair value of the Group’s marketable securities that a quoted market price is based on Level 1 inputs. § Level 2: Valuation techniques for which the lowest level input that is significant to the fair value measurement is directly or indirectly observed. Level 2 inputs include prices of similar assets, prices obtained through quotations made by stockbrokers, and prices that can be substantially corroborated with other observable data with the same contractual terms. For derivative contracts for which a quoted market price is not available, fair value estimations are generally determined using models and other valuation methods, the key inputs for which include future prices, volatility estimates, price correlation, counterparty credit risk and market liquidity, as appropriate. For other assets and liabilities, fair value estimations are generally based on the net present value of expected future cash. § Level 3: Valuation techniques for which the lowest level input that is significant to the fair value measurement is unobservable. The Group does not use Level-3 inputs for the measurement of financial assets and liabilities. The Group may use Level-3 inputs for the calculation the recoverable amount of certain non-financial assets for the purpose of impairment testing. Effective interest rate method The effective interest rate method is a method of calculating the amortized cost of a financial instrument and accounting of income or financial cost over the relevant period. The effective interest rate is the discount rate that exactly discounts estimated future cash receipts or payments (including all fees, transaction costs and other premiums or discounts) through the expected life of the financial instrument (or, when appropriate, at a shorter period), to the net carrying amount on initial recognition. Impairment The Group evaluates, on each reporting date, if there is objective evidence that a financial asset or group of financial assets are impaired. Financial assets are evaluated for the impairment indicators at the end of each reporting period. Financial assets are considered to be impaired when there is objective evidence that, as a result of one or more events that occurred after initial recognition, the estimated future cash flows of the asset have been affected. For financial assets measured at amortized cost, the amount of the impairment loss recognized is the difference between the asset’s carrying amount and the present value of estimated future cash flows, discounted at the financial asset’s original effective interest rate. De-recognition of financial assets Ecopetrol derecognizes a financial asset only upon the expiration of the contractual rights to the cash flows of the asset or, when it has transferred its rights to receive such cash flows or has assumed the obligation to pay the cash flows received in full without material delay to a third party and (a) it has transferred substantially all the risks and benefits inherent in the ownership of the financial asset or (b) it has neither transferred nor retained substantially all the risks and benefits of the asset, but has transferred control of the asset. When the Group does neither transfer nor retain substantially all the risks and benefits of the asset or transfer control of the asset, the Group continues to recognize the transferred asset, to the extent of its continuing participation, and it also recognizes the associated liability.
Description of accounting policy for determining components of cash and cash equivalents [text block]	4.1.1 Cash and cash equivalents Cash and cash equivalents include cash on hand, financial investments that are highly liquid, bank deposits and special funds with original maturity dates of ninety days or less which are subject to an insignificant risk of changes in value.
Description of accounting policy for financial assets [text block]	4.1.2 Financial assets The Group classifies its financial assets in the following categories: a) Financial assets measured at fair value through profit or loss Financial assets at fair value through profit or loss are financial assets held for trading and financial assets designated at the time of the initial recognition at fair value through profit or loss. Financial assets are classified as held for trading if they are acquired to be sold or repurchased in the short term. They are recognized at their fair value and losses or profits arising at the time of re-measurement are recognized in the statement of profit or loss. b) Financial assets measured at fair value with changes in other comprehensive income These are equity instruments of other non-controlled and non-strategic companies not allowing for any type of control or significant influence thereon and where the Group’s management does not intend to negotiate with them in the short-term. These investments are recorded at their fair value and unrealized gains or losses are recognized in other comprehensive income and credited to the available for sale reserve until the investment is derecognized, at which time, the cumulative gain or loss is recognized in other operating income, or the investment is determined to be impaired, when the cumulative loss is reclassified from the available to sale reserve to the statement of profit or loss. c) Loans and receivables Loans to employees are initially recorded using the present value of the future cash flows, discounted at the current market rate for similar loans. If the interest rate is less than the current market rate, fair value will be less than the amount of the loan. This difference is recorded as a benefit to employees.
Description of accounting policy for financial liabilities [text block]	4.1.3 Financial liabilities Financial liabilities correspond to the financing obtained by the Group through bank credit facilities and bonds, accounts payable to suppliers and creditors. Bank credit facilities and bonds are initially recognized at their fair value, net of transactions cost. After initial recognition, interest-bearing credit facilities and bonds are subsequently measured at amortized cost, using the effective interest rate method. The effective interest method amortization is included as a financial expense in the statement of profit or loss. Accounts payable to suppliers and creditors are short-term financial liabilities recorded at nominal value, since it does not significantly differ from fair value. A financial liability is derecognized when the obligation specified in the corresponding contract is paid or expired. When an existing financial liability has been replaced by another from the same lender, under substantially different terms, or the terms of an existing liability are substantially modified, such modification is treated as the de-recognition of the original liability and recognized as a new liability. The difference between the respective carrying amounts is recognized in the statement of profit or loss.
Description of accounting policy for derivative financial instruments and hedging [text block]	4.1.4 Derivative financial instruments and hedging activities Financial derivative instruments are initially recognized in the statement of financial position as assets or liabilities and are measured at fair value on the date on which the derivative is recorded and subsequently measured at fair value. Changes in the fair value of derivatives are recognized as gains or losses in the statement of profit or loss, except for the effective portion of cash flow hedges, which is recognized in other comprehensive income and later reclassified to profit or loss when the hedge item affects profit or loss. Changes in fair value of derivative contracts, which do not qualify or are not designated as hedges, including forward contracts for the purchase and sale of commodities under negotiation for physical delivery or receipt of the commodity are recorded in profit or loss. Derivatives embedded in the host contract are accounted for as separate derivatives at fair value if their economic characteristics and risks are not closely related to those of the host contracts and the and the host contracts are not held for trading or designated at fair value through profit or loss. These embedded derivatives are measured at fair value with changes in fair value recognized in profit or loss.
Description of accounting policy for hedging [text block]	4.1.5 Hedging operations For purposes of hedge accounting, hedges are classified as: § Fair value hedges, when hedging the exposure to changes in fair value of a recognized asset or liability, or unrecognized firm commitment, or an identifiable portion of such asset, liability or firm commitment. § Cash flow hedges when hedging the exposure to variability in cash flows that is either attributable to a particular risk associated with a recognized asset or liability or a highly probable forecast transaction. § Hedges of a net investment in a foreign operation. At the inception of the hedging relationship, the Group formally designates and documents the hedge relationship between the hedging instrument and the hedged item, together with its risk management objectives and strategy to perform hedging transactions. Such hedges are expected to be highly effective in achieving offsetting changes in fair value or cash flows and are; assessed on an ongoing basis to determine that they have been highly effective throughout the financial reporting periods for which they were designated.
Description of accounting policy for cash flow hedge [text block]	4.1.5.1 Cash flow hedge The effective portion of the gain or loss of the hedging instrument is recognized in other comprehensive income, while any ineffective portion is recognized in the consolidated statement of profit or loss, in the net financial results line item. The amounts previously recognized in other comprehensive income are transferred to profit or loss, when the hedged transaction affects profit or loss. When the hedged item is the cost of a non-financial asset or liability, the amounts previously recognized in other comprehensive income are transferred to the initial carrying amount of the non-financial asset or liability. If the hedging instrument expires or is sold, terminated or exercised without replacement or rollover, or if its designation as a hedge is revoked or when the hedge no longer meets the criteria for hedge accounting, any cumulative gain or loss previously recognized in other comprehensive income remains separately in equity until the forecast transaction occurs is recognized in the consolidated statement of profit or loss. When it is no longer expected that the initially hedged transaction will occur. Ecopetrol designates long-term loans as hedging instruments for its exposure to the exchange risk in future oil exports. See Note 30 for further information.
Description of accounting policy for hedge of net investments in foreign operation [text block]	4.1.5.2 Hedge of net investment in a foreign operation Hedges of net investment in a foreign operation are accounted in a way similar to the cash flow hedges. Gains or losses on of the hedging instrument related to the effective portion of the hedge are recognized in other comprehensive income, while any gains or losses relating to the ineffective portion are recognized in the statement profit or loss. Cumulative gains or losses recorded in equity is transferred to the consolidated statement of profit or loss when the foreign operation is partially or totally disposed of. Ecopetrol allocates long-term loans as hedging instruments for its exposure to foreign exchange risk on its investment in subsidiaries whose functional currency is the U.S. dollar. See Note 30 for further information.
Description of accounting policy for measuring inventories [text block]	4.2 Inventories Inventories are stated at the lower of cost and net realizable value. Inventories mainly comprise crude oil, fuels and petrochemicals and consumable inventories (spares and supplies). The cost of crude oil is the production costs, including transportation costs. The cost required to bring the pipeline into working order, is treated as part of the related pipeline. The cost of other inventories is determined based on the weighted average cost method, which includes acquisition costs (deducting commercial discounts, rebates and other similar items), transformation, and other costs incurred to bring inventory to their current location and condition, such as transportation costs. Consumable inventories (spares and supplies) are recognized as inventory and then charged to expense, maintenance or project to the extent that such items are consumed. Ecopetrol estimates the net realizable value of inventories at the end of the period. When the circumstances that previously caused inventories to be written down below cost no longer exist, or when there is clear evidence of an increase in the net realizable value because of a change in economic circumstances, the amount of the write-down is reversed. The reversal cannot be greater than the amount of the original write-down, so that the new carrying amount will always be the lower of the cost and the revised net realizable value.
Description of accounting policy for transactions with related parties [text block]	4.3 Related parties Related parties are considered those in which one party has the ability to control, or has joint control of the other, or exercises significant influence over the other party in making financial or operational decisions, or is a member of key management personnel (or close relative of a member). The Group considers related parties to be associates, joint ventures, key management executives, entities managing resources for payment of employee post-employment benefit plans and Colombian government entities for the purposes of certain relevant transactions, such as the purchase of hydrocarbons and the fuel price stabilization fund (see Note 4.16).
Description of accounting policy for investment in associates [text block]	4.3.1 Investments in associates An associate is an entity over which the Ecopetrol Business Group has significant influence but not control. Significant influence is the power to participate in the financial and operational policy decisions of the investee, but it is not control or joint control over those policies. Generally, these entities are those in which the Group holds an equity interest with voting rights of 20 50 Investments in associates are accounted for using the equity method. Under this method, the investment in an associate is initially recognized at cost. The carrying amount of the investment is adjusted to recognize changes in the Group’s share of net assets of the associate since the acquisition date. Goodwill related to the associate is included in the carrying amount of the investment and is not tested for impairment separately. The Group's share of the results of operations of the associate is recognized in the consolidated statement of profit or loss. Any change in other comprehensive income is recognized in other comprehensive income of the Group. After application of the equity method, the Group determines if it is necessary to recognize an impairment on its investment in its associate. At each reporting date, the Group determines whether there is objective evidence that the investment is impaired. If there is such evidence, the amount of the impairment is calculated as the difference between the recoverable amount and its carrying value, and then the impairment is recognized in the consolidated statement of profit or loss. When necessary, the Group makes adjustments to the accounting policies of associates to ensure consistency with the policies adopted by the Group. Additionally, the equity method of these companies is measured on their most recent financial statements.
Description of accounting policy for investments in joint ventures [text block]	4.3.2 Joint ventures A joint venture is a type of joint arrangement whereby the parties that have joint control of the arrangement have rights to the net assets of the joint arrangement. Joint control exists only when decisions about the relevant activities require unanimous consent of the parties sharing such control. The accounting treatment for the recognition of joint ventures is the same as investments in associates.
Description of accounting policy for joint operations [text block]	4.4 Joint operations A joint operation is a type of joint arrangement whereby the parties that have joint control of the arrangement have rights to the assets and obligations for the liabilities, relating to the arrangement. Joint operation contracts are entered into between Ecopetrol and third parties to share risk, secure capital, maximize operating efficiency and optimize the recovery of reserves. In these joint operations, one party is designated as the operator to execute the operations and report to partners according to their participating interests. Likewise, each party takes its share of the produced hydrocarbons (crude oil or gas) according to their share in production. When Ecopetrol participates as a non-operator partner, it records the assets, liabilities, sales revenues, cost of sales and expenses based on the operator’s report. When Ecopetrol is the direct operator of joint venture contracts, it records its percentage of assets, liabilities, sales revenues, costs and expenses, based on the participation of each partner in the items corresponding to assets, liabilities, sales revenues, costs and expenses. When the Group acquires or increases its participation in a joint operation in which the activity constitutes a business combination, such transaction is recorded applying the acquisition method in accordance with IFRS 3 - Business combination. The acquisition cost is the sum of the consideration transferred, which corresponds to the fair value, on the date of acquisition of the assets transferred and the liabilities incurred. Any transaction cost related to the acquisition or increased share in the joint operation that constitutes a business combination is recognized in the consolidated statement of profit or loss. The excess of the sum of the consideration transferred and the amount paid in the operation is recognized as goodwill. If the result is in an excess value of the net assets acquired over the amount paid in the operation, the difference is recognized as income in the consolidated statement of profit or loss on the date of recognition of the transaction.
Description of accounting policy for non-current assets or disposal groups classified as held for sale [text block]	4.5 Non-current assets held for sale Non-current assets are classified as held for sale if their carrying values will be recovered principally through a sale transaction rather than through continued use. Non-current assets are classified as held for sale only when the sale is highly probable within one year from the classification date and the asset (or group of assets) is available for immediate sale in its present condition. These assets are measured at the lower of their carrying amount and fair value less related costs of disposal. See Note 13 for further information.
Description of accounting policy for property, plant and equipment [text block]	4.6 Property, plant and equipment Recognition and measurement Property, plant and equipment are stated at cost less accumulated depreciation and accumulated impairment losses. Tangible components related to natural and environmental resources are part of property, plant and equipment. The initial cost of an assets comprises its purchase price or construction cost, including import duties and non-refundable purchase taxes, any costs directly attributable to bringing the asset into operation, costs of employee benefits arising directly from the construction or acquisition, borrowing costs incurred that are attributable to the acquisition and construction of qualifying assets and the initial estimate of the costs of dismantling and abandonment of the item. Spare parts and servicing equipment are recorded as inventories and recognized as an expense as they are used. Major spare parts and stand-by equipment that the entity expects to use during more than one period are recognized as property, plant and equipment. Any gain or loss arising from the disposal of a property, plant and equipment is recognized in profit or loss of the period. Subsequent disbursements Subsequent disbursements correspond to all payments to be made on existing assets in order to increase or extend the initial expected useful life, increase productivity or productive efficiency, allow for significant reduction of operating costs, increase the level of reserves in exploration or production areas or replace a part or component of an asset that is considered critical for the operation. The costs of repair, conservation and maintenance of a day to day nature are expensed as incurred. However, disbursements related to major maintenance are capitalized. Depreciation Property, plant and equipment is depreciated using the straight-line method, except for those associated with exploration and production activities which are depreciated using the units-of-production method. Technical useful lives are updated annually considering factors such as: additions or improvements (due to parts replacement or critical components for the asset’s operation), technological advances, obsolescence and other factors; the effect of this change is recognized from the period in which it was executed. Depreciation of an asset starts when it is ready to be used. Useful lives are determined based on the period over which an asset is expected to be available for use, physical exhaustion, technical or commercial obsolescence and legal limits or restrictions over the use of the asset. The estimated useful life of assets fluctuates in the following ranges: Plant and equipment 15 - 65 years Pipelines, networks and lines 10 - 59 years Buildings 12 - 80 years Other 5 - 33 years Land is recorded separately from buildings and facilities and is not subject to depreciation. Depreciation methods and useful lives are reviewed annually and adjusted if appropriate
Description of accounting policy for exploration and evaluation expenditures [text block]	Natural and environmental resources Recognition and measurement Ecopetrol uses the successful efforts method to account for exploration and production of crude oil and gas activities, following the provisions of IFRS 6 – Exploration for the evaluation of mineral resources. Exploration costs Acquisition and exploration costs are recorded as exploration and evaluation assets until the determination of whether the exploration drilling is successful or not; if determined to be unsuccessful, all costs incurred are recognized as expenses in the consolidated statement of profit or loss. Exploration costs are those incurred with the objective of identifying areas that are considered to have prospects of containing oil and gas reserves, including geological and geophysical, seismic costs, viability, and others, which are recognized as expenses when incurred. Furthermore, disbursements associated with the drilling of exploratory wells and those related to stratigraphic wells of an exploratory nature are charged as assets until it is determined if they are commercially viable; otherwise, they are expensed in the consolidated statement of profit or loss as dry wells expense. Other expenditures are recognized as expenses when incurred. An exploration and evaluation asset is no longer classified as such when the technical feasibility and commercial viability of extracting a mineral resource are demonstrable. Exploration and evaluation assets are reclassified to the natural and environmental resources account after being assessed for impairment. All capitalized costs are subjected to technical and commercial revisions at least once a year to confirm the evaluation and exploration efforts continue on the fields; otherwise, these costs are written off through to profit or loss. Exploration costs are net of the revenues obtained from the sale of crude oil during the extensive testing period, net of cost of sales, since they are considered necessary to complete the asset. Development costs Development costs correspond to those costs incurred to obtain access to proved reserves and to provide facilities for extracting, treating, gathering and storing. When a project is approved for development, the corresponding capitalized acquisition and exploration costs are classified as natural and environmental resources and costs subsequent to the exploration phase are capitalized as development costs of the properties that contain such natural resources. All development costs are capitalized, including drilling costs of unsuccessful development wells. Production costs Production costs are those incurred to operate and maintain productive wells, and are part of the corresponding equipment and facilities. Production activity includes extraction of oil and gas to the surface, its gathering, treatment and processing as well as storage in the field. Production costs are expenses recorded in the consolidated statement of profit or loss as incurred unless they add oil and gas reserves, in which case they are capitalized. Production and support equipment is recognized at cost and is part of property, plant and equipment subject to depreciation. Capitalized costs also include decommissioning, dismantling, retiring and restoration costs, as well as the estimated cost of future environmental obligations. The estimation includes plugging and abandonment costs, facility dismantling and environmental recovery of areas and wells. Changes arising in new abandonment liability estimations and environmental remediation are capitalized in the carrying amount of the related asset. Depletion Depletion of natural and environmental resources is determined using the unit-of-production method per field, using proved developed reserves as a base, except in limited exceptional cases that require greater judgment by Management to determine a better amortization factor of future economic benefits over the useful life of the asset. Depreciation rates are reviewed annually, based on reserves reports and the impact of any changes is recognized prospectively in the financial statements. Reserves are audited by internationally recognized external consultants and approved by the Company’s Board of Directors. Proved reserves consist of the estimated quantities of crude oil and natural gas demonstrated with reasonable certainty by geological and engineering data to be recoverable in future years from known reserves under existing economic and operating conditions, that is, at the prices and costs that apply at the date of the estimation. Impairment Assets associated to exploration, evaluation and production are subject to review for possible impairment in their carrying amount. See notes 3.2 – Asset impairment (recovery) and 4.12 - Impairment of non-financial assets.
Description of accounting policy for borrowing costs [text block]	4.8 Capitalization of borrowing costs Borrowing costs related to the acquisition, construction or production of a qualifying asset that requires a substantial period of time to get ready for its intended use are capitalized as part of the cost of such asset when it is probable that future economic benefits associated with the item will flow to the Group and costs can be measured reliably. Other borrowing costs are recognized as finance costs. Projects that have been suspended but that the Group intends to continue to pursue their development in the future, are not considered qualifying assets for the purpose of capitalization of borrowing costs.
Description of accounting policy for intangible assets other than goodwill [text block]	4.9 Intangible assets Intangible assets with a defined useful life, are stated at cost less accumulated amortization and any impairment loss. Intangible assets are amortized under the straight-line method, over their estimated useful lives. The estimated useful lives and amortization method are revised at the end of each reporting period; any change in estimates is recognized on a prospective basis. The disbursements in relation to research activities are expensed as incurred.
Description of accounting policy for goodwill [text block]	4.10 Goodwill Goodwill is initially measured at cost (being the excess of the aggregate of the consideration transferred and the amount recognized for non-controlling interest and any previous interest held over the net identifiable assets acquired and liabilities assumed). After initial recognition goodwill is measured at cost less any accumulated impairment loss. Goodwill is not amortized but tested for impairment annually.
Description of accounting policy for leases [text block]	4.11 Leases Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards of ownership. All other leases are classified as operating leases. Assets held under finance leases, when Ecopetrol is the lessee, are recognized in the consolidated statement of financial position at an amount equal to the fair value of the leased asset or, if lower, the present value of the minimum lease payment. These assets are depreciated over the asset's useful life. When there is no reasonable certainty that the company will obtain ownership of the asset at the end of the contract, the leased assets are depreciated in the shortest period between the asset estimated useful life and the lease term. The corresponding liability to the lessor is included in the consolidated statement of financial position as a finance lease obligation, in the loans and financing line item. Lease payments are apportioned between financial charges and reduction of lease liabilities in order to achieve a constant rate of interest on the liability remaining balance. Interest expense is recognized in profit or loss. Operating lease payments are recognized as an expense on a straight-line basis over the lease term, except where another systematic prorating basis is more representative of the time pattern of economic benefits from the lease. Contingent rentals arising under operating leases are recognized as an expense in the period in which they are incurred.
Description of accounting policy for impairment of assets [text block]	4.12 Impairment of non-financial assets In order to evaluate if any tangible or intangible assets are impaired, Ecopetrol compares its carrying amount with its recoverable amount at the end of each reporting period or earlier, if there is any indicator that an asset may be impaired. For purposes of impairment testing, the assets are grouped into cash generating units (CGU), provided that those assets individually considered do not generate cash inflows that, to a greater extent, are independent from those generated by other assets or CGUs. The group of assets in different CGUs requires the exercise of professional judgment and the consideration, among other parameters, of the business segments. In this sense, in the Exploration and Production segment, each CGU corresponds to each one of the different contractual areas commonly called “fields”; by exception, in those cases where the cash inflows generated by several fields are interdependent from each other, those fields are grouped into a single CGU. In the case of the Refining and Petrochemicals segment, each CGUs corresponds to each one of the refineries of the Ecopetrol Business Group and for the Transportation segment; each pipeline is taken as an independent CGU. The recoverable amount of the asset is the higher amount of the fair value less costs of disposal or its value in use. If the recoverable amount of an asset (or of a CGU) is lower than its net carrying amount, such amount (or that of the CGU) is reduced to its recoverable amount, recognizing an impairment loss in the statement of profit or loss. Fair value less costs of disposal is usually higher than the value in use for the asset’s in the production segment due to some significant restrictions in the estimation of future cash flows, such as: a) future capital expenses that improve the CGU performance, which could result in expected increase of net cash flows, and b) items before taxes that reflect specific business risks, resulting in a higher discount rate. Fair value less costs of disposal is determined as the sum of the future discounted cash flows adjusted to the estimated risk. The estimations of expected future cash flows used in the assessment of impairment of the assets include estimates of futures commodity prices, supply and demand estimations, and the margins of the products. Fair value less costs of disposal, as described above, is compared to valuation multiples and quoted prices of shares in companies comparable to Ecopetrol, in order to determine if it is reasonable. When an impairment loss is recorded, future amortization expenses are calculated on the basis of the adjusted recoverable amount. Impairment losses may be recovered only if the recovery is related to a change in estimations used after impairment loss was recognized. These recoveries do not exceed the carrying amount of the assets net of depreciation or amortization that would have been determined if such impairment had not been recognized. The carrying amount of non-current assets reclassified as assets held-for-sale is compared to its fair value less costs of disposal. No other provision for depreciation, depletion or amortization is recorded if the fair value less costs of sale is lower than the carrying amount.
Description of accounting policy for provisions [text block]	4.13 Provisions and contingent liabilities Provisions are recognized when Ecopetrol has a current obligation (legal or implied) as a result of a past event, it is probable that Ecopetrol will be required to settle the obligation, and a reliable estimation can be made of the amount of the obligation. Where applicable, they are recorded at present value, using a rate reflecting the liability specific risk. Future environmental decommissioning costs related to current or future operations, are accounted for as expenses or assets, as the case may be. Expenditures related to past operations that do not contribute to the obtaining of current or future benefits, are expensed as incurred. The recognition of these provisions coincides with the identification of an obligation related to environmental remediation and Ecopetrol uses available information to determine a reasonable estimation of the related cost. Provisions for which a negative outcome is assessed as possible are not recognized but are disclosed in the explanatory notes; including those for which the amount cannot be estimated. If there is an expectation that the provision will be reimbursed, either in whole or in part, for example by virtue of an insurance contract, the amounts expected to be reimbursed are recognized as a separate asset only when such reimbursement is almost certain. If the effect of the time value of money is significant, the provisions are discounted using the current market rate before taxes reflecting, as applicable, the liability specific risks. When recognizing the discount, the increase of the provision resulting from time elapsed is recognized as financial cost in the profit or loss statement. Asset retirement obligation Liabilities associated with the retirement of assets are recognized when there are current obligations, either legal or implied, related to the abandonment and dismantling of wells, facilities, pipelines, buildings and equipment. The obligation is usually recorded when the assets are installed or the surface or the environment are altered at the operating sites. These liabilities are calculated using the discounted cash flow method, using a pre-tax rate reflecting current market conditions similar liabilities and considering the economic limits of the field or the useful life of the respective asset. When it is not possible to determine a reliable estimation in the period in which the obligation originates, a provision is recognized when there is sufficient information available to make the best estimation. The carrying amount of the provision is reviewed and adjusted annually considering changes in the assumptions used for its estimation, using a rate that reflects the liability specific risk. Any change in the present value of the estimated expenditure is reflected as an adjustment to the provision and the corresponding property, plant and equipment and natural and environmental resources. When a decrease in the asset retirement obligation related to a producing asset exceeds the carrying amount of the asset, the excess is recognized the consolidated statement of profit or loss. The financial cost of updating these liabilities is recognized in results for the period as financial expense.
Description of accounting policy for income tax and other taxes [text block]	4.14 Income tax and other taxes Income tax expense is comprised of income tax payable for the period (including, income tax and income tax for equality - CREE, as appropriate) and the effect of deferred taxes in each period. Current income taxes are recognized in income except when they relate to items recognized in other comprehensive income, in which case the corresponding tax effect is also recognized in other comprehensive income. Income tax assets and liabilities are presented separately in the consolidated statement of financial position except where there is a right of set-off within fiscal jurisdictions and an intention to settle such balances on a net basis.
Description of accounting policy for income tax [text block]	4.14.1 Current income tax The Group determines the provision for income tax based on the highest amount between taxable income and presumptive income (the minimum estimated amount of taxable profit on which the law expects to quantify and collect income taxes). Taxable income differs from profit before tax as reported in the consolidated statement of profit or loss, because of: items of income or expense that are taxable or deductible in other periods, special taxable deductions, tax losses and income and line items measured that, according to applicable tax laws in each jurisdiction, are considered nontaxable or nondeductible.
Description of accounting policy for deferred income tax [text block]	4.14.2 Deferred income tax Deferred tax is provided using the liability method for temporary differences between the carrying amounts of existing assets and liabilities in the consolidated financial statements and their respective tax bases. A deferred tax liability is recognized for all taxable temporary differences. A deferred tax asset is recognized for all deductible temporary differences and for all accumulated tax losses, if there is a reasonable expectation that the Group will generate future tax profits against which they will be used. Deferred taxes on assets and liabilities are calculated based on the tax rates that are expected to apply during the years in which temporary differences between the carrying amounts and tax bases are expected to be reversed. The carrying amount of a deferred tax asset is subject to review at the end of each reporting period and it is reduced to the extent it is no longer probable that there Group will generate enough future taxable profit to realize such deferred tax asset. In the statement of financial position, deferred tax assets are reflected net and as an offset against deferred tax liabilities, depending on the overall tax position in a particular jurisdiction and on the same taxable entity. Deferred taxes are not recognized when they arise in the initial recognition of an asset or liability in a transaction (except in a business combination) and at the time of the transaction, does not affect the accounting or tax profit, or in respect of the taxes on the possible future distribution of accumulated profits of subsidiaries or investments accounted for by the equity method, if at the time of the distribution it may be controlled by Ecopetrol and it is probable that the retained earnings will be reinvested by the Group companies and, therefore, will not be distributed to Ecopetrol.
Description of accounting policy for taxes other than income tax [text block]	4.14.3 Other taxes The Group recognizes in profit or loss the costs and expenses related to other taxes than the income tax, such as the wealth tax, which is determined based on the tax equity, the industry and commerce tax on income obtained in the municipalities for performance of commercial, industrial and service activities, and the transport tax on volumes loaded in the transport systems. Taxes are calculated in accordance with current tax regulations. For more details, see Note 10.
Description of accounting policy for employee benefits [text block]	4.15 Employee benefits Salaries and benefits for Ecopetrol staff are governed by the Colombian Collective Labor (Agreement 01 of 1977), and, by the Colombian Substantive Labor Code. In addition to the legally mandated benefits, employees are entitled to fringe benefits which are subject to the place of work, type of work, length of service, and basic salary. An annual interest of 12% is recognized on accumulated severance amounts for each employee, and the payment of compensation is provided for when special circumstances arise resulting in the non-voluntary termination of the contract, without justified cause, and in periods other than the probationary period. Ecopetrol belonged to the special pension regime under which pension liabilities are Ecopetrol’s responsibility and not pension fund’s responsibility. However, Law 797 of January 29, 2003 and Legislative Act 001 of 2005 determined that Ecopetrol will no longer belong to the said regime and that from that point on employees would be part of the General Pension Regime. Consequently, pension obligations related to employees pensioned until July 31, 2010 are still Ecopetrol’s responsibility. Employees are entitled to such pension bonus if they worked with Ecopetrol prior to January 29, 2003, but whose labor agreement expired without renewal before that date. All labor benefits of employees who joined Ecopetrol before 1990 are Ecopetrol’s responsibility, without the involvement of any social security entity or institution. Service cost for the employee and his/her relatives registered with the Group is determined by means of a mortality table, prepared based on facts occurring during the year. For employees who joined Ecopetrol after the Act 50 of 1990 went in effect, Ecopetrol makes periodic contributions for severance payments, pensions and labor risks to the respective funds. In 2008, Ecopetrol partially commuted the value corresponding to monthly pension payments from its pension liabilities, transferring such liabilities and their underlying amounts to autonomous pension funds (PAP, for its acronym in Spanish). The funds transferred, and returns on those funds, cannot be redirected nor they can be returned to the Group until all of the pension obligations have been fulfilled. The commuted obligation covers allowances and pension bonds payments; while health and education remains under the labor liability in charge of Ecopetrol. Employee-benefits are divided into four groups comprised as follows: a) Short-term employee benefits and post-employment defined benefits: Benefits to employees in the short term mainly correspond to those which payment will be made in the term of twelve months following the closing of the period in which the employees have rendered their services. These mainly include salaries, severance payments, vacation, bonuses and other benefits. Post-employment benefits of defined contributions correspond to the periodic payments for severance, pensions and labor risk payments that the Group makes to the respective funds that assume these obligations in their entirety. The above benefits are recognized as an expense with an associated liability after deducting any already paid amounts. b) Post-employment defined benefit plans: In the defined benefits plan, the Group provides the benefits agreed to current and former employees and assumes the actuarial and investment risks. The following benefits are classified as long-term defined benefit plans recognized in the financial statements according to the calculations of an independent actuary: § Pensions § Pension bonds § Health § Educational plan § Retroactive severances Liabilities recognized in the statement of financial position in respect of these benefit plans are the present value of the defined benefit obligation at the date of the statement of financial position, less the fair value of plan assets. The defined benefit obligation is calculated annually by independent actuaries using the projected credit unit method, which takes into account employees’ years of service and, for pensions, average or final pensionable remuneration. This obligation is discounted at its present value using interest rates of high-quality government bonds denominated in the currency in which the benefits will be paid and of a duration consistent with the plan obligations. These actuarial calculations involve several assumptions that could differ from the events that will effectively take place in the future. Said assumptions include the determination of the discount rate, future salary increases, mortality rates and future pension increase. Because of the complexity of the calculation, the underlying assumptions and long-term nature of these plans, the obligations for defined benefits are extremely sensitive to changes in assumptions. All key assumptions are revised at the end of the reported period. In determining the appropriate discount rate, in absence of a broad high quality bond market, Management considers interest rates corresponding to the class B TES bonds issued by the Colombian Government as its best reference, at an appropriate discount rate with maturities extrapolated in line with the term expected for each benefit plan. The mortality rate is based on the particular country’s rate, which latest version is the RV08 mortality table published in resolution 1555 of October 2010. The future salary and pension increases are linked to the country's future inflation rates. Note 22 - Provisions for employee benefits provides further details on key assumptions used. The amounts recognized in the consolidated statement of profit or loss related to employees defined benefit plans are comprised mainly by service cost and the net financial expense. Service cost includes mainly the increase in present value of the benefit obligation during the period (current service cost) and the amount resulting from a new benefit plan. Plan amendments corresponds to changes in benefits and are usually recognized when all legal and regulatory approvals have been obtained and the effects have been conveyed to the employees involved. The net financial expense is calculated using the net liability for defined benefits as compared with the yield curve of the discount rate at the beginning of each year for each plan. The net defined benefit liability or asset resulting from actuarial profits and losses, the asset ceiling effect and the asset profitability, excluding the value of recognized in the consolidated statement of profit or loss, are recognized in other comprehensive income. When the plan assets exceed the gross obligation, the recognized asset is limited to the lower of the surplus in the defined benefits plan and the ceiling of assets determined using a discount rate based on Colombian Government bonds. (a) Other long term benefits Other long-term benefit is the five-year term bonus which also considered in the actuarial calculation. This benefit is a cash bond that accumulates annually and is paid every five years to employees. The Group recognizes in the consolidated statement of profit or loss the service cost, the net financial cost and the adjustment to the obligation of the defined benefit plan. (b) Termination benefits Termination benefits are recognized only when a detailed plan exists for such process and there is no possibility to withdraw the offer. The Group recognizes a liability and an expense for termination benefits at the earliest date between the date when the offer of such benefits cannot be withdrawn and the date when the restructuring costs are recognized.
Description of accounting policy for recognition of revenue [text block]	4.16 Sales revenue recognition Sales revenue from crude oil and natural gas sales is recognized at the time of transfer of title to the buyer, including risks and rewards of ownership. In the case of refined and petrochemical products, sales revenue is recognized when products are shipped by the refinery and subsequently adjusted in accordance with price changes when dealing with regulated price products, as explained bellow. Sales revenue from transportation services is recognized when products are transported and delivered to the buyer in accordance with contractual terms. In all other cases, sales revenue is recognized at the time it is earned and a true, probable and quantifiable right to demand its payment arises. Under current regulations, Ecopetrol and Refinería de Cartagena S.A. sell regular gasoline and mid-distillates at a regulated price. In accordance with Decree 1068 of 2015, the Ministry of Mines and Energy calculates semiannually and settles Ecopetrol’s net position to be stabilized for each fuel by the Fuel Price Stabilization Fund (FEPC, for its acronym in Spanish). The amount to be settled is calculated as the volume sold during the corresponding period multiplied by the difference between the international parity price and the reference price actually charged. The net position is calculated by adding all differentials throughout the six month period in Colombian pesos in favor of the Group and chargeable to the FEPC. The international parity price is the daily price of gasoline and diesel oil of the respective month in Colombian pesos, indexed to the United States of America Gulf market price, calculated in accordance with Resolution 18 0522 of 2010. The reference price is the price per gallon fixed by the Ministry of Energy and Mines, at which refiners or importers sell gasoline or diesel to the national market. Therefore, this difference represents a higher or lower value of sales revenues for Ecopetrol S.A. and Refinería de Cartagena S.A.
Description of accounting policy for expenses [text block]	4.17 Costs and expenses Costs and expenses are presented according to their nature; they are detailed in the related disclosures in cost of sales, and administrative, operating, projects and other associated expenses.
Description of accounting policy for finance income and costs [text block]	4.18 Finance income (expenses) Finance income and expenses include mainly: a) borrowings costs on loans and financing, except for those that are capitalized on qualifying asset, b) gains and losses on changes in fair value of financial instruments measured at fair value through profit or loss, c) currency exchange differences of financial assets and liabilities, except for debt instruments designated as hedging instruments, d) interest expenses as a result of discounting long-term liabilities (abandonment costs and pension liabilities), e) dividends derived from equity instruments measured at fair value with changes in other comprehensive income.
Description of accounting policy for segment reporting [text block]	4.19 Information by business segment Ecopetrol presents the respective disclosures relative to its business segments in its consolidated financial statements in accordance with paragraph 4 of IFRS 8 - Operation segments. The operation of the Ecopetrol Business Group is performed through three business segments: 1) Exploration and Production, 2) Transport and Logistics, and 3) Refining, Petrochemical and Biofuels. This segmentation is based on management of objectives and corporate strategic plan, considering that these businesses: (a) are engaged in differential commercial activities, which generate sales revenue and incur costs and expenses; (b) the operational results are revised regularly by the Group's Governance that makes operational decisions to allocate resources to the various segments and assess their performance; and (c) there is differentiated financial information available. Internal transfers represent sales to inter-company segments and are registered and presented at market prices. a) Exploration and production b) Transport and Logistics: c) Refining and Petrochemicals: See figures of the information by segments in Note 33.

Cash and cash equivalents (Tabl

Cash and cash equivalents (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of detailed information about Cash and cash equivalents [text block]	Cash and cash equivalents details as of December 31, 2017 and 2016 is as follows: 2017 2016 Banks 5,484,981 3,319,465 Short-term investments 2,459,438 5,090,048 Cash 1,466 954 7,945,885 8,410,467
Credit quality of issuers of investments [Member]
Disclosure of external credit grades [text block]	The following table reflects the credit quality of issuers of investments included in cash and cash equivalents: Rating 2017 2016 AAA 2,807,170 3,198,394 A1 2,922,714 1,466,015 BRC1 + 1,152,593 312,290 F1 896,231 545,872 Aa3 99,029 - Aa2 27,868 - A-2 27,350 - No rating available 12,750 67,185 F2 180 409,717 A1+ - 73,470 F1+ - 2,188,471 Prime-2 - 78,989 F3 - 37,172 Prime-3 - 32,748 B - 144 7,945,885 8,410,467

Trade and other receivables, 46

Trade and other receivables, net (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of trade and other receivables, net [Abstract]
Disclosure of detailed information about trade and other receivables [text block]	2017 2016 Current Customers Foreign 2,052,829 1,366,322 Domestic 1,533,058 1,180,577 Fuel price stabilization fund (1) 2,256,312 1,203,811 Related parties (Note 31) 23,013 97,730 Industrial services 26,223 60,025 Accounts receivable from employees (2) 34,461 42,407 Other 173,022 261,829 6,098,918 4,212,701 Non-current Accounts receivable from employees (2) 484,504 425,468 Related parties (Note 31) 154,810 170,121 Fuel price stabilization fund (1) 77,510 77,510 Other 60,308 56,311 777,132 729,410 (1) Accounts receivable from the Ministry of Finance and Public Credit, arising from the differences between the international parity price of regular motor gasoline and diesel and the prices charged by the Group, in accordance with Resolution 180522 issued on March 29, 2010, as amended. The Ministry of Finance and Public Credit actually settles the payments. (2) Ecopetrol transferred the administration, management and control of loans granted to employees to Cavipetrol (“Corporación de los trabajadores de la Empresa Colombiana de Petróleos Ecopetrol S.A.”).
Disclosure of allowance for credit losses [text block]	2017 2016 Opening balance 144,329 160,406 Additions of allowances, net 35,229 19,438 Accounts receivable write-off and uses (9,542) (35,515) Closing balance 170,016 144,329

Inventories, net (Tables)

Inventories, net (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Inventories, net [Abstract]
Disclosure of detailed information about inventories [Text Block]	The balance of inventories, net of allowance for losses, as of December 31, 2017 and 2016 is as follows: 2017 2016 Crude oil 1,836,363 1,557,267 Fuels and petrochemicals 1,481,777 1,270,870 Materials for the production of goods 1,283,256 1,013,764 4,601,396 3,841,901
Disclosure of other provisions [text block]	The following is the changes of the allowance for losses, for the years ended December 31, 2017 and 2016: 2017 2016 Opening balance 265,435 198,539 Additions 9,134 41,957 Foreign currency translation (4,266) 50,053 Uses (75,796) (25,114) Closing balance 194,507 265,435

Other financial assets (Tables)

Other financial assets (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of detailed information about other financial assets [Text Block]	The balance of other financial assets as of December 31, 2017 and 2016 is as follows: 2017 2016 Assets measured at fair value through profit or loss Investment Portfolio - Local currency 3,310,338 2,519,311 Investment Portfolio - Foreign currency 3,194,287 4,116,987 6,504,625 6,636,298 Assets measured at amortized cost 3,636 4,152 Hedging instruments 25,464 46,445 Total 6,533,725 6,686,895 Current 2,967,878 5,315,537 Non-current 3,565,847 1,371,358 6,533,725 6,686,895
Disclosure of detailed information about maturity analysis of other financial assets [text Block]	The following are the maturities of other financial assets as of December 31, 2017 and 2016: 2017 2016 Up to 1 year 2,967,878 5,315,537 1-2 years 1,588,145 838,786 2-5 years 1,817,558 497,204 > 5 years 160,144 35,368 6,533,725 6,686,895
Disclosure of fair value measurement of assets [text block]	The following is the balance of other financial assets by fair value hierarchy level as of December 31, 2017 and 2016: 2017 2016 Level 1 317,912 25,066 Level 2 6,186,713 6,611,232 6,504,625 6,636,298
Other financial assets [Member]
Disclosure of external credit grades [text block]	The following table reflects the credit quality of the issuers of other financial assets measured at fair value through profit or loss: Rating 2017 2016 AAA 3,175,727 1,858,665 A1 1,149,606 3,060,660 AA+ 1,067,989 50,192 BBB- 378,939 - A 300,179 - AA- 233,668 3,730 A+ 175,767 - BBB 21,835 - AA - 5,289 F1+ - 1,636,039 No rating available 915 21,723 6,504,625 6,636,298

Taxes (Tables)

Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Taxes [Abstract]
Disclosure of detailed information about current tax assets and liabilities [text block]	The balance of current tax assets and tax liabilities as of December 31, 2017 and 2016 is as follows: 2017 2016 Current tax assets Income tax (1) 165,437 308,868 Credit tax balance (2) 234,410 598,140 Other taxes 225,527 222,090 Total 625,374 1,129,098 Current tax liabilities Income tax (1) 1,305,011 1,478,294 National tax and surcharge on gasoline 136,706 324,402 Carbon tax 51,383 - Other taxes (3) 512,588 328,244 Total 2,005,688 2,130,940 (1) Corresponds to the resulting value after subtracting advanced tax payments, favorable balances and advance payments settled in the previous year's statement. The main variation compared to the previous period corresponds to the decrease in non-deductible expenses, and the effects of the tax reform on issues such as depreciation and exchange difference. (2) Includes mainly the value added tax (VAT) receivable balance. (3) Mainly includes VAT payable balances and industry and commerce tax.
Disclosure of detailed information about income tax Expenses [text block]	The following is a detail of the income tax recognized in profit or loss for the years ended December 31, 2017, 2016 and 2015: 2017 2016 2015 Current income tax 5,144,962 4,517,336 3,510,546 Adjustments to prior years’ tax (68,270) - - Deferred income tax 723,576 25,710 (2,800,193) Income tax expenses 5,800,268 4,543,046 710,353
Disclosure of detailed information about reconciliation of the expected income tax expense -benefit [text block]	The reconciliation between the income tax expenses and the tax determined based on the official rate applicable to the Group in Colombia is as follows: 2017 2016 2015 Net income (loss) before income tax 13,769,662 7,790,526 (5,578,626) Statutory rate 40 % 40 % 39 % Income tax at statutory rate 5,507,865 3,116,210 (2,175,664) ETR reconciliation items: Effect in changes in tax rates and tax base (CREE tax) 910 807,989 2,063,782 Non-deductible wealth tax 85,872 229,375 253,422 Foreign currency translation and exchange difference (186,787) (234,316) 310,657 Prior year taxes 274,777 140,630 (21,233) Non-deductible expenses 129,531 486,300 251,246 Valuation of investments - - 48,129 Non-taxable income (11,900) (3,142) (19,986) Income tax calculated 5,800,268 4,543,046 710,353 Current 5,076,692 4,517,336 3,510,546 Deferred 723,576 25,710 (2,800,193) 5,800,268 4,543,046 710,353
Disclosure of deferred taxes [text block]	The following is the detail of the deferred tax balance on gains as of December 31, 2017 and 2016: 2017 2016 Deferred tax assets 4,016,161 4,248,014 Deferred tax liabilities (1,333,280) (1,639,703) Net deferred income tax 2,682,881 2,608,311
Disclosure of temporary difference, unused tax losses and unused tax credits [text block]	2017 2016 Deferred tax assets (liabilities) Provisions (3) 1,840,988 1,875,965 Employee benefits (2) 1,373,561 656,997 Loss carry forwards 611,766 477,808 Accounts payable 208,618 311,607 Accounts receivable 94,864 133,840 Property plant and equipment and Natural and environmental resources (1) (1,006,299) (220,315) Goodwill (408,932) (345,288) Borrowings and other financial liabilities - (113,497) Others (31,685) (168,806) 2,682,881 2,608,311 Deferred tax assets 4,016,161 4,248,014 Deferred tax liabilities (1,333,280) (1,639,703) 2,682,881 2,608,311 (1) For tax purposes, natural and environmental resources and property, plant and equipment have a useful life and a depreciation and amortization calculation methodology different from those determined as per international accounting standards. (2) Actuarial calculations for health, retirement pensions, education, pension bonds and other benefits to long-term employees. (3) The most representative item corresponds to the provision for well abandonment.
Disclosure of detailed information about movement of deferred tax assets and deferred tax liabilities [text block]	The following is the detail of the deferred tax assets (liabilities) for the years ended December 31, 2017 and 2016: Property Provisions Employee Loss Accounts As of December 31, 2015 205,499 1,824,844 - 238,193 726,256 Recognized in profit or loss (425,814) 51,121 40,300 239,615 (414,649) Recognized in OCI - 0 616,697 - - As of December 31, 2016 (220,315) 1,875,965 656,997 477,808 311,607 Recognized in profit or loss (785,984) (34,977) (22,818) 133,958 (102,989) Recognized in OCI - - 739,382 - - As of December 31, 2017 (1,006,299) 1,840,988 1,373,561 611,766 208,618 Goodwill Borrowings Accounts Others Total As of December 31, 2015 (262,290) (540,811) 17,927 3,804 2,213,422 Recognized in profit or loss (82,998) 427,314 115,913 23,488 (25,710) Recognized in OCI - - - (196,098) 420,599 As of December 31, 2016 (345,288) (113,497) 133,840 (168,806) 2,608,311 Recognized in profit or loss (63,644) 113,497 (38,976) 78,357 (723,576) Recognized in OCI - - - 58,764 798,146 As of December 31, 2017 (408,932) - 94,864 (31,685) 2,682,881
Disclosure of detailed information about movement of deferred income tax [text block]	The movements of deferred income tax for the years ended December 31, 2017 and 2016 are as follows: 2017 2016 Opening balance 2,608,311 2,213,422 Deferred tax recognized in profit or loss (723,576) (25,710) Deferred tax recognized in other comprehensive income (a) 798,146 420,599 Closing balance 2,682,881 2,608,311
Disclosure of detailed information about breakdown of other comprehensive income [text block]	The following is the composition of the income tax recorded against other comprehensive income: December 31, 2017 Pre-tax Deferred After tax Actuarial valuation gains (losses) 2,251,656 (739,382) 1,512,274 Cash flow coverage for crude exports 80,896 (54,056) 26,840 Other 12,119 (4,708) 7,411 2,344,671 (798,146) 1,546,525 December 31, 2016 Pre-tax Deferred After tax Actuarial valuation gains (losses) 1,770,139 (616,697) 1,153,442 Cash flow hedging for future crude oil exports (537,353) 220,596 (316,757) Derivative financial instruments (56,804) 22,722 (34,082) Other - (47,220) (47,220) 1,175,982 (420,599) 755,383

Equity instruments measured a50

Equity instruments measured at fair value (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of equity instruments measured at fair value [Abstract]
Disclosure of detailed information about equity instruments measured at fair value [text block]	The movement of equity instruments measured at fair value as of December 31, 2017 and 2016 is as follows: 2017 2016 Opening balance 51,610 913,488 Fair value adjustments (7,828) 126,205 Proceeds from sale of shares (56,930) (966,715) Profit (loss) on sale of shares 13,236 (21,368) Transfers (88) - Closing balance - 51,610

Other assets (Tables)

Other assets (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of other assets [Abstract]
Disclosure of detailed information about other assets [text Block]	The balance as of December 31, 2017 and 2016 of other assets is comprised as follows: 2017 2016 Current Partners in joint operations (1) 583,656 735,032 Prepaid expenses 115,866 140,606 Advanced payments to contractors and suppliers 103,762 151,871 Related parties (Note 31) 7,716 7,135 Other assets 69,425 988 880,425 1,035,632 Non-current Abandonment and pension funds (2) 323,621 312,423 Employee benefits 202,012 187,969 Advanced payments and deposits 74,225 63,402 Judicial deposits and attachments 43,248 140,338 Trust funds 32,748 87,602 Other assets 5,155 35,002 681,009 826,736 (1) Corresponds to the net value of cash calls and cutbacks generated in relation to the operations carried out with partners through Exploration and Production (E&P) contracts, Technical Evaluations (TEA) contracts and agreements entered in to with the National Hydrocarbons Agency (ANH), as well as through association contracts and other types of contracts. (2) Corresponds to Ecopetrol’s share in trusts established to support costs of abandonment of wells and dismantling of facilities as well as the payment of future retirement pensions in some association contracts.

Assets held for sale and thei52

Assets held for sale and their related liabilities (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Assets Held For Sale And Their Related Liabilites [Abstract]
Description of detailed information about assets and liabilities held for sale [text block]	The balance as of December 31, 2017 and 2016 of assets held for sale and their related liabilities, which do not correspond to discontinued operations, included: 2017 2016 Assets held for sale Surplus project materials (1) 56,049 65,703 Property, plant and equipment (2) 48,091 36,902 Oil fields (3) - 29,611 104,140 132,216 Liabilities related to assets held for sale Oil fields (3) - 40,128 - 40,128 (1) Mainly includes assets remaining from the expansion project of the oil pipeline for transport of extra heavy crude conducted by Oleoducto Central SA - Ocensa. In 2017, the Group sold part of these assets, generating a loss of COP$ 2,337 (2) Includes buildings and land belonging to Ecopetrol and Andean Chemicals Ltd., the latter related to Louisiana Green Fuels (ethanol plant, water plant and harvesters). The Group recorded an impairment loss on these assets of COP$ 11,292 (3) Corresponds mainly to the Sogamoso, Rio Zulia, Rio de Oro and Puerto Barco, Santana, Nancy Maxine Burdine and Valdivia Almagro oil fields, awarded through an auction in November 2016. During the second and third quarter of 2017, Ecopetrol obtained the approval of the assignment of rights of these areas by the ANH, with the transfer of the assets and the corresponding sale being formalized. These operations generated a net profit of COP $ 168,726

Investments in associates and53

Investments in associates and joint ventures (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Investments in associates and joint ventures [Abstract]
Disclosure of investment entities [text block]	The balance as of December 31, 2017 and 2016 of investments in associates and joint ventures, is as follows: 2017 2016 Investment in joint ventures Equion Energy Limited 1,057,466 1,156,430 Offshore International Group 845,325 937,938 Ecodiesel Colombia SA 38,383 39,525 1,941,174 2,133,893 Less impairment: Equion Energy Limited (296,427) (253,683) Offshore International Group (539,465) (577,053) 1,105,282 1,303,157 Investments in associates Invercolsa SA 223,963 243,156 Serviport SA 9,905 5,255 Olefinas Port Society 1,214 1,126 235,082 249,537 Less impairment: Serviport SA (9,904) - 225,178 249,537 1,330,460 1,552,694
Disclosure of detailed information about changes in investments in subsidiaries, associates and joint ventures [text block]	For the year ended December 31, 2017: Associates Joint Total Opening balance 249,537 1,303,157 1,552,694 Effects of equity method through: Profit or loss 46,669 46,869 93,538 Other comprehensive income - (14,752) (14,752) Dividends declared (61,124) (224,837) (285,961) Impairment (Note 18.1.2) (9,904) (5,155) (15,059) Closing balance 225,178 1,105,282 1,330,460 For the year ended December 31, 2016: Associates Joint Total Opening balance 69,516 1,862,418 1,931,934 Effects of equity method through: Profit or loss 48,299 13,046 61,345 Other comprehensive income 173,772 (49,127) 124,645 Dividends declared (42,050) (384,787) (426,837) Impairment (Note 18.1.2) - (127,858) (127,858) Reclassifications - (10,535) (10,535) Closing balance 249,537 1,303,157 1,552,694
Disclosure of information for impairment loss recognised or reversed for individual asset or cash-generating unit [text block]	The breakdown of assets, liabilities and results of the two main investments in associates and joint ventures, Equion Energy Limited and the Offshore International Group, as of December 31, 2017 and 2016 is as follows: 2017 2016 Equion Offshore Equion Offshore Energy International Energy International Limited Group Limited Group Statement of financial position Current assets 909,927 289,618 712,078 317,700 Non-current assets 955,849 1,568,395 1,406,510 1,693,947 Total assets 1,865,776 1,858,013 2,118,588 2,011,647 Current liabilities 430,130 192,513 417,203 147,090 Non-current liabilities 98,835 657,746 170,527 671,577 Total liabilities 528,965 850,259 587,730 818,667 Equity 1,336,811 1,007,754 1,530,858 1,192,980 Other complementary information Cash and cash equivalents 170,618 32,490 300,689 22,224 Current financial liabilities 336,352 97,960 328,497 21,408 Non-current financial liabilities 2,921 214,259 309 356,353 2017 2016 2015 Equion Offshore Equion Offshore Equion Offshore Energy International Energy International Energy International Limited Group Limited Group Limited Group Statement of profit or loss Sales revenue 1,213,692 393,210 1,204,301 379,811 1,218,796 463,660 Costs (793,999) (508,461) (969,318) (502,107) (958,467) (654,095) Administrative expenses and others 12,188 (103,340) (44,810) (221,238) (74,258) (128,895) Financial income (expenses) 2,373 (20,264) 59,143 (12,010) 37,970 (8,528) Income tax (180,546) 60,575 30,199 107,507 (209,221) 90,294 Financial year results 253,708 (178,280) 279,515 (248,037) 14,820 (237,564) Other comprehensive results 913,728 - 935,847 - 1,024,423 - Other complementary information Dividends paid to the Ecopetrol 217,075 - 375,035 - 284,984 - Depreciation and amortization 557,970 232,953 678,488 228,250 642,369 229,317
Disclosure of detailed information about reconciliation of investments in joint ventures [text block]	Included below, there is a reconciliation of equity between the most significant participations and the carrying amount of investments as of December 31, 2017 and 2016: 2017 2016 Equion Offshore Equion Offshore Energy International Energy International Limited Group Limited Group Equity of the associate 1,336,811 1,007,754 1,530,858 1,192,980 % of Ecopetrol’s ownership 51 % 50 % 51 % 50 % Ecopetrol’s ownership 681,773 503,877 780,738 596,490 Additional value of the investment 375,693 341,448 375,693 341,448 Impairment (296,427) (539,465) (253,684) (577,053) Carrying amount of the investment 761,039 305,860 902,747 360,885

Property, plant and equipment (

Property, plant and equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of property plant and equipment explanatory [Abstract]
Disclosure of property, plant and equipment and its depreciation and impairment [Text Block]	The following shows a breakdown of the changes in property, plant and equipment and depreciation and impairment for the years ended December 31, 2017 and 2016: Plant and Pipelines, Work in Buildings Lands Other Total Cost Balance as of December 31, 2016 42,608,276 29,087,782 4,874,406 6,911,757 3,894,220 3,482,439 90,858,880 Additions/capitalizations 904,854 876,940 (102) 363,836 14,631 203,124 2,363,283 Increase in abandonment costs 51,619 105,097 - - - - 156,716 Capitalized financial interests 38,847 33,875 8,501 6,941 1,027 20,113 109,304 Exchange differences capitalized 2,636 2,299 577 471 70 672 6,725 Disposals (67,326) (56,147) (26,991) (6,539) (23) (2,727) (159,753) Foreign currency translation (136,501) (49,800) (13,302) (4,904) (7,850) (3,394) (215,751) Transfers (2) (840,511) 2,000,003 (976,771) 347,024 (62,720) (893,531) (426,506) Balance as of December 31, 2017 42,561,894 32,000,049 3,866,318 7,618,586 3,839,355 2,806,696 92,692,898 Accumulated depreciation and impairment losses Balance as of December 31, 2016 (15,511,995) (9,965,554) (262,597) (2,088,478) (26,852) (674,902) (28,530,378) Depreciation expense (1,996,614) (1,479,792) - (416,698) - (106,878) (3,999,982) Recovery (losses) for impairment (Note 18) 1,014,613 316,360 (372,804) 11,538 (7,794) 16,006 977,919 Disposals 54,244 13,464 - 807 - 2,583 71,098 Foreign currency translation 15,166 32,729 - 3,929 - 3,802 55,626 Transfers (2) 1,644,613 (1,378,833) 81,981 (179,660) (4,876) (26,032) 137,193 Balance as of December 31, 2017 (14,779,973) (12,461,626) (553,420) (2,668,562) (39,522) (785,421) (31,288,524) Net balance as of December 31, 2016 27,096,281 19,122,228 4,611,809 4,823,279 3,867,368 2,807,537 62,328,502 Net balance as of December 31, 2017 27,781,921 19,538,423 3,312,898 4,950,024 3,799,833 2,021,275 61,404,374 (1) The balance of work in progress as of December 31, 2017, mainly includes investments in production at the Castilla field, the integral plan of electrical energy and secondary recovery of Yarigui and the modernization project of the Barrancabermeja refinery. (2) Transfers correspond mainly to transfers to: a) inventory of project materials for use in the operation for COP$ 250,239 7,222 31,852 Plant and Pipelines, Work in Buildings Lands Other Total Cost Balance as of December 31, 2015 37,360,222 26,856,085 11,015,010 6,479,356 4,068,951 3,653,798 89,433,422 Additions/capitalizations 1,457,547 1,383,352 (107,181) 360,596 41,202 511,413 3,646,929 (Decrease) increase in abandonment costs (84,780) (78,712) - - - 6,137 (157,355) Capitalized interest - - 205,662 - - 37,116 242,778 Exchange differences capitalized - - 8,639 - - - 8,639 Disposals (158,193) (21,814) (16,031) (12,540) 713 (15,455) (223,320) Foreign currency translation (42,870) (298,750) (1,629,613) (9,832) (69,878) 12,416 (2,038,527) Other (reclassifications) (2) 4,076,350 1,247,621 (4,602,080) 94,177 (146,768) (722,986) (53,686) Balance as of December 31, 2016 42,608,276 29,087,782 4,874,406 6,911,757 3,894,220 3,482,439 90,858,880 Accumulated depreciation and impairment Balance as of December 31, 2015 (13,469,749) (8,572,373) (19,566) (1,698,791) (13,689) (554,181) (24,328,349) Depreciation expense (1,869,604) (1,426,659) - (392,294) - (102,621) (3,791,178) Impairment (Note 17) (659,223) 33,048 (3,270) 57,157 24,067 (13,517) (561,738) Disposals 121,382 14,022 - 7,021 15 11,524 153,964 Foreign currency translation 272,582 138,611 38,904 12,658 - 8,007 470,762 Other (reclassifications) (2) 92,617 (152,203) (278,665) (74,229) (37,245) (24,114) (473,839) Balance as of December 31, 2016 (15,511,995) (9,965,554) (262,597) (2,088,478) (26,852) (674,902) (28,530,378) Net balance as of December 31, 2016 27,096,281 19,122,228 4,611,809 4,823,279 3,867,368 2,807,537 62,328,502 (1) The balance of work in progress as of December 31, 2016, mainly includes investments made in the development projects of the Castilla y Chichimene fields, integral energy plan (PIEEL for its acronym in Spanish), primary and secondary development of the Tibú-Socuabo project and modernization of the Refinería de Barrancabermeja. (2) Corresponds mainly to transfers to: a) inventory of project materials for use in the operation for COP$ (712,967) 68,750 116,692

Natural and environmental res55

Natural and environmental resources (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Natural and environmental resources [Abstract]
Disclosure of detailed Information about natural and environmental resources explanatory [text Block]	Oil Asset Exploration and Total Cost Balance as of December 31, 2016 47,079,096 2,304,915 4,818,124 54,202,135 Additions/capitalizations 2,422,203 59,345 944,857 3,426,405 Acquisition of interests in joint operations (Note 32.3) 141,950 - - 141,950 Adjustment to fair value of participation in joint operations (Note 32.3) 451,095 - - 451,095 Increase (decrease) in abandonment costs 224 (143,241) 25,935 (117,082) Disposals (38,072) (629) (214,850) (253,551) Dry wells (2) - - (898,264) (898,264) Capitalized financial interests 72,395 - 9,952 82,347 Exchange differences capitalized 4,913 - 675 5,588 Foreign currency translation (62,446) (573) (14,504) (77,523) Transfers (3) 112,500 (4,554) (163,117) (55,171) Balance as of December 31, 2017 50,183,858 2,215,263 4,508,808 56,907,929 Accumulated amortization and impairment losses Balance as of December 31, 2016 (30,470,415) (1,390,673) - (31,861,088) Depletion expense (3,979,179) (194,140) - (4,173,319) Recovery (losses) for impairment (Note 18) 376,934 - - 376,934 Disposals 37,808 290 - 38,098 Foreign currency translation 42,114 245 - 42,359 Transfers (3) (22,225) (423) - (22,648) Balance as of December 31, 2017 (34,014,963) (1,584,701) - (35,599,664) Net balance as of December 31, 2016 16,608,681 914,242 4,818,124 22,341,047 Net balance as of December 31, 2017 16,168,895 630,562 4,508,808 21,308,265 (1) The balance of exploration and evaluation includes mainly investments made in the Purple Angel, Tayrona and unconventional hydrocarbons projects and in the developing fields, Piedemonte, Castilla y Tibú. (2) Includes mainly dry wells in operation of: 1) Ecopetrol S.A. for (COP$ 450,524 312,684 57,877 (3) Corresponds mainly to transfers to property, plant and Oil investments Asset retirement Exploration and Total Cost Balance as of December 31, 2015 44,148,353 1,762,374 6,189,142 52,099,869 Additions/capitalizations 3,045,474 10,391 (934,570) 2,121,295 Increase (decrease) in abandonment costs - 566,213 (4,062) 562,151 Disposals (26,548) (37,942) (121,032) (185,522) Dry wells (2) - - (342,691) (342,691) Capitalized financial interests - - 98,431 98,431 Exchange differences capitalized - - 7,259 7,259 Foreign currency translation (352,766) (8,049) (103,728) (464,543) Other 264,583 11,928 29,375 305,886 Balance as of December 31, 2016 47,079,096 2,304,915 4,818,124 54,202,135 Accumulated depreciation and impairment loss Balance as of December 31, 2015 (26,874,774) (1,181,798) - (28,056,572) Depletion expense (3,496,998) (208,769) - (3,705,767) Impairment (Note 18) (239,151) - - (239,151) Disposals 26,320 37,942 - 64,262 Foreign currency translation 218,898 5,171 - 224,069 Other (104,710) (43,219) - (147,929) Balance as of December 31, 2016 (30,470,415) (1,390,673) - (31,861,088) Net balance as of December 31, 2015 17,273,579 580,576 6,189,142 24,043,297 Net balance as of December 31, 2016 16,608,681 914,242 4,818,124 22,341,047 (1) The balance of exploration and evaluation mainly includes investments in production projects of direct operation in Castilla, Chichimene and Piedemonte. Additionally, it includes offshore exploration projects: Fuerte Sur, Kronos and Tayrona and Onshore: Caño Sur block, CPO 10 and non-conventional hydrocarbons program. (2) Includes dry wells in operation of: 1) Ecopetrol for COP$ 302,965 26,273 5,032 5,049 3,372 (3) Corresponds mainly of transfers to: a) non-current assets held for sale for COP$ 244,387 (68,898) (17,532)
Disclosure of detailed information about classification by age from completion date of the suspended exploratory wells [text block]	2017 2016 2015 Between 1 and 3 years (a) 600,767 1,300,874 490,184 Between 3 and 5 years (b) 791,261 197,997 100,316 More than 5 years (c) 250,219 153,552 161,392 Total suspended exploratory wells 1,642,247 1,652,423 751,892 No. of projects exceeding 1 year 24 24 59 Wells under 1 year of suspended 2,480 528,313 280,801 (a) Corresponds mainly to discovery wells of Ecopetrol America Inc: Leon 2 and Warrior # 1, which are under evaluation. (b) The balance corresponds mainly to discovery wells of Ecopetrol America Inc: Leon 1, which are under evaluation and Rydberg which is currently working on the development plan and feasibility (c) Corresponds mainly to wells of Offshore International Group, which are temporarily abandoned.

Intangible assets (Tables)

Intangible assets (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of detailed information about intangible assets [abstract]
Disclosure of detailed information about intangible assets [text block]	The following is the movement of intangibles and their amortization and impairment for the years ended December 31, 2017 and 2016: Licenses and Other Total Cost Balance as of December 31, 2016 784,320 138,982 923,302 Acquisitions 169,545 6,323 175,868 Disposals (9,469) - (9,469) Foreign currency translation (1,414) (92) (1,506) Transfers 17,574 23,339 40,913 Balance as of December 31, 2017 960,556 168,552 1,129,108 Accumulated amortization Balance as of December 31, 2016 (583,680) (67,490) (651,170) Amortization of the period (89,216) (18,830) (108,046) Disposals 8,744 - 8,744 Foreign currency translation 979 - 979 Transfers (2,242) 2,853 611 Balance as of December 31, 2017 (665,415) (83,467) (748,882) Net balance as of December 31, 2016 200,640 71,492 272,132 Net balance as of December 31, 2017 295,141 85,085 380,226 Useful life < 5 years < 7 years Licenses Other Total Cost Balance as of December 31, 2015 733,115 244,063 977,178 Additions 63,560 5,693 69,253 Disposals (29,099) - (29,099) Foreign currency translation (9,359) (149) (9,508) Reclassifications 26,103 (110,625) (84,522) Balance as of December 31, 2016 784,320 138,982 923,302 Accumulated amortization Balance as of December 31, 2015 (533,784) (55,343) (589,127) Amortization expense (81,913) (28,142) (110,055) Disposals 29,097 - 29,097 Foreign currency translation 8,527 1 8,528 Reclassifications (5,607) 15,994 10,387 Balance as of December 31, 2016 (583,680) (67,490) (651,170) Balance as of December 31, 2015 199,331 188,720 388,051 Balance as of December 31, 2016 200,640 71,492 272,132 Useful life < 5 years < 7 years (1) Corresponds mainly to easements.

Impairment of long-term assets

Impairment of long-term assets (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Detailed Information About Impairment Of Noncurrent Assets [Text Block]	Based on impairment tests conducted by the Group, the following (recoveries) losses for impairment of long term assets for the years ended December 31, 2017, 2016 and 2015 are presented: Expense (recovery of) impairment by segment 2017 2016 2015 Production and exploration (183,718) 196,448 4,504,495 Refining and Petrochemicals (1,067,965) 773,361 3,278,993 Transport and Logistics (59,455) (41,062) 81,387 (1,311,138) 928,747 7,864,875 Recognized in: Property, plant and equipment (Note 15) (977,919) 561,738 4,144,754 Natural resources (Note 16) (376,934) 239,151 2,865,076 Investment in joint ventures and associates (Note 14) 15,059 127,858 588,144 Other non-current assets 28,656 - - Goodwill - - 266,901 (1,311,138) 928,747 7,864,875
Disclosure of detailed information about impairment losses of assets of refining and petrochemicals segment [Text Block]	2017 Cash generating units Carrying amount Recoverable (Recovery) Refinería de Cartagena 20,578,412 22,012,710 (1,434,298) Refinería de Barrancabermeja (projects) 1,172,773 898,786 273,987 Bioenergy 757,741 665,395 92,346 22,508,926 23,576,891 (1,067,965) 2016 Cash generating units Carrying amount Recoverable Expenses for Refinería de Cartagena 21,672,367 21,206,515 465,852 Bioenergy 925,955 618,446 307,509 22,598,322 21,824,961 773,361 2015 Cash generating units Carrying amount Recoverable Expenses for Refinería de Cartagena 26,561,335 23,335,096 3,226,240 Bioenergy 642,139 589,386 52,753 27,203,474 23,924,482 3,278,993
Investments accounted for using equity method [member]
Disclosure Of Detailed Informations About Impairment Losses Reversals Of Assets [Text Block]	As a result, Ecopetrol recognized an expense for (recovery of) impairment in the value of its investments in companies as of December 31, as follows: 2017 2016 2015 Equion Energy Limited 42,744 81,155 172,528 Offshore International Group (37,589) 46,703 415,616 Total 5,155 127,858 588,144
Explorations And Productions Segments [Member]
Disclosure Of Detailed Informations About Impairment Losses Reversals Of Assets Of Exploration And Production Segment [Text Block]	The breakdown of the expenses for (recovery of) impairment of fields for the years ended December 31, 2017, 2016 and 2015 includes: 2017 Cash generating units Carrying amount Recoverable Expense for Oil fields in Colombia Expense 2,172,747 1,588,207 584,540 Recovery 13,229,212 23,906,828 (298,210) Fields operated abroad Recovery 748,510 1,324,010 (475,203) (188,873) 2016 Cash generating units Carrying amount Recoverable Expense for Oil fields in Colombia Expense 5,258,265 4,902,943 1,117,020 Recovery 17,502,391 36,704,807 (1,090,434) Fields operated abroad Expense 688,895 647,272 42,004 68,590 2015 Cash generating units Carrying amount Recoverable Expense for Oil fields in Colombia 10,323,500 7,645,665 2,430,923 Fields operated abroad 1,242,979 24,451 1,218,528 3,649,451
Exploration and production [Member]
Disclosure Of Detailed Informations About Impairment Losses Reversals Of Assets [Text Block]	The expenses for (recovery of) asset impairment of the Exploration and Production segment for the years ended December 31 of 2017, 2016 and 2015 is as follows: 2017 2016 2015 Oilfields (188,873) 68,590 3,649,451 Investment in joint ventures and associates (Note 14) 5,155 127,858 588,144 Goodwill - - 266,900 (183,718) 196,448 4,504,495

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Goodwill [Abstract]
Disclosure of reconciliation of changes in goodwill [text block]	The balance as of December 31, 2017 and 2016 of goodwill in acquisitions of subsidiaries is as follows: 2017 2016 Transport and Logistics Oleoducto Central S.A. 683,496 683,496 Exploration and Production Hocol Petroleum Ltd. 537,598 537,598 Refining and Petrochemicals Andean Chemical Ltd 127,812 127,812 Propilco S.A 108,137 108,137 1,457,043 1,457,043 Less impairment Hocol Petroleum Ltd. (297,121) (297,121) 1,159,922 1,159,922

Loans and borrowings (Tables)

Loans and borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of loans and borrowings [Abstract]
Disclosure of detailed information about borrowings [text block]	The balances of the loans and financing, which are recorded at amortized cost, as of December 31, 2017 and 2016 are: Weighted average effective interest rate as of December 31 2017 2016 2017 2016 Local currency Bonds 8.9 % 8.6 % 1,692,471 2,008,203 Syndicated loan 8.7 % 9.5 % 3,307,950 3,828,329 Other (1) 7.7 % 9.1 % 978,795 905,266 5,979,216 6,741,798 Foreign currency Bonds 6.1 % 6.1 % 29,166,594 29,310,165 Commercial loans – Refinería de Cartagena 4.3 % 4.1 % 7,401,781 7,988,678 Commercial loans 4.3 % 2.9 % 528,815 7,945,693 Other (1) 471,429 235,693 37,568,619 45,480,229 43,547,835 52,222,027 Current (2) 5,144,504 4,126,203 Non-current 38,403,331 48,095,824 43,547,835 52,222,027 (1) Includes financial leasing and debt in connection with build, operate, maintenance and transfer (BOMT) contracts. (2) The increase in the current portion is mainly due to the expiration of: i) the first tranche of local bonds issued by Ecopetrol S.A. in 2013, and ii) the 5-year series of international bonds issued in 2013 by Ecopetrol S.A.. These bonds mature in August and September 2018, respectively.
Disclosure of detailed information about borrowings by maturity [text block]	The following are the maturities of loans and borrowing as of December 31, 2017: Up to 1 1-5 years 5-10 years > 10 years Total Local Currency Bonds 253,172 742,512 322,956 373,831 1,692,471 Syndicated loan 739,348 2,009,420 559,182 - 3,307,950 Other 98,729 415,599 308,121 156,346 978,795 1,091,249 3,167,531 1,190,259 530,177 5,979,216 Foreign currency Bonds 2,651,174 9,948,238 12,018,813 4,548,369 29,166,594 Commercial loans – Refinería de Cartagena 958,918 3,635,848 2,807,015 - 7,401,781 Commercial loans 153,873 315,849 59,093 - 528,815 Other 289,290 119,014 63,125 - 471,429 4,053,255 14,018,949 14,948,046 4,548,369 37,568,619 5,144,504 17,186,480 16,138,305 5,078,546 43,547,835 (1) Includes short-term credit and the current portion of long-term debt, as applicable. The following are the maturities of loans and borrowing as of December 31, 2016: Up to 1 1 - 5 years 5-10 years > 10 years Total Local currency Bonds 312,207 955,204 357,015 383,777 2,008,203 Commercial loans 793,743 2,375,023 659,563 - 3,828,329 Others 58,952 333,372 339,009 173,933 905,266 Total local currency 1,164,902 3,663,599 1,355,587 557,710 6,741,798 Foreign currency Bonds 1,648,707 10,956,507 12,133,576 4,571,375 29,310,165 Commercial loan Refinería de Cartagena 875,734 3,549,216 3,472,379 91,349 7,988,678 Other commercial loans 371,804 7,450,587 123,302 - 7,945,693 Other 65,056 114,226 56,411 - 235,693 Total foreign currency 2,961,301 22,070,536 15,785,668 4,662,724 45,480,229 4,126,203 25,734,135 17,141,255 5,220,434 52,222,027 (1) Includes short-term credit and the current portion of long-term debt, as applicable.
Disclosure of detailed information about borrowings by interest rate type [text block]	20.4 Breakdown by type of interest rate and currency The following is the breakdown of loans and borrowing by type of interest rate as of December 31, 2017 and 2016: 2017 2016 Local currency Fixed rate 143,156 299,472 Floating rate 5,836,060 6,442,326 5,979,216 6,741,798 Foreign currency Fixed rate 35,062,742 35,719,486 Floating rate 2,505,877 9,760,743 37,568,619 45,480,229 43,547,835 52,222,027
Disclosure of net financial debt explanatory [Text Block]	The following is the movement of net financial debt as of December 31, 2017, 2016 and 2015: Cash and Other financial Loans and Net financial equivalents assets (1) borrowings debt Balance as of December 31, 2015 6,550,450 1,585,379 (53,223,338) (45,087,509) Cash flow 2,086,350 5,446,507 1,050,723 8,583,580 Exchange difference: Recognized in profit or loss (226,333) (12,837) 1,252,420 1,013,250 Recognized in other comprehensive income - - 612,983 612,983 Financial cost registered to projects - - (357,107) (357,107) Financial income (expense) recognized in profit or loss - 59,593 (2,765,024) (2,705,431) Foreign currency translation - (6,462) 593,384 586,922 Other movements not generating cash flow (2) - (385,285) 613,932 228,647 Balance as of December 31, 2016 8,410,467 6,686,895 (52,222,027) (37,124,665) Cash flow (174,272) (564,755) 11,259,492 10,520,465 Exchange difference: Recognized in profit or loss (290,310) 208,394 147,993 66,077 Recognized in other comprehensive income - - 70,958 70,958 Financial cost registered to projects - - (203,964) (203,964) Financial income (expense) recognized in profit or loss - 104,706 (2,385,994) (2,281,288) Foreign currency translation - 39,628 (76,171) (36,543) Other movements that do not generate cash flow - 58,857 (138,122) (79,265) Balance as of December 31, 2017 7,945,885 6,533,725 (43,547,835) (29,068,225) (1) The balance of other financial assets as of December 31, 2015 includes the value of the securities related to Santiago de las Atalayas for COP$ 699,832 (2) Corresponds to operations with remittances financed in dollars with domestic banks for the payment of imports.

Trade and other payables (Table

Trade and other payables (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure Of Trade and other payables [Abstract]
Disclosure Detailed information of trade and other payables [Text Block]	The balance of trade and other payables, as of December 31, 2017 and 2016, is comprised as follows: 2017 2016 Suppliers 5,088,957 4,687,353 Partners’ advances 880,420 864,971 Withholding tax 376,169 379,194 Related parties 129,520 114,420 Insurance and reinsurance 121,555 110,530 Agreements in transport contracts (1) 91,324 111,899 Deposits received from third parties 25,523 209,570 Dividends payable (2) 3,723 11,193 Various creditors 280,485 389,126 6,997,676 6,878,256 Current 6,968,207 6,854,363 Non-current 29,469 23,893 6,997,676 6,878,256 (1) Corresponds to the value of debt from agreements in transport contracts of oil pipelines and poliducts, impacted by volumetric adjustments, compensation for quality and other inventory management agreements. (2) Dividends declared at the General Shareholders' Meeting on 2016 profits, amounting to 945,684

Provisions for employees bene61

Provisions for employees benefits (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of defined benefit plans [abstract]
Disclosure of detailed information about provision balances for employee benefits [Text Block]	The following are the balances of provisions for employee benefits as of December 31, 2017 and 2016: 2017 2016 Post-employment benefits Healthcare 5,367,005 4,475,540 Pension 1,327,859 76,695 Education 502,260 333,379 Bonds 348,442 263,563 Other plans 77,636 67,945 Termination benefits - Voluntary retirement plan 155,286 161,796 7,778,488 5,378,918 Social benefits and salaries 485,939 423,360 Other employee benefits 67,867 73,300 8,332,294 5,875,578 Current 1,829,819 1,974,496 Non-current 6,502,475 3,901,082 8,332,294 5,875,578
Disclosure of net defined benefit liability (asset) [text block]	The following table shows the movement in liabilities and assets, net of post-employment benefits and termination benefits, as of December 31, 2017 and 2016: Pension and bonds (1) Other Total 2017 2016 2017 2016 2017 2016 Liabilities for employee benefits Opening balance 12,463,433 10,435,546 5,041,133 4,170,047 17,504,566 14,605,593 Current service cost - - 52,164 53,771 52,164 53,771 Past service cost - - - 164,271 - 164,271 Interest expense 872,524 876,076 350,060 333,894 1,222,584 1,209,970 Actuarial losses (gains) 1,621,184 1,915,767 1,012,205 616,834 2,633,389 2,532,601 Benefits paid (809,677) (763,956) (350,130) (297,684) (1,159,807) (1,061,640) Closing balance 14,147,464 12,463,433 6,105,432 5,041,133 20,252,896 17,504,566 Plan assets Opening balance 12,123,175 11,181,604 2,473 - 12,125,648 11,181,604 Return on assets 848,677 950,704 385 - 849,062 950,704 Contributions to funds - - 22,465 - 22,465 - Variation in the ceiling of assets - 379,884 - - - 379,884 Benefits paid (809,677) (771,528) (22,078) 2,406 (831,755) (769,122) Actuarial gains (losses) 308,988 382,511 - 67 308,988 382,578 Closing balance 12,471,163 12,123,175 3,245 2,473 12,474,408 12,125,648 Net post-employment benefits liability 1,676,301 340,258 6,102,187 5,038,660 7,778,488 5,378,918 (1) There is no cost for the pension and pension plans service, due to the fact that the beneficiaries were retired as of July 31, 2010.
Disclosure of detailed information about movement of defined benefits plans recognized in results and other comprehensive income [Text Block]	The following table shows the movement in profit and loss and in other comprehensive income as of December 31, 2017 and 2016: 2017 2016 Recognized in profit or loss Current service cost 52,164 53,771 Past service cost - 164,271 Interest expense, net 373,522 259,266 Remedies 13,889 - 439,575 477,308 Recognized in other comprehensive income Healthcare (794,535) (792,093) Pension and pension bonds (1,312,195) (1,533,256) Education and severance (203,779) 175,259 Termination benefits - Voluntary retirement plan (3) 67 Change in the effect of the asset ceiling - 379,884 (2,310,512) (1,770,139) Deferred tax 762,469 616,697 Other comprehensive income, net of taxes (1,548,043) (1,153,442)
Disclosure of fair value of plan assets [text block]	The following is the composition of the plan assets of pension and pension bonds by type of investment as of December 31, 2017 and 2016: 2017 2016 Bonds issued by the national government 4,349,400 4,410,326 Bonds of private entities 2,967,030 2,880,958 Other local currency 2,337,580 2,910,083 Other public bonds 1,149,200 693,061 Variable yield 605,380 305,052 Bonds of foreign entities 558,920 622,817 Other foreign currency 503,653 300,878 12,471,163 12,123,175
Disclosure of detailed information about fair value hierarchy of plan assets [Text Block]	The following table reflects the credit quality of the issuers and counterparties in assets held by the autonomous pension funds: Rating 2017 2016 AAA 4,870,932 4,467,642 Nation 4,471,274 4,610,251 AA+ 690,391 470,944 BAA2 371,972 141,940 BBB 246,795 150,808 F1+ 230,321 416,439 BBB- 192,636 23,237 BBB+ 159,103 193,835 BRC 1+ 118,008 309,282 AA 58,234 79,750 BAA3 45,699 131,993 A 39,048 4,175 A3 29,098 61,325 AA3 27,051 14,385 AA- 18,770 34,197 VRR1 + 14,112 55,821 BAA1 5,296 5,274 Other qualifications 9,621 66,470 No rating available 872,802 885,407 12,471,163 12,123,175
Disclosure of analysis of present value of defined benefit obligation that distinguishes nature, characteristics and risks [text block]	The following are the actuarial assumptions used in determining the present value of defined employee benefit obligations used for the actuarial calculations as of December 31, 2017 and 2016: 2017 Pension Bonds Health Education Other benefits Discount rate 6.50 % 6.25 % 6.50 % 5.50 % 5.51% Salary growth rate N/A N/A N/A N/A 4.75% / 4.25% Expected inflation rate 3.00 % 3.00 % 3.00 % 3.00 % 3.00% Pension growth rate 3.00 % N/A N/A N/A N/A Cost trend Short-term rate N/A N/A 6.00 % 4.00 % N/A Long-term rate N/A N/A 4.00 % 4.00 % N/A 2016 Pension Bonds Health Education Other benefits Discount rate 7.25 % 7.00 % 7.25 % 6.50 % 6.67% Salary growth rate N/A N/A N/A N/A 4.25% Expected inflation rate 3.00 % 3.00 % 3.00 % 3.00 % 3.00% Pension growth rate 3.00 % N/A N/A N/A N/A Cost trend Short-term rate N/A N/A 3.00 % 4.00 % N/A Long term rate N/A N/A 4.00 % 4.00 % N/A N/A: Not applicable for this benefit. (1) Weighted average discount rate.
Disclosure of information about maturity profile of defined benefit obligation [text block]	Period Pension Other Total 2018 880,298 374,315 1,254,613 2019 877,165 355,241 1,232,406 2020 899,128 358,292 1,257,420 2021 921,333 361,655 1,282,988 2022 952,531 362,998 1,315,529 2023-2026 5,201,619 1,824,756 7,026,375
Disclosure of sensitivity analysis for actuarial assumptions [text block]	Pension Bonds Health Education Other Discount rate -50 basis points 13,948,863 1,032,967 5,775,492 527,839 242,117 +50 basis points 12,440,607 948,129 4,962,688 480,224 230,501 Inflation rate -50 basis points 12,386,975 946,675 N/A N/A 156,021 +50 basis points 14,003,214 1,033,715 N/A N/A 161,094 Salary growth rate -50 basis points N/A N/A N/A N/A 76,336 +50 basis points N/A N/A N/A N/A 79,150 Cost trend -50 basis points N/A N/A 4,982,874 479,829 N/A +50 basis points N/A N/A 5,797,753 528,104 N/A

Accrued liabilities and provi62

Accrued liabilities and provisions (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of accrued liabilities and provisions [Abstract]
Disclosure of accrued liabilities and provisions [Text Block]	Below is the breakdown of the changes in the different categories of provisions and contingenciesas of December 31, 2017 and 2016: Asset Environmental retirement contingencies obligation Litigation and others Total Balance as of December 31, 2016 5,064,660 209,932 643,278 5,917,870 Increase in abandonment costs 39,634 - - 39,634 Additions (recoveries) 110,587 (19,185) 106,532 197,934 Uses (66,469) (7,742) (19,613) (93,824) Financial costs 379,891 - (367) 379,524 Foreign currency translation (979) (39) 718 (300) Transfers (1) - - 96,611 96,611 Balance as of December 31, 2017 5,527,324 182,966 827,159 6,537,449 Current 199,824 159,881 199,123 558,828 Non-current 5,327,500 23,085 628,036 5,978,621 5,527,324 182,966 827,159 6,537,449 Asset Environmental retirement Comuneros contingencies obligation Litigation provision and others Total Balance as of December 31, 2015 4,452,369 99,798 702,486 822,694 6,077,347 Increase in abandonment costs 404,797 - - - 404,797 Additions (recoveries) 18,285 44,120 (702,486) (74,312) (714,393) Uses (68,460) (4,585) - (31,218) (104,263) Financial costs 317,448 - - (173) 317,275 Foreign currency translation (14,703) (355) - (2,759) (17,817) Transfers (1) (45,076) 70,954 - (70,954) (45,076) Balance as of December 31, 2016 5,064,660 209,932 - 643,278 5,917,870 Current 330,057 146,767 - 345,130 821,954 Non-current 4,734,603 63,165 - 298,148 5,095,916 5,064,660 209,932 - 643,278 5,917,870 (1) Mainly includes transfers to liabilities associated with assets held for sale.
Disclosure of contingent liabilities [text block]	The following is a summary of the main legal proceedings recognized in the statement of financial position whose amount exceeds COP$13,000 million, where the expectation of loss is probable Proceeding 2017 2016 Provision for the payment of the 2016 legal stability contract premium with the Ministry of Finance and Public Credit regarding investment in Reficar 64,104 59,528 Litigation with Schrader Camargo, supplier of Reficar 17,003 17,003 Settlement before the Procuraduría General de la Nación with the firms Acciona Infraestructura S.A. and Mantenimiento y Montajes S.A., August 18, 2016. In 2017, it was ruled in favor of the Group and the provision was reversed. - 44,986
Disclosure of detailed information about unrecorded contingent liabilities [Text Block]	The following is a summary of the main contingent liabilities that have not been recognized in the statement of financial position as, according to the evaluations made by internal and external advisors of the Group, the expectation of loss is not probable as at December 31, 2017 and 2016: Proceedings 2017 2016 Environmental damage caused by a terrorist attack in 2015 against the Transandino pipeline. 209,220 - Breaking of the economic and financial balance with contractor for the construction of the transport system. 110,266 - On March 14, 2016, a lawsuit was filed for default settling the contract between Konidol and Ecopetrol, which caused Ecopetrol incurred excess costs in the maintenance contract in 2016. 62,131 62,131 Salary readjustments to the amounts established by Ecopetrol for personnel, related to a contract with a third party for the commissioning and construction of surface facilities for production and exploration projects. 60,313 - Compensation to third parties for damage caused by hydrocarbon spills during a tanker truck accident on the Villeta - Guaduas road oil spills. 43,333 43,333 Contractual imbalance with a third party in relation to road connection works. 31,679 - Settlement of differences with a supplier under a contract whose purpose was the engineering, procurement and construction management of project P135. Although the parties reached a preliminary settlement agreement, the Comptroller General's Office did not approve it and the process continues in the evidentiary stage. The result of these processes is subject to the decision of the arbitrator. 30,027 - Contractual controversy with a third party in relation with seismic acquisition services and seismic program processing. 30,000 - Recalculation of legal and non-legal social benefits on sums paid for the benefit of saving incentives. 16,562 16,562 Controversy regarding income tax returns for taxable years 2010 and 2011 of Hocol, related to deductions in exploration fixed assets. In September 2017, Hocol paid taxes on the tax revenue processes of taxable years 2010 and 2011 of $ 89,271 - 344,915
Disclosure of detailed information about contingent assets [Text Block]	The following is a breakdown of the Group’s principal contingent assets, where the associated contingent gain is likely, but not certain as of December 31, 2017 and 2016: Proceedings 2017 2016 Ocensa claim that seeks the payment of the negative balance by Equion Energia Limited and Santiago Oil Group, which are reflected in Ocensa's volumetric balances. 112,735 - Claim for reimbursement based on a disagreement with Ecopetrol corresponding to investment in facilities in the Guaduas field of the "Rio Seco" association contract. 40,711 40,746 Environmental incident in 2011, in the Caño Limón Coveñas Pipeline. 35,000 - Criminal claim filed by Ecopetrol against the administrator of agreements with a corporation for alleged document falsification. 32,000 - Breach of a pipe purchase order because the physical characteristics of the coating do not match what was contracted. 21,232 21,232 Nullity of administrative act issued by the DIAN, which ordered a special contribution for public works contracts. 13,214 13,214 Claim against Metapetroleum for damage suffered due to the late delivery of crude volumes under the Quifa association contract. - 25,421

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of equity [Abstract]
Disclosure of detailed information about share capital, reserves and other equity interest [text block]	The following is the composition of the Group’s reserves as of December 31, 2017 and 2016: 2017 2016 Legal reserve 1,426,151 1,269,680 Fiscal and statutory reserves 512,632 289,164 Occasional reserves 239,086 - Total 2,177,869 1,558,844
Disclosure of detailed information about balance and breakdown of changes in equity reserves [Text Block]	The movement of equity reserves is the following for the years ended December 31, 2017 and 2016: 2017 2016 Opening balance 1,558,844 5,546,570 Release of reserves (289,164) (406,983) Allocation to reserves 908,189 289,164 Legal reserve used to offset previous year loss (Note 24.4) - (3,869,907) Closing balance 2,177,869 1,558,844
Disclosure of detailed information about balance and breakdown of changes in retained earnings [Text Block]	The following is the balance 2017 2016 Opening balance (402,462) (6,814,432) Profit attributable to owners of Ecopetrol’s shareholders 7,178,539 2,447,881 Release of reserves 289,164 406,983 Allocation to reserves (908,189) (289,164) Dividends declared (1) (945,684) - Legal reserve used to offset previous year loss (2) - 3,869,907 Other movements (1,066) (23,637) Closing balance 5,210,302 (402,462) (1) The Company distributes dividends based on its separate annual financial statements, prepared under International Financial Reporting Standards accepted in Colombia (NCIF, by its acronym in Spanish). The Ordinary General Shareholders' Meeting, held on March 31, 2017, approved the proposal for profit distribution proposal for 2016 and set the distribution of dividends of COP$ 945,684 Dividends paid in 2017 attributable to the shareholders of Ecopetrol S.A. amounted to COP$ 945,661 690,177 558,986 1,022,121 (2) The Ordinary General Meeting of Shareholders, held on March 31, 2016, approved the proposal for profit distribution, which established that there would be no distribution for the year 2015, given the net loss occurred in that year; in addition, the shareholders voted to use the legal reserve to offset this loss, as permitted by the Article 456 of the Colombian Code of Commerce. The amount of losses offset by releases from the legal reserve after tax and mandatory allocations amounted to COP$ 3,869,907
Disclosure of analysis of other comprehensive income by item [text block]	The following is the composition of the other comprehensive income attributable to the shareholders of the parent company, Ecopetrol S.A., net tax as of December 31, 2017 and 2016 2017 2016 Actuarial gain on defined benefit plans (553,091) 994,953 Gain (loss) on equity instruments measured at fair value (1) - 7,828 Cash flow hedges for future exports (Note 30.2.2) 159,295 244,131 Hedge of a net investment in a foreign operation (Note 30.2.3) (97,362) (155,359) Cash flow hedge with derivative instruments 6,942 (19,042) Others - 11,817 Foreign currency translation 7,883,231 8,138,382 7,399,015 9,222,710 (1) During 2016 the Group reclassified to the statement of profit or loss COP$ 68,497 19,405
Disclosure of earnings per share [text block]	2017 2016 2015 Profit (loss) attributable to Ecopetrol’s shareholders 7,178,539 2,447,881 (7,193,859) Weighted average number of outstanding shares 41,116,694,690 41,116,694,690 41,116,694,690 Net basic earnings (loss) per share (Colombian pesos) 174.6 59.5 (175.0)

Sales revenue (Tables)

Sales revenue (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Sales revenue [Abstract]
Disclosure of detailed information about breakdown of sales revenue [Table Text Block]	The following is the breakdown of sales revenue for the years ended December 31, 2017, 2016 and 2015: 2017 2016 2015 National sales Mid-distillates 9,590,326 8,553,503 10,215,224 Gasoline 6,990,187 6,092,739 6,128,208 Services 3,873,352 4,043,284 4,435,274 Natural gas 1,815,754 1,988,336 1,845,345 Crude oil 909,871 553,666 491,279 Plastic and rubber 833,982 724,708 724,392 LPG and propane 509,619 405,869 335,494 Asphalts 275,803 340,400 461,188 Other products 1,207,245 994,645 988,346 26,006,139 23,697,150 25,624,750 Recognition of price differential (1) 2,229,953 1,048,022 441,871 28,236,092 24,745,172 26,066,621 Foreign sales Crude oil 21,479,063 17,278,579 21,181,265 Fuel oil 1,982,408 2,158,539 2,166,469 Gasoline and turbo fuels 1,223,994 1,046,758 93,125 Diesel 1,213,740 1,604,498 81,982 Plastic and rubber 1,169,101 1,171,342 1,096,730 Natural gas 32,303 58,809 182,950 LPG and propane 15,631 8,568 - Trading of crude - - 1,309,196 Cash flow hedge for future exports – Reclassification to profit or loss (Note 30.2.2) 160,772 33,074 7,646 Other 441,124 380,222 161,287 27,718,136 23,740,389 26,280,650 55,954,228 48,485,561 52,347,271 (1) Corresponds to the application of Decree 1880 of September 2014 and Resolution 180522 of 2010, which defined the procedure for price differentials (value generated by the difference between the parity price and the regulated price, which can be positive or negative). See Note 4.16 – Sales revenue recognition, for more details.
Disclosure of disaggregation of revenue from contracts with customers [Table Text Block]	The following are the sales revenue by geographic area for the years ended December 31, 2017, 2016 and 2015: 2017 % 2016 % 2015 % Colombia 28,236,092 50.5 % 24,745,172 51.0 % 26,066,621 49.8 % United States 12,532,932 22.4 % 11,956,967 24.7 % 11,921,720 22.8 % Asia 6,136,796 11.0 % 2,717,414 5.6 % 6,123,593 11.7 % Central America and the Caribbean 6,070,565 10.8 % 3,551,894 7.3 % 3,366,978 6.4 % South America and others 1,947,226 3.5 % 2,568,163 5.3 % 886,433 1.7 % Europe 1,030,617 1.8 % 2,945,951 6.1 % 3,981,926 7.6 % 55,954,228 100 % 48,485,561 100 % 52,347,271 100 %

Cost of sales (Tables)

Cost of sales (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of cost of sales before impairment of non-current assets [Abstract]
Disclosure of detailed information about cost of sales of non current assets [text Block]	2017 2016 2015 Variable costs Imported products (1) 11,637,419 12,049,477 12,935,878 Depreciation, amortization and depletion 5,765,186 5,333,245 5,166,455 Purchases of hydrocarbons - ANH (2) 4,338,576 3,178,199 3,741,010 Purchases of crude in association and concession 2,240,704 1,517,829 1,928,938 Process materials 889,122 608,535 366,454 Hydrocarbon transport services 665,714 783,307 1,380,733 Electric energy 561,424 618,675 424,920 Purchases of other products and gas 488,056 519,884 703,163 Taxes and contributions (3) 449,959 478,332 481,029 Services contracted in associations 195,689 305,326 563,032 Others (4) (663,916) (432,694) (322,547) 26,567,933 24,960,115 27,369,065 Fixed costs Depreciation and amortization 2,366,849 2,050,739 1,433,263 Maintenance 2,038,970 1,998,128 2,334,130 Labor costs 1,815,213 1,571,511 1,542,701 Services contracted 1,414,056 1,083,176 1,301,094 Services contracted in associations 1,008,336 1,260,470 1,415,422 General costs 510,128 383,842 461,994 Materials and operating supplies 468,205 333,258 435,238 Taxes and contributions 343,505 391,032 461,624 Hydrocarbon transport services 333,671 157,463 147,733 Non-capitalized costs of projects 41,459 61,689 92,252 10,340,392 9,291,308 9,625,451 36,908,325 34,251,423 36,994,516 (1) Imported products correspond mainly to diesel fuel and diluent to facilitate the transport of heavy crude oil. (2) Corresponds to purchases of crude oil by Ecopetrol from the National Hydrocarbons Agency (ANH) derived from national production, both of the Group in direct operation and of third parties. (3) Includes gas royalties paid and carbon tax. (4) Corresponds to the capitalization of production costs to inventory.

Administrative, operations an66

Administrative, operations and project expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Administration, operation and project expenses [Abstract]
Disclosure of detailed information on general and administration expense [text block]	The following is the detail of administration, operation and project expenses, according to their function, for the years ended December 31, 2017, 2016 and 2015: 2017 2016 2015 Administrative expenses General expenses 723,341 556,563 393,971 Labor expenses 624,424 657,051 491,748 Taxes (1) 362,963 663,889 730,841 Depreciation and amortization 53,796 45,765 84,425 1,764,524 1,923,268 1,700,985 Operations and project expenses Exploration costs 1,341,940 728,590 1,584,249 Commissions, fees, freights and services 471,657 568,513 878,259 Taxes 324,223 286,331 348,871 Labor expenses 310,947 278,383 309,021 Maintenance 122,273 147,197 181,630 Depreciation and amortization 95,516 177,252 86,215 Fee for regulatory entities 63,470 87,325 77,909 Corporate projects 29,702 301,854 456,159 Others 166,337 176,242 111,955 2,926,065 2,751,687 4,034,268 (1) Mainly corresponds to the recognition of the wealth tax. See Note 10 - Taxes.

Other operating income net (Tab

Other operating income net (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Other operating income and expenses, net [Abstract]
Disclosure of other operating income expense [Table Text Block]	The following is the detail of other operating income or expenses for the years ended December 31, 2017, 2016 and 2015: 2017 2016 2015 (Expense) recovery of provisions for litigations (72,408) 112,999 205,879 Expense for gas pipeline availability BOMT contracts (1) (72,318) (125,077) (124,957) Impairment expense of short-term assets (68,800) (98,739) (2,858) Profit (loss) on sale of assets 40,227 (82,200) 6,744 Gain on acquisition of interests in joint operation (Note 32.3) 451,095 - - Compensation received - 17,790 29,848 Deferred income BOMT contract’s (2) - 211,768 193,197 Other income 227,607 237,571 70,685 505,403 274,112 378,538 (1) Corresponds to the services rendered in connection with the BOMT contracts for the construction, operation, maintenance and transfer of gas pipelines with Transgas. This contract terminated in August 2017. (2) Corresponds to the amortization of the deferred income recognized by Ecopetrol in 2007 for the advance payment made by the Ministry of Finance and Public Credit of the obligations by Ecogas, in relation to the BOMT contracts for the construction, operation, maintenance and transfer of gas pipelines, signed between Ecopetrol and Transgas de Occidente, Centragas and Gases de Boyacá and Santander S.A. in 1997. The amortization of this deferred income ended in December 2016.

Financial result, net (Tables)

Financial result, net (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of financial result, net [Abstract]
Disclosure Of Finance Income Expense Explanatory [Table Text Block]	The following is the detail of financial results for the years ended December 31, 2017, 2016 and 2015: 2017 2016 2015 Finance income Results from financial assets and others 739,148 136,715 164,615 Yields and interests 405,562 386,001 293,506 Gain on sale of equity instruments 13,236 47,129 72,339 Resources from Santiago de las Atalayas (1) - 688,664 - Other financial income 1,410 53,234 91,464 1,159,356 1,311,743 621,924 Finance expenses Interest (2) (2,385,994) (2,765,024) (1,768,618) Financial cost of other liabilities (3) (753,047) (580,491) (627,827) Results from financial assets (481,308) (48,997) (167,869) Other financial expenses (40,252) (69,028) (154,100) (3,660,601) (3,463,540) (2,718,414) Foreign exchange gain (loss), net 5,514 976,430 (5,566,614) Financial result, net (2,495,731) (1,175,367) (7,663,104) (1) Corresponds to the recovery of the provision “Comuneros – Santiago de las Atalayas”. Its balance consisted mainly from the valuation and financial gains generated while the cash that was subject to the reserve (see Note 23.3 for more information). (2) As of December 31, 2017, borrowing costs for the financing of developing natural resources and property, plant and equipment of COP$ 191,651 341,209 744,426 (3) Includes

Risk management (Tables)

Risk management (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of detailed information about financial risk management [Line Items]
Disclosure Of Detailed Information About The Carrying Values For Financial Assets And Liabilities Denominated In Foreign Currencies [Text Block]	The following table sets out the carrying amount for financial assets and liabilities denominated in foreign currency as of December 31, 2017 and 2016: (in US$ Million) 2017 2016 Cash and cash equivalents 1,203 1,916 Other financial assets 1,072 1,367 Trade receivables and payables, net (7) (282) Loans and borrowings (12,590) (15,172) Net liability position (10,322) (12,171)
Disclosure of detailed information about hedging instruments [text block]	(US$ Million) 2017 2016 Hedging instrument at the beginning of the period 5,312 5,376 Reassignment of hedging instruments 1,803 870 Realization of exports (1,803) (870) Capital payments (1) (1,980) (64) Hedging instrument at the end of the period 3,332 5,312 (1) On June 30, 2017, Ecopetrol prepaid the entire outstanding balance of the international syndicated loan whose nominal value was US$ 1,925
Disclosure of detailed information about movement of other comprehensive income by item explanatory [text Block]	The following is the movement of accumulated foreign currency gains and losses in respect of the cash flow hedge recognized in other comprehensive income for the years ended December 31, 2017 and 2016: 2017 2016 Opening balance (244,131) 217,291 Exchange difference 15,934 (724,395) Reclassification to profit or loss 160,772 (33,074) Ineffectiveness (9,247) - Deferred income tax (82,622) 296,047 Closing balance (159,294) (244,131)
Disclosure of detailed information about expected reclassification of exchange differences accumulated in other comprehensive income to profit or loss [Table Text Block]	The expected reclassification of the cumulative exchange rate difference in other comprehensive income to the profit or loss statement, taking an exchange rate of COP$2,984 per US$1.00 is as follows: Year Before Taxes After taxes 2018 95,462 (33,439) 62,023 2019 66,039 (23,132) 42,907 2020 23,804 (8,338) 15,466 2021 21,541 (7,545) 13,996 2022 21,541 (7,545) 13,996 2023 16,786 (5,880) 10,906 245,173 (85,879) 159,294
Sensitivity analysis for types of market risk [text block]	The Group’s risk management strategy involves the use of non-derivative financial instruments related to cash flow hedges for future exports and hedges of a net investment in a foreign operation in order to minimize exposure to currency rate risk, which is detailed below. Scenario / Variation in Effect on income Effect on other 1 % 2,715 305,293 5 % 13,577 1,526,465
Analysis of age of financial assets that are past due but not impaired [text block]	Ecopetrol does not have a significant concentration of credit risk. An aging analysis of the accounts receivable portfolio in arrears, but not impaired, as of December 31, 2017 and 2016 is as follows: 2017 2016 Less than 3-month overdue 65,354 179,008 Between 3- and 6-month overdue 1,131 14,275 More than 6-month overdue 79,688 103,574 146,173 296,857
Disclosure of financial instruments by type of interest rate [text block]	The following table provides information about the sensitivity of Group’s results and other comprehensive income for the next 12 months to variations in interest rate of 100 basis points: Effect on profit or loss (+/-) Effect on Other Financial Financial Plan assets +100 basis points (66,120) 112,383 (171,031) -100 basis points 66,120 (112,282) 183,988
Disclosure of how entity manages liquidity risk [text block]	The following is a summary of the maturity of financial liabilities as of December 31, 2017. The amounts disclosed in the table are the contractual undiscounted cash flows. The payments in foreign currency were restated taking a constant exchange rate of COP$2,984.00 per US dollar. Consequently, these amounts may not reconcile with the amounts disclosed on the consolidated statement of financial position: Up to 1 year 1-5 years 5-10 years > 10 years Total Loans (payment of principal and interest) 5,040,130 28,151,892 18,873,280 15,484,650 67,549,952 Trade and other payables 6,968,207 134,815 - - 7,103,022 Total 12,008,337 28,286,707 18,873,280 15,484,650 74,652,974
Disclosure of detailed information about levearage ratio [Text Block]	Net financial debt is calculated by taking short-term and long-term loans and borrowings less cash and cash equivalents and investments in securities as of December 31 of each year. The level of leverage is calculated as the ratio between net financial debt and the sum of equity and net financial debt. 2017 2016 Loans and borrowings (Note 20) 43,547,835 52,222,027 Cash and cash equivalents (Note 6) (7,945,885) (8,410,467) Other financial assets (Note 9) (6,533,725) (6,686,895) Net financial debt 29,068,225 37,124,665 Equity (Note 24) 48,215,699 43,560,501 Leverage 37.61 % 46.01 %
Hedges of net investment in foreign operations [member]
Disclosure of detailed information about financial risk management [Line Items]
Disclosure of detailed information about hedging instruments [text block]	The following is the movement of accumulated foreign currency gains and losses in respect of the net investment hedge recognized in other comprehensive income for the years ended December 31, 2017 and 2016 2017 2016 Opening balance 155,359 - Exchange difference (86,892) 231,879 Ineffectiveness 329 - Deferred income tax 28,566 (76,520) Closing balance 97,362 155,359

Related parties (Tables)

Related parties (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of transactions between related parties [abstract]
Disclosure of interests in other entities [text block]	associates Accounts Accounts Other Accounts Loans Other Joint Ventures Equion Energy Limited (1) 4,010 - 7,716 101,472 259,760 7 Ecodiesel Colombia S.A. 362 - - 22,228 - - Associates Invercolsa S.A. 18,641 - - - - - Offshore International Group Inc. (2) - 154,810 - - - - Serviport S.A. - - - 5,820 - - Balance as of December 31, 2017 23,013 154,810 7,716 129,520 259,760 7 Current 23,013 - 7,716 129,520 259,760 7 Non-current - 154,810 - - - - 23,013 154,810 7,716 129,520 259,760 7 Accounts Accounts Other assets Accounts Loans Joint Ventures Equion Energy Limited 97,601 - 7,135 89,666 30,644 Ecodiesel Colombia SA 129 - - 20,765 - Offshore International Group (2) - 170,121 - - - Associates Serviport SA - - - 3,989 - Balance as of December 31, 2016 97,730 170,121 7,135 114,420 30,644 Current 97,730 - 7,135 114,420 30,644 Non-current - 170,121 - - - 97,730 170,121 7,135 114,420 30,644 Loans with related parties: (1) Deposits held by Equion in Capital AG for a nominal value of US$ 77 1.44 (2) Loan granted by Ecopetrol SA to Savia Perú SA (subsidiary of Offshore International Group) for US$ 57 4.99 49
Disclosure of transactions between related parties [text block]	The main transactions with related parties for years ended December 31, 2017, 2016 and 2015 are detailed as follows: 2017 2016 2015 Sales and Purchases Sales and Purchases Sales and Purchases Joint Ventures Equion Energy Limited 425,881 598,636 491,698 418,618 515,968 190,158 Ecodiesel Colombia SA 6,583 259,269 5,744 265,584 7,245 267,647 Offshore International Group 15,188 - 6,285 - - - Associates Serviport SA - - - 24,572 - - Total 447,652 857,905 503,727 708,774 523,213 457,805
Disclosure of information about key management personnel [text block]	As of December 31, 2017, the following Key Management Officers owned less than 1% of the outstanding shares of Ecopetrol SA as follows: Key management personnel % Shares Felipe Bayón <1% outstanding shares Mauricio Cárdenas Santamaría <1% outstanding shares Héctor Manosalva Rojas <1% outstanding shares Rafael Espinosa Rozo <1% outstanding shares

Joint operations (Tables)

Joint operations (Tables)	12 Months Ended
	Dec. 31, 2017
Contract where entity not operator [Member]
Disclosure of joint operations [line items]
Disclosure of interests in joint arrangements [text block]	Contracts in which Ecopetrol is not the operator Partners Contract Type % Geographic area of Chipirón 30-40% Harvest 30% Occidental Andina LLC Cravo Norte Production 50% Colombia Rondón 50% Chevron Petroleum Group Guajira Production 57% Colombia Mansarovar Energy Colombia Ltd Nare Production 50% Colombia Meta Petroleum Corp Quifa Production 40% Colombia Equion Energy Limited Piedemonte Production 50% Colombia Casanare 64% Corocora 56% Perenco Colombia Limited Estero Production 89% Colombia Garcero 76% Orocúe 63% ONGC Videsh Limited RC-10 Caribbean Round Exploration 50% North Caribbean Offshore Petrobras, Repsol &; Statoil Tayrona Exploration 30% North Caribbean Offshore Repsol &; Statoil TEA GUA OFF-1 Exploration 50% North Caribbean Offshore Anadarko Fuerte Norte Exploration 50% North Caribbean Offshore Shell Deep Rydberg/Aleatico Exploration 29% Gulf of Mexico Repsol - Leon Lion Exploration 40% Gulf of Mexico Noble Energy Gunflint Production 32% Gulf of Mexico Murphy Oil Dalmatian Production 30% Gulf of Mexico Anadarko K2 Production 21% Gulf of Mexico Equion Energia Limited Niscota Production 20% Brazil Chevron CE-M-715_R11 Exploration 50% Brazil
Contract where Entity is operator [Member]
Disclosure of joint operations [line items]
Disclosure of interests in joint arrangements [text block]	Contracts in which Ecopetrol is the operator Partners Contract Type % Geographic VMM29 ExxonMobil Exploration Colombia CR2 Exploration 50% Colombia C62 Talisman Colombia Oil CPO9 Exploration 55% Colombia ONGC Videsh Limited Colombia Branch RC9 Exploration 50% Colombia CPVEN Sucursal Colombia VMM32 Exploration 51% Colombia Shell Exploration and Production CR4 Exploration 50% Colombia Hocol S.A. AMA4 Exploration 100% Colombia SK Innovation Co Ltd. San Jacinto Exploration 70% Colombia Repsol Exploración Colombia S.A. Catleya Exploration 50% Colombia Emerald Energy PLC Suc. Colombia Cardon Exploration 50% Colombia Gas Ltd. CPO9 - Akacias Production 55% Colombia Occidental Andina LLC La Cira Infantas Production 58% Colombia Teca 86% Colombia Ramshorn International Limited Guariquies I Production 50% Colombia Equion Energy Limited Cusiana Production 98% Colombia Perenco Oil And Gas San Jacinto Rio Paez Production 18% Colombia Cepsa Colombia San Jacinto Rio Paez Production 18% Colombia Total Colombia Mundo Nuevo Exploration 15% Colombia Talisman Oil &; Gas Mundo Nuevo Exploration 15% Colombia Lewis Clarinero Exploration 50% Colombia Maurel &; Prom Suramerica CPO17 Exploration 50% Colombia Equion Energia Limited Alto Magdalena Pipeline OAM 45% Colombia Emerald Energy Alto Magdalena Pipeline OAM 45% Colombia Frontera Energy Alto Magdalena Pipeline OAM 45% Colombia ONGC Videsh Limited Block RC-9 Contract- Caribbean Round No. 37-2007 Exploration 50% Gulf of Mexico JX Nippon FAZ-M-320_R11 Exploration 70% Brazil JX Nippon POT-M-567_R11 Exploration 100% Brazil

Information by segments (Tables

Information by segments (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of operating segments [abstract]
Disclosure of operating segments [text block]	Below are the consolidated statements of profit or loss by segment For the year ended on December 31, 2017 Exploration Refining and Transport Eliminations Total Third-party sales 25,004,320 27,343,359 3,606,549 - 55,954,228 Inter-segment sales 11,490,614 1,300,657 6,991,515 (19,782,786) - Total sales revenue 36,494,934 28,644,016 10,598,064 (19,782,786) 55,954,228 Fixed costs 8,055,925 2,886,745 2,637,604 (3,239,880) 10,340,394 Variable costs 18,254,159 23,968,650 634,231 (16,289,109) 26,567,931 Cost of sales 26,310,084 26,855,395 3,271,835 (19,528,989) 36,908,325 Gross profit 10,184,850 1,788,621 7,326,229 (253,797) 19,045,903 Administrative expenses 781,386 516,501 466,669 (32) 1,764,524 Operation and project expenses 2,070,916 965,457 142,847 (253,155) 2,926,065 Impairment of non-current assets (183,718) (1,067,965) (59,455) - (1,311,138) Other operating income and expenses, net (545,218) 11,694 28,121 - (505,403) Operating income 8,061,484 1,362,934 6,748,047 (610) 16,171,855 Financial result, net Financial income 1,062,393 164,006 106,659 (173,702) 1,159,356 Financial expenses (2,288,576) (1,110,874) (434,664) 173,513 (3,660,601) Foreign exchange gain (loss), net (101,030) 163,992 (57,448) - 5,514 (1,327,213) (782,876) (385,453) (189) (2,495,731) Share of profits of associates 120,786 15,245 (42,493) - 93,538 Income before tax 6,855,057 595,303 6,320,101 (799) 13,769,662 Income tax (3,034,556) (238,625) (2,527,087) - (5,800,268) Net profit (loss) for the period 3,820,501 356,678 3,793,014 (799) 7,969,394 Profit (loss) attributable to: Group owners of parent 3,820,501 358,859 2,999,978 (799) 7,178,539 Non-controlling interest - (2,181) 793,036 - 790,855 3,820,501 356,678 3,793,014 (799) 7,969,394 Supplementary information Depreciation, depletion and amortization 5,981,294 1,188,871 1,111,182 - 8,281,347 For the year ended December 31, 2016 Exploration and Refining and Transportation Eliminations Total Third-party sales 20,527,332 24,194,024 3,764,205 - 48,485,561 Inter-segment sales 7,693,878 629,690 6,884,571 (15,208,139) - Total sales revenue 28,221,210 24,823,714 10,648,776 (15,208,139) 48,485,561 Fixed cost 6,940,074 2,458,745 2,861,269 (2,968,780) 9,291,308 Variable cost 16,032,574 20,385,242 488,522 (11,946,223) 24,960,115 Cost of sales 22,972,648 22,843,987 3,349,791 (14,915,003) 34,251,423 Gross profit 5,248,562 1,979,727 7,298,985 (293,136) 14,234,138 Administrative expenses 832,266 574,413 516,884 (295) 1,923,268 Operation and projects expenses 1,656,960 1,206,718 180,353 (292,344) 2,751,687 Impairment of non-current assets 196,448 773,361 (41,062) - 928,747 Other operating income and expenses, net (349,419) 20,947 53,559 801 (274,112) Operating income 2,912,307 (595,712) 6,589,251 (1,298) 8,904,548 Financial result, net Financial income 983,472 46,469 61,373 220,429 1,311,743 Financial expenses (2,017,641) (952,006) (262,844) (231,049) (3,463,540) Foreign exchange gain (loss), net 923,573 94,715 (41,858) - 976,430 (110,596) (810,822) (243,329) (10,620) (1,175,367) Share of profit of associates 39,397 22,785 (837) - 61,345 Income before tax 2,841,108 (1,383,749) 6,345,085 (11,918) 7,790,526 Income tax (1,518,738) (446,595) (2,577,713) - (4,543,046) Net income for the period 1,322,370 (1,830,344) 3,767,372 (11,918) 3,247,480 Income attributable to: Group owners of parent 1,322,370 (1,823,020) 2,960,449 (11,918) 2,447,881 Non-controlling interest - (7,324) 806,923 - 799,599 1,322,370 (1,830,344) 3,767,372 (11,918) 3,247,480 Supplementary information Depreciation, depletion and amortization 5,482,827 1,145,780 978,394 - 7,607,001 For the year ended December 31, 2015 Exploration and Refining and Transportation Eliminations Total Third-party sales 25,669,213 22,456,866 4,221,192 - 52,347,271 Inter-segment sales 6,063,398 788,810 6,623,358 (13,475,566) - Total Revenue 31,732,611 23,245,676 10,844,550 (13,475,566) 52,347,271 Fixed costs 7,208,632 1,902,797 3,304,815 (2,790,793) 9,625,451 Variable costs 18,500,240 18,856,011 439,607 (10,426,793) 27,369,065 Cost of sales 25,708,872 20,758,808 3,744,422 (13,217,586) 36,994,516 Gross income 6,023,739 2,486,868 7,100,128 (257,980) 15,352,755 Administrative expenses 731,626 451,250 518,109 - 1,700,985 Operation and projects expenses 2,969,723 1,155,301 157,596 (248,352) 4,034,268 Impairment of non-current assets 4,504,497 3,278,993 81,388 - 7,864,878 Other operating income and expenses, net (399,954) 122,595 (101,182) - (378,541) Operating income (1,782,153) (2,521,271) 6,444,217 (9,628) 2,131,165 Finance results, net Financial income 536,121 135,622 86,568 (136,387) 621,924 Financial expenses (1,774,090) (451,906) (492,485) 67 (2,718,414) Foreign exchange gain (loss), net (4,798,741) (949,176) 181,303 - (5,566,614) (6,036,710) (1,265,460) (224,614) (136,320) (7,663,104) Share of profit of companies (70,407) 23,187 533 - (46,687) Income before tax (7,889,270) (3,763,544) 6,220,136 (145,948) (5,578,626) Income tax 2,037,650 (257,256) (2,490,747) - (710,353) Net income (loss) for the period (5,851,620) (4,020,800) 3,729,389 (145,948) (6,288,979) Income attributable to: Group owners of parent (5,851,620) (4,016,050) 2,819,759 (145,948) (7,193,859) Non-controlling interest - (4,750) 909,630 - 904,880 (5,851,620) (4,020,800) 3,729,389 (145,948) (6,288,979) Supplementary information Depreciation, depletion and amortization 5,318,587 570,033 881,738 - 6,770,358
Disclosure of products and services [text block]	The sales by product for each segment are detailed below for the years ended December 31, 2017, 2016 and 2015: For the year ended on December 31, 2017 Exploration Refining and Transport and Eliminations Total Local sales Mid-distillates 1,334 9,588,992 - - 9,590,326 Gasoline - 8,052,289 - (1,062,102) 6,990,187 Services 181,384 221,910 10,597,698 (7,127,640) 3,873,352 Natural gas 2,540,233 4 - (724,483) 1,815,754 Crude oil 11,668,529 - - (10,758,658) 909,871 Plastic and rubber - 833,982 - - 833,982 LPG and propane 199,796 309,823 - - 509,619 Asphalts 34,834 240,969 - - 275,803 Other products 214,059 1,103,089 - (109,903) 1,207,245 14,840,169 20,351,058 10,597,698 (19,782,786) 26,006,139 Recognition of price differential - 2,229,953 - - 2,229,953 14,840,169 22,581,011 10,597,698 (19,782,786) 28,236,092 Foreign sales Crude oil 21,426,665 52,398 - - 21,479,063 Fuel oil - 1,982,408 - - 1,982,408 Gasoline and turbo fuels - 1,223,994 - - 1,223,994 Diesel - 1,213,740 - - 1,213,740 Plastic and rubber - 1,169,101 - - 1,169,101 Natural gas 32,303 - - - 32,303 LPG and propane 15,631 - - - 15,631 Cash flow hedge for future exports – Reclassification to profit or loss 160,772 - - - 160,772 Other 19,393 421,364 367 - 441,124 21,654,764 6,063,005 367 - 27,718,136 36,494,933 28,644,016 10,598,065 (19,782,786) 55,954,228 For the year ended December 31, 2016 Exploration Refining and Transportation Eliminations Total Local sales Med-distillates - 8,553,503 - - 8,553,503 Gasoline and turbo fuel - 6,465,939 - (373,200) 6,092,739 Services 73,247 41,736 10,572,170 (6,643,869) 4,043,284 Natural gas 2,383,323 11,763 - (406,750) 1,988,336 Plastic and rubber - 724,708 - - 724,708 L.P.G. and propane 90,783 319,644 - (4,558) 405,869 Crude oil 5,284,554 - - (4,730,888) 553,666 Asphalts 31,277 309,123 - - 340,400 Aromatics - 186,228 - - 186,228 Oil fuel 1,382 146,866 - - 148,248 Other products 424,952 669,568 75,793 (510,144) 660,169 8,289,518 17,429,078 10,647,963 (12,669,409) 23,697,150 Recognition of price differential - 1,048,022 - - 1,048,022 8,289,518 18,477,100 10,647,963 (12,669,409) 24,745,172 Foreign sales Crude 19,516,197 - - (2,237,618) 17,278,579 Oil fuel - 2,158,539 - - 2,158,539 Med-distillates - 1,594,945 - - 1,594,945 Plastic and rubber - 1,171,342 - - 1,171,342 Gasoline and turbo fuel - 1,046,758 - - 1,046,758 Natural gas 350,685 - - (291,875) 58,810 L.P.G. and propane 6,342 2,225 - - 8,567 Cash flow hedging – Reclassification to profit or loss 33,074 - - - 33,074 Other products 25,395 363,250 814 316 389,775 19,931,693 6,337,059 814 (2,529,177) 23,740,389 Total sales revenue 28,221,211 24,814,159 10,648,777 (15,198,586) 48,485,561 For the year ended December 31, 2015 Exploration and Refining and Transportation Eliminations Total Local sales Med-distillates 25,782 10,206,599 - (17,157) 10,215,224 Gasoline - 6,464,661 - (336,453) 6,128,208 Services 118,812 198,369 10,822,078 (6,703,985) 4,435,274 Natural gas 2,198,284 - - (352,939) 1,845,345 Crude oil 5,847,368 - - (5,356,089) 491,279 Diesel and asphalts 49,583 411,605 - - 461,188 Plastic and rubber - 724,392 - - 724,392 L.P.G. and propane 154,201 190,346 - (9,053) 335,494 Other products 262,906 1,070,725 22,472 (367,757) 988,346 8,656,936 19,266,697 10,844,550 (13,143,433) 25,624,750 Recognition of price differential - 441,871 - - 441,871 8,656,936 19,708,568 10,844,550 (13,143,433) 26,066,621 Foreign sales Crude 21,495,762 - - (314,497) 21,181,265 Fuel oil - 2,166,469 - - 2,166,469 Trading of crude 1,309,196 - - - 1,309,196 Natural gas 233,500 - - (50,550) 182,950 Gasoline and turbo fuel 27,756 65,369 - - 93,125 Diesel - 81,982 - - 81,982 Plastic and rubber - 1,096,730 - - 1,096,730 Cash flow hedging – Reclassification to profit or loss 7,646 - - - 7,646 Other products and services 1,815 126,558 - 32,914 161,287 23,075,675 3,537,108 - (332,133) 26,280,650 Total revenue 31,732,611 23,245,676 10,844,550 (13,475,566) 52,347,271
Disclosure Of Detailed Informat Disclosure of detailed information about investment property segmentwise [Text Block]	The following are the investments amounts made by each segment for the years ended December 31, 2017, 2016 and 2015: 2017 Exploration Refining and Transport and Total Property, plant and equipment 927,282 606,749 829,252 2,363,283 Natural and environmental resources 3,568,355 - - 3,568,355 Intangibles 154,155 4,941 16,772 175,868 4,649,792 611,690 846,024 6,107,506 2016 Exploration Refining and Transport and Total Property, plant and equipment 1,208,464 1,099,850 1,338,615 3,646,929 Natural and environmental resources 2,121,295 - - 2,121,295 Intangibles 53,774 10,274 5,205 69,253 3,383,533 1,110,124 1,343,820 5,837,477 2015 Exploration Refining and Transport and Total Property, plant and equipment 2,460,975 3,590,279 2,497,679 8,548,933 Natural and environmental resources 6,856,761 - - 6,856,761 Intangibles 69,126 18,494 24,635 112,255 9,386,862 3,608,773 2,522,314 15,517,949

Supplemental information on o73

Supplemental information on oil and gas producing activities (Tables)	12 Months Ended
	Dec. 31, 2017
Exploration for and evaluation of mineral resources [Abstract]
Disclosure of detailed information about capitalized costs relating to oil and gas producing activities [Text Block]	(a) Capitalized costs relating to oil and gas exploration and production activities 2017 2016 2015 Natural and environmental properties 48,129,595 47,097,475 45,789,713 Wells, equipment and facilities - property, plant and equipment 30,405,565 29,931,039 21,822,897 Exploration and production projects 6,632,812 6,855,832 9,145,198 Accumulated depreciation, depletion and amortization (51,791,897) (49,714,944) (39,743,147) Net capitalized cost 33,376,075 34,169,402 37,014,661
Disclosure of detailed information about costs Incurred in oil and gas property acquisition, exploration, and development activities [Text Block]	(b) Costs incurred in oil and gas exploration and developed activities Costs incurred are summarized below and include both amounts expensed and capitalized in the corresponding period. 2017 2016 2015 Acquisition of proved properties (1) 591,875 - - Acquisition of unproved properties (2) 164,180 - 357,772 Exploration costs 1,095,588 852,097 1,012,264 Development costs 3,599,385 2,190,426 8,018,131 5,451,028 3,042,523 9,388,167 (1) On December 11, 2017, Ecopetrol América Inc. acquired the 11.6 share 9.2 20.8 (2) Corresponds mainly to investments made by Ecopetrol América Inc in offshore exploration projects of the Warrior and Rydberg wells. For 2015, relates to drilling for the Leon 2 exploratory project, operated by Repsol as well as acquisition of the lease sales 235 and 246 (unproven lands).
Disclosure of detailed information about results of operations for oil and gas exploration and production activities [Text Block]	(c) Results of operations for oil and gas exploration and production activities The Group’s results of operations from oil and gas exploration and production activities for the years ended December 31, 2017, 2016 and 2015 are as follows: 2017 2016 2015 Net revenues Sales 29,823,565 21,322,662 26,039,708 Transfers 7,518,216 7,734,195 5,692,902 37,341,781 29,056,857 31,732,610 Production costs (1) 6,535,794 5,785,950 6,006,563 Depreciation, depletion and amortization (2) 6,349,382 5,927,466 6,234,190 Other production costs (3) 14,066,593 12,370,540 14,457,836 Exploration expenses (4) 1,342,952 730,393 1,586,940 Other expenses (5) 882,743 1,684,590 6,364,414 29,177,464 26,498,939 34,649,943 Income before income tax expense 8,164,317 2,557,918 (2,917,333) Income tax expense (3,678,955) (1,367,357) (371,376) Results of operations for exploration and production activities 4,485,362 1,190,561 (3,288,709) (1) Production costs are lifting costs incurred to operate and maintain productive wells and related equipment and facilities including costs such as operating labor, materials, supplies, and fuel consumed in operations and the costs of operating natural gas liquids plants. In addition, they include expenses 380,810 305,653 206,570 (2) In accordance with IAS 37 the expense related to asset retirement obligations were 179,601 188,370 294,849 (3) Corresponds to transportation costs and naphtha that are not part of the Group’s (4) Exploration expenses include the costs of geological and geophysical activities as well as the non-productive exploratory wells. (5) Corresponds to administration and marketing expenses.
Disclosure of detailed information about proved developed and undeveloped oil and gas reserve quantities [Text Block]	2017 2016 2015 Oil Gas Total Oil Gas Total Oil Gas Total (Mbls) (Gpc) (Mbe) (Mbls) (Gpc) (Mbe) (Mbls) (Gpc) (Mbe) Proved reserves: Opening balance 1,033 3,218 1,598 1,239 3,479 1,849 1,465 3,529 2,084 Revisions of previous estimates (1) 124 294 175 (50) (23) (54) (64) 225 (25) Improved recovery 72 4 73 11 1 11 16 3 17 Purchases 3 2 4 - - - - - - Extensions and discoveries 44 - 43 22 25 27 24 - 24 Production (188) (264) (234) (189) (264) (235) (202) (278) (251) Closing balance 1,088 3,254 1,659 1,033 3,218 1,598 1,239 3,479 1,849 Proved developed reserves: Opening balance 779 3,131 1,329 913 3,176 1,470 1,042 3,284 1,618 Closing balance 818 3,158 1,372 779 3,131 1,329 913 3,176 1,470 Proved undeveloped reserves: Opening balance 254 87 269 326 303 379 423 245 466 Closing balance 270 96 287 254 87 269 326 303 379 (1) Represents changes in previous proved reserves, upward or downward, resulting from new information (except for an increase in proved area), usually obtained from development drilling and production history or result from changes in economic factors.
Disclosure of detailed information about schedule of standardized measure of discounted future cash flows relating to proved crude oil and gas eserves [Text Block]	The standardized measure of discounted future net cash flows related to the above proved crude oil and natural gas reserves is calculated in accordance with the requirements of ASU 2010-03. Estimated future cash inflows from production under SEC requirements are computed by applying unweighted arithmetic average of the first-day-of-the-month for oil and gas price to year-end quantities of estimated net proved reserves, with cost factors based on those at the end of each year, currently enacted tax rates and a 10% annual discount factor. In our view, the information so calculated does not provide a reliable measure of future cash flows from proved reserves, nor does it permit a realistic comparison to be made of one entity with another because the assumptions used cannot reflect the varying circumstances within each entity. In addition, a substantial but unknown proportion of future real cash flows from oil and gas production activities is expected to derive from reserves which have already been discovered, but which cannot yet be regarded as proved. 2017 2016 2015 Future cash inflows 182,114,282 140,458,230 176,865,586 Future costs Production (70,159,534) (60,705,779) (76,363,169) Development (14,860,992) (12,005,835) (16,498,118) Income taxes (23,660,328) (15,400,000) (30,052,830) Future net cash flow 73,433,428 52,346,616 53,951,469 10% discount factor (22,216,583) (18,221,004) (19,117,422) Standardized measure of discounted net cash flows 51,216,845 34,125,612 34,834,047
Disclosure of detailed information about principal sources of change in standardized measure of discounted future net cash flows [Text Block]	The following are the principal sources of change in the standardized measure of discounted net cash flows in 2017, 2016 and 2015: 2017 2016 2015 Net change in sales and transfer prices and in production cost (lifting) related to future production 26,918,170 3,603,876 (50,472,025) Changes in estimated future development costs (1,978,913) (4,767,340) 592,529 Sales and transfer of oil and gas produced, net of production costs (30,805,987) (23,270,907) (25,726,047) Net change due to extension discoveries 284,374 154,352 (93,190) Net change due to purchase and sales of minerals in place 211,777 (83,450) - Net change due to revisions in quantity estimates 9,090,882 (2,570,103) (985,217) Previously estimated development costs incurred during the period 3,482,570 5,042,697 10,769,369 Accretion of discount 4,416,512 5,423,781 11,321,221 Timing and other 11,934,458 6,394,404 (4,381,037) Net change in income taxes (6,462,611) 9,364,255 18,775,304 Aggregate change in the standardized measure of discounted future net cash flows for the year 17,091,232 (708,435) (40,199,093)

Exhibit 1. Consolidated subsi74

Exhibit 1. Consolidated subsidiaries, associates and joint ventures (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of consolidated subsidiaries, associates and joint ventures [Abstract]
Disclosure of interests in subsidiaries [text block]	Consolidated subsidiary companies (1/2) Group Functional Ownership Activity Country/Domicile Geographic Equity, net Profit Total Total Ecopetrol Global Energy SLU U.S. Dollar 100 % Investment vehicle Spain Spain 3,056,580 102,120 3,056,719 139 Ecopetrol Oleo é Gas do Brasil Ltda. Real 100 % Exploration and exploitation of hydrocarbons Brazil Brazil 36,385 (54,591) 50,933 14,548 Ecopetrol del Perú S.A. U.S. Dollar 100 % Exploration and exploitation of hydrocarbons Peru Peru 48,969 (2,271) 51,792 2,823 Ecopetrol America Inc. U.S. Dollar 100 % Exploration and exploitation of hydrocarbons United States United States 2,964,718 163,529 3,368,997 404,279 Black Gold Re Ltd. U.S. Dollar 100 % Reinsurer of Ecopetrol and its subordinates Bermuda Bermuda 607,199 28,135 729,125 121,926 Ecopetrol Germany Gmbh U.S. Dollar 100 % Exploration and exploitation of hydrocarbons Germany Angola 2,345 (118) 2,773 428 Hocol Petroleum Limited U.S. Dollar 100 % Investment vehicle Bermuda Bermuda 2,223,406 (135,261) 2,223,464 58 Hocol S.A. U.S. Dollar 100 % Exploration, exploitation and production of hydrocarbons Cayman Islands Colombia 1,529,052 (60,103) 2,747,950 1,218,898 Andean Chemicals Ltd. U.S. Dollar 100 % Investment vehicle Bermuda Bermuda 5,168,133 (526,869) 5,169,911 1,778 Refinería de Cartagena S.A * U.S. Dollar 100 % Refining, commercialization and distribution of hydrocarbons Colombia Colombia 17,008,913 39,195 25,805,231 8,796,318 Propileno del Caribe Propilco S.A. U.S. Dollar 100 % Production and commercialization of polypropylene resin Colombia Colombia 1,414,530 225,175 1,927,883 513,353 COMAI - Compounding and Masterbatching Industry Colombian Peso 100 % Manufacture of polypropylene compounds and masterbatches Colombia Colombia 141,580 114,241 202,879 61,299 * Information taken from the audited financial statements. Group Functional Ownership Activity Country/Domicile Geographic Equity, net Profit (loss) Total Total Bioenergy S.A. Colombian Peso 99.04 % Production of biofuels Colombia Colombia 335,858 (237,846) 433,582 97,724 Bioenergy Zona Franca SAS Colombian Peso 99.04 % Production of biofuels Colombia Colombia 246,866 (197,949) 702,627 455,761 Amandine Holdings Corp. Colombian Peso 99.04 % On sale Panama Panama 6,657 - 6,657 - The Arces Group Corp. Colombian Peso 99.04 % On sale Panama Panama 5,100 - 5,100 - Cenit SAS Colombian Peso 100 % Storage and transportation by hydrocarbon pipelines Colombia Colombia 13,801,943 3,014,820 15,243,690 1,441,747 Oleoducto Central SA - Ocensa U.S. Dollar 72.65 % Transportation by crude oil pipelines Colombia Colombia 3,014,831 1,667,219 6,205,436 3,190,605 Oleoducto de los Llanos Colombian Peso 65 % Transportation by crude oil pipelines Panama Colombia 1,106,571 321,792 1,919,509 812,938 Oleoducto de Colombia SA - ODC Colombian Peso 73 % Transportation by crude oil pipelines Colombia Colombia 351,308 202,432 555,250 203,942 Bicentenario de Colombia SAS Colombian Peso 55.97 % Transportation activity by crude oil pipelines Colombia Colombia 1,069,490 385,500 3,205,369 2,135,879 Ecopetrol Capital AG U.S. Dollar 100 % Financing, liquidation of financing of group companies or any type of company Switzerland Switzerland 1,240,473 145,970 5,806,746 4,566,273 Ecopetrol Global Capital SLU Euro 100 % Investment vehicle Spain Spain 20 (51) 39 19 Esenttia Resinas del Perú U.S. Dollar 100 % Marketing polypropylene resins and masterbatches Peru Peru 3,866 (84) 15,981 12,115 Ecopetrol Costa Afuera SAS Colombian Peso 100 % Offshore Caribbean exploration Colombia Colombia 15,671 (69,242) 139,192 123,521 ECP Hidrocarburos de México SA de CV U.S. Dollar 100 % Offshore Caribbean exploration Mexico Mexico 4,100 (3,653) 5,851 1,751
Disclosure of interests in associates [text block]	Group Functional Ownership Activity Country/Domicile Geographic Equity, Profit Total Total Associates Invercolsa SA (*) Colombian Peso 43 % Holding with investments in transport and distribution of natural gas and LPG Colombia Colombia 516,640 84,628 560,368 43,728 Serviport SA (*) Colombian Peso 49 % Services for the support of loading and unloading of oil ships, supply of equipment, technical inspections and load measurements Colombia Colombia 20,212 2,031 70,966 50,754 Sociedad Portuaria Olefinas y Derivados S.A. (*) Colombian Peso 50 % Construction, use, maintenance and administration of port facilities, ports, private docks. Colombia Colombia 2,847 178 3,189 342 Joint Ventures Equion Energy Limited U.S. Dollar 51 % Exploration, exploitation and production of hydrocarbons United Kingdom Colombia 1,336,811 253,709 1,865,776 528,965 Ecodiesel Colombia SA (*) Colombian Peso 50 % Production, marketing and distribution of biofuels and oleo chemicals Colombia Colombia 76,766 13,236 128,420 51,654 Offshore International Group (*) U.S. Dollar 50 % Exploration, development, production and processing of hydrocarbons United States Peru 1,007,754 (178,280) 1,858,013 850,259 (*) Information available as of November 30, 2017

Reporting entity (Details Textu

Reporting entity (Details Textual)	12 Months Ended
	Dec. 31, 2017
Disclosure of reporting entity [Abstract]
Proportion of shares available for public trade	11.51%
Proportion of shares held by majority share holders	88.49%

Accounting policies (Details)

Accounting policies (Details)	12 Months Ended
	Dec. 31, 2017
Plant and equipment [Member] | Bottom of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	15 years
Plant and equipment [Member] | Top of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	65 years
Pipelines, networks and lines [member] | Bottom of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	10 years
Pipelines, networks and lines [member] | Top of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	59 years
Buildings [member] | Bottom of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	12 years
Buildings [member] | Top of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	80 years
Other [member] | Bottom of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	5 years
Other [member] | Top of range [member]
Disclosure of accounting policies [Line Items]
Useful lives or depreciation rates, property, plant and equipment	33 years

Accounting policies (Details Te

Accounting policies (Details Textual)	Dec. 31, 2017
Bottom of range [member]
Disclosure of accounting policies [Line Items]
Percentage of voting equity interests acquired	20.00%
Top of range [member]
Disclosure of accounting policies [Line Items]
Percentage of voting equity interests acquired	50.00%

Cash and cash equivalents (Deta

Cash and cash equivalents (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Banks	$ 5,484,981	$ 3,319,465
Short-term investments	2,459,438	5,090,048
Cash	1,466	954
Cash and cash equivalents	$ 7,945,885	$ 8,410,467	$ 6,550,450	$ 7,618,178

Cash and cash equivalents (De79

Cash and cash equivalents (Details 1) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash and cash equivalents	$ 7,945,885	$ 8,410,467	$ 6,550,450	$ 7,618,178
AAA [Member]
Cash and cash equivalents	2,807,170	3,198,394
A One [Member]
Cash and cash equivalents	2,922,714	1,466,015
BRC One Plus [Member]
Cash and cash equivalents	1,152,593	312,290
F One [Member]
Cash and cash equivalents	896,231	545,872
AA Three [Member]
Cash and cash equivalents	99,029	0
F Two [Member]
Cash and cash equivalents	180	409,717
A One Plus [Member]
Cash and cash equivalents	0	73,470
F One Plus [Member]
Cash and cash equivalents	0	2,188,471
Prime Two [Member]
Cash and cash equivalents	0	78,989
F Three [Member]
Cash and cash equivalents	0	37,172
Prime Three [Member]
Cash and cash equivalents	0	32,748
B [Member]
Cash and cash equivalents	0	144
AA Two [Member]
Cash and cash equivalents	27,868	0
A Two [Member]
Cash and cash equivalents	27,350	0
No rating available [Member]
Cash and cash equivalents	$ 12,750	$ 67,185

Cash and cash equivalents (De80

Cash and cash equivalents (Details Textual) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of cash and cash equivalents [Abstract]
Restricted cash and cash equivalents	$ 96,758	$ 114,206
Average rate of return on cash and cash equilents	4.20%	3.50%

Trade and other receivables, 81

Trade and other receivables, net (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Customers
Foreign		$ 2,052,829	$ 1,366,322
Domestic		1,533,058	1,180,577
Fuel price stabilization fund	[1]	2,256,312	1,203,811
Related parties (Note 31)		23,013	97,730
Industrial services		26,223	60,025
Accounts receivable from employees	[2]	34,461	42,407
Other		173,022	261,829
Total current		6,098,918	4,212,701
Non-current
Accounts receivable from employees	[2]	484,504	425,468
Related parties (Note 31)		154,810	170,121
Fuel price stabilization fund	[1]	77,510	77,510
Other		60,308	56,311
Total non-current		$ 777,132	$ 729,410
[1]	Accounts receivable from the Ministry of Finance and Public Credit, arising from the differences between the international parity price of regular motor gasoline and diesel and the prices charged by the Group, in accordance with Resolution 180522 issued on March 29, 2010, as amended. The Ministry of Finance and Public Credit actually settles the payments.
[2]	Ecopetrol transferred the administration, management and control of loans granted to employees to Cavipetrol (“Corporación de los trabajadores de la Empresa Colombiana de Petróleos Ecopetrol S.A.")

Trade and other receivables, 82

Trade and other receivables, net (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of trade and other receivables, net [Abstract]
Opening balance	$ 144,329	$ 160,406
Additions of allowances, net	35,229	19,438
Accounts receivable write-off and uses	(9,542)	(35,515)
Closing balance	$ 170,016	$ 144,329

Inventories, net (Details)

Inventories, net (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Inventories, net [Abstract]
Crude oil	$ 1,836,363	$ 1,557,267
Fuels and petrochemicals	1,481,777	1,270,870
Materials for the production of goods	1,283,256	1,013,764
Current inventories	$ 4,601,396	$ 3,841,901

Inventories, net (Details 1)

Inventories, net (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Inventories, net [Abstract]
Opening balance	$ 265,435	$ 198,539
Additions	9,134	41,957
Foreign currency translation	(4,266)	50,053
Uses	(75,796)	(25,114)
Closing balance	$ 194,507	$ 265,435

Other financial assets (Details

Other financial assets (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Assets measured at fair value through profit or loss
Financial assets at fair value through profit or loss	$ 6,504,625	$ 6,636,298
Amortized cost
Other financial assets	6,533,725	6,686,895
Current	2,967,878	5,315,537
Non-current	3,565,847	1,371,358
Assets measured at amortized cost [Member]
Amortized cost
Other financial assets	3,636	4,152
Hedging instruments [Member]
Amortized cost
Other financial assets	25,464	46,445
Investment portfolio in local currency [Member]
Assets measured at fair value through profit or loss
Financial assets at fair value through profit or loss	3,310,338	2,519,311
Investment portfolio in foreign currency [Member]
Assets measured at fair value through profit or loss
Financial assets at fair value through profit or loss	$ 3,194,287	$ 4,116,987

Other financial assets (Detai86

Other financial assets (Details 1) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Other financial assets [Line Items]
Other financial assets	$ 6,533,725	$ 6,686,895
Not later than one year [member]
Disclosure of Other financial assets [Line Items]
Other financial assets	2,967,878	5,315,537
Later than one year and not later than two years [member]
Disclosure of Other financial assets [Line Items]
Other financial assets	1,588,145	838,786
Later than two years and not later than five yearse [Member]
Disclosure of Other financial assets [Line Items]
Other financial assets	1,817,558	497,204
Later than five years [member]
Disclosure of Other financial assets [Line Items]
Other financial assets	$ 160,144	$ 35,368

Other financial assets (Detai87

Other financial assets (Details 2) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Other financial assets [Line Items]
Financial assets at fair value through profit or loss	$ 6,504,625	$ 6,636,298
Level 1
Disclosure of Other financial assets [Line Items]
Financial assets at fair value through profit or loss	317,912	25,066
Level 2
Disclosure of Other financial assets [Line Items]
Financial assets at fair value through profit or loss	$ 6,186,713	$ 6,611,232

Other financial assets (Detai88

Other financial assets (Details 3) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Financial assets at fair value through profit or loss	$ 6,504,625	$ 6,636,298
AAA [member]
Financial assets at fair value through profit or loss	3,175,727	1,858,665
A1 [member]
Financial assets at fair value through profit or loss	1,149,606	3,060,660
AA+ [member]
Financial assets at fair value through profit or loss	1,067,989	50,192
BBB- [member]
Financial assets at fair value through profit or loss	378,939	0
A [member]
Financial assets at fair value through profit or loss	300,179	0
AA- [member]
Financial assets at fair value through profit or loss	233,668	3,730
A+ [member]
Financial assets at fair value through profit or loss	175,767	0
BBB [member]
Financial assets at fair value through profit or loss	21,835	0
AA [member]
Financial assets at fair value through profit or loss	0	5,289
F1+ [member]
Financial assets at fair value through profit or loss	0	1,636,039
No rating available [member]
Financial assets at fair value through profit or loss	$ 915	$ 21,723

Other financial assets (Detai89

Other financial assets (Details Textual)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Colombian pesos [Member]
Disclosure of Other financial assets [line Items]
Average rate of return on investments	7.40%	8.10%
US Dollar [Member]
Disclosure of Other financial assets [line Items]
Average rate of return on investments	1.10%	0.80%

Taxes (Details)

Taxes (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Current tax assets
Current tax assets		$ 625,374	$ 1,129,098
Current tax liabilities
Current tax liabilities		2,005,688	2,130,940
Income tax [Member]
Current tax liabilities
Current tax liabilities	[1]	1,305,011	1,478,294
National tax on gasoline and surtax on gasoline [Member]
Current tax liabilities
Current tax liabilities		136,706	324,402
Other taxes [Member]
Current tax liabilities
Current tax liabilities	[2]	512,588	328,244
Carbon tax [Member]
Current tax liabilities
Current tax liabilities		51,383	0
Income tax [Member]
Current tax assets
Current tax assets	[1]	165,437	308,868
Credit tax balance [Member]
Current tax assets
Current tax assets	[3]	234,410	598,140
Other taxes [Member]
Current tax assets
Current tax assets		$ 225,527	$ 222,090
[1]	Corresponds to the resulting value after subtracting advanced tax payments, favorable balances and advance payments settled in the previous year's statement. The main variation compared to the previous period corresponds to the decrease in non-deductible expenses, and the effects of the tax reform on issues such as depreciation and exchange difference.
[2]	Mainly includes VAT payable balances and industry and commerce tax.
[3]	Includes mainly the value added tax (VAT) receivable balance.

Taxes (Details 1)

Taxes (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Taxes [Abstract]
Current income tax	$ 5,144,962	$ 4,517,336	$ 3,510,546
Adjustments to prior years’ tax	(68,270)	0	0
Deferred income tax	723,576	25,710	(2,800,193)
Income tax expenses	$ 5,800,268	$ 4,543,046	$ 710,353

Taxes (Details 2)

Taxes (Details 2) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Taxes [Abstract]
Net income (loss) before income tax	$ 13,769,662	$ 7,790,526	$ (5,578,626)
Statutory rate	40.00%	40.00%	39.00%
Income tax at statutory rate	$ 5,507,865	$ 3,116,210	$ (2,175,664)
ETR reconciliation items:
Effect in changes in tax rates and effect in tax base (CREE)	910	807,989	2,063,782
Non deductible wealth tax	85,872	229,375	253,422
Foreign currency translation and exchange difference	(186,787)	(234,316)	310,657
Prior year taxes	274,777	140,630	(21,233)
Non-deductible expenses	129,531	486,300	251,246
Valuation of investments	0	0	48,129
Non taxable income	(11,900)	(3,142)	(19,986)
Income tax calculated	5,800,268	4,543,046	710,353
Current	5,144,962	4,517,336	3,510,546
Deferred	723,576	25,710	(2,800,193)
Income tax	$ 5,800,268	$ 4,543,046	$ 710,353

Taxes (Details 3)

Taxes (Details 3) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Taxes [Abstract]
Deferred tax assets	$ 4,016,161	$ 4,248,014
Deferred tax liabilities	(1,333,280)	(1,639,703)
Net deferred income tax	$ 2,682,881	$ 2,608,311

Taxes (Details 4)

Taxes (Details 4) - COP ($) $ in Millions	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Disclosure Of Taxes [Line Items]
Deferred tax assets	$ 4,016,161		$ 4,248,014
Deferred tax liabilities	(1,333,280)		(1,639,703)
Deferred tax assets (liabilities)	2,682,881		2,608,311		$ 2,213,422
Property, plant and equipment and Natural and environmental resources [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	(1,006,299)	[1]	(220,315)	[1]	205,499
Provisions [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	1,840,988	[2]	1,875,965	[2]	1,824,844
Employee benefits [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	1,373,561	[3]	656,997	[3]	0
Loss carry forwards [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	611,766		477,808		238,193
Accounts payable [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	208,618		311,607		726,256
Borrowings and other financial liabilities [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	0		(113,497)		(540,811)
Accounts receivable [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	94,864		133,840		17,927
Others [Member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	(31,685)		(168,806)		3,804
Goodwill [member]
Disclosure Of Taxes [Line Items]
Deferred tax assets (liabilities)	$ (408,932)		$ (345,288)		$ (262,290)
[1]	For tax purposes, natural and environmental resources and property, plant and equipment have a useful life and a depreciation and amortization calculation methodology different from those determined as per international accounting standards.
[2]	The most representative item corresponds to the provision for well abandonment.
[3]	Actuarial calculations for health, retirement pensions, education, pension bonds and other benefits to long-term employees.

Taxes (Details 5)

Taxes (Details 5) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Disclosure Of Taxes [Line Items]
Opening balance		$ 2,608,311		$ 2,213,422
Recognized in profit or loss		(723,576)		(25,710)
Deferred tax	[1]	798,146		420,599
Closing balance		2,682,881		2,608,311
Property, plant and equipment and natural resources [Member]
Disclosure Of Taxes [Line Items]
Opening balance		(220,315)	[2]	205,499
Recognized in profit or loss		(785,984)		(425,814)
Deferred tax		0		0
Closing balance	[2]	(1,006,299)		(220,315)
Provisions [Member]
Disclosure Of Taxes [Line Items]
Opening balance		1,875,965	[3]	1,824,844
Recognized in profit or loss		(34,977)		51,121
Deferred tax		0		0
Closing balance	[3]	1,840,988		1,875,965
Employee benefits [Member]
Disclosure Of Taxes [Line Items]
Opening balance		656,997	[4]	0
Recognized in profit or loss		(22,818)		40,300
Deferred tax		739,382		616,697
Closing balance	[4]	1,373,561		656,997
Loss carry forwards [Member]
Disclosure Of Taxes [Line Items]
Opening balance		477,808		238,193
Recognized in profit or loss		133,958		239,615
Deferred tax		0		0
Closing balance		611,766		477,808
Accounts payables [Member]
Disclosure Of Taxes [Line Items]
Opening balance		311,607		726,256
Recognized in profit or loss		(102,989)		(414,649)
Deferred tax		0		0
Closing balance		208,618		311,607
Accounts receivables [Member]
Disclosure Of Taxes [Line Items]
Opening balance		133,840		17,927
Recognized in profit or loss		(38,976)		115,913
Deferred tax		0		0
Closing balance		94,864		133,840
Borrowings and other financial liabilities [Member]
Disclosure Of Taxes [Line Items]
Opening balance		(113,497)		(540,811)
Recognized in profit or loss		113,497		427,314
Deferred tax		0		0
Closing balance		0		(113,497)
Others [Member]
Disclosure Of Taxes [Line Items]
Opening balance		(168,806)		3,804
Recognized in profit or loss		78,357		23,488
Deferred tax		58,764		(196,098)
Closing balance		(31,685)		(168,806)
Goodwill [member]
Disclosure Of Taxes [Line Items]
Opening balance		(345,288)		(262,290)
Recognized in profit or loss		(63,644)		(82,998)
Deferred tax		0		0
Closing balance		$ (408,932)		$ (345,288)
[1]	The following is the composition of the income tax recorded against other comprehensive income:
[2]	For tax purposes, natural and environmental resources and property, plant and equipment have a useful life and a depreciation and amortization calculation methodology different from those determined as per international accounting standards.
[3]	The most representative item corresponds to the provision for well abandonment.
[4]	Actuarial calculations for health, retirement pensions, education, pension bonds and other benefits to long-term employees.

Taxes (Details 6)

Taxes (Details 6) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Taxes [Abstract]
Opening balance		$ 2,608,311	$ 2,213,422
Deferred tax recognized in profit or loss		(723,576)	(25,710)
Deferred tax recognized in other comprehensive income	[1]	798,146	420,599
Closing balance		$ 2,682,881	$ 2,608,311
[1]	The following is the composition of the income tax recorded against other comprehensive income:

Taxes (Details 7)

Taxes (Details 7) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about income tax [Line Items]
Pre-tax		$ 2,344,671	$ 1,175,982
Deferred tax	[1]	798,146	420,599
After tax		1,546,525	755,383
Other [member]
Disclosure of detailed information about income tax [Line Items]
Pre-tax		12,119	0
Deferred tax		(4,708)	(47,220)
After tax		7,411	(47,220)
Derivative financial instruments [member]
Disclosure of detailed information about income tax [Line Items]
Pre-tax			(56,804)
Deferred tax			22,722
After tax			(34,082)
Cash flow hedging for future crude oil exports [member]
Disclosure of detailed information about income tax [Line Items]
Pre-tax		80,896	(537,353)
Deferred tax		(54,056)	220,596
After tax		26,840	(316,757)
Actuarial valuation gains (losses) [member]
Disclosure of detailed information about income tax [Line Items]
Pre-tax		2,251,656	1,770,139
Deferred tax		(739,382)	(616,697)
After tax		$ 1,512,274	$ 1,153,442
[1]	The following is the composition of the income tax recorded against other comprehensive income:

Taxes (Details Textual)

Taxes (Details Textual) - COP ($) $ in Millions	1 Months Ended	12 Months Ended				48 Months Ended
	Dec. 23, 2014	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			40.00%	40.00%	39.00%
Presumptive income, percentage on beginning equity			3.00%			3.00%
Disclosure of information about methods, inputs and assumptions used for measuring obligations for returns, refunds and other similar obligations			Tax returns may be reviewed by the tax authorities within 5 years following the filing date and/or amendment, if the returns reflected tax losses.
Average effective tax rate			42.10%	58.30%
Increase (decrease) in deferred tax liability (asset)			$ 97,803
Description of nature of potential income tax consequences that would result from payment of dividend			The rate of this tax will be 5%. Furthermore, the tax rate for dividends will be 35%. In this scenario, the 5% tax on dividends will apply on the amount of the tax distribution, once it has been reduced with the 35% income tax.
Current wealth tax Paid			$ 226,778
Current wealth tax expense -income				$ 569,756
Description of applicability of surtax			 A surtax was established on income tax for 2017 and 2018, of 6% and 4%, respectively, which is applicable when taxable income exceeds COP$800 million.
Description of tax losses carry forward			Accumulated tax loss balance generated starting January 1, 2017 can be offset with the liquid income generated over the following 12 years (unlimited for those with CEJ).
Deferred tax assets			$ 4,016,161	$ 4,248,014		$ 4,248,014
Deferred tax assets for accumulated income tax losses			4,078,439
Unused tax losses [member]
Disclosure of detailed information about income tax [Line Items]
Deferred tax Refineria			$ 44,475
Scenario plan [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate		33.00%
surtax on income for equality In Year 2017 [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			6.00%
surtax on income for equality In Year 2018 [Member] | Scenario plan [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate		4.00%
Value added tax [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			19.00%
Tax rate effect from change in tax rate			5.00%
Bioenergy S.A, Bionergy Zona Franca [Member] | Unused tax losses [member]
Disclosure of detailed information about income tax [Line Items]
Deferred tax assets			$ 53,328
Refineria de Cartagena [Member]
Disclosure of detailed information about income tax [Line Items]
Deferred tax assets			$ 611,766
Ecopetrol Group [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			40.00%
Colombia [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate						25.00%
Surcharge Rate						9.00%
Wealth Tax determined			$ 1,000
Colombia [Member] | surtax on income for equality In Year 2015 [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate	5.00%
Colombia [Member] | surtax on income for equality In Year 2016 [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate	6.00%
Colombia [Member] | surtax on income for equality In Year 2017 [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate	8.00%
Colombia [Member] | surtax on income for equality In Year 2018 [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate	9.00%
Colombia [Member] | Capital gain tax [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate						10.00%
Colombia [Member] | Bottom of range [member] | surtax on income for equality In Year 2015 [Member]
Disclosure of detailed information about income tax [Line Items]
Accounting profit	$ 800
Colombia [Member] | Bottom of range [member] | surtax on income for equality In Year 2016 [Member]
Disclosure of detailed information about income tax [Line Items]
Accounting profit	800
Colombia [Member] | Bottom of range [member] | surtax on income for equality In Year 2017 [Member]
Disclosure of detailed information about income tax [Line Items]
Accounting profit	800
Colombia [Member] | Bottom of range [member] | surtax on income for equality In Year 2018 [Member]
Disclosure of detailed information about income tax [Line Items]
Accounting profit	$ 800
Free Trade Zone Area [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			20.00%	15.00%		15.00%
Presumtive income tax			3.50%
Free Trade Zone Area [Member] | Ecopetrol Group [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			15.00%
Free trade zone with legal stability contract [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			15.00%
Presumtive income tax			3.00%
Free trade zone with legal stability contract [Member] | Ecopetrol Group [Member]
Disclosure of detailed information about income tax [Line Items]
Applicable tax rate			20.00%

Equity instruments measured a99

Equity instruments measured at fair value (Details) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of equity instruments measured at fair value [line Items]
Opening balance	$ 51,610
Closing balance	0	$ 51,610
Non-current assets held for sale [member]
Disclosure of equity instruments measured at fair value [line Items]
Opening balance	51,610	913,488
Fair value adjustments	(7,828)	126,205
Proceeds from sale of shares	(56,930)	(966,715)
Profit (loss) on sale of shares	13,236	(21,368)
Transfers	(88)	0
Closing balance	$ 0	$ 51,610

Equity instruments measured 100

Equity instruments measured at fair value (Details Textual) - Empresa de Energia de Bogota [member] - COP ($) $ / shares in Units, $ in Millions	1 Months Ended
	Oct. 19, 2017	Jul. 29, 2017
Disclosure of equity instruments measured at fair value [line Items]
Number of shares held in other entity sold	17,465,872
Total cash receipt from sales of equity or debt instruments of other entities, clasified as investing activities	$ 34,932
Sale price per share	$ 2,000
First auction [Member]
Disclosure of equity instruments measured at fair value [line Items]
Number of shares held in other entity sold		10,999,163
Total cash receipt from sales of equity or debt instruments of other entities, clasified as investing activities		$ 21,998
Sale price per share		$ 2,000

Other assets (Details)

Other assets (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Current
Partners in joint operations	[1]	$ 583,656	$ 735,032
Advanced payments to contractors and suppliers		103,762	151,871
Prepaid expenses		115,866	140,606
Related parties (Note 31)		7,716	7,135
Other current assets		69,425	988
Total current		880,425	1,035,632
Non-current
Abandonment and pension funds	[2]	323,621	312,423
Employee benefits		202,012	187,969
Judicial deposits and attachments		43,248	140,338
Trust funds		32,748	87,602
Advances and deposits		74,225	63,402
Other assets		5,155	35,002
Total non-current		$ 681,009	$ 826,736
[1]	Corresponds to the net value of cash calls and cutbacks generated in relation to the operations carried out with partners through Exploration and Production (E&P) contracts, Technical Evaluations (TEA) contracts and agreements entered in to with the National Hydrocarbons Agency (ANH), as well as through association contracts and other types of contracts.
[2]	Corresponds to Ecopetrol’s share in trusts established to support costs of abandonment of wells and dismantling of facilities as well as the payment of future retirement pensions in some association contracts.

Assets held for sale and the102

Assets held for sale and their related liabilities (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Assets held for sale Abstract [Abstract]
Assets held for sale		$ 104,140	$ 132,216
Liabilities held for sale Abstract [Abstract]
Liabilities related to assets held for sale		0	40,128
Surplus project materials [Member]
Assets held for sale Abstract [Abstract]
Assets held for sale	[1]	56,049	65,703
Other property, plant and equipment [member]
Assets held for sale Abstract [Abstract]
Assets held for sale	[2]	48,091	36,902
Oil fields [Member]
Assets held for sale Abstract [Abstract]
Assets held for sale	[3]	0	29,611
Liabilities held for sale Abstract [Abstract]
Liabilities related to assets held for sale	[3]	$ 0	$ 40,128
[1]	Mainly includes assets remaining from the expansion project of the oil pipeline for transport of extra heavy crude conducted by Oleoducto Central SA - Ocensa. In 2017, the Group sold part of these assets, generating a loss of COP$2,337 and expects to continue selling the remainder of these assets during 2018 depending on market conditions.
[2]	Includes buildings and land belonging to Ecopetrol and Andean Chemicals Ltd., the latter related to Louisiana Green Fuels (ethanol plant, water plant and harvesters). The Group recorded an impairment loss on these assets of COP$11,292 and continues with its plan to sell these assets depending on market conditions.
[3]	Corresponds mainly to the Sogamoso, Rio Zulia, Rio de Oro and Puerto Barco, Santana, Nancy Maxine Burdine and Valdivia Almagro oil fields, awarded through an auction in November 2016. During the second and third quarter of 2017, Ecopetrol obtained the approval of the assignment of rights of these areas by the ANH, with the transfer of the assets and the corresponding sale being formalized. These operations generated a net profit of COP $ 168,726. The liabilities associated with these assets corresponded to the dismantling and abandonment of the Group’s obligations.

Assets held for sale and the103

Assets held for sale and their related liabilities (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)
Other property, plant and equipment [member]
Disclosure of assets held for sale and their related liabilities [Line Items]
Impairment loss on financial assets	$ 11,292
Oil fields [Member]
Disclosure of assets held for sale and their related liabilities [Line Items]
Gain on assignment of rights	168,726
Surplus project materials [Member]
Disclosure of assets held for sale and their related liabilities [Line Items]
Losses on disposals of non-current assets	$ 2,337

Investments in associates an104

Investments in associates and joint ventures (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investments in joint ventures
Investments in joint ventures	$ 1,105,282	$ 1,303,157
Investments in associates
Investments in associates	225,178	249,537
Investments in joint ventures and associates	1,330,460	1,552,694	$ 1,931,934
Gross carrying amount [member]
Investments in joint ventures
Investments in joint ventures	1,941,174	2,133,893
Investments in associates
Investments in associates	235,082	249,537
Invercolsa S.A. [member] | Gross carrying amount [member]
Investments in associates
Investments in associates	223,963	243,156
Serviport S.A. [member] | Gross carrying amount [member]
Investments in associates
Investments in associates	9,905	5,255
Serviport S.A. [member] | Accumulated impairment [member]
Investments in associates
Investments in associates	(9,904)	0
Olefinas Port Society [Member] | Gross carrying amount [member]
Investments in associates
Investments in associates	1,214	1,126
Equion Energia Limited [Member]
Investments in joint ventures
Investments in joint ventures	761,039	902,747
Equion Energia Limited [Member] | Gross carrying amount [member]
Investments in joint ventures
Investments in joint ventures	1,057,466	1,156,430
Equion Energia Limited [Member] | Accumulated impairment [member]
Investments in joint ventures
Investments in joint ventures	(296,427)	(253,683)
Offshore International Group [member]
Investments in joint ventures
Investments in joint ventures	305,860	360,885
Offshore International Group [member] | Gross carrying amount [member]
Investments in joint ventures
Investments in joint ventures	845,325	937,938
Offshore International Group [member] | Accumulated impairment [member]
Investments in joint ventures
Investments in joint ventures	(539,465)	(577,053)
Ecodiesel Colombia S.A. [member] | Gross carrying amount [member]
Investments in joint ventures
Investments in joint ventures	$ 38,383	$ 39,525

Investments in associates an105

Investments in associates and joint ventures (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Investments in associates and joint ventures [Line Items]
Opening balance	$ 1,552,694	$ 1,931,934
Effects of equity method through:
Profit or loss	93,538	61,345	$ (46,687)
Other comprehensive income	(14,752)	124,645
Dividends declared	(285,961)	(426,837)
Impairment	(15,059)	(127,858)
Reclassifications		(10,535)
Closing balance	1,330,460	1,552,694	1,931,934
Joint ventures [member]
Disclosure of Investments in associates and joint ventures [Line Items]
Opening balance	1,303,157	1,862,418
Effects of equity method through:
Profit or loss	46,869	13,046
Other comprehensive income	(14,752)	(49,127)
Dividends declared	(224,837)	(384,787)
Impairment	(5,155)	(127,858)
Reclassifications		(10,535)
Closing balance	1,105,282	1,303,157	1,862,418
Associates [member]
Disclosure of Investments in associates and joint ventures [Line Items]
Opening balance	249,537	69,516
Effects of equity method through:
Profit or loss	46,669	48,299
Other comprehensive income	0	173,772
Dividends declared	(61,124)	(42,050)
Impairment	(9,904)	0
Reclassifications		0
Closing balance	$ 225,178	$ 249,537	$ 69,516

Investments in associates an106

Investments in associates and joint ventures (Details 2) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of financial position
Current assets		$ 23,224,016	$ 24,129,162
Non-current assets		94,623,396	94,829,815
Total assets		117,847,412	118,958,977
Current liabilities		16,846,611	16,387,358
Non-current liabilities		52,785,102	59,011,118
Total liabilities		69,631,713	75,398,476
Equity		48,215,699	43,560,501	$ 43,100,963	$ 48,534,228
Other complementary information
Cash and cash equivalents		7,945,885	8,410,467	6,550,450	$ 7,618,178
Financial obligations, short-term	[1]	5,144,504	4,126,203
Financial obligations, long-term		38,403,331	48,095,824
Statement of profit or loss
Sales revenue		55,954,228	48,485,561	52,347,271
Costs		36,908,325	34,251,423	36,994,516
Administrative expenses and others		(1,764,524)	(1,923,268)	(1,700,985)
Financial income (expenses)		(2,495,731)	(1,175,367)	(7,663,104)
Income tax		5,800,268	4,543,046	710,353
Net income for the period		7,969,394	3,247,480	(6,288,979)
Other comprehensive income		(1,815,907)	(1,728,607)	7,039,199
Offshore International Group [member]
Statement of financial position
Current assets		289,618	317,700
Non-current assets		1,568,395	1,693,947
Total assets		1,858,013	2,011,647
Current liabilities		192,513	147,090
Non-current liabilities		657,746	671,577
Total liabilities		850,259	818,667
Equity		1,007,754	1,192,980
Other complementary information
Cash and cash equivalents		32,490	22,224
Financial obligations, short-term		97,960	21,408
Financial obligations, long-term		214,259	356,353
Statement of profit or loss
Sales revenue		393,210	379,811	463,660
Costs		(508,461)	(502,107)	(654,095)
Administrative expenses and others		(103,340)	(221,238)	(128,895)
Financial income (expenses)		(20,264)	(12,010)	(8,528)
Income tax		60,575	107,507	90,294
Net income for the period		(178,280)	(248,037)	(237,564)
Other comprehensive income		0	0	0
Dividends paid to the Ecopetrol Business Group		0	0	0
Depreciation and amortization		232,953	228,250	229,317
Equion Energia Limited [Member]
Statement of financial position
Current assets		909,927	712,078
Non-current assets		955,849	1,406,510
Total assets		1,865,776	2,118,588
Current liabilities		430,130	417,203
Non-current liabilities		98,835	170,527
Total liabilities		528,965	587,730
Equity		1,336,811	1,530,858
Other complementary information
Cash and cash equivalents		170,618	300,689
Financial obligations, short-term		336,352	328,497
Financial obligations, long-term		2,921	309
Statement of profit or loss
Sales revenue		1,213,692	1,204,301	1,218,796
Costs		(793,999)	(969,318)	(958,467)
Administrative expenses and others		12,188	(44,810)	(74,258)
Financial income (expenses)		2,373	59,143	37,970
Income tax		(180,546)	30,199	(209,221)
Net income for the period		253,708	279,515	14,820
Other comprehensive income		913,728	935,847	1,024,423
Dividends paid to the Ecopetrol Business Group		217,075	375,035	284,984
Depreciation and amortization		$ 557,970	$ 678,488	$ 642,369
[1]	The increase in the current portion is mainly due to the expiration of: i) the first tranche of local bonds issued by Ecopetrol S.A. in 2013, and ii) the 5-year series of international bonds issued in 2013 by Ecopetrol S.A.. These bonds mature in August and September 2018, respectively.

Investments in associates an107

Investments in associates and joint ventures (Details 3) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Investments in associates and joint ventures [Line Items]
Equity	$ 48,215,699	$ 43,560,501	$ 43,100,963	$ 48,534,228
Investments in joint ventures	1,105,282	1,303,157
Equion Energy Limited [Member]
Disclosure of Investments in associates and joint ventures [Line Items]
Equity	$ 1,336,811	$ 1,530,858
% of Ecopetrol’s ownership	51.00%	51.00%
Ecopetrol’s ownership	$ 681,773	$ 780,738
Additional value of the investment	375,693	375,693
Investments in joint ventures	761,039	902,747
Equion Energy Limited [Member] | Accumulated impairment [member]
Disclosure of Investments in associates and joint ventures [Line Items]
Investments in joint ventures	(296,427)	(253,683)
Offshore International Group [member]
Disclosure of Investments in associates and joint ventures [Line Items]
Equity	$ 1,007,754	$ 1,192,980
% of Ecopetrol’s ownership	50.00%	50.00%
Ecopetrol’s ownership	$ 503,877	$ 596,490
Additional value of the investment	341,448	341,448
Investments in joint ventures	305,860	360,885
Offshore International Group [member] | Accumulated impairment [member]
Disclosure of Investments in associates and joint ventures [Line Items]
Investments in joint ventures	$ (539,465)	$ (577,053)

Investments in associates an108

Investments in associates and joint ventures (Details Textual) - Invercolsa S.A [Member] - shares shares in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2011
Disclosure of Investments in associates and joint ventures [Line Items]
Equivalent Percentage of Associate´s Social Capital assigned to Ecopetrol by a Court		11.58%
Equivalent Percentage of Associate´s Social Capital Ownership	43.35%
Ecopetrol [Member]
Disclosure of Investments in associates and joint ventures [Line Items]
Number of shares investments in associates assigned to Ecopetrol by a Court		324

Property, plant and equipmen109

Property, plant and equipment (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		$ 62,328,502
Ending Balance		61,404,374		$ 62,328,502
Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		90,858,880		89,433,422
Additions/capitalizations		2,363,283		3,646,929
Increase (Decrease) in abandonment costs		156,716		(157,355)
Capitalized financial interests		109,304		242,778
Exchange differences capitalized		6,725		8,639
Disposals		(159,753)		(223,320)
Foreign currency translation		(215,751)		(2,038,527)
Other (reclassifications)	[1]	0		(53,686)
Transfers	[2]	(426,506)		0
Ending Balance		92,692,898		90,858,880
Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		(28,530,378)		(24,328,349)
Disposals		71,098		153,964
Foreign currency translation		55,626		470,762
Depreciation expense		(3,999,982)		(3,791,178)
Recovery (losses) for impairment (Note 18)		977,919		(561,738)
Other (reclassifications)	[1]	0		(473,839)
Transfers	[2]	137,193		0
Ending Balance		(31,288,524)		(28,530,378)
Plant and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		27,096,281
Ending Balance		27,781,921		27,096,281
Plant and equipment [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		42,608,276		37,360,222
Additions/capitalizations		904,854		1,457,547
Increase (Decrease) in abandonment costs		51,619		(84,780)
Capitalized financial interests		38,847		0
Exchange differences capitalized		2,636		0
Disposals		(67,326)		(158,193)
Foreign currency translation		(136,501)		(42,870)
Other (reclassifications)	[1]	0		4,076,350
Transfers	[2]	(840,511)		0
Ending Balance		42,561,894		42,608,276
Plant and equipment [member] | Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		(15,511,995)		(13,469,749)
Disposals		54,244		121,382
Foreign currency translation		15,166		272,582
Depreciation expense		(1,996,614)		(1,869,604)
Recovery (losses) for impairment (Note 18)		1,014,613		(659,223)
Other (reclassifications)	[1]	0		92,617
Transfers	[2]	1,644,613		0
Ending Balance		(14,779,973)		(15,511,995)
Pipelines, networks and lines [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		19,122,228
Ending Balance		19,538,423		19,122,228
Pipelines, networks and lines [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		29,087,782		26,856,085
Additions/capitalizations		876,940		1,383,352
Increase (Decrease) in abandonment costs		105,097		(78,712)
Capitalized financial interests		33,875		0
Exchange differences capitalized		2,299		0
Disposals		(56,147)		(21,814)
Foreign currency translation		(49,800)		(298,750)
Other (reclassifications)	[1]	0		1,247,621
Transfers	[2]	2,000,003		0
Ending Balance		32,000,049		29,087,782
Pipelines, networks and lines [member] | Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		(9,965,554)		(8,572,373)
Disposals		13,464		14,022
Foreign currency translation		32,729		138,611
Depreciation expense		(1,479,792)		(1,426,659)
Recovery (losses) for impairment (Note 18)		316,360		33,048
Other (reclassifications)	[1]	0		(152,203)
Transfers	[2]	(1,378,833)		0
Ending Balance		(12,461,626)		(9,965,554)
Work in progress [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance	[3]	4,611,809
Ending Balance		3,312,898	[4]	4,611,809	[3]
Work in progress [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance	[3]	4,874,406	[4]	11,015,010
Additions/capitalizations		(102)	[4]	(107,181)	[3]
Increase (Decrease) in abandonment costs		0	[4]	0	[3]
Capitalized financial interests		8,501	[4]	205,662	[3]
Exchange differences capitalized		577	[4]	8,639	[3]
Disposals		(26,991)	[4]	(16,031)	[3]
Foreign currency translation		(13,302)	[4]	(1,629,613)	[3]
Other (reclassifications)	[1]	0		(4,602,080)	[3]
Transfers	[2]	(976,771)	[4]	0
Ending Balance	[4]	3,866,318		4,874,406	[3]
Work in progress [member] | Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance	[3]	(262,597)	[4]	(19,566)
Disposals		0	[4]	0	[3]
Foreign currency translation		0	[4]	38,904	[3]
Depreciation expense		0	[4]	0	[3]
Recovery (losses) for impairment (Note 18)		(372,804)	[4]	(3,270)	[3]
Other (reclassifications)	[1]	0		(278,665)	[3]
Transfers	[2]	81,981	[4]	0
Ending Balance	[4]	(553,420)		(262,597)	[3]
Buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		4,823,279
Ending Balance		4,950,024		4,823,279
Buildings [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		6,911,757		6,479,356
Additions/capitalizations		363,836		360,596
Increase (Decrease) in abandonment costs		0		0
Capitalized financial interests		6,941		0
Exchange differences capitalized		471		0
Disposals		(6,539)		(12,540)
Foreign currency translation		(4,904)		(9,832)
Other (reclassifications)	[1]	0		94,177
Transfers	[2]	347,024		0
Ending Balance		7,618,586		6,911,757
Buildings [member] | Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		(2,088,478)		(1,698,791)
Disposals		807		7,021
Foreign currency translation		3,929		12,658
Depreciation expense		(416,698)		(392,294)
Recovery (losses) for impairment (Note 18)		11,538		57,157
Other (reclassifications)	[1]	0		(74,229)
Transfers	[2]	(179,660)		0
Ending Balance		(2,668,562)		(2,088,478)
Lands [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		3,867,368
Ending Balance		3,799,833		3,867,368
Lands [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		3,894,220		4,068,951
Additions/capitalizations		14,631		41,202
Increase (Decrease) in abandonment costs		0		0
Capitalized financial interests		1,027		0
Exchange differences capitalized		70		0
Disposals		(23)		713
Foreign currency translation		(7,850)		(69,878)
Other (reclassifications)	[1]	0		(146,768)
Transfers	[2]	(62,720)		0
Ending Balance		3,839,355		3,894,220
Lands [member] | Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		(26,852)		(13,689)
Disposals		0		15
Foreign currency translation		0		0
Depreciation expense		0		0
Recovery (losses) for impairment (Note 18)		(7,794)		24,067
Other (reclassifications)	[1]	0		(37,245)
Transfers	[2]	(4,876)		0
Ending Balance		(39,522)		(26,852)
Other [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		2,807,537
Ending Balance		2,021,275		2,807,537
Other [member] | Cost [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		3,482,439		3,653,798
Additions/capitalizations		203,124		511,413
Increase (Decrease) in abandonment costs		0		6,137
Capitalized financial interests		20,113		37,116
Exchange differences capitalized		672		0
Disposals		(2,727)		(15,455)
Foreign currency translation		(3,394)		12,416
Other (reclassifications)	[1]	0		(722,986)
Transfers	[2]	(893,531)		0
Ending Balance		2,806,696		3,482,439
Other [member] | Accumulated depreciation and impairment losses [member]
Disclosure of detailed information about property, plant and equipment [line items]
Beginning Balance		(674,902)		(554,181)
Disposals		2,583		11,524
Foreign currency translation		3,802		8,007
Depreciation expense		(106,878)		(102,621)
Recovery (losses) for impairment (Note 18)		16,006		(13,517)
Other (reclassifications)	[1]	0		(24,114)
Transfers	[2]	(26,032)		0
Ending Balance		$ (785,421)		$ (674,902)
[1]	Corresponds mainly to transfers to: a) inventory of project materials for use in the operation for COP$(712,967) mainly Ecopetrol and Reficar, b) opening of the intangible part of projects to natural resources for COP$68,750 and c) other COP$116,692.
[2]	Transfers correspond mainly to transfers to: a) inventory of project materials for use in the operation for COP$ 250,239, b) classification of the intangible part of projects to natural resources for COP$ 7,222 and c) others for COP$ 31,852.
[3]	The balance of work in progress as of December 31, 2016, mainly includes investments made in the development projects of the Castilla y Chichimene fields, integral energy plan (PIEEL for its acronym in Spanish), primary and secondary development of the Tibú-Socuabo project and modernization of the Refinería de Barrancabermeja.
[4]	The balance of work in progress as of December 31, 2017, mainly includes investments in production at the Castilla field, the integral plan of electrical energy and secondary recovery of Yarigui and the modernization project of the Barrancabermeja refinery.

Property, plant and equipmen110

Property, plant and equipment (Details Textual) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Inventory [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Increase (decrease) through transfers from (to) investment property, property, plant and equipment	$ 250,239	$ (712,967)
Intangible Part Of Natural Resources [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Increase (decrease) through transfers from (to) investment property, property, plant and equipment	7,222	68,750
Other assets [member]
Disclosure of detailed information about property, plant and equipment [line items]
Increase (decrease) through transfers from (to) investment property, property, plant and equipment	$ 31,852	$ 116,692

Natural and environmental re111

Natural and environmental resources (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016
Disclosure of Natural and environmental resources [Line Items]
Net balance as of December 31, 2016		$ 22,341,047		$ 24,043,297
Net balance as of December 31, 2017		21,308,265		22,341,047
Oil and gas investments [Member]
Disclosure of Natural and environmental resources [Line Items]
Net balance as of December 31, 2016		16,608,681		17,273,579
Net balance as of December 31, 2017		16,168,895		16,608,681
Asset retirement cost [Member]
Disclosure of Natural and environmental resources [Line Items]
Net balance as of December 31, 2016		914,242		580,576
Net balance as of December 31, 2017		630,562		914,242
Exploration and evaluation [member]
Disclosure of Natural and environmental resources [Line Items]
Net balance as of December 31, 2016	[2]	4,818,124	[1]	6,189,142
Net balance as of December 31, 2017	[1]	4,508,808		4,818,124	[2]
Natural and environmental resources [Member] | Cost [member]
Disclosure of Natural and environmental resources [Line Items]
Balance		54,202,135		52,099,869
Additions/capitalizations		3,426,405		2,121,295
Acquisition of interests in joint operations		141,950
Adjustment to fair value of participation in joint operations		451,095
Increase (decrease) in abandonment costs		(117,082)		562,151
Disposals		(253,551)		(185,522)
Dry wells		(898,264)	[3]	(342,691)	[4]
Capitalized financial interests		82,347		98,431
Exchange differences capitalized		5,588		7,259
Foreign currency translation		(77,523)		(464,543)
Transfers	[5]	(55,171)
Other				305,886
Balance		56,907,929		54,202,135
Natural and environmental resources [Member] | Cost [member] | Oil and gas investments [Member]
Disclosure of Natural and environmental resources [Line Items]
Balance		47,079,096		44,148,353
Additions/capitalizations		2,422,203		3,045,474
Acquisition of interests in joint operations		141,950
Adjustment to fair value of participation in joint operations		451,095
Increase (decrease) in abandonment costs		224		0
Disposals		(38,072)		(26,548)
Dry wells		0	[3]	0	[4]
Capitalized financial interests		72,395		0
Exchange differences capitalized		4,913		0
Foreign currency translation		(62,446)		(352,766)
Transfers	[5]	112,500
Other				264,583
Balance		50,183,858		47,079,096
Natural and environmental resources [Member] | Cost [member] | Asset retirement cost [Member]
Disclosure of Natural and environmental resources [Line Items]
Balance		2,304,915		1,762,374
Additions/capitalizations		59,345		10,391
Acquisition of interests in joint operations		0
Adjustment to fair value of participation in joint operations		0
Increase (decrease) in abandonment costs		(143,241)		566,213
Disposals		(629)		(37,942)
Dry wells		0	[3]	0	[4]
Capitalized financial interests		0		0
Exchange differences capitalized		0		0
Foreign currency translation		(573)		(8,049)
Transfers	[5]	(4,554)
Other				11,928
Balance		2,215,263		2,304,915
Natural and environmental resources [Member] | Cost [member] | Exploration and evaluation [member]
Disclosure of Natural and environmental resources [Line Items]
Balance	[2]	4,818,124	[1]	6,189,142
Additions/capitalizations		944,857	[1]	(934,570)	[2]
Acquisition of interests in joint operations	[1]	0
Adjustment to fair value of participation in joint operations	[1]	0
Increase (decrease) in abandonment costs		25,935	[1]	(4,062)	[2]
Disposals		(214,850)	[1]	(121,032)	[2]
Dry wells		(898,264)	[1],[3]	(342,691)	[2],[4]
Capitalized financial interests		9,952	[1]	98,431	[2]
Exchange differences capitalized		675	[1]	7,259	[2]
Foreign currency translation		(14,504)	[1]	(103,728)	[2]
Transfers	[1],[5]	(163,117)
Other	[2]			29,375
Balance	[1]	4,508,808		4,818,124	[2]
Natural and environmental resources [Member] | Accumulated depletion and impairment [member]
Disclosure of Natural and environmental resources [Line Items]
Balance		(31,861,088)		(28,056,572)
Depletion expense		(4,173,319)		(3,705,767)
Impairment				(239,151)
Recovery (losses) for impairment		376,934
Disposals		38,098		64,262
Foreign currency translation		42,359		224,069
Transfers	[5]	(22,648)
Other				(147,929)
Balance		(35,599,664)		(31,861,088)
Natural and environmental resources [Member] | Accumulated depletion and impairment [member] | Oil and gas investments [Member]
Disclosure of Natural and environmental resources [Line Items]
Balance		(30,470,415)		(26,874,774)
Depletion expense		(3,979,179)		(3,496,998)
Impairment				(239,151)
Recovery (losses) for impairment		376,934
Disposals		37,808		26,320
Foreign currency translation		42,114		218,898
Transfers	[5]	(22,225)
Other				(104,710)
Balance		(34,014,963)		(30,470,415)
Natural and environmental resources [Member] | Accumulated depletion and impairment [member] | Asset retirement cost [Member]
Disclosure of Natural and environmental resources [Line Items]
Balance		(1,390,673)		(1,181,798)
Depletion expense		(194,140)		(208,769)
Impairment				0
Recovery (losses) for impairment		0
Disposals		290		37,942
Foreign currency translation		245		5,171
Transfers	[5]	(423)
Other				(43,219)
Balance		(1,584,701)		(1,390,673)
Natural and environmental resources [Member] | Accumulated depletion and impairment [member] | Exploration and evaluation [member]
Disclosure of Natural and environmental resources [Line Items]
Balance	[2]	0	[1]	0
Depletion expense		0	[1]	0	[2]
Impairment	[2]			0
Recovery (losses) for impairment	[1]	0
Disposals		0	[1]	0	[2]
Foreign currency translation		0	[1]	0	[2]
Transfers	[1],[5]	0
Other	[2]			0
Balance	[1]	$ 0		$ 0	[2]
[1]	The balance of exploration and evaluation includes mainly investments made in the Purple Angel, Tayrona and unconventional hydrocarbons projects and in the developing fields, Piedemonte, Castilla y Tibú.
[2]	The balance of exploration and evaluation mainly includes investments in production projects of direct operation in Castilla, Chichimene and Piedemonte. Additionally, it includes offshore exploration projects: Fuerte Sur, Kronos and Tayrona and Onshore: Caño Sur block, CPO 10 and non-conventional hydrocarbons program.
[3]	Includes mainly dry wells in operation of: 1) Ecopetrol S.A. for (COP$450,524): Kronos, Brama, Catfish and Venus, among others, 2) Ecopetrol America Inc for (COP$312,684): Warrior # 2 and Parmer and 3) Ecopetrol Costa Afuera for (COP$57,877): Molusco.
[4]	Includes dry wells in operation of: 1) Ecopetrol for COP$302,965; 2) ECP Oil and Gas Germany GmbH for COP$26,273; 3) Ecopetrol America Inc. for COP$5,032; 4) Hocol S.A. for COP$5,049 and 5) Ecopetrol Brasil for COP$3,372.
[5]	Corresponds mainly to transfers to property, plant and equipment.

Natural and environmental re112

Natural and environmental resources (Details 1) - Suspended exploratory wells [Member] - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Natural and environmental resources [Line Items]
Intangible exploration and evaluation assets		$ 1,642,247	$ 1,652,423	$ 751,892
No. of projects exceeding 1 year		24	24	59
Later than one year and not later than three years [member]
Disclosure of Natural and environmental resources [Line Items]
Intangible exploration and evaluation assets	[1]	$ 600,767	$ 1,300,874	$ 490,184
Later than three years and not later than five years [member]
Disclosure of Natural and environmental resources [Line Items]
Intangible exploration and evaluation assets	[2]	791,261	197,997	100,316
Later than five years [member]
Disclosure of Natural and environmental resources [Line Items]
Intangible exploration and evaluation assets	[3]	250,219	153,552	161,392
Not later than one year [member]
Disclosure of Natural and environmental resources [Line Items]
Intangible exploration and evaluation assets		$ 2,480	$ 528,313	$ 280,801
[1]	Corresponds mainly to discovery wells of Ecopetrol America Inc: Leon 2 and Warrior # 1, which are under evaluation.
[2]	The balance corresponds mainly to discovery wells of Ecopetrol America Inc: Leon 1, which are under evaluation and Rydberg which is currently working on the development plan and feasibility studies.
[3]	Corresponds mainly to wells of Offshore International Group, which are temporarily abandoned.

Natural and environmental re113

Natural and environmental resources (Details Textual) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Non-current assets held for sale [member]
Disclosure of Natural and environmental resources [Line Items]
Transfers		$ 244,387
Other [Member]
Disclosure of Natural and environmental resources [Line Items]
Transfers		(17,532)
Property, plant and equipment [member]
Disclosure of Natural and environmental resources [Line Items]
Transfers		(68,898)
Ecopetrol [Member]
Disclosure of Natural and environmental resources [Line Items]
Dry wells	$ 450,524	302,965
ECP Oil and Gas Germany GmbH [Member]
Disclosure of Natural and environmental resources [Line Items]
Dry wells		26,273
Ecopetrol America Inc [Member]
Disclosure of Natural and environmental resources [Line Items]
Dry wells	312,684	5,032
Hocol S.A [Member]
Disclosure of Natural and environmental resources [Line Items]
Dry wells		5,049
Ecopetrol Brasil [Member]
Disclosure of Natural and environmental resources [Line Items]
Dry wells		$ 3,372
Ecopetrol Costa Afuera [Member]
Disclosure of Natural and environmental resources [Line Items]
Dry wells	$ 57,877

Intangible assets (Details)

Intangible assets (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about intangible assets [line items]
Beggining Balance		$ 272,132	$ 388,051
Ending Balance		380,226	272,132
Licences and Software member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance		200,640	199,331
Ending Balance		$ 295,141	$ 200,640
Intangibles, Useful life		< 5 years	< 5 years
Other intangible assets [member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance	[1]	$ 71,492	$ 188,720
Ending Balance	[1]	$ 85,085	$ 71,492
Intangibles, Useful life	[1]	< 7 years	< 7 years
Cost [member] | Licences and Software member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance		$ 784,320	$ 733,115
Acquisitions\Additions		169,545	63,560
Disposals		(9,469)	(29,099)
Foreign currency translation		(1,414)	(9,359)
Reclassifications			26,103
Transfers		17,574
Ending Balance		960,556	784,320
Cost [member] | Other intangible assets [member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance	[1]	138,982	244,063
Acquisitions\Additions	[1]	6,323	5,693
Disposals	[1]	0	0
Foreign currency translation	[1]	(92)	(149)
Reclassifications	[1]		(110,625)
Transfers	[1]	23,339
Ending Balance	[1]	168,552	138,982
Cost [member] | Intangible assets [Member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance		923,302	977,178
Acquisitions\Additions		175,868	69,253
Disposals		(9,469)	(29,099)
Foreign currency translation		(1,506)	(9,508)
Reclassifications			(84,522)
Transfers		40,913
Ending Balance		1,129,108	923,302
Accumulated amortization [member] | Licences and Software member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance		(583,680)	(533,784)
Amortization expense		(89,216)	(81,913)
Disposals		8,744	29,097
Foreign currency translation		979	8,527
Reclassifications			(5,607)
Transfers		(2,242)
Ending Balance		(665,415)	(583,680)
Accumulated amortization [member] | Other intangible assets [member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance	[1]	(67,490)	(55,343)
Amortization expense	[1]	(18,830)	(28,142)
Disposals	[1]	0	0
Foreign currency translation	[1]	0	1
Reclassifications	[1]		15,994
Transfers	[1]	2,853
Ending Balance	[1]	(83,467)	(67,490)
Accumulated amortization [member] | Intangible assets [Member]
Disclosure of detailed information about intangible assets [line items]
Beggining Balance		(651,170)	(589,127)
Amortization expense		(108,046)	(110,055)
Disposals		8,744	29,097
Foreign currency translation		979	8,528
Reclassifications			10,387
Transfers		611
Ending Balance		$ (748,882)	$ (651,170)
[1]	Corresponds mainly to easements.

Impairment of long-term asse115

Impairment of long-term assets (Details) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	$ (1,311,138)	$ 928,747	$ 7,864,875
Production and exploration [Member] | Impairment by segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	(183,718)	196,448	4,504,495
Refining and petrochemicals [Member] | Impairment by segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	(1,067,965)	773,361	3,278,993
Transportation and logistics [Member] | Impairment by segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	(59,455)	(41,062)	81,387
Natural resources [Member] | Financial statement segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	(376,934)	239,151	2,865,076
Investment in joint ventures and associates [Member] | Financial statement segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	15,059	127,858	588,144
Other non-current assets [Member] | Financial statement segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	28,656	0	0
Goodwill [member] | Financial statement segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	0	0	266,901
Property, plant and equipment [Member] | Financial statement segment [Member]
Disclosure of detailed information about impairment of non-current assets [Line Items]
Total of the impairment charge	$ (977,919)	$ 561,738	$ 4,144,754

Impairment of long-term asse116

Impairment of long-term assets (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impairment loss - Exploration and production segment (reversal of impairment loss) recognised in profit or loss	$ (183,718)	$ 196,448	$ 4,504,495
Oilfields [Member]
Impairment loss - Exploration and production segment (reversal of impairment loss) recognised in profit or loss	(188,873)	68,590	3,649,451
Investment in joint ventures and associates [Member]
Impairment loss - Exploration and production segment (reversal of impairment loss) recognised in profit or loss	5,155	127,858	588,144
Goodwill [Member]
Impairment loss - Exploration and production segment (reversal of impairment loss) recognised in profit or loss	$ 0	$ 0	$ 266,900

Impairment of long-term asse117

Impairment of long-term assets (Details 2) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impairment loss	$ (15,059)	$ (127,858)
Impairment loss (reversal of impairment loss) recognised in profit or loss	(183,718)	196,448	$ 4,504,495
Oil fields [Member]
Impairment loss (reversal of impairment loss) recognised in profit or loss	(188,873)	68,590	3,649,451
Oil fields in Colombia | Oil fields [Member] | Expense (recovery) for impairment
Impairment loss	584,540	1,117,020	2,430,923
Reversal of impairment loss	(298,210)	(1,090,434)
Oil fields in Colombia | Oil fields [Member] | Carrying amount
Impairment loss	2,172,747	5,258,265	10,323,500
Reversal of impairment loss	13,229,212	17,502,391
Oil fields in Colombia | Oil fields [Member] | Recoverable amount
Impairment loss	1,588,207	4,902,943	7,645,665
Reversal of impairment loss	23,906,828	36,704,807
Fields operated abroad | Oil fields [Member] | Expense (recovery) for impairment
Impairment loss	(475,203)	42,004	1,218,528
Fields operated abroad | Oil fields [Member] | Carrying amount
Impairment loss	748,510	688,895	1,242,979
Fields operated abroad | Oil fields [Member] | Recoverable amount
Impairment loss	$ 1,324,010	$ 647,272	$ 24,451

Impairment of long-term asse118

Impairment of long-term assets (Details 3) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Investment in associates and joint ventures	$ 5,155	$ 127,858	$ 588,144
Offshore International Group
Investment in associates and joint ventures	(37,589)	46,703	415,616
Equion Energy Limited
Investment in associates and joint ventures	$ 42,744	$ 81,155	$ 172,528

Impairment of long-term asse119

Impairment of long-term assets (Details 4) - Refining and Petrochemical segment [Member] - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	$ (1,067,965)	$ 773,361	$ 3,278,993
Carrying amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	22,508,926	22,598,322	27,203,474
Recoverable amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	23,576,891	21,824,961	23,924,482
Refineria de Cartagena [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	(1,434,298)	465,852	3,226,240
Refineria de Cartagena [Member] | Carrying amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	20,578,412	21,672,367	26,561,335
Refineria de Cartagena [Member] | Recoverable amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	22,012,710	21,206,515	23,335,096
Refineria de Barrancabermeja (projects)
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	273,987
Refineria de Barrancabermeja (projects) | Carrying amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	1,172,773
Refineria de Barrancabermeja (projects) | Recoverable amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	898,786
Bioenergy
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	92,346	307,509	52,753
Bioenergy | Carrying amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	757,741	925,955	642,139
Bioenergy | Recoverable amount [Member]
Impairment loss - Refining and petrochemical segment (reversal of impairment loss) recognized in profit or loss	$ 665,395	$ 618,446	$ 589,386

Impairment of long-term asse120

Impairment of long-term assets (Details Textual) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Equion Energy Limited [Member]
Disclosure of impairment of long-term assets [Line Items]
Discount rate used in current estimate of value in use	8.20%	8.90%
Refineria de Barrancabermeja [Member]
Disclosure of impairment of long-term assets [Line Items]
Expense for impairment	$ 273,987
Offshore international group [Member]
Disclosure of impairment of long-term assets [Line Items]
Discount rate used in current estimate of value in use	8.60%	8.00%
Refineria de Cartagena [Member]
Disclosure of impairment of long-term assets [Line Items]
Discount rate used in current estimate of value in use	6.00%	6.30%
Bioenergy [Member]
Disclosure of impairment of long-term assets [Line Items]
Discount rate used in current estimate of value in use	6.20%	6.70%
Transportation and logistics segment [Member]
Disclosure of impairment of long-term assets [Line Items]
Reversal of impairment loss	$ 59,455	$ 41,062
Oil fields [Member]
Disclosure of impairment of long-term assets [Line Items]
Information about prices based on information provided by specialized market analysts and management analysts	The forecasts include US$52.9/barrel for 2018, US$ 72.5/barrel average for the next six years and US$81.9/barrel as of the year 2030.
Refining and Petrochemical segment [Member]
Disclosure of impairment of long-term assets [Line Items]
Information about prices based on information provided by specialized market analysts and management analysts		In 2016, the assumptions made used a price of US$56.8/ barrel in 2017, US $67.9/barrel average for the medium term and US$80/ barrel in the long term.
Bottom of range [member]
Disclosure of impairment of long-term assets [Line Items]
Weighted average cost of capital, significant unobservable inputs, assets	7.90%	7.90%
Top of range [member]
Disclosure of impairment of long-term assets [Line Items]
Weighted average cost of capital, significant unobservable inputs, assets	8.90%	8.90%

Goodwill (Details)

Goodwill (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Goodwill From Acquisitions [Abstract]
Goodwill	$ 1,159,922	$ 1,159,922
Oleoducto central S.A [Member]
Goodwill From Acquisitions [Abstract]
Goodwill	683,496	683,496
Hocol Petroleum Ltd. [member]
Goodwill From Acquisitions [Abstract]
Goodwill	537,598	537,598
Andean Chemical Ltd [member]
Goodwill From Acquisitions [Abstract]
Goodwill	127,812	127,812
Propilco S.A [Member]
Goodwill From Acquisitions [Abstract]
Goodwill	108,137	108,137
Gross carrying amount [member]
Goodwill From Acquisitions [Abstract]
Goodwill	1,457,043	1,457,043
Accumulated impairment [member]
Goodwill From Acquisitions [Abstract]
Goodwill	$ (297,121)	$ (297,121)

Loans and borrowings (Details)

Loans and borrowings (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Disclosure of Loans and borrowings [Line Items]
Borrowings		$ 43,547,835	$ 52,222,027
Less short-term	[1]	5,144,504	4,126,203
Total long-term		38,403,331	48,095,824
Local currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		$ 5,979,216	$ 6,741,798
Local currency [Member] | Syndicated Loan [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings, interest rate		8.70%	9.50%
Borrowings		$ 3,307,950	$ 3,828,329
Local currency [Member] | Other borrowings [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings, interest rate	[2]	7.70%	9.10%
Borrowings	[2]	$ 978,795	$ 905,266
Local currency [Member] | Bonds [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings, interest rate		8.90%	8.60%
Borrowings		$ 1,692,471	$ 2,008,203
Foreign currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		$ 37,568,619	$ 45,480,229
Foreign currency [Member] | Commercial loans [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings, interest rate		4.30%	2.90%
Borrowings		$ 528,815	$ 7,945,693
Foreign currency [Member] | Commercial loan-Refineria de Cartagena [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings, interest rate		4.30%	4.10%
Borrowings		$ 7,401,781	$ 7,988,678
Foreign currency [Member] | Other borrowings [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[2]	$ 471,429	$ 235,693
Foreign currency [Member] | Bonds [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings, interest rate		6.10%	6.10%
Borrowings		$ 29,166,594	$ 29,310,165
[1]	The increase in the current portion is mainly due to the expiration of: i) the first tranche of local bonds issued by Ecopetrol S.A. in 2013, and ii) the 5-year series of international bonds issued in 2013 by Ecopetrol S.A.. These bonds mature in August and September 2018, respectively.
[2]	Includes financial leasing and debt in connection with build, operate, maintenance and transfer (BOMT) contracts.

Loans and borrowings (Details 1

Loans and borrowings (Details 1) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Disclosure of Loans and borrowings [Line Items]
Borrowings		$ 43,547,835	$ 52,222,027
Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	5,144,504	4,126,203
From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		17,186,480	25,734,135
From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		16,138,305	17,141,255
More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		5,078,546	5,220,434
Local currency [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		5,979,216	6,741,798
Local currency [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	1,091,249	1,164,902
Local currency [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		3,167,531	3,663,599
Local currency [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		1,190,259	1,355,587
Local currency [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		530,177	557,710
Local currency [member] | Bonds [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		1,692,471	2,008,203
Local currency [member] | Bonds [Member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	253,172	312,207
Local currency [member] | Bonds [Member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		742,512	955,204
Local currency [member] | Bonds [Member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		322,956	357,015
Local currency [member] | Bonds [Member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		373,831	383,777
Local currency [member] | Commercial loans and other [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			3,828,329
Local currency [member] | Commercial loans and other [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]		793,743
Local currency [member] | Commercial loans and other [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			2,375,023
Local currency [member] | Commercial loans and other [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			659,563
Local currency [member] | Commercial loans and other [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			0
Local currency [member] | Other borrowings [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		978,795	905,266
Local currency [member] | Other borrowings [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	98,729	58,952
Local currency [member] | Other borrowings [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		415,599	333,372
Local currency [member] | Other borrowings [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		308,121	339,009
Local currency [member] | Other borrowings [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		156,346	173,933
Local currency [member] | Syndicated loans [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		3,307,950
Local currency [member] | Syndicated loans [Member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	739,348
Local currency [member] | Syndicated loans [Member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		2,009,420
Local currency [member] | Syndicated loans [Member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		559,182
Local currency [member] | Syndicated loans [Member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		0
Foreign currency [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		37,568,619	45,480,229
Foreign currency [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	4,053,255	2,961,301
Foreign currency [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		14,018,949	22,070,536
Foreign currency [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		14,948,046	15,785,668
Foreign currency [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		4,548,369	4,662,724
Foreign currency [member] | Bonds [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		29,166,594	29,310,165
Foreign currency [member] | Bonds [Member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	2,651,174	1,648,707
Foreign currency [member] | Bonds [Member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		9,948,238	10,956,507
Foreign currency [member] | Bonds [Member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		12,018,813	12,133,576
Foreign currency [member] | Bonds [Member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		4,548,369	4,571,375
Foreign currency [member] | Commercial loans and other [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		528,815
Foreign currency [member] | Commercial loans and other [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	153,873
Foreign currency [member] | Commercial loans and other [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		315,849
Foreign currency [member] | Commercial loans and other [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		59,093
Foreign currency [member] | Commercial loans and other [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		0
Foreign currency [member] | Other borrowings [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		471,429	235,693
Foreign currency [member] | Other borrowings [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	289,290	65,056
Foreign currency [member] | Other borrowings [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		119,014	114,226
Foreign currency [member] | Other borrowings [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		63,125	56,411
Foreign currency [member] | Other borrowings [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		0	0
Foreign currency [member] | Commercial loan-refineria de cartagena [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		7,401,781	7,988,678
Foreign currency [member] | Commercial loan-refineria de cartagena [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]	958,918	875,734
Foreign currency [member] | Commercial loan-refineria de cartagena [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		3,635,848	3,549,216
Foreign currency [member] | Commercial loan-refineria de cartagena [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		2,807,015	3,472,379
Foreign currency [member] | Commercial loan-refineria de cartagena [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings		$ 0	91,349
Foreign currency [member] | Other commercial loans [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			7,945,693
Foreign currency [member] | Other commercial loans [member] | Up to 1 year [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	[1]		371,804
Foreign currency [member] | Other commercial loans [member] | From 1 to 5 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			7,450,587
Foreign currency [member] | Other commercial loans [member] | From 5 to 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			123,302
Foreign currency [member] | Other commercial loans [member] | More than 10 years [member]
Disclosure of Loans and borrowings [Line Items]
Borrowings			$ 0
[1]	Includes short-term credit and the current portion of long-term debt, as applicable.

Loans and borrowings (Details 2

Loans and borrowings (Details 2) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Loans and borrowings [Line Items]
Borrowings	$ 43,547,835	$ 52,222,027
Local currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	5,979,216	6,741,798
Foreign currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	37,568,619	45,480,229
Fixed interest rate [member] | Local currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	143,156	299,472
Fixed interest rate [member] | Foreign currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	35,062,742	35,719,486
Floating interest rate [member] | Local currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	5,836,060	6,442,326
Floating interest rate [member] | Foreign currency [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings	$ 2,505,877	$ 9,760,743

Loans and borrowings (Details 3

Loans and borrowings (Details 3) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Cash flow		$ 444,827		$ 4,594,640		$ 10,985,933
Exchange difference Recognized in profit or loss		5,514		976,430		(5,566,614)
Financial cost registered to projects		3,660,601		3,463,540		2,718,414
Financial income (expense) recognized in profit or loss		(2,495,731)		(1,175,367)		(7,663,104)
Cash and equivalents [Member]
Begining Balance		8,410,467		6,550,450
Cash flow		(174,272)		2,086,350
Exchange difference Recognized in profit or loss		(290,310)		(226,333)
Exchange difference Recognized in other comprehensive income		0		0
Financial cost registered to projects		0		0
Financial income (expense) recognized in profit or loss		0		0
Foreign currency translation		0		0
Other movements not generating cash flow		0		0	[1]
Ending Balance		7,945,885		8,410,467		6,550,450
Other financial assets [Member]
Begining Balance	[2]	6,686,895		1,585,379
Cash flow	[2]	(564,755)		5,446,507
Exchange difference Recognized in profit or loss	[2]	208,394		(12,837)
Exchange difference Recognized in other comprehensive income	[2]	0		0
Financial cost registered to projects	[2]	0		0
Financial income (expense) recognized in profit or loss	[2]	104,706		59,593
Foreign currency translation	[2]	39,628		(6,462)
Other movements not generating cash flow		58,857	[2]	(385,285)	[1]
Ending Balance	[2]	6,533,725		6,686,895		1,585,379
Loans and borrowings [Member]
Begining Balance		(52,222,027)		(53,223,338)
Cash flow		11,259,492		1,050,723
Exchange difference Recognized in profit or loss		147,993		1,252,420
Exchange difference Recognized in other comprehensive income		70,958		612,983
Financial cost registered to projects		(203,964)		(357,107)
Financial income (expense) recognized in profit or loss		(2,385,994)		(2,765,024)
Foreign currency translation		(76,171)		593,384
Other movements not generating cash flow		(138,122)		613,932	[1]
Ending Balance		(43,547,835)		(52,222,027)		(53,223,338)
Net financial debt [Member]
Begining Balance		(37,124,665)		(45,087,509)
Cash flow		10,520,465		8,583,580
Exchange difference Recognized in profit or loss		66,077		1,013,250
Exchange difference Recognized in other comprehensive income		70,958		612,983
Financial cost registered to projects		(203,964)		(357,107)
Financial income (expense) recognized in profit or loss		(2,281,288)		(2,705,431)
Foreign currency translation		(36,543)		586,922
Other movements not generating cash flow		(79,265)		228,647	[1]
Ending Balance		$ (29,068,225)		$ (37,124,665)		$ (45,087,509)
[1]	Corresponds to operations with remittances financed in dollars with domestic banks for the payment of imports.
[2]	The balance of other financial assets as of December 31, 2015 includes the value of the securities related to Santiago de las Atalayas for COP$699,832, which at that date were restricted.

Loans and borrowings (Details T

Loans and borrowings (Details Textual) $ in Millions, $ in Millions	Aug. 14, 2017COP ($)	Jun. 08, 2016USD ($)	Dec. 31, 2017COP ($)	Dec. 31, 2016COP ($)	Dec. 31, 2015COP ($)	Dec. 31, 2017USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Disclosure of Loans and borrowings [Line Items]
Notional amount							$ 1,925
Borrowings			$ 43,547,835	$ 52,222,027
Repayments of borrowings, classified as financing activities	$ 990,000		9,007,340	3,149,917	$ 4,903,592
Financial instruments designated as hedging instruments, at fair value						$ 8,532		$ 10,512
Loans Payable Fair Value			45,781,317	52,109,438
Other financial assets			$ 6,533,725	$ 6,686,895
Santiago de las Atalayas [Member]
Disclosure of Loans and borrowings [Line Items]
Other financial assets					$ 699,832
Export Development Canada [Member]
Disclosure of Loans and borrowings [Line Items]
Notional amount						300
Hedges of net investment in foreign operations [member]
Disclosure of Loans and borrowings [Line Items]
Financial instruments designated as hedging instruments, at fair value						5,200		$ 5,200
Cash flow hedges [member]
Disclosure of Loans and borrowings [Line Items]
Financial instruments designated as hedging instruments, at fair value						3,332
Foreign Currency Bonds Eight [Member]
Disclosure of Loans and borrowings [Line Items]
Borrowings Initiation Date		June 8, 2016
Notional amount		$ 500
Borrowings, interest rate		5.875%
Borrowings		$ 1,800
Foreign Currency Commercial Loans Seven [Member]
Disclosure of Loans and borrowings [Line Items]
Prepaid Loan						$ 175

Trade and other payables (Detai

Trade and other payables (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Trade and other payables [Abstract]
Suppliers		$ 5,088,957	$ 4,687,353
Partners’ advances		880,420	864,971
Withholding tax		376,169	379,194
Related parties		129,520	114,420
Insurance and reinsurance		121,555	110,530
Agreements in transport contracts	[1]	91,324	111,899
Deposits received from third parties		25,523	209,570
Dividends payable	[2]	3,723	11,193
Various creditors		280,485	389,126
Trade and other payables		6,997,676	6,878,256
Current		6,968,207	6,854,363
Non-current		29,469	23,893
Trade and other payables		$ 6,997,676	$ 6,878,256
[1]	Corresponds to the value of debt from agreements in transport contracts of oil pipelines and poliducts, impacted by volumetric adjustments, compensation for quality and other inventory management agreements.
[2]	Dividends declared at the General Shareholders' Meeting on 2016 profits, amounting to COP$945,684, were paid in April 2017.

Provisions for employees ben128

Provisions for employees benefits (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Post-employment benefits
Current	$ 1,829,819	$ 1,974,496
Non-current	6,502,475	3,901,082
Provisions for employee benefits	8,332,294	5,875,578
Healthcare [Member]
Post-employment benefits
Provisions for employee benefits	5,367,005	4,475,540
Pension [Member]
Post-employment benefits
Provisions for employee benefits	1,327,859	76,695
Education [Member]
Post-employment benefits
Provisions for employee benefits	502,260	333,379
Bonds [Member]
Post-employment benefits
Provisions for employee benefits	348,442	263,563
Other plans [Member]
Post-employment benefits
Provisions for employee benefits	77,636	67,945
Termination benefits - Voluntary retirement plan [Member]
Post-employment benefits
Provisions for employee benefits	155,286	161,796
Post employment and termination benefits [Member]
Post-employment benefits
Provisions for employee benefits	7,778,488	5,378,918
Other Employment Benefts [Member]
Post-employment benefits
Provisions for employee benefits	67,867	73,300
Social benefits and salaries [Member]
Post-employment benefits
Provisions for employee benefits	$ 485,939	$ 423,360

Provisions for employees ben129

Provisions for employees benefits (Details 1) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Employee benefits liabilities
Opening balance		$ 17,504,566	$ 14,605,593
Current service cost		52,164	53,771
Past service cost		0	164,271
Interest expense		1,222,584	1,209,970
Actuarial losses (gains)		2,633,389	2,532,601
Benefits paid		(1,159,807)	(1,061,640)
Closing balance		20,252,896	17,504,566
Plan assets
Opening balance		12,125,648	11,181,604
Return on assets		849,062	950,704
Contributions to funds		22,465	0
Variation in the ceiling of assets		0	379,884
Benefits paid		(831,755)	(769,122)
Actuarial gains (losses)		308,988	382,578
Closing balance		12,474,408	12,125,648
Net post-employment benefits liability		7,778,488	5,378,918
Pension and pension bonds [Member]
Employee benefits liabilities
Opening balance	[1]	12,463,433	10,435,546
Current service cost	[1]	0	0
Past service cost	[1]	0	0
Interest expense	[1]	872,524	876,076
Actuarial losses (gains)	[1]	1,621,184	1,915,767
Benefits paid	[1]	(809,677)	(763,956)
Closing balance	[1]	14,147,464	12,463,433
Plan assets
Opening balance	[1]	12,123,175	11,181,604
Return on assets	[1]	848,677	950,704
Contributions to funds	[1]	0	0
Variation in the ceiling of assets	[1]	0	379,884
Benefits paid	[1]	(809,677)	(771,528)
Actuarial gains (losses)	[1]	308,988	382,511
Closing balance	[1]	12,471,163	12,123,175
Net post-employment benefits liability	[1]	1,676,301	340,258
Healthcare, Education and others [Member]
Employee benefits liabilities
Opening balance		5,041,133	4,170,047
Current service cost		52,164	53,771
Past service cost		0	164,271
Interest expense		350,060	333,894
Actuarial losses (gains)		1,012,205	616,834
Benefits paid		(350,130)	(297,684)
Closing balance		6,105,432	5,041,133
Plan assets
Opening balance		2,473	0
Return on assets		385	0
Contributions to funds		22,465	0
Variation in the ceiling of assets		0	0
Benefits paid		(22,078)	2,406
Actuarial gains (losses)		0	67
Closing balance		3,245	2,473
Net post-employment benefits liability		$ 6,102,187	$ 5,038,660
[1]	There is no cost for the pension and pension plans service, due to the fact that the beneficiaries were retired as of July 31, 2010.

Provisions for employees ben130

Provisions for employees benefits (Details 2) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Recognized in profit or loss
Current service cost	$ 52,164	$ 53,771
Past service cost	0	164,271
Interest expense, net	373,522	259,266
Remedies	13,889	0
Benefits plan costs recognized in profit or loss	439,575	477,308
Recognized in other comprehensive income
Recognized in other comprehensive income	(2,310,512)	(1,770,139)
Deferred tax	762,469	616,697
Other comprehensive income, net of taxes	(1,548,043)	(1,153,442)	$ 1,404,602
Change in the effect of the asset ceiling
Recognized in other comprehensive income
Recognized in other comprehensive income	0	379,884
Healthcare [Member]
Recognized in other comprehensive income
Recognized in other comprehensive income	(794,535)	(792,093)
Pension and pension bonds [Member]
Recognized in other comprehensive income
Recognized in other comprehensive income	(1,312,195)	(1,533,256)
Education and severance [member]
Recognized in other comprehensive income
Recognized in other comprehensive income	(203,779)	175,259
Termination benefits - Voluntary retirement plan [Member]
Recognized in other comprehensive income
Recognized in other comprehensive income	$ (3)	$ 67

Provisions for employee benefit

Provisions for employee benefits (Details 3) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of defined benefit plans [line items]
Assets of benefit plan	$ 12,474,408	$ 12,125,648	$ 11,181,604
Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Assets of benefit plan	12,471,163	12,123,175
Variable yield [Member] | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Debt instruments, amount contributed to fair value of plan assets	605,380	305,052
Other local currency [Member] | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Cash and cash equivalents, amount contributed to fair value of plan assets	2,337,580	2,910,083
Other foreign currency [Member] | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Cash and cash equivalents, amount contributed to fair value of plan assets	503,653	300,878
Bonds of private entities [Member] | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Debt instruments, amount contributed to fair value of plan assets	2,967,030	2,880,958
Other public bonds | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Debt instruments, amount contributed to fair value of plan assets	1,149,200	693,061
Bonds of foreign entities [Member] | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Debt instruments, amount contributed to fair value of plan assets	558,920	622,817
Bonds issued by the national government | Pension Trust [Member]
Disclosure of defined benefit plans [line items]
Debt instruments, amount contributed to fair value of plan assets	$ 4,349,400	$ 4,410,326

Provisions for employees ben132

Provisions for employees benefits (Details 4) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	$ 12,471,163	$ 12,123,175
AAA [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	4,870,932	4,467,642
Nation [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	4,471,274	4,610,251
AA+ [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	690,391	470,944
BAA2 [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	371,972	141,940
BBB [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	246,795	150,808
F1+ [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	230,321	416,439
BBB- [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	192,636	23,237
BBB+ [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	159,103	193,835
BRC 1+ [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	118,008	309,282
AA [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	58,234	79,750
BAA3 [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	45,699	131,993
A [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	39,048	4,175
A3 [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	29,098	61,325
AA3 [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	27,051	14,385
AA- [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	18,770	34,197
VRR1 + [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	14,112	55,821
BAA1 [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	5,296	5,274
Other qualifications [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	9,621	66,470
No rating available [member]
Disclosure of defined benefit plans [line items]
Plan assets, at fair value	$ 872,802	$ 885,407

Provisions for employee bene133

Provisions for employee benefits (Details 5)		Dec. 31, 2017	Dec. 31, 2016
Bonds [Member]
Disclosure of detailed information about provision for employee benefits [Line Items]
Discount rate		6.25%	7.00%
Salary growth rate
Expected inflation rate		3.00%	3.00%
Pension growth rate
Cost trend - Short-term rate
Cost trend - Long-term rate
Health
Disclosure of detailed information about provision for employee benefits [Line Items]
Discount rate		6.50%	7.25%
Salary growth rate
Expected inflation rate		3.00%	3.00%
Pension growth rate
Cost trend - Short-term rate		6.00%	3.00%
Cost trend - Long-term rate		4.00%	4.00%
Education [Member]
Disclosure of detailed information about provision for employee benefits [Line Items]
Discount rate		5.50%	6.50%
Salary growth rate
Expected inflation rate		3.00%	3.00%
Pension growth rate
Cost trend - Short-term rate		4.00%	4.00%
Cost trend - Long-term rate		4.00%	4.00%
Pension [Member]
Disclosure of detailed information about provision for employee benefits [Line Items]
Discount rate		6.50%	7.25%
Salary growth rate
Expected inflation rate		3.00%	3.00%
Pension growth rate		3.00%	3.00%
Cost trend - Short-term rate
Cost trend - Long-term rate
Other benefits [Member]
Disclosure of detailed information about provision for employee benefits [Line Items]
Discount rate	[1]	5.51%	6.67%
Salary growth rate	[1]		4.25%
Expected inflation rate	[1]	3.00%	3.00%
Pension growth rate	[1]
Cost trend - Short-term rate	[1]
Cost trend - Long-term rate	[1]
Other benefits [Member] | Top of range [member]
Disclosure of detailed information about provision for employee benefits [Line Items]
Salary growth rate	[1]	4.75%
Other benefits [Member] | Bottom of range [member]
Disclosure of detailed information about provision for employee benefits [Line Items]
Salary growth rate	[1]	4.25%
[1]	Weighted average discount rate.

Provisions for employee bene134

Provisions for employee benefits (Details 6) $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)
2,018
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	$ 1,254,613
2018 | Other benefits [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	374,315
2018 | Pension and bonds [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	880,298
2,019
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	1,232,406
2019 | Other benefits [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	355,241
2019 | Pension and bonds [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	877,165
2,020
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	1,257,420
2020 | Other benefits [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	358,292
2020 | Pension and bonds [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	899,128
2,021
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	1,282,988
2021 | Other benefits [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	361,655
2021 | Pension and bonds [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	921,333
2,022
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	1,315,529
2022 | Other benefits [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	362,998
2022 | Pension and bonds [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	952,531
2023-2026
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	7,026,375
2023-2026 | Other benefits [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	1,824,756
2023-2026 | Pension and bonds [Member]
Disclosure of defined benefit plans [line items]
Estimate of contributions expected to be paid to plan for next annual reporting period	$ 5,201,619

Provisions for employee bene135

Provisions for employee benefits (Details 7) $ in Millions	Dec. 31, 2017COP ($)
Discount rate [Member] | Pension [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	$ 13,948,863
+50 basis points	12,440,607
Discount rate [Member] | Bonds [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	1,032,967
+50 basis points	948,129
Discount rate [Member] | Education [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	527,839
+50 basis points	480,224
Discount rate [Member] | Other benefits [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	242,117
+50 basis points	230,501
Discount rate [Member] | Health [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	5,775,492
+50 basis points	4,962,688
Inflation rate [Member] | Pension [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	12,386,975
+50 basis points	14,003,214
Inflation rate [Member] | Bonds [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	946,675
+50 basis points	1,033,715
Inflation rate [Member] | Education [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Inflation rate [Member] | Other benefits [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	156,021
+50 basis points	161,094
Inflation rate [Member] | Health [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Salary growth rate [Member] | Pension [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Salary growth rate [Member] | Bonds [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Salary growth rate [Member] | Education [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Salary growth rate [Member] | Other benefits [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	76,336
+50 basis points	79,150
Salary growth rate [Member] | Health [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Cost trend [Member] | Pension [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Cost trend [Member] | Bonds [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Cost trend [Member] | Education [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	479,829
+50 basis points	528,104
Cost trend [Member] | Other benefits [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points
+50 basis points
Cost trend [Member] | Health [Member]
Reasonable possible change in discount rate [Abstract]
-50 basis points	4,982,874
+50 basis points	$ 5,797,753

Provisions for employees ben136

Provisions for employees benefits (Details Textual) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of defined benefit plans [line items]
Termination benefits expense	$ 155,286	$ 161,796
Level 1 of fair value hierarchy [member]
Disclosure of defined benefit plans [line items]
Percentage of plan assets	46.00%
Level 2 of fair value hierarchy [member]
Disclosure of defined benefit plans [line items]
Percentage of plan assets	54.00%

Accrued liabilities and prov137

Accrued liabilities and provisions (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Disclosure of accrued liabilities and provisions [Line Items]
Balance Beginning period		$ 5,917,870	$ 6,077,347
Increase in abandonment costs		39,634	404,797
Additions (recoveries)		197,934	(714,393)
Uses		(93,824)	(104,263)
Financial cost		379,524	317,275
Foreign currency translation		(300)	(17,817)
Transfers	[1]	96,611	(45,076)
Balance End Period		6,537,449	5,917,870
Current				$ 558,828	$ 821,954
Non-current				5,978,621	5,095,916
Total		5,917,870	5,917,870	6,537,449	5,917,870
Asset retirement obligation [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Balance Beginning period		5,064,660	4,452,369
Increase in abandonment costs		39,634	404,797
Additions (recoveries)		110,587	18,285
Uses		(66,469)	(68,460)
Financial cost		379,891	317,448
Foreign currency translation		(979)	(14,703)
Transfers	[1]	0	(45,076)
Balance End Period		5,527,324	5,064,660
Current				199,824	330,057
Non-current				5,327,500	4,734,603
Total		5,064,660	5,064,660	5,527,324	5,064,660
Litigation [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Balance Beginning period		209,932	99,798
Increase in abandonment costs		0	0
Additions (recoveries)		(19,185)	44,120
Uses		(7,742)	(4,585)
Financial cost		0	0
Foreign currency translation		(39)	(355)
Transfers	[1]	0	70,954
Balance End Period		182,966	209,932
Current				159,881	146,767
Non-current				23,085	63,165
Total		209,932	209,932	182,966	209,932
Environmental contingencies and others [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Balance Beginning period		643,278	822,694
Increase in abandonment costs		0	0
Additions (recoveries)		106,532	(74,312)
Uses		(19,613)	(31,218)
Financial cost		(367)	(173)
Foreign currency translation		718	(2,759)
Transfers	[1]	96,611	(70,954)
Balance End Period		827,159	643,278
Current				199,123	345,130
Non-current				628,036	298,148
Total		643,278	643,278	$ 827,159	643,278
Comuneros provision [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Balance Beginning period		0	702,486
Increase in abandonment costs			0
Additions (recoveries)			(702,486)
Uses			0
Financial cost			0
Foreign currency translation			0
Transfers	[1]		0
Balance End Period			0
Current					0
Non-current					0
Total		$ 0	$ 702,486		$ 0
[1]	Mainly includes transfers to liabilities associated with assets held for sale.

Accrued liabilities and prov138

Accrued liabilities and provisions (Details 1) - Legal proceedings contingent liability [member] - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Ministry of Finance and Public Credit [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent liabilities	$ 64,104	$ 59,528
Acciona Infraestructura S.A. y Mantenimiento y Montajes S.A. [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent liabilities	0	44,986
Schrader Camargo [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent liabilities	$ 17,003	$ 17,003

Accrued liabilities and prov139

Accrued liabilities and provisions (Details 2) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Legal proceedings contingent liability [member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	$ 62,131	$ 62,131
Contingent liability arising from post-employment benefit obligations [member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	16,562	16,562
Tax contingent liability 2010 [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	0	344,915
Damage of transandino pipeline [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	209,220	0
Breaking of the economic and financial balance [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	110,266	0
Salary readjustments [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	60,313	0
Damage caused by oil spills [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	43,333	43,333
Contractual imbalance road connection works [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	31,679	0
Differences with supplier in contract settlement [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	30,027	0
seismic acquisition service [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Loss contingency, unrecorded amount	$ 30,000	$ 0

Accrued liabilities and prov140

Accrued liabilities and provisions (Details 3) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Ocensa claim [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	$ 112,735	$ 0
Claim for disagreement of Ecopetrol [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	40,711	40,746
Environmental incident [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	35,000	0
Document falsification [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	32,000	0
Breach of the pipe purchase order [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	21,232	21,232
Nullity of DIAN administrative act, contingent asset [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	13,214	13,214
Claim against Metapetroleum [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Estimated financial effect of contingent assets	$ 0	$ 25,421

Accrued liabilities and prov141

Accrued liabilities and provisions (Details Textual) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016COP ($)
Disclosure of accrued liabilities and provisions [Line Items]
Mandatory investments, natural resources	1.00%
Description of recognition of legal proceedings	The following is a summary of the main legal proceedings recognized in the statement of financial position whose amount exceeds COP$13,000 million, where the expectation of loss is probable
Refineria de Cartagena [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Legal proceedings in process, claims made, value	$ 2,000
Legal proceedings in process, damages sought, value	213
Proceeds from legal settlement	$ 122
Santiago de las Atalayas [Member] | Top of range [member]
Disclosure of accrued liabilities and provisions [Line Items]
Unused provision reversed, other provisions		$ 688,664
Asset retirement obligation [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Discount rate applied to cash flow projections	6.93%	7.93%
Transportation [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Discount rate applied to cash flow projections	7.02%	8.20%
Refining [Member]
Disclosure of accrued liabilities and provisions [Line Items]
Discount rate applied to cash flow projections	7.37%	8.99%

Equity (Details)

Equity (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of changes in equity [Line Items]
Other reserves	$ 2,177,869	$ 1,558,844
Legal reserve [member]
Disclosure of changes in equity [Line Items]
Other reserves	1,426,151	1,269,680
Fiscal and statutory reserves [member]
Disclosure of changes in equity [Line Items]
Other reserves	512,632	289,164
Occasional reserves [member]
Disclosure of changes in equity [Line Items]
Other reserves	$ 239,086	$ 0

Equity (Details 1)

Equity (Details 1) $ in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2016USD ($)	Dec. 31, 2017COP ($)	Dec. 31, 2016COP ($)
Disclosure of changes in equity [Line Items]
Opening balance		$ 43,560,501	$ 43,100,963
Allocation to reserves	$ 3,869,907
Legal reserve used to offset previous year loss (Note 24.4)			0
Closing balance		48,215,699	43,560,501
Equity reserves [Member]
Disclosure of changes in equity [Line Items]
Opening balance		1,558,844	5,546,570
Release of reserves		(289,164)	(406,983)
Allocation to reserves		908,189	289,164
Legal reserve used to offset previous year loss (Note 24.4)		0	(3,869,907)
Closing balance		$ 2,177,869	$ 1,558,844

Equity (Details 2)

Equity (Details 2) $ in Millions, $ in Millions		1 Months Ended	12 Months Ended
		Mar. 31, 2016USD ($)	Dec. 31, 2017COP ($)	Dec. 31, 2016COP ($)	Dec. 31, 2015COP ($)
Disclosure of changes in equity [Line Items]
Opening balance			$ 43,560,501	$ 43,100,963	$ 48,534,228
Profit attributable to owners of Ecopetrol’s shareholders			7,969,394	3,247,480	(6,288,979)
Allocation to reserves		$ 3,869,907
Dividends declared			(1,497,178)	(1,029,612)	(6,183,572)
Legal reserve used to offset previous year loss			0	0	0
Other movements			(1,111)	(29,723)	87
Closing balance			48,215,699	43,560,501	43,100,963
Retained earnings and dividends [member]
Disclosure of changes in equity [Line Items]
Opening balance			(402,462)	(6,814,432)
Profit attributable to owners of Ecopetrol’s shareholders			7,178,539	2,447,881
Release of reserves			289,164	406,983
Allocation to reserves			(908,189)	(289,164)
Dividends declared	[1]		(945,684)	0
Legal reserve used to offset previous year loss	[2]		0	3,869,907
Other movements			(1,066)	(23,637)
Closing balance			$ 5,210,302	$ (402,462)	$ (6,814,432)
[1]	The Company distributes dividends based on its separate annual financial statements, prepared under International Financial Reporting Standards accepted in Colombia (NCIF, by its acronym in Spanish). The Ordinary General Shareholders' Meeting, held on March 31, 2017, approved the proposal for profit distribution proposal for 2016 and set the distribution of dividends of COP$945,684. Dividends paid in 2017 attributable to the shareholders of Ecopetrol S.A. amounted to COP$945,661 (2016 - COP$690,177) and those of the non-controlling interest of subsidiary companies to COP $ 558,986 (2016 - COP$1,022,121).
[2]	The Ordinary General Meeting of Shareholders, held on March 31, 2016, approved the proposal for profit distribution, which established that there would be no distribution for the year 2015, given the net loss occurred in that year; in addition, the shareholders voted to use the legal reserve to offset this loss, as permitted by the Article 456 of the Colombian Code of Commerce. The amount of losses offset by releases from the legal reserve after tax and mandatory allocations amounted to COP$3,869,907.

Equity (Details 3)

Equity (Details 3) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Disclosure of changes in equity [Line Items]
Actuarial gain on defined benefit plans		$ (1,548,043)		$ (1,153,442)		$ 1,404,602
Cash flow hedges for future exports (Note 30.2.2)		159,294
Foreign currency translation		15,934		(724,395)
Equity		48,215,699		43,560,501		43,100,963	$ 48,534,228
Other comprehensive income attributable to owners of parent [member]
Disclosure of changes in equity [Line Items]
Actuarial gain on defined benefit plans		(553,091)		994,953
Gain (loss) on equity instruments measured at fair value (1)	[1]	0		7,828
Cash flow hedges for future exports (Note 30.2.2)		159,295		244,131
Hedge of a net investment in a foreign operation (Note 30.2.3)		(97,362)		(155,359)
Cash flow hedge with derivative instruments		6,942		(19,042)
Others		0		11,817
Foreign currency translation		7,883,231		8,138,382
Equity		$ 7,399,015	[1]	$ 9,222,710	[1]	$ 10,846,004	$ 3,980,749
[1]	During 2016 the Group reclassified to the statement of profit or loss COP$68,497 (2015 - COP$19,405) arising from the realization of accumulated fair value gains on equity of assets available for sale - Empresa de Energía de Bogotá and Interconexión Eléctrica S.A.

Equity (Details 4)

Equity (Details 4) - COP ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of equity [Abstract]
Profit (loss) attributable to Ecopetrol’s shareholders	$ 7,178,539	$ 2,447,881	$ (7,193,859)
Weighted average number of outstanding shares	41,116,694,690	41,116,694,690	41,116,694,690
Net basic earnings (loss) per share (Colombian pesos)	$ 174.6	$ 59.5	$ (175)

Equity (Details Textual)

Equity (Details Textual) $ / shares in Units, $ in Millions, $ in Millions	1 Months Ended		12 Months Ended
	Mar. 31, 2017COP ($)$ / shares	Mar. 31, 2016USD ($)	Dec. 31, 2017COP ($)shares	Dec. 31, 2016COP ($)	Dec. 31, 2015COP ($)	Sep. 30, 2011COP ($)	Dec. 31, 2007COP ($)
Disclosure of changes in equity [Line Items]
Capital commitments			$ 36,540,000
Number of shares authorised | shares			60,000,000,000
Number of shares subscribed | shares			41,116,694,690
Proportion of shares available for public trade			11.51%
Number of shares available for public trade | shares			4,731,905,873
Proportion of shares held by majority share holders			88.49%
Number of shares held by majority share holders | shares			36,384,788,817
Capital reserve			$ 11,499,933
Number of shares reserved for issue under options and contracts for sale of shares | shares			18,883,305,310
Subscribed and Paid-In-Capital			$ 25,040,067	$ 25,040,067
Additional paid-in capital							$ 4,457,997
Additional paid-in capital receivable			$ (142)
Proportion of legal reserve derive from net income			10.00%
Proportion of legal reserve			50.00%
Proportion of statutory tax reserve from appropriation of profits			70.00%
Increase decrease through transfer between legal reserve and retained earnings, equity		$ 3,869,907
Dividends recognised as distributions to owners per share | $ / shares	$ 945,684
Dividends paid to non-controlling interests, classified as financing activities			$ 558,986	1,022,121
Dividends paid to equity holders of parent, classified as financing activities			945,661	690,177
Realized gain loss on proceeds from sales of equity instruments measured at fair value, net of tax				$ 68,497	$ 19,405
Reserve for New Exploration	$ 239,086
Share-based payment arrangements [member]
Disclosure of changes in equity [Line Items]
Additional paid-in capital						$ 2,118,468
Financial guarantee contracts [member]
Disclosure of changes in equity [Line Items]
Additional paid-in capital			$ 31,377

Sales revenue (Details)

Sales revenue (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about sales revenue [Line Items]
Revenue		$ 55,954,228	$ 48,485,561	$ 52,347,271
Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue From Sale Of Goods And Rendering Of Services Before Price Differential Adjustment		26,006,139	23,697,150	25,624,750
Increase decrease in sale price differential	[1]	2,229,953	1,048,022	441,871
Revenue		28,236,092	24,745,172	26,066,621
Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		27,718,136	23,740,389	26,280,650
Med-distillates [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		9,590,326	8,553,503	10,215,224
Med-distillates [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods			1,594,945
Gasoline and turbo fuel [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		6,990,187	6,092,739	6,128,208
Gasoline and turbo fuel [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		1,223,994	1,046,758	93,125
Services [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from rendering of services		3,873,352	4,043,284	4,435,274
Natural Gass [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		1,815,754	1,988,336	1,845,345
Natural Gass [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		32,303	58,809	182,950
Plastic and rubber [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		833,982	724,708	724,392
Plastic and rubber [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		1,169,101	1,171,342	1,096,730
L.P.G. and propane [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		509,619	405,869	335,494
L.P.G. and propane [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		15,631	8,568	0
Crude [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		21,479,063	17,278,579	21,181,265
Asphalts [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		275,803	340,400	461,188
Other products [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		1,207,245	994,645	988,346
Other products [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		441,124	380,222	161,287
Cash flow hedging - Reclassification to profit or loss [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		160,772	33,074	7,646
Fuel oil [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods			148,248
Fuel oil [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		1,982,408	2,158,539	2,166,469
Crude Oil's [Member] | Domestic sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		909,871	553,666	491,279
Trading of crude [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		0	0	1,309,196
Diesel [Member] | Foreign sales [Member]
Disclosure of detailed information about sales revenue [Line Items]
Revenue from sale of goods		$ 1,213,740	$ 1,604,498	$ 81,982
[1]	Corresponds to the application of Decree 1880 of September 2014 and Resolution 180522 of 2010, which defined the procedure for price differentials (value generated by the difference between the parity price and the regulated price, which can be positive or negative). See Note 4.16 – Sales revenue recognition, for more details.

Sales revenue (Details 1)

Sales revenue (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	100.00%	100.00%	100.00%
Revenue	$ 55,954,228	$ 48,485,561	$ 52,347,271
Colombia [Member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	50.50%	51.00%	49.80%
Revenue	$ 28,236,092	$ 24,745,172	$ 26,066,621
United States Of America [Member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	22.40%	24.70%	22.80%
Revenue	$ 12,532,932	$ 11,956,967	$ 11,921,720
Asia [member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	11.00%	5.60%	11.70%
Revenue	$ 6,136,796	$ 2,717,414	$ 6,123,593
Europe [member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	1.80%	6.10%	7.60%
Revenue	$ 1,030,617	$ 2,945,951	$ 3,981,926
Central America And Caribbean [Member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	10.80%	7.30%	6.40%
Revenue	$ 6,070,565	$ 3,551,894	$ 3,366,978
South America And Others [Member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	3.50%	5.30%	1.70%
Revenue	$ 1,947,226	$ 2,568,163	$ 886,433

Sales revenue (Details Textual)

Sales revenue (Details Textual)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	100.00%	100.00%	100.00%
Terpel [Member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	14.30%	14.40%	14.40%
Others [Member]
Disclosure of detailed information about sales revenue [Line Items]
Percentage of entitys revenue	10.00%

Cost of sales (before impairmen

Cost of sales (before impairment of non-current assets) (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about cost of sales of non current assets [line Items]
Taxes and contributions		$ 5,800,268	$ 4,543,046	$ 710,353
Total Variable Costs		26,567,933	24,960,115	27,369,065
Total Fixed Costs		10,340,392	9,291,308	9,625,451
Cost of sales		36,908,325	34,251,423	36,994,516
Varible costs [member]
Disclosure of detailed information about cost of sales of non current assets [line Items]
Imported products	[1]	11,637,419	12,049,477	12,935,878
Depreciation, amortization and depletion		5,765,186	5,333,245	5,166,455
Purchases of hydrocarbons - ANH	[2]	4,338,576	3,178,199	3,741,010
Purchases of crude in association and concession		2,240,704	1,517,829	1,928,938
Process materials		889,122	608,535	366,454
Hydrocarbon transport services		665,714	783,307	1,380,733
Electric energy		561,424	618,675	424,920
Purchases of other products and gas		488,056	519,884	703,163
Taxes and contributions	[3]	449,959	478,332	481,029
Services contracted in associations		195,689	305,326	563,032
Others	[4]	(663,916)	(432,694)	(322,547)
Fixed costs [member]
Disclosure of detailed information about cost of sales of non current assets [line Items]
Depreciation and amortization		2,366,849	2,050,739	1,433,263
Maintenance		2,038,970	1,998,128	2,334,130
Labor cost		1,815,213	1,571,511	1,542,701
Hydrocarbon transport services		333,671	157,463	147,733
Taxes and contributions		343,505	391,032	461,624
Services contracted		1,414,056	1,083,176	1,301,094
Services contracted in associations		1,008,336	1,260,470	1,415,422
General costs		510,128	383,842	461,994
Materials and operating supplies		468,205	333,258	435,238
Non-capitalized costs of projects		$ 41,459	$ 61,689	$ 92,252
[1]	Imported products correspond mainly to diesel fuel and diluent to facilitate the transport of heavy crude oil.
[2]	Corresponds to purchases of crude oil by Ecopetrol from the National Hydrocarbons Agency (ANH) derived from national production, both of the Group in direct operation and of third parties.
[3]	Includes gas royalties paid and carbon tax.
[4]	Corresponds to the capitalization of production costs to inventory.

Administrative, operations a152

Administrative, operations and project expenses (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about general and administration expense [Line Items]
Administrative expenses		$ 1,764,524	$ 1,923,268	$ 1,700,985
Operating expense		2,926,065	2,751,687	4,034,268
Administrative expenses [Member]
Disclosure of detailed information about general and administration expense [Line Items]
General expenses		723,341	556,563	393,971
Labor expenses		624,424	657,051	491,748
Taxes	[1]	362,963	663,889	730,841
Depreciation and amortization		53,796	45,765	84,425
Operations and project expenses [Member]
Disclosure of detailed information about general and administration expense [Line Items]
Exploration costs		1,341,940	728,590	1,584,249
Commissions, fees, freights and services		471,657	568,513	878,259
Labor expenses		310,947	278,383	309,021
Taxes		324,223	286,331	348,871
Maintenance		122,273	147,197	181,630
Depreciation and amortization		95,516	177,252	86,215
Fee for regulatory entities		63,470	87,325	77,909
Corporate projects		29,702	301,854	456,159
Others		$ 166,337	$ 176,242	$ 111,955
[1]	Mainly corresponds to the recognition of the wealth tax. See Note 10 - Taxes.

Other operating income net (Det

Other operating income net (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Other operating income and expenses, net [Abstract]
(Expense) recovery of provisions for litigations		$ (72,408)	$ 112,999	$ 205,879
Expense for gas pipeline availability BOMT contracts	[1]	(72,318)	(125,077)	(124,957)
Impairment expense of short-term assets		(68,800)	(98,739)	(2,858)
Profit (loss) on sale of assets		40,227	(82,200)	6,744
Gain on acquisition of interests in joint operation (Note 32.3)		451,095	0	0
Compensation received		0	17,790	29,848
Deferred income BOMT contract’s	[2]	0	211,768	193,197
Other income		227,607	237,571	70,685
Other operating income (expense)		$ 505,403	$ 274,112	$ 378,538
[1]	Corresponds to the services rendered in connection with the BOMT contracts for the construction, operation, maintenance and transfer of gas pipelines with Transgas. This contract terminated in August 2017.
[2]	Corresponds to the amortization of the deferred income recognized by Ecopetrol in 2007 for the advance payment made by the Ministry of Finance and Public Credit of the obligations by Ecogas, in relation to the BOMT contracts for the construction, operation, maintenance and transfer of gas pipelines, signed between Ecopetrol and Transgas de Occidente, Centragas and Gases de Boyacá and Santander S.A. in 1997. The amortization of this deferred income ended in December 2016.

Financial result, net (Details)

Financial result, net (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finance income
Results from financial assets and others		$ 739,148	$ 136,715	$ 164,615
Yield and interest		405,562	386,001	293,506
Gain on sale of equity instruments		13,236	47,129	72,339
Resources from Santiago de las Atalayas (1)	[1]	0	688,664	0
Other finance income		1,410	53,234	91,464
Finance income		1,159,356	1,311,743	621,924
Finance expenses
Interest (2)	[2]	(2,385,994)	(2,765,024)	(1,768,618)
Financial cost of other liabilities (3)	[3]	(753,047)	(580,491)	(627,827)
Results from financial assets		(481,308)	(48,997)	(167,869)
Other financial expenses		(40,252)	(69,028)	(154,100)
Finance costs		(3,660,601)	(3,463,540)	(2,718,414)
Foreign exchange gain (loss), net (4)		5,514	976,430	(5,566,614)
Financial result, net		$ (2,495,731)	$ (1,175,367)	$ (7,663,104)
[1]	Corresponds to the recovery of the provision “Comuneros – Santiago de las Atalayas”. Its balance consisted mainly from the valuation and financial gains generated while the cash that was subject to the reserve (see Note 23.3 for more information).
[2]	As of December 31, 2017, borrowing costs for the financing of developing natural resources and property, plant and equipment of COP$191,651 (2016 - COP$341,209 and 2015 - COP$744,426) were capitalized.
[3]	Includes the financial expense of the asset retirement obligation and the liabilities for post-employment benefits.

Financial result, net (Details

Financial result, net (Details Textual) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of financial result, net [Abstract]
Interest costs capitalised	$ 191,651	$ 341,209	$ 744,426

Risk management (Details)

Risk management (Details) $ in Millions, $ in Millions	Dec. 31, 2017COP ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016COP ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015COP ($)	Dec. 31, 2014COP ($)
Disclosure of detailed information about financial risk management [Line Items]
Cash and cash equivalents	$ (7,945,885)		$ (8,410,467)		$ (6,550,450)	$ (7,618,178)
Other financial assets	(6,533,725)		(6,686,895)
Loans and borrowings	$ 43,547,835		$ 52,222,027
US Dollar [Member]
Disclosure of detailed information about financial risk management [Line Items]
Cash and cash equivalents		$ 1,203		$ 1,916
Other financial assets		1,072		1,367
Trade receivables and payables, net		(7)		(282)
Loans and borrowings		(12,590)		(15,172)
Net liability position		$ (10,322)		$ (12,171)

Risk management (Details 1)

Risk management (Details 1) - Currency risk [member] $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)
One Percent variations in exchange rate, Effect on income before income taxes	$ 2,715
One Percent variations in exchange rate, other comprehensive income	305,293
Five Percent variations in exchange rate, Effect on income before income taxes	13,577
Five Percent variations in exchange rate, other omprehensive income	$ 1,526,465

Risk management (Details 2)

Risk management (Details 2) - Non-Derivative Hedging Instrument [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Hedging instrument at the beginning of the period		$ 5,312	$ 5,376
Reassignment of hedging instruments		1,803	870
Realized exports		(1,803)	(870)
Capital payments	[1]	(1,980)	(64)
Hedging instrument at the end of the period		$ 3,332	$ 5,312
[1]	On June 30, 2017, Ecopetrol prepaid the entire outstanding balance of the international syndicated loan whose nominal value was US$ 1,925 million and original maturity date was in February 2020.

Risk management (Details 3)

Risk management (Details 3) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Disclosure of financial risk management [Abstract]
Opening balance	$ (244,131)	$ 217,291
Exchange difference on hedging instruments	15,934	(724,395)
Reclassification to profit or loss	160,772	(33,074)
Ineffectiveness	(9,247)	0
Deferred income tax	(82,622)	296,047
Closing balance	$ (159,294)	$ (244,131)

Risk management (Details 4)

Risk management (Details 4) $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	$ 245,173
Taxes	(85,879)
After taxes	159,294
2,018
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	95,462
Taxes	(33,439)
After taxes	62,023
2,019
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	66,039
Taxes	(23,132)
After taxes	42,907
2,020
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	23,804
Taxes	(8,338)
After taxes	15,466
2,021
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	21,541
Taxes	(7,545)
After taxes	13,996
2,022
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	21,541
Taxes	(7,545)
After taxes	13,996
2,023
Disclosure of detailed information about financial risk management [Line Items]
Before taxes	16,786
Taxes	(5,880)
After taxes	$ 10,906

Risk management (Details 5)

Risk management (Details 5) - Hedges of net investment in foreign operations [member] - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Hedging instrument at the beginning of the period	$ 155,359	$ 0
Exchange difference	(86,892)	231,879
Ineffectiveness	329	0
Deferred income tax	28,566	(76,520)
Hedging instrument at the end of the period	$ 97,362	$ 155,359

Risk management (Details 6)

Risk management (Details 6) - Financial assets past due but not impaired [member] - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Disclosure of detailed information about financial risk management [Line Items]
Financial assets	$ 146,173	$ 296,857
Later than three months [member]
Disclosure of detailed information about financial risk management [Line Items]
Financial assets	65,354	179,008
Later than three months and not later than six months [member]
Disclosure of detailed information about financial risk management [Line Items]
Financial assets	1,131	14,275
Later Than Six Month [Member]
Disclosure of detailed information about financial risk management [Line Items]
Financial assets	$ 79,688	$ 103,574

Risk management (Details 7)

Risk management (Details 7) $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)
Increase in floating interest (+100 basis points)
Disclosure of detailed information about financial risk management [Line Items]
Financial assets (Financial expenses)	$ (66,120)
Financial liabilities (Financial income)	112,383
Plan assets (Other comprehensive income)	(171,031)
Decrease in floating interest (-100 basis points)
Disclosure of detailed information about financial risk management [Line Items]
Financial assets (Financial income)	66,120
Financial liabilities (Financial expenses)	(112,282)
Plan assets (Other comprehensive income)	$ 183,988

Risk management (Details 8)

Risk management (Details 8) $ in Millions	Dec. 31, 2017COP ($)
Disclosure of detailed information about financial risk management [Line Items]
Loans (principal and interests)	$ 67,549,952
Trade and other accounts payable	7,103,022
Total	74,652,974
Up to 1 year
Disclosure of detailed information about financial risk management [Line Items]
Loans (principal and interests)	5,040,130
Trade and other accounts payable	6,968,207
Total	12,008,337
1-5 years
Disclosure of detailed information about financial risk management [Line Items]
Loans (principal and interests)	28,151,892
Trade and other accounts payable	134,815
Total	28,286,707
5-10 years
Disclosure of detailed information about financial risk management [Line Items]
Loans (principal and interests)	18,873,280
Trade and other accounts payable	0
Total	18,873,280
> 10 years
Disclosure of detailed information about financial risk management [Line Items]
Loans (principal and interests)	15,484,650
Trade and other accounts payable	0
Total	$ 15,484,650

Risk management (Details 9)

Risk management (Details 9) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of detailed information about financial risk management [Line Items]
Loans and borrowings (Note 20)	$ 43,547,835	$ 52,222,027
Cash and cash equivalents	(7,945,885)	(8,410,467)	$ (6,550,450)	$ (7,618,178)
Other financial assets	(6,533,725)	(6,686,895)
Net financial debt	29,068,225	37,124,665
Equity (Note 24)	$ 48,215,699	$ 43,560,501	$ 43,100,963	$ 48,534,228
Leverage	37.61%	46.01%

Risk management (Details Textua

Risk management (Details Textual) $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016COP ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015COP ($)	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Disclosure of detailed information about financial risk management [Line Items]
Closing foreign exchange rate	$ 2,984		$ 3,000.71		$ 3,149.47
Financial instruments designated as hedging instruments, at fair value		$ 8,532					$ 10,512
Gain (loss) on hedge ineffectiveness recognised in profit or loss	$ 99,971,000,000		42,865,000,000
Maximum percentage of cash investment held in portfolio, non current	1.00%	1.00%
Liquidity Surplus Used for Prepayment of borrowings		$ 2,400
Notional amount						$ 1,925
Net short position contracts		325		$ 323
Other comprehensive gains losses on hedges of derivative instruments net of tax	$ 35,769,000,000		$ 33,869,000,000
Hedges of net investment in foreign operations [member]
Disclosure of detailed information about financial risk management [Line Items]
Financial instruments designated as hedging instruments, at fair value		5,200					$ 5,200
Foreign Currency Commercial Loans Six [Member]
Disclosure of detailed information about financial risk management [Line Items]
Notional amount						$ 1,925
Colombian Peso [Member]
Disclosure of detailed information about financial risk management [Line Items]
Gross financial assets set off against financial liabilities subject to offsetting, enforceable master netting arrangements or similar agreements		8,532
Gross financial liabilities subject to offsetting, enforceable master netting arrangements or similar agreements		91
US Dollar [Member]
Disclosure of detailed information about financial risk management [Line Items]
Gross financial liabilities subject to offsetting, enforceable master netting arrangements or similar agreements		$ 1,699
Floating interest rate [member]
Disclosure of detailed information about financial risk management [Line Items]
Borrowings, interest rate		19.00%	31.00%				31.00%
Peso portfolio [Member]
Disclosure of detailed information about financial risk management [Line Items]
Maximum percentage of cash investment held in portfolio	10.00%	10.00%
U.S. dollor portfolio [Member]
Disclosure of detailed information about financial risk management [Line Items]
Maximum percentage of cash investment held in portfolio, current	5.00%	5.00%
Commodity price risk [member]
Disclosure of detailed information about financial risk management [Line Items]
Net financial assets subject to offsetting, enforceable master netting arrangements or similar agreements in statement of financial position			$ 3,181,000,000		$ 4,141,000,000
Currency risk [member]
Disclosure of detailed information about financial risk management [Line Items]
The Increase Decrease In Foreign exchange Rate	3.30%	3.30%	11.20%	11.20%	37.30%

Related parties (Details)

Related parties (Details) - COP ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Investments in joint ventures and associates [abstract]
Accounts receivable		$ 23,013	$ 97,730
Accounts receivable-Loans		154,810	170,121
Other assets		7,716	7,135
Accounts payable		129,520	114,420
Loans		259,760	30,644
Other liabilities		7
Accounts receivable, Current		23,013	97,730
Accounts receivable, Non-current		0	0
Accounts receivable - Loans, Current		0	0
Accounts receivable - Loans, Non-current		154,810	170,121
Other assets, Current		7,716	7,135
Other assets, Non-current		0	0
Accounts payable, Current		129,520	114,420
Accounts payable, Non-current		0	0
Loans, Current		259,760	30,644
Loans, Non-current		0	0
Other liabilities, Current		7
Other liabilities, Non-current		0
Serviport S.A. [member]
Investments in joint ventures and associates [abstract]
Accounts receivable		0	0
Accounts receivable-Loans		0	0
Other assets		0	0
Accounts payable		5,820	3,989
Loans		0	0
Other liabilities		0
Invercolsa S.A [Member]
Investments in joint ventures and associates [abstract]
Accounts receivable		18,641
Accounts receivable-Loans		0
Other assets		0
Accounts payable		0
Loans		0
Other liabilities		0
Offshore international group [Member]
Investments in joint ventures and associates [abstract]
Accounts receivable	[1]	0	0
Accounts receivable-Loans	[1]	154,810	170,121
Other assets	[1]	0	0
Accounts payable	[1]	0	0
Loans	[1]	0	0
Other liabilities	[1]	0
Equion Energia Limited [Member]
Investments in joint ventures and associates [abstract]
Accounts receivable	[2]	4,010	97,601
Accounts receivable-Loans	[2]	0	0
Other assets	[2]	7,716	7,135
Accounts payable	[2]	101,472	89,666
Loans	[2]	259,760	30,644
Other liabilities	[2]	7
Ecodiesel Colombia SA [Member]
Investments in joint ventures and associates [abstract]
Accounts receivable		362	129
Accounts receivable-Loans		0	0
Other assets		0	0
Accounts payable		22,228	20,765
Loans		0	$ 0
Other liabilities		$ 0
[1]	Loan granted by Ecopetrol SA to Savia Perú SA (subsidiary of Offshore International Group) for US$57 million in 2016, with an interest rate of 4.99% payable semiannually from 2017 and maturating in 2021. The balance in nominal value of this loan as of December 31, 2017 is US$49 million.
[2]	Deposits held by Equion in Capital AG for a nominal value of US$ 77 million with maturity in January 2018 and a weighted average rate of 1.44%.

Related parties (Details 1)

Related parties (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of transactions between related parties [line items]
Sales And Services, Related Party Transactions	$ 447,652	$ 503,727	$ 523,213
Purchases And Other Assets, Related Party Transactions	857,905	708,774	457,805
Serviport S.A. [member]
Disclosure of transactions between related parties [line items]
Sales And Services, Related Party Transactions	0	0	0
Purchases And Other Assets, Related Party Transactions	0	24,572	0
Equion Energia Limited [Member]
Disclosure of transactions between related parties [line items]
Sales And Services, Related Party Transactions	425,881	491,698	515,968
Purchases And Other Assets, Related Party Transactions	598,636	418,618	190,158
Ecodiesel Colombia S.A. [member]
Disclosure of transactions between related parties [line items]
Sales And Services, Related Party Transactions	6,583	5,744	7,245
Purchases And Other Assets, Related Party Transactions	259,269	265,584	267,647
Offshore International Group [member]
Disclosure of transactions between related parties [line items]
Sales And Services, Related Party Transactions	15,188	6,285	0
Purchases And Other Assets, Related Party Transactions	$ 0	$ 0	$ 0

Related parties (Details 2)

Related parties (Details 2)	12 Months Ended
	Dec. 31, 2017
Mauricio Cardenas Santamaria [Member]
Disclosure of transactions between related parties [line items]
Key Management Personnel Shareholding Description	<1% outstanding shares
Hector Manosalva Rojas [Member]
Disclosure of transactions between related parties [line items]
Key Management Personnel Shareholding Description	<1% outstanding shares
Rafael Espinosa Rozo [Member]
Disclosure of transactions between related parties [line items]
Key Management Personnel Shareholding Description	<1% outstanding shares
Felipe Bayon [Member]
Disclosure of transactions between related parties [line items]
Key Management Personnel Shareholding Description	<1% outstanding shares

Related parties (Details Textua

Related parties (Details Textual) $ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017COP ($)	Dec. 31, 2016COP ($)	Dec. 31, 2015COP ($)	Jan. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Disclosure of transactions between related parties [line items]
Loans and receivables					$ 49
Key management personnel compensation	$ 4,426,000	$ 4,140,000	$ 3,870,000
Virtual Meetings Attendance Fee Percentage	50.00%
Cancellation of fees	$ 1,877	1,253
Payment Of Key Management Personnel Compensation	20,669	13,901
Provisions for employee benefits	$ 8,332,294	5,875,578
Ownership Interest Held By Government	88.49%
Description of any retirement benefit plan termination terms	five-year term (2016 - 2021)
Executive officers [Member]
Disclosure of transactions between related parties [line items]
Provisions for employee benefits	$ 5,401	$ 4,674
Offshore International Group [member]
Disclosure of transactions between related parties [line items]
Loans and receivables						$ 57
Loans And Receivable Interest Rate		4.99%				4.99%
Equion Energy Limited [Member]
Disclosure of transactions between related parties [line items]
Loans and receivables				$ 77
Loans And Receivable Interest Rate				1.44%

Joint operations (Details)

Joint operations (Details) - Contract where entity not operator [Member]	12 Months Ended
	Dec. 31, 2017
Equion Energy Limited [Member]
Disclosure of joint operations [line items]
Contract	Niscota
Type	Production
% Participation	20.00%
Geographic area of operations	Brazil
Murphy Oil [Member]
Disclosure of joint operations [line items]
Contract	Dalmatian
Type	Production
% Participation	30.00%
Geographic area of operations	Gulf of Mexico
Chipiron Contract [Member] | Occidental Andina LLC [Member]
Disclosure of joint operations [line items]
Contract	Chipirón
Type	Production
Geographic area of operations	Colombia
Chipiron Contract [Member] | Occidental Andina LLC [Member] | Bottom of range [member]
Disclosure of joint operations [line items]
% Participation	30.00%
Chipiron Contract [Member] | Occidental Andina LLC [Member] | Top of range [member]
Disclosure of joint operations [line items]
% Participation	40.00%
Harvest Contract [Member] | Occidental Andina LLC [Member]
Disclosure of joint operations [line items]
Contract	Harvest
Type	Production
% Participation	30.00%
Geographic area of operations	Colombia
Cravo norte Contract [Member] | Occidental Andina LLC [Member]
Disclosure of joint operations [line items]
Contract	Cravo Norte
Type	Production
% Participation	50.00%
Geographic area of operations	Colombia
Rondon Contract [Member] | Occidental Andina LLC [Member]
Disclosure of joint operations [line items]
Contract	Rondón
Type	Production
% Participation	50.00%
Geographic area of operations	Colombia
Guajira Contract [Member] | Chevron Petroleum Group [Member]
Disclosure of joint operations [line items]
Contract	Guajira
Type	Production
% Participation	57.00%
Geographic area of operations	Colombia
Nare Contract [Member] | Mansarovar Energy Colombia Ltd [Member]
Disclosure of joint operations [line items]
Contract	Nare
Type	Production
% Participation	50.00%
Geographic area of operations	Colombia
Quifa Contract [Member] | Meta Petroleum Corp [Member]
Disclosure of joint operations [line items]
Contract	Quifa
Type	Production
% Participation	40.00%
Geographic area of operations	Colombia
Piedemonte Contract [Member] | Equion Energy Limited [Member]
Disclosure of joint operations [line items]
Contract	Piedemonte
Type	Production
% Participation	50.00%
Geographic area of operations	Colombia
Casanare Contract One [Member] | Perenco Colombia Limited [Member]
Disclosure of joint operations [line items]
Contract	Casanare
Type	Production
% Participation	64.00%
Geographic area of operations	Colombia
Corocora Contract One [Member] | Perenco Colombia Limited [Member]
Disclosure of joint operations [line items]
Contract	Corocora
Type	Production
% Participation	56.00%
Geographic area of operations	Colombia
Estero Contract One [Member] | Perenco Colombia Limited [Member]
Disclosure of joint operations [line items]
Contract	Estero
Type	Production
% Participation	89.00%
Geographic area of operations	Colombia
Garcero Contract One [Member] | Perenco Colombia Limited [Member]
Disclosure of joint operations [line items]
Contract	Garcero
Type	Production
% Participation	76.00%
Geographic area of operations	Colombia
Orocue Contract One [Member] | Perenco Colombia Limited [Member]
Disclosure of joint operations [line items]
Contract	Orocúe
Type	Production
% Participation	63.00%
Geographic area of operations	Colombia
Gunflint Contract [Member] | Noble Energy [Member]
Disclosure of joint operations [line items]
Contract	Gunflint
Type	Production
% Participation	32.00%
Geographic area of operations	Gulf of Mexico
K2 Contract [Member] | Anadarko [Member]
Disclosure of joint operations [line items]
Contract	K2
Type	Production
% Participation	21.00%
Geographic area of operations	Gulf of Mexico
Ronda Caribe RC-10 Contract [Member] | ONGC Videsh Limited Sucursal Colombia [Member]
Disclosure of joint operations [line items]
Contract	RC-10 Caribbean Round
Type	Exploration
% Participation	50.00%
Geographic area of operations	North Caribbean Offshore
Tayrona Contract [Member] | Petrobras, Repsol Statoil [Member]
Disclosure of joint operations [line items]
Contract	Tayrona
Type	Exploration
% Participation	30.00%
Geographic area of operations	North Caribbean Offshore
TEA GUA OFF-1 Contract [Member] | Repsol & Statoil [Member]
Disclosure of joint operations [line items]
Contract	TEA GUA OFF-1
Type	Exploration
% Participation	50.00%
Geographic area of operations	North Caribbean Offshore
Fuerte Norte Contract [Member] | Anadarko [Member]
Disclosure of joint operations [line items]
Contract	Fuerte Norte
Type	Exploration
% Participation	50.00%
Geographic area of operations	North Caribbean Offshore
Deep Rydberg/Aleatico Contract [Member] | Shell [Member]
Disclosure of joint operations [line items]
Contract	Deep Rydberg/Aleatico
Type	Exploration
% Participation	29.00%
Geographic area of operations	Gulf of Mexico
Leon Contract [Member] | Repsol [Member]
Disclosure of joint operations [line items]
Contract	Lion
Type	Exploration
% Participation	40.00%
Geographic area of operations	Gulf of Mexico
CE-M-715_R11 [Member] | Chevron [Member]
Disclosure of joint operations [line items]
Contract	CE-M-715_R11
Type	Exploration
% Participation	50.00%
Geographic area of operations	Brazil

Joint operations (Details 1)

Joint operations (Details 1) - Contract where Entity is operator [Member]	12 Months Ended
	Dec. 31, 2017
Cepsa Colombia [Member]
Disclosure of joint operations [line items]
Contract	San Jacinto Rio Paez
Type	Production
% Participation	18.00%
Geographic area of operations	Colombia
VMM29 Contract [Member] | ExxonMobil Exploration Colombia [Member]
Disclosure of joint operations [line items]
Contract	VMM29
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
CR2 Contract [Member] | ExxonMobil Exploration Colombia [Member]
Disclosure of joint operations [line items]
Contract	CR2
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
C62 Contract [Member] | ExxonMobil Exploration Colombia [Member]
Disclosure of joint operations [line items]
Contract	C62
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
CPO9 Contract [Member] | Talisman Colombia Oil [Member]
Disclosure of joint operations [line items]
Contract	CPO9
Type	Exploration
% Participation	55.00%
Geographic area of operations	Colombia
VMM32 Contract [Member] | CPVEN Sucursal Colombia [Member]
Disclosure of joint operations [line items]
Contract	VMM32
Type	Exploration
% Participation	51.00%
Geographic area of operations	Colombia
CR4 Contract [Member] | Shell Exploracion and Produccion [Member]
Disclosure of joint operations [line items]
Contract	CR4
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
San Jacinto Contract [Member] | SK Innovation Co Ltd. [Member]
Disclosure of joint operations [line items]
Contract	San Jacinto
Type	Exploration
% Participation	70.00%
Geographic area of operations	Colombia
Catleya Contract [Member] | Repsol Exploracion Colombia S.A. [Member]
Disclosure of joint operations [line items]
Contract	Catleya
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
Cardon Contract [Member] | Emerald Energy PLC Suc. Colombia [Member]
Disclosure of joint operations [line items]
Contract	Cardon
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
CPO 17 Contract [Member] | Maurel Prom Suramerica [Member]
Disclosure of joint operations [line items]
Contract	CPO17
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
Clarinero Contract [Member] | Lewis [Member]
Disclosure of joint operations [line items]
Contract	Clarinero
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
CPO9 - Akacias Contract [Member] | Gas Ltd. [Member]
Disclosure of joint operations [line items]
Contract	CPO9 - Akacias
Type	Production
% Participation	55.00%
Geographic area of operations	Colombia
La Cira Infantas Contract [Member] | Occidental Andina LLC [Member]
Disclosure of joint operations [line items]
Contract	La Cira Infantas
Type	Production
% Participation	58.00%
Geographic area of operations	Colombia
Teca Contract [Member] | Occidental Andina LLC [Member]
Disclosure of joint operations [line items]
Contract	Teca
% Participation	86.00%
Geographic area of operations	Colombia
Guariquies I Contract [Member] | Ramshorn International Limited [Member]
Disclosure of joint operations [line items]
Contract	Guariquies I
Type	Production
% Participation	50.00%
Geographic area of operations	Colombia
AMA4 Contract [Member] | Hocol S.A [Member]
Disclosure of joint operations [line items]
Contract	AMA4
Type	Exploration
% Participation	100.00%
Geographic area of operations	Colombia
RC9 Contract [Member] | ONGC Videsh Limited Sucursal Colombia [Member]
Disclosure of joint operations [line items]
Contract	RC9
Type	Exploration
% Participation	50.00%
Geographic area of operations	Colombia
Cusiana Contract [Member] | Equion Energy Limited [Member]
Disclosure of joint operations [line items]
Contract	Cusiana
Type	Production
% Participation	98.00%
Geographic area of operations	Colombia
San Jacinto Rio Paez Contract [Member] | Perenco Oil And Gas [Member]
Disclosure of joint operations [line items]
Contract	San Jacinto Rio Paez
Type	Production
% Participation	18.00%
Geographic area of operations	Colombia
Mundo Nuevo Contract [Member] | Total Colombia [Member]
Disclosure of joint operations [line items]
Contract	Mundo Nuevo
Type	Exploration
% Participation	15.00%
Geographic area of operations	Colombia
Mundo Nuevo Contract [Member] | Talisman Oil & Gas [Member]
Disclosure of joint operations [line items]
Contract	Mundo Nuevo
Type	Exploration
% Participation	15.00%
Geographic area of operations	Colombia
Alto Magdalena Pipeline Contract [Member] | Equion Energy Limited [Member]
Disclosure of joint operations [line items]
Contract	Alto Magdalena Pipeline
Type	OAM
Geographic area of operations	Colombia
Alto Magdalena Pipeline Contract [Member] | Emerald Energy [Member]
Disclosure of joint operations [line items]
Contract	Alto Magdalena Pipeline
Type	OAM
% Participation	45.00%
Geographic area of operations	Colombia
Alto Magdalena Pipeline Contract [Member] | Equion Energia Limited [Member]
Disclosure of joint operations [line items]
% Participation	45.00%
Alto Magdalena Pipeline Contract [Member] | Frontera Energy [Member]
Disclosure of joint operations [line items]
Contract	Alto Magdalena Pipeline
Type	OAM
% Participation	45.00%
Geographic area of operations	Colombia
Block RC-9 Contract- Caribbean Round No. 37-2007 Contract [Member] | ONGC Videsh Limited [Member]
Disclosure of joint operations [line items]
Contract	Block RC-9 Contract- Caribbean Round No. 37-2007
Type	Exploration
% Participation	50.00%
Geographic area of operations	Gulf of Mexico
FAZMR11 Contract [Member] | JX Nippon [Member]
Disclosure of joint operations [line items]
Contract	FAZ-M-320_R11
Type	Exploration
% Participation	70.00%
Geographic area of operations	Brazil
POTMR11 Contract [Member] | JX Nippon [Member]
Disclosure of joint operations [line items]
Contract	POT-M-567_R11
Type	Exploration
% Participation	100.00%
Geographic area of operations	Brazil

Joint operations (Details Textu

Joint operations (Details Textual) $ in Millions	Dec. 11, 2017USD ($)	Jul. 03, 2016	Dec. 31, 2016COP ($)	Dec. 31, 2017COP ($)	Dec. 11, 2017COP ($)	Dec. 11, 2017USD ($)	Jul. 01, 2016USD ($)
Disclosure of joint operations [line items]
Investments in joint ventures			$ 1,303,157,000,000	$ 1,105,282,000,000
MCX Exploration USA LLC [Member] | K2 oil field [Member]
Disclosure of joint operations [line items]
Percentage of voting equity interests acquired					11.60%	11.60%
Proportion of voting rights held in joint operation	20.80%		9.20%
Identifiable assets acquired liabilities assumed net of deferred taxes						$ 146
Consideration transferred, acquisition-date fair value net of deferred taxes						98
Cash transferred				141,950,000,000		47.6
Identifiable assets acquired (liabilities assumed)						198.4
Consideration transferred, acquisition-date fair value					$ 451,095	$ 150.8
Acquisition-related costs for transaction recognised separately from acquisition of assets and assumption of liabilities in business combination	$ 0.2
Equion Energia Limited [Member]
Disclosure of joint operations [line items]
Investments in joint ventures			$ 902,747,000,000	$ 761,039,000,000
Cusiana Planta de gas Contract [Member] | Equion Energia Limited [Member]
Disclosure of joint operations [line items]
Proportion of ownership interest in joint operation		98.00%
Cusiana Planta de gas Contract [Member] | Contract where Entity is operator [Member] | Equion and Emerald [Member]
Disclosure of joint operations [line items]
Proportion of ownership interest in joint operation		2.00%
BOMT contracts [member]
Disclosure of joint operations [line items]
Investments in joint ventures							$ 46

Information by segments (Detail

Information by segments (Details) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Revenue	$ 55,954,228	$ 48,485,561	$ 52,347,271
Cost of sales	36,908,325	34,251,423	36,994,516
Gross profit	19,045,903	14,234,138	15,352,755
Administrative expenses	1,764,524	1,923,268	1,700,985
Operation and projects expenses	2,926,065	2,751,687	4,034,268
Impairment of non-current assets	(1,311,138)	928,747	7,864,875
Other operating income and expenses, net	(505,403)	(274,112)	(378,541)
Operating income	16,171,855	8,904,548	2,131,165
Financial result, net
Finance income	1,159,356	1,311,743	621,924
Financial expenses	(3,660,601)	(3,463,540)	(2,718,414)
Foreign exchange gain (loss), net	5,514	976,430	(5,566,614)
Financial result, net	(2,495,731)	(1,175,367)	(7,663,104)
Share of profit of associates	93,538	61,345	(46,687)
Income before tax	13,769,662	7,790,526	(5,578,626)
Income tax expense	(5,800,268)	(4,543,046)	(710,353)
Net profit (loss) for the period	7,969,394	3,247,480	(6,288,979)
Net profit (loss) for the period
Group owners of parent	7,178,539	2,447,881	(7,193,859)
Non-controlling interest	790,855	799,599	904,880
Net income	7,969,394	3,247,480	(6,288,979)
Supplementary information
Depreciation, depletion and amortization	8,281,347	7,607,001	6,770,358
Third Party Sales [Member]
Disclosure of operating segments [line items]
Revenue	55,954,228	48,485,561	52,347,271
Inter-Segment Sales [Member]
Disclosure of operating segments [line items]
Revenue	0	0	0
Fixed Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	10,340,394	9,291,308	9,625,451
Variable Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	26,567,931	24,960,115	27,369,065
Exploration and Production [member]
Disclosure of operating segments [line items]
Revenue	36,494,934	28,221,210	31,732,611
Cost of sales	26,310,084	22,972,648	25,708,872
Gross profit	10,184,850	5,248,562	6,023,739
Administrative expenses	781,386	832,266	731,626
Operation and projects expenses	2,070,916	1,656,960	2,969,723
Impairment of non-current assets	(183,718)	196,448	4,504,497
Other operating income and expenses, net	(545,218)	(349,419)	(399,954)
Operating income	8,061,484	2,912,307	(1,782,153)
Financial result, net
Finance income	1,062,393	983,472	536,121
Financial expenses	(2,288,576)	(2,017,641)	(1,774,090)
Foreign exchange gain (loss), net	(101,030)	923,573	(4,798,741)
Financial result, net	(1,327,213)	(110,596)	(6,036,710)
Share of profit of associates	120,786	39,397	(70,407)
Income before tax	6,855,057	2,841,108	(7,889,270)
Income tax expense	(3,034,556)	(1,518,738)	2,037,650
Net profit (loss) for the period	3,820,501	1,322,370	(5,851,620)
Net profit (loss) for the period
Group owners of parent	3,820,501	1,322,370	(5,851,620)
Non-controlling interest	0	0	0
Net income	3,820,501	1,322,370	(5,851,620)
Supplementary information
Depreciation, depletion and amortization	5,981,294	5,482,827	5,318,587
Exploration and Production [member] | Third Party Sales [Member]
Disclosure of operating segments [line items]
Revenue	25,004,320	20,527,332	25,669,213
Exploration and Production [member] | Inter-Segment Sales [Member]
Disclosure of operating segments [line items]
Revenue	11,490,614	7,693,878	6,063,398
Exploration and Production [member] | Fixed Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	8,055,925	6,940,074	7,208,632
Exploration and Production [member] | Variable Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	18,254,159	16,032,574	18,500,240
Refining and Petrochemicals [member]
Disclosure of operating segments [line items]
Revenue	28,644,016	24,823,714	23,245,676
Cost of sales	26,855,395	22,843,987	20,758,808
Gross profit	1,788,621	1,979,727	2,486,868
Administrative expenses	516,501	574,413	451,250
Operation and projects expenses	965,457	1,206,718	1,155,301
Impairment of non-current assets	(1,067,965)	773,361	3,278,993
Other operating income and expenses, net	11,694	20,947	122,595
Operating income	1,362,934	(595,712)	(2,521,271)
Financial result, net
Finance income	164,006	46,469	135,622
Financial expenses	(1,110,874)	(952,006)	(451,906)
Foreign exchange gain (loss), net	163,992	94,715	(949,176)
Financial result, net	(782,876)	(810,822)	(1,265,460)
Share of profit of associates	15,245	22,785	23,187
Income before tax	595,303	(1,383,749)	(3,763,544)
Income tax expense	(238,625)	(446,595)	(257,256)
Net profit (loss) for the period	356,678	(1,830,344)	(4,020,800)
Net profit (loss) for the period
Group owners of parent	358,859	(1,823,020)	(4,016,050)
Non-controlling interest	(2,181)	(7,324)	(4,750)
Net income	356,678	(1,830,344)	(4,020,800)
Supplementary information
Depreciation, depletion and amortization	1,188,871	1,145,780	570,033
Refining and Petrochemicals [member] | Third Party Sales [Member]
Disclosure of operating segments [line items]
Revenue	27,343,359	24,194,024	22,456,866
Refining and Petrochemicals [member] | Inter-Segment Sales [Member]
Disclosure of operating segments [line items]
Revenue	1,300,657	629,690	788,810
Refining and Petrochemicals [member] | Fixed Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	2,886,745	2,458,745	1,902,797
Refining and Petrochemicals [member] | Variable Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	23,968,650	20,385,242	18,856,011
Transport and Logistics [member]
Disclosure of operating segments [line items]
Revenue	10,598,064	10,648,776	10,844,550
Cost of sales	3,271,835	3,349,791	3,744,422
Gross profit	7,326,229	7,298,985	7,100,128
Administrative expenses	466,669	516,884	518,109
Operation and projects expenses	142,847	180,353	157,596
Impairment of non-current assets	(59,455)	(41,062)	81,388
Other operating income and expenses, net	28,121	53,559	(101,182)
Operating income	6,748,047	6,589,251	6,444,217
Financial result, net
Finance income	106,659	61,373	86,568
Financial expenses	(434,664)	(262,844)	(492,485)
Foreign exchange gain (loss), net	(57,448)	(41,858)	181,303
Financial result, net	(385,453)	(243,329)	(224,614)
Share of profit of associates	(42,493)	(837)	533
Income before tax	6,320,101	6,345,085	6,220,136
Income tax expense	(2,527,087)	(2,577,713)	(2,490,747)
Net profit (loss) for the period	3,793,014	3,767,372	3,729,389
Net profit (loss) for the period
Group owners of parent	2,999,978	2,960,449	2,819,759
Non-controlling interest	793,036	806,923	909,630
Net income	3,793,014	3,767,372	3,729,389
Supplementary information
Depreciation, depletion and amortization	1,111,182	978,394	881,738
Transport and Logistics [member] | Third Party Sales [Member]
Disclosure of operating segments [line items]
Revenue	3,606,549	3,764,205	4,221,192
Transport and Logistics [member] | Inter-Segment Sales [Member]
Disclosure of operating segments [line items]
Revenue	6,991,515	6,884,571	6,623,358
Transport and Logistics [member] | Fixed Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	2,637,604	2,861,269	3,304,815
Transport and Logistics [member] | Variable Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	634,231	488,522	439,607
Elimination of intersegment amounts [member]
Disclosure of operating segments [line items]
Revenue	(19,782,786)	(15,208,139)	(13,475,566)
Cost of sales	(19,528,989)	(14,915,003)	(13,217,586)
Gross profit	(253,797)	(293,136)	(257,980)
Administrative expenses	(32)	(295)	0
Operation and projects expenses	(253,155)	(292,344)	(248,352)
Impairment of non-current assets	0	0	0
Other operating income and expenses, net	0	801	0
Operating income	(610)	(1,298)	(9,628)
Financial result, net
Finance income	(173,702)	220,429	(136,387)
Financial expenses	173,513	(231,049)	67
Foreign exchange gain (loss), net	0	0	0
Financial result, net	(189)	(10,620)	(136,320)
Share of profit of associates	0	0	0
Income before tax	(799)	(11,918)	(145,948)
Income tax expense	0	0	0
Net profit (loss) for the period	(799)	(11,918)	(145,948)
Net profit (loss) for the period
Group owners of parent	(799)	(11,918)	(145,948)
Non-controlling interest	0	0	0
Net income	(799)	(11,918)	(145,948)
Supplementary information
Depreciation, depletion and amortization	0	0	0
Elimination of intersegment amounts [member] | Third Party Sales [Member]
Disclosure of operating segments [line items]
Revenue	0	0	0
Elimination of intersegment amounts [member] | Inter-Segment Sales [Member]
Disclosure of operating segments [line items]
Revenue	(19,782,786)	(15,208,139)	(13,475,566)
Elimination of intersegment amounts [member] | Fixed Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	(3,239,880)	(2,968,780)	(2,790,793)
Elimination of intersegment amounts [member] | Variable Cost [Member]
Disclosure of operating segments [line items]
Cost of sales	$ (16,289,109)	$ (11,946,223)	$ (10,426,793)

Information by segments (Det175

Information by segments (Details 1) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Total sales revenue		$ 55,954,228	$ 48,485,561	$ 52,347,271
Domestic sales [Member]
Disclosure of operating segments [line items]
Revenue From Sale Of Goods And Rendering Of Services Before Price Differential Adjustment		26,006,139	23,697,150	25,624,750
Recognition of price differential	[1]	2,229,953	1,048,022	441,871
Total sales revenue		28,236,092	24,745,172	26,066,621
Domestic sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,207,245	660,169	988,346
Domestic sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		509,619	405,869	335,494
Domestic sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,815,754	1,988,336	1,845,345
Domestic sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		6,990,187	6,092,739	6,128,208
Domestic sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		833,982	724,708	724,392
Domestic sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		9,590,326	8,553,503	10,215,224
Domestic sales [Member] | Aromatics [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			186,228
Domestic sales [Member] | Crude Oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		909,871	553,666	491,279
Domestic sales [Member] | Services [Member]
Disclosure of operating segments [line items]
Services		3,873,352	4,043,284	4,435,274
Domestic sales [Member] | Diesel and asphalts [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		275,803	340,400	461,188
Domestic sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			148,248
Foreign sales [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		27,718,136	23,740,389	26,280,650
Foreign sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		441,124	389,775
Foreign sales [Member] | Cash flow hedging - Reclassification to profit or loss [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		160,772	33,074	7,646
Foreign sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		15,631	8,568	0
Foreign sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		32,303	58,809	182,950
Foreign sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,223,994	1,046,758	93,125
Foreign sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,169,101	1,171,342	1,096,730
Foreign sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			1,594,945
Foreign sales [Member] | Oil fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,982,408	2,158,539
Foreign sales [Member] | Crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		21,479,063	17,278,579	21,181,265
Foreign sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,982,408	2,158,539	2,166,469
Foreign sales [Member] | Trading of crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	1,309,196
Foreign sales [Member] | Diesel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,213,740	1,604,498	81,982
Foreign sales [Member] | Other products and services [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				161,287
Exploration and Production [member]
Disclosure of operating segments [line items]
Total sales revenue		36,494,933	28,221,211	31,732,611
Exploration and Production [member] | Domestic sales [Member]
Disclosure of operating segments [line items]
Revenue From Sale Of Goods And Rendering Of Services Before Price Differential Adjustment		14,840,169	8,289,518	8,656,936
Recognition of price differential		0	0	0
Total sales revenue		14,840,169	8,289,518	8,656,936
Exploration and Production [member] | Domestic sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		214,059	424,952	262,906
Exploration and Production [member] | Domestic sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		199,796	90,783	154,201
Exploration and Production [member] | Domestic sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		2,540,233	2,383,323	2,198,284
Exploration and Production [member] | Domestic sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Exploration and Production [member] | Domestic sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Exploration and Production [member] | Domestic sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,334	0	25,782
Exploration and Production [member] | Domestic sales [Member] | Aromatics [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0
Exploration and Production [member] | Domestic sales [Member] | Crude Oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		11,668,529	5,284,554	5,847,368
Exploration and Production [member] | Domestic sales [Member] | Services [Member]
Disclosure of operating segments [line items]
Services		181,384	73,247	118,812
Exploration and Production [member] | Domestic sales [Member] | Diesel and asphalts [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		34,834	31,277	49,583
Exploration and Production [member] | Domestic sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			1,382
Exploration and Production [member] | Foreign sales [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		21,654,764	19,931,693	23,075,675
Exploration and Production [member] | Foreign sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		19,393	25,395
Exploration and Production [member] | Foreign sales [Member] | Cash flow hedging - Reclassification to profit or loss [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		160,772	33,074	7,646
Exploration and Production [member] | Foreign sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		15,631	6,342
Exploration and Production [member] | Foreign sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		32,303	350,685	233,500
Exploration and Production [member] | Foreign sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	27,756
Exploration and Production [member] | Foreign sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Exploration and Production [member] | Foreign sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0
Exploration and Production [member] | Foreign sales [Member] | Oil fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0
Exploration and Production [member] | Foreign sales [Member] | Crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		21,426,665	19,516,197	21,495,762
Exploration and Production [member] | Foreign sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				0
Exploration and Production [member] | Foreign sales [Member] | Trading of crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				1,309,196
Exploration and Production [member] | Foreign sales [Member] | Diesel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0		0
Exploration and Production [member] | Foreign sales [Member] | Other products and services [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				1,815
Refining and Petrochemicals [member]
Disclosure of operating segments [line items]
Total sales revenue		28,644,016	24,814,159	23,245,676
Refining and Petrochemicals [member] | Domestic sales [Member]
Disclosure of operating segments [line items]
Revenue From Sale Of Goods And Rendering Of Services Before Price Differential Adjustment		20,351,058	17,429,078	19,266,697
Recognition of price differential		2,229,953	1,048,022	441,871
Total sales revenue		22,581,011	18,477,100	19,708,568
Refining and Petrochemicals [member] | Domestic sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,103,089	669,568	1,070,725
Refining and Petrochemicals [member] | Domestic sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		309,823	319,644	190,346
Refining and Petrochemicals [member] | Domestic sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		4	11,763	0
Refining and Petrochemicals [member] | Domestic sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		8,052,289	6,465,939	6,464,661
Refining and Petrochemicals [member] | Domestic sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		833,982	724,708	724,392
Refining and Petrochemicals [member] | Domestic sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		9,588,992	8,553,503	10,206,599
Refining and Petrochemicals [member] | Domestic sales [Member] | Aromatics [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			186,228
Refining and Petrochemicals [member] | Domestic sales [Member] | Crude Oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Refining and Petrochemicals [member] | Domestic sales [Member] | Services [Member]
Disclosure of operating segments [line items]
Services		221,910	41,736	198,369
Refining and Petrochemicals [member] | Domestic sales [Member] | Diesel and asphalts [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		240,969	309,123	411,605
Refining and Petrochemicals [member] | Domestic sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			146,866
Refining and Petrochemicals [member] | Foreign sales [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		6,063,005	6,337,059	3,537,108
Refining and Petrochemicals [member] | Foreign sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		421,364	363,250
Refining and Petrochemicals [member] | Foreign sales [Member] | Cash flow hedging - Reclassification to profit or loss [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Refining and Petrochemicals [member] | Foreign sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	2,225
Refining and Petrochemicals [member] | Foreign sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Refining and Petrochemicals [member] | Foreign sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,223,994	1,046,758	65,369
Refining and Petrochemicals [member] | Foreign sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,169,101	1,171,342	1,096,730
Refining and Petrochemicals [member] | Foreign sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			1,594,945
Refining and Petrochemicals [member] | Foreign sales [Member] | Oil fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,982,408	2,158,539
Refining and Petrochemicals [member] | Foreign sales [Member] | Crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		52,398	0	0
Refining and Petrochemicals [member] | Foreign sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				2,166,469
Refining and Petrochemicals [member] | Foreign sales [Member] | Trading of crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				0
Refining and Petrochemicals [member] | Foreign sales [Member] | Diesel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		1,213,740		81,982
Refining and Petrochemicals [member] | Foreign sales [Member] | Other products and services [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				126,558
Transportation and Logistics [member]
Disclosure of operating segments [line items]
Total sales revenue		10,598,065	10,648,777	10,844,550
Transportation and Logistics [member] | Domestic sales [Member]
Disclosure of operating segments [line items]
Revenue From Sale Of Goods And Rendering Of Services Before Price Differential Adjustment		10,597,698	10,647,963	10,844,550
Recognition of price differential		0	0	0
Total sales revenue		10,597,698	10,647,963	10,844,550
Transportation and Logistics [member] | Domestic sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	75,793	22,472
Transportation and Logistics [member] | Domestic sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Domestic sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Domestic sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Domestic sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Domestic sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Domestic sales [Member] | Aromatics [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0
Transportation and Logistics [member] | Domestic sales [Member] | Crude Oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Domestic sales [Member] | Services [Member]
Disclosure of operating segments [line items]
Services		10,597,698	10,572,170	10,822,078
Transportation and Logistics [member] | Domestic sales [Member] | Diesel and asphalts [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Foreign sales [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		367	814	0
Transportation and Logistics [member] | Foreign sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		367	814
Transportation and Logistics [member] | Foreign sales [Member] | Cash flow hedging - Reclassification to profit or loss [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Foreign sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0
Transportation and Logistics [member] | Foreign sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Foreign sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Foreign sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Foreign sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0
Transportation and Logistics [member] | Foreign sales [Member] | Oil fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0
Transportation and Logistics [member] | Foreign sales [Member] | Crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Transportation and Logistics [member] | Foreign sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0	0
Transportation and Logistics [member] | Foreign sales [Member] | Trading of crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				0
Transportation and Logistics [member] | Foreign sales [Member] | Diesel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0		0
Transportation and Logistics [member] | Foreign sales [Member] | Other products and services [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				0
Elimination of intersegment amounts [member]
Disclosure of operating segments [line items]
Total sales revenue		(19,782,786)	(15,198,586)	(13,475,566)
Elimination of intersegment amounts [member] | Domestic sales [Member]
Disclosure of operating segments [line items]
Revenue From Sale Of Goods And Rendering Of Services Before Price Differential Adjustment		(19,782,786)	(12,669,409)	(13,143,433)
Recognition of price differential		0	0	0
Total sales revenue		(19,782,786)	(12,669,409)	(13,143,433)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		(109,903)	(510,144)	(367,757)
Elimination of intersegment amounts [member] | Domestic sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	(4,558)	(9,053)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		(724,483)	(406,750)	(352,939)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		(1,062,102)	(373,200)	(336,453)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Elimination of intersegment amounts [member] | Domestic sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	(17,157)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Aromatics [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0
Elimination of intersegment amounts [member] | Domestic sales [Member] | Crude Oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		(10,758,658)	(4,730,888)	(5,356,089)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Services [Member]
Disclosure of operating segments [line items]
Services		(7,127,640)	(6,643,869)	(6,703,985)
Elimination of intersegment amounts [member] | Domestic sales [Member] | Diesel and asphalts [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Elimination of intersegment amounts [member] | Foreign sales [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	(2,529,177)	(332,133)
Elimination of intersegment amounts [member] | Foreign sales [Member] | Other products [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	316
Elimination of intersegment amounts [member] | Foreign sales [Member] | Cash flow hedging - Reclassification to profit or loss [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Elimination of intersegment amounts [member] | Foreign sales [Member] | L.P.G. and propane [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Natural Gas [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	(291,875)	(50,550)
Elimination of intersegment amounts [member] | Foreign sales [Member] | Gasoline and turbo fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Plastic and rubber [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0	0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Med-distillates [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Oil fuel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		0	(2,237,618)	(314,497)
Elimination of intersegment amounts [member] | Foreign sales [Member] | Fuel oil [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods			$ 0	0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Trading of crude [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Diesel [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods		$ 0		0
Elimination of intersegment amounts [member] | Foreign sales [Member] | Other products and services [Member]
Disclosure of operating segments [line items]
Revenue from sale of goods				$ 32,914
[1]	Corresponds to the application of Decree 1880 of September 2014 and Resolution 180522 of 2010, which defined the procedure for price differentials (value generated by the difference between the parity price and the regulated price, which can be positive or negative). See Note 4.16 – Sales revenue recognition, for more details.

Information by segments (Det176

Information by segments (Details 2) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of operating segments [line items]
Investment property	$ 6,107,506	$ 5,837,477	$ 15,517,949
Property, plant and equipment [Member]
Disclosure of operating segments [line items]
Investment property	2,363,283	3,646,929	8,548,933
Natural and environmental resources [Member]
Disclosure of operating segments [line items]
Investment property	3,568,355	2,121,295	6,856,761
Intangibles [Member]
Disclosure of operating segments [line items]
Investment property	175,868	69,253	112,255
Exploration and Production [member]
Disclosure of operating segments [line items]
Investment property	4,649,792	3,383,533	9,386,862
Exploration and Production [member] | Property, plant and equipment [Member]
Disclosure of operating segments [line items]
Investment property	927,282	1,208,464	2,460,975
Exploration and Production [member] | Natural and environmental resources [Member]
Disclosure of operating segments [line items]
Investment property	3,568,355	2,121,295	6,856,761
Exploration and Production [member] | Intangibles [Member]
Disclosure of operating segments [line items]
Investment property	154,155	53,774	69,126
Refining and Petrochemicals [member]
Disclosure of operating segments [line items]
Investment property	611,690	1,110,124	3,608,773
Refining and Petrochemicals [member] | Property, plant and equipment [Member]
Disclosure of operating segments [line items]
Investment property	606,749	1,099,850	3,590,279
Refining and Petrochemicals [member] | Natural and environmental resources [Member]
Disclosure of operating segments [line items]
Investment property	0	0	0
Refining and Petrochemicals [member] | Intangibles [Member]
Disclosure of operating segments [line items]
Investment property	4,941	10,274	18,494
Transportation and Logistics [member]
Disclosure of operating segments [line items]
Investment property	846,024	1,343,820	2,522,314
Transportation and Logistics [member] | Property, plant and equipment [Member]
Disclosure of operating segments [line items]
Investment property	829,252	1,338,615	2,497,679
Transportation and Logistics [member] | Natural and environmental resources [Member]
Disclosure of operating segments [line items]
Investment property	0	0	0
Transportation and Logistics [member] | Intangibles [Member]
Disclosure of operating segments [line items]
Investment property	$ 16,772	$ 5,205	$ 24,635

Subsequent events (Details Text

Subsequent events (Details Textual) $ in Millions, $ in Millions	Apr. 13, 2018USD ($)	Mar. 14, 2018	Aug. 14, 2017COP ($)	Dec. 31, 2017COP ($)	Dec. 31, 2016COP ($)	Dec. 31, 2015COP ($)
Disclosure of non-adjusting events after reporting period [line items]
Prepayment of borrowings, classified as financing activities			$ 990,000	$ 9,007,340	$ 3,149,917	$ 4,903,592
Prepayment of Borrowings [Member]
Disclosure of non-adjusting events after reporting period [line items]
Prepayment of borrowings, classified as financing activities	$ 350
Notes due outstanding, percentage	4.25%
Notes due outstanding, maturity date	Sep. 18, 2018
Investments in Associates [Member] | Ecopetrol Energia SAS E.S.P. [Member] | Direct Ownership [Member]
Disclosure of non-adjusting events after reporting period [line items]
Proportion of ownership interest in subsidiary		99.00%
Investments in Associates [Member] | Ecopetrol Energia SAS E.S.P. [Member] | Indirect Ownership [Member]
Disclosure of non-adjusting events after reporting period [line items]
Proportion of ownership interest in subsidiary		1.00%

Supplemental information on 178

Supplemental information on oil and gas producing activities (Details) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exploration for and evaluation of mineral resources [Abstract]
Natural and environmental properties	$ 48,129,595	$ 47,097,475	$ 45,789,713
Wells, equipment and facilities - property, plant and equipment	30,405,565	29,931,039	21,822,897
Exploration and production projects	6,632,812	6,855,832	9,145,198
Accumulated depreciation, depletion and amortization	(51,791,897)	(49,714,944)	(39,743,147)
Net capitalized costs	$ 33,376,075	$ 34,169,402	$ 37,014,661

Supplemental information on 179

Supplemental information on oil and gas producing activities (Details 1) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exploration for and evaluation of mineral resources [Abstract]
Acquisition of Proved properties	[1]	$ 591,875	$ 0	$ 0
Acquisition of unproved properties	[2]	164,180	0	357,772
Exploration costs		1,095,588	852,097	1,012,264
Development costs		3,599,385	2,190,426	8,018,131
Total costs incurred		$ 5,451,028	$ 3,042,523	$ 9,388,167
[1]	On December 11, 2017, Ecopetrol América Inc. acquired the 11.6% interest in the K2 oil field in the Gulf of Mexico from MCX; increasing its share from 9.2% to 20.8%.
[2]	Corresponds mainly to investments made by Ecopetrol América Inc in offshore exploration projects of the Warrior and Rydberg wells. For 2015, relates to drilling for the Leon 2 exploratory project, operated by Repsol as well as acquisition of the lease sales 235 and 246 (unproven lands).

Supplemental information on 180

Supplemental information on oil and gas producing activities (Details 2) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net revenues
Sales		$ 29,823,565	$ 21,322,662	$ 26,039,708
Transfers		7,518,216	7,734,195	5,692,902
Total		37,341,781	29,056,857	31,732,610
Production cost	[1]	6,535,794	5,785,950	6,006,563
Depreciation, depletion and amortization	[2]	6,349,382	5,927,466	6,234,190
Other production costs	[3]	14,066,593	12,370,540	14,457,836
Exploration expenses	[4]	1,342,952	730,393	1,586,940
Other expenses	[5]	882,743	1,684,590	6,364,414
Total		29,177,464	26,498,939	34,649,943
Income before income tax		8,164,317	2,557,918	(2,917,333)
Income tax expenses		(3,678,955)	(1,367,357)	(371,376)
Results of operations for producing activities		$ 4,485,362	$ 1,190,561	$ (3,288,709)
[1]	Production costs are lifting costs incurred to operate and maintain productive wells and related equipment and facilities including costs such as operating labor, materials, supplies, and fuel consumed in operations and the costs of operating natural gas liquids plants. In addition, they include expenses related to the asset retirement obligations that were recognized during 2017, 2016 and 2015 of COP$380,810, COP$305,653 and COP$206,570, respectively.
[2]	In accordance with IAS 37 the expense related to asset retirement obligations that were recognized during 2017, 2016 and 2015 in depreciation, depletion and amortization, were COP$179,601, COP$188,370 and COP$294,849, respectively.
[3]	Corresponds to transportation costs and naphtha that are not part of the Group’s lifting cost.
[4]	Exploration expenses include the costs of geological and geophysical activities as well as the non-productive exploratory wells.
[5]	Corresponds to administration and marketing expenses.

Supplemental information on 181

Supplemental information on oil and gas producing activities (Details 3)		12 Months Ended
		Dec. 31, 2017gal	Dec. 31, 2016galbbl	Dec. 31, 2015gal
Reserve Quantities Proved Developed and Undeveloped Oil and Gas Reserve Quantities [Line Items]
Opening balance		1,598	1,849	2,084
Proved Reserves, Revisions of Previous Estimates	[1]	175	54	25
Proved Reserves, Improved Recovery		73	11	17
Proved Reserves, Purchases		4	0	0
Proved Reserves, Extensions, Discoveries, and Additions		43	27	24
Proved Reserves, Production		(234)	(235)	(251)
Closing balance		1,659	1,598	1,849
Proved developed reserves: Opening balance		1,329	1,470	1,618
Proved developed reserves: Closing balance		1,372	1,329	1,470
Proved undeveloped reserves: Opening balance		269	379	466
Proved undeveloped reserves: Closing balance		287	269	379
Gas [Member]
Reserve Quantities Proved Developed and Undeveloped Oil and Gas Reserve Quantities [Line Items]
Opening balance		3,218	3,479	3,529
Proved Reserves, Revisions of Previous Estimates	[1]	294	23	225
Proved Reserves, Improved Recovery		4	1	3
Proved Reserves, Purchases		2	0	0
Proved Reserves, Extensions, Discoveries, and Additions		0	25	0
Proved Reserves, Production		(264)	(264)	(278)
Closing balance		3,254	3,218	3,479
Proved developed reserves: Opening balance		3,131	3,176	3,284
Proved developed reserves: Closing balance		3,158	3,131	3,176
Proved undeveloped reserves: Opening balance		87	303	245
Proved undeveloped reserves: Closing balance		96	87	303
Oil [Member]
Reserve Quantities Proved Developed and Undeveloped Oil and Gas Reserve Quantities [Line Items]
Opening balance		1,033	1,239	1,465
Proved Reserves, Revisions of Previous Estimates	[1]	124	50	64
Proved Reserves, Improved Recovery		72	11	16
Proved Reserves, Purchases		3	0	0
Proved Reserves, Extensions, Discoveries, and Additions		44	22	24
Proved Reserves, Production		(188)	(189)	(202)
Closing balance		1,088	1,033	1,239
Proved developed reserves: Opening balance		779	913	1,042
Proved developed reserves: Closing balance		818	779	913
Proved undeveloped reserves: Opening balance		254	326	423
Proved undeveloped reserves: Closing balance		270	254	326
[1]	Represents changes in previous proved reserves, upward or downward, resulting from new information (except for an increase in proved area), usually obtained from development drilling and production history or result from changes in economic factors.

Supplemental information on 182

Supplemental information on oil and gas producing activities (Details 4) - COP ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exploration for and evaluation of mineral resources [Abstract]
Future cash inflows	$ 182,114,282	$ 140,458,230	$ 176,865,586
Future costs
Production	(70,159,534)	(60,705,779)	(76,363,169)
Development	(14,860,992)	(12,005,835)	(16,498,118)
Income taxes	(23,660,328)	(15,400,000)	(30,052,830)
Future net cash flow	73,433,428	52,346,616	53,951,469
10% discount factor	(22,216,583)	(18,221,004)	(19,117,422)
Standardized measure of discounted net cash flows	$ 51,216,845	$ 34,125,612	$ 34,834,047

Supplemental information on 183

Supplemental information on oil and gas producing activities (Details 5) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exploration for and evaluation of mineral resources [Abstract]
Net change in sales and transfer prices and in production cost (lifting) related to future production	$ 26,918,170	$ 3,603,876	$ (50,472,025)
Changes in estimated future development costs	(1,978,913)	(4,767,340)	592,529
Sales and transfer of oil and gas produced, net of production costs	(30,805,987)	(23,270,907)	(25,726,047)
Net change due to extension discoveries	284,374	154,352	(93,190)
Net change due to purchase and sales of minerals in place	211,777	(83,450)	0
Net change due to revisions in quantity estimates	9,090,882	(2,570,103)	(985,217)
Previously estimated development costs incurred during the period	3,482,570	5,042,697	10,769,369
Accretion of discount	4,416,512	5,423,781	11,321,221
Timing and other	11,934,458	6,394,404	(4,381,037)
Net change in income taxes	(6,462,611)	9,364,255	18,775,304
Aggregate change in the standardized measure of discounted future net cash flows for the year	$ 17,091,232	$ (708,435)	$ (40,199,093)

Supplemental information on 184

Supplemental information on oil and gas producing activities (Details Textual) - COP ($) $ in Millions	Dec. 11, 2017	Dec. 12, 2017	Dec. 10, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exploration For And Evaluation Of Mineral Resources [Line Items]
Natural and Environmental Properties, Including Asset Retirement Obligations				$ 598,125	$ 766,909	$ 580,575
Accretion expense related to the asset retirement obligations				380,810	305,653	206,570
Depreciation, depletion and amortization related to asset retirement obligations				$ 179,601	$ 188,370	$ 294,849
Percentage of crude oil and gas production based on value				20.10%	17.70%	17.90%
Percentage of crude oil and gas production based on volume				48.40%	46.10%	37.40%
K2 oil field [Member] | MCX Exploration USA LLC [Member]
Exploration For And Evaluation Of Mineral Resources [Line Items]
Percentage of interest in product acquired	11.60%
Proportion of ownership interest in associate		20.80%	9.20%

Exhibit 1. Consolidated subs185

Exhibit 1. Consolidated subsidiaries, associates and joint ventures (Details) - COP ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Equity		$ 48,215,699	$ 43,560,501	$ 43,100,963	$ 48,534,228
Profit (loss) of the year		7,969,394	3,247,480	$ (6,288,979)
Total assets		117,847,412	118,958,977
Total liabilities		$ 69,631,713	$ 75,398,476
Ecopetrol Global Energy SLU [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Investment vehicle
Country/Domicile		Spain
Geographic area of operations		Spain
Equity		$ 3,056,580
Profit (loss) of the year		102,120
Total assets		3,056,719
Total liabilities		$ 139
Ecopetrol Oleo e Gas do Brasil Ltda [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Real
Ownership interest Ecopetrol		100.00%
Activity		Exploration and exploitation of hydrocarbons
Country/Domicile		Brazil
Geographic area of operations		Brazil
Equity		$ 36,385
Profit (loss) of the year		(54,591)
Total assets		50,933
Total liabilities		$ 14,548
Ecopetrol del Peru S.A. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Exploration and exploitation of hydrocarbons
Country/Domicile		Peru
Geographic area of operations		Peru
Equity		$ 48,969
Profit (loss) of the year		(2,271)
Total assets		51,792
Total liabilities		$ 2,823
Ecopetrol America Inc [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Exploration and exploitation of hydrocarbons
Country/Domicile		United States
Geographic area of operations		United States
Equity		$ 2,964,718
Profit (loss) of the year		163,529
Total assets		3,368,997
Total liabilities		$ 404,279
Black Gold Re Ltd. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Reinsurer of Ecopetrol and its subordinates
Country/Domicile		Bermuda
Geographic area of operations		Bermuda
Equity		$ 607,199
Profit (loss) of the year		28,135
Total assets		729,125
Total liabilities		$ 121,926
Ecopetrol Germany Gmbh [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Exploration and exploitation of hydrocarbons
Country/Domicile		Germany
Geographic area of operations		Angola
Equity		$ 2,345
Profit (loss) of the year		(118)
Total assets		2,773
Total liabilities		$ 428
Hocol petroleum limited [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Investment vehicle
Country/Domicile		Bermuda
Geographic area of operations		Bermuda
Equity		$ 2,223,406
Profit (loss) of the year		(135,261)
Total assets		2,223,464
Total liabilities		$ 58
Hocol S.A [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Exploration, exploitation and production of hydrocarbons
Country/Domicile		Cayman Islands
Geographic area of operations		Colombia
Equity		$ 1,529,052
Profit (loss) of the year		(60,103)
Total assets		2,747,950
Total liabilities		$ 1,218,898
Refineria de Cartagena S.A [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	[1]	U.S. Dollar
Ownership interest Ecopetrol	[1]	100.00%
Activity	[1]	Refining, commercialization and distribution of hydrocarbons
Country/Domicile	[1]	Colombia
Geographic area of operations	[1]	Colombia
Equity	[1]	$ 17,008,913
Profit (loss) of the year	[1]	39,195
Total assets	[1]	25,805,231
Total liabilities	[1]	$ 8,796,318
Propileno del Caribe Propilco S.A. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Production and commercialization of polypropylene resin
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 1,414,530
Profit (loss) of the year		225,175
Total assets		1,927,883
Total liabilities		$ 513,353
COMAI - Compounding and Masterbatching Industry [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		100.00%
Activity		Manufacture of polypropylene compounds and masterbatches
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 141,580
Profit (loss) of the year		114,241
Total assets		202,879
Total liabilities		$ 61,299
Bioenergy S.A. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		99.04%
Activity		Production of biofuels
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 335,858
Profit (loss) of the year		(237,846)
Total assets		433,582
Total liabilities		$ 97,724
Bioenergy Zona Franca SAS [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		99.04%
Activity		Production of biofuels
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 246,866
Profit (loss) of the year		(197,949)
Total assets		702,627
Total liabilities		$ 455,761
Amandine Holdings Corp. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		99.04%
Activity		On sale
Country/Domicile		Panama
Geographic area of operations		Panama
Equity		$ 6,657
Profit (loss) of the year		0
Total assets		6,657
Total liabilities		$ 0
The Arces Group Corp. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		99.04%
Activity		On sale
Country/Domicile		Panama
Geographic area of operations		Panama
Equity		$ 5,100
Profit (loss) of the year		0
Total assets		5,100
Total liabilities		$ 0
Cenit SAS [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		100.00%
Activity		Storage and transportation by hydrocarbon pipelines
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 13,801,943
Profit (loss) of the year		3,014,820
Total assets		15,243,690
Total liabilities		$ 1,441,747
Oleoducto Central SA - Ocensa [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		72.65%
Activity		Transportation by crude oil pipelines
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 3,014,831
Profit (loss) of the year		1,667,219
Total assets		6,205,436
Total liabilities		$ 3,190,605
Oleoducto de los Llanos [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		65.00%
Activity		Transportation by crude oil pipelines
Country/Domicile		Panama
Geographic area of operations		Colombia
Equity		$ 1,106,571
Profit (loss) of the year		321,792
Total assets		1,919,509
Total liabilities		$ 812,938
Oleoducto de Colombia SA - ODC [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		73.00%
Activity		Transportation by crude oil pipelines
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 351,308
Profit (loss) of the year		202,432
Total assets		555,250
Total liabilities		$ 203,942
Bicentenario de Colombia SAS [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		55.97%
Activity		Transportation activity by crude oil pipelines
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 1,069,490
Profit (loss) of the year		385,500
Total assets		3,205,369
Total liabilities		$ 2,135,879
Ecopetrol Capital AG [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Financing, liquidation of financing of group companies or any type of company
Country/Domicile		Switzerland
Geographic area of operations		Switzerland
Equity		$ 1,240,473
Profit (loss) of the year		145,970
Total assets		5,806,746
Total liabilities		$ 4,566,273
Ecopetrol Global Capital SLU [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Euro
Ownership interest Ecopetrol		100.00%
Activity		Investment vehicle
Country/Domicile		Spain
Geographic area of operations		Spain
Equity		$ 20
Profit (loss) of the year		(51)
Total assets		39
Total liabilities		$ 19
Esenttia Resinas del Peru [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Marketing polypropylene resins and masterbatches
Country/Domicile		Peru
Geographic area of operations		Peru
Equity		$ 3,866
Profit (loss) of the year		(84)
Total assets		15,981
Total liabilities		$ 12,115
Ecopetrol Costa Afuera SAS [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		Colombian Peso
Ownership interest Ecopetrol		100.00%
Activity		Offshore Caribbean exploration
Country/Domicile		Colombia
Geographic area of operations		Colombia
Equity		$ 15,671
Profit (loss) of the year		(69,242)
Total assets		139,192
Total liabilities		$ 123,521
ECP Hidrocarburos de Mexico SA de CV [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Offshore Caribbean exploration
Country/Domicile		Mexico
Geographic area of operations		Mexico
Equity		$ 4,100
Profit (loss) of the year		(3,653)
Total assets		5,851
Total liabilities		$ 1,751
Andean Chemicals Ltd. [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency		U.S. Dollar
Ownership interest Ecopetrol		100.00%
Activity		Investment vehicle
Country/Domicile		Bermuda
Geographic area of operations		Bermuda
Equity		$ 5,168,133
Profit (loss) of the year		(526,869)
Total assets		5,169,911
Total liabilities		$ 1,778
[1]	Information taken from the audited financial statements.

Exhibit 1. Consolidated subs186

Exhibit 1. Consolidated subsidiaries, associates and joint ventures (Details 1) - COP ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Equity	$ 48,215,699	$ 43,560,501	$ 43,100,963	$ 48,534,228
Profit (loss) of the year	7,969,394	3,247,480	(6,288,979)
Total assets	117,847,412	118,958,977
Total liabilities	$ 69,631,713	$ 75,398,476
Equion Energy Limited [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Ownership interest Ecopetrol, joint venture	51.00%	51.00%
Equity	$ 1,336,811	$ 1,530,858
Profit (loss) of the year	253,708	279,515	14,820
Total assets	1,865,776	2,118,588
Total liabilities	$ 528,965	$ 587,730
Equion Energy Limited [Member] | Joint ventures [member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	U.S. Dollar
Ownership interest Ecopetrol, joint venture	51.00%
Activity, joint venture	Exploration, exploitation and production of hydrocarbons
Country/Domicile, joint venture	United Kingdom
Geographic area of operations, joint venture	Colombia
Equity	$ 1,336,811
Profit (loss) of the year	253,709
Total assets	1,865,776
Total liabilities	$ 528,965
Ecodiesel colombia S.A [Member] | Joint ventures [member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	Colombian Peso
Ownership interest Ecopetrol, joint venture	50.00%
Activity, joint venture	Production, marketing and distribution of biofuels and oleo chemicals
Country/Domicile, joint venture	Colombia
Geographic area of operations, joint venture	Colombia
Equity	$ 76,766
Profit (loss) of the year	13,236
Total assets	128,420
Total liabilities	$ 51,654
Offshore international group [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Ownership interest Ecopetrol, joint venture	50.00%	50.00%
Equity	$ 1,007,754	$ 1,192,980
Profit (loss) of the year	(178,280)	(248,037)	$ (237,564)
Total assets	1,858,013	2,011,647
Total liabilities	$ 850,259	$ 818,667
Offshore international group [Member] | Joint ventures [member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	U.S. Dollar
Ownership interest Ecopetrol, joint venture	50.00%
Activity, joint venture	Exploration, development, production and processing of hydrocarbons
Country/Domicile, joint venture	United States
Geographic area of operations, joint venture	Peru
Equity	$ 1,007,754
Profit (loss) of the year	(178,280)
Total assets	1,858,013
Total liabilities	$ 850,259
Invercolsa S.A [Member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Ownership interest Ecopetrol, associate	43.35%
Invercolsa S.A [Member] | Associates [member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	Colombian Peso
Ownership interest Ecopetrol, associate	43.00%
Activity, associate	Holding with investments in transport and distribution of natural gas and LPG
Country/Domicile, associate	Colombia
Geographic area of operations, associate	Colombia
Equity	$ 516,640
Profit (loss) of the year	84,628
Total assets	560,368
Total liabilities	$ 43,728
Serviport S.A [Member] | Associates [member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	Colombian Peso
Ownership interest Ecopetrol, associate	49.00%
Activity, associate	Services for the support of loading and unloading of oil ships, supply of equipment, technical inspections and load measurements
Country/Domicile, associate	Colombia
Geographic area of operations, associate	Colombia
Equity	$ 20,212
Profit (loss) of the year	2,031
Total assets	70,966
Total liabilities	$ 50,754
Sociedad Portuaria Olefinas y Derivados S.A. [Member] | Associates [member]
Disclosure of consolidated subsidiaries, associates and joint ventures [Line Items]
Functional currency	Colombian Peso
Ownership interest Ecopetrol, associate	50.00%
Activity, associate	Construction, use, maintenance and administration of port facilities, ports, private docks.
Country/Domicile, associate	Colombia
Geographic area of operations, associate	Colombia
Equity	$ 2,847
Profit (loss) of the year	178
Total assets	3,189
Total liabilities	$ 342