Oasis Midstream Partners (OMP) 10-K 27 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 19, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-38212
Entity Registrant Name	Oasis Midstream Partners LP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-1208855
Entity Address, Address Line One	1001 Fannin Street
Entity Address, Address Line Two	Suite 1500
Entity Address, City or Town	Houston
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77002
City Area Code	281
Local Phone Number	404-9500
Title of 12(b) Security	Common Units Representing Limited Partner Interests
Trading Symbol	OMP
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Public Float			$ 232,535,400
Entity Common Stock, Shares Outstanding		33,811,366
Documents Incorporated by Reference	None
Entity Central Index Key	0001652133
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Common Units
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		20,061,366
Subordinated Units
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		13,750,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 4,168	$ 6,649	[1]
Accounts receivable	5,969	2,481	[1]
Accounts receivable – Oasis Petroleum	77,571	81,022	[1]
Prepaid expenses	1,923	1,418	[1]
Other current assets	138	22	[1]
Total current assets	89,769	91,592	[1]
Property, plant and equipment	1,155,503	942,578	[1]
Less: accumulated depreciation and amortization	(98,982)	(62,730)	[1]
Total property, plant and equipment, net	1,056,521	879,848	[1]
Operating lease assets	5,207
Other assets	3,172	2,452	[1]
Total assets	1,154,669	973,892	[1]
Current liabilities
Accounts payable	2,478	2,180	[1]
Accounts payable – Oasis Petroleum	27,139	33,014	[1]
Accrued liabilities	50,210	60,954	[1]
Accrued interest payable	508	442	[1]
Operating lease liabilities	3,005
Other current liabilities	594	0	[1]
Total current liabilities	83,934	96,590	[1]
Long-term debt	458,500	318,000	[1]
Asset retirement obligations	1,747	1,630	[1]
Operating lease liabilities	2,216
Other liabilities	3,644	0	[1]
Total liabilities	550,041	416,220	[1]
Commitments and contingencies			[1]
Equity
General Partner	1,026	112	[1]
Total partners’ equity	292,370	238,630	[1]
Non-controlling interests	312,258	312,815	[1]
Delaware Predecessor	0	6,227	[1]
Total equity	604,628	557,672	[1]
Total liabilities and equity	1,154,669	973,892	[1]
Common Units
Equity
Limited partners	$ 225,339	$ 192,581	[1]
Units issued (shares)	20,029,026	20,045,196
Units outstanding (shares)	20,029,026	20,045,196
Subordinated Units
Equity
Limited partners	$ 66,005	$ 45,937	[1]
Units issued (shares)	13,750,000	13,750,000
Units outstanding (shares)	13,750,000	13,750,000
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Consolidated Balance Sheets Par

Consolidated Balance Sheets Parenthetical - shares	Dec. 31, 2019	Dec. 31, 2018
Common Units
Units issued (shares)	20,029,026	20,045,196
Units outstanding (shares)	20,029,026	20,045,196
Subordinated Units
Units issued (shares)	13,750,000	13,750,000
Units outstanding (shares)	13,750,000	13,750,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Revenues
Total revenues	$ 410,191	$ 273,770	[1]	$ 182,216
Operating expenses
Operating and maintenance	74,226	63,685	[1]	39,441
Depreciation and amortization	36,358	28,409	[1]	15,730
General and administrative	31,009	23,897	[1]	18,597
Total operating expenses	177,419	123,424	[1]	79,853
Operating income	232,772	150,346	[1]	102,363
Interest expense, net of capitalized interest	(17,538)	(2,580)	[1]	(6,965)
Other income (expense)	(3)	(14)	[1]	7
Total other expense, net	(17,541)	(2,594)	[1]	(6,958)
Income before income taxes	215,231	147,752	[1]	95,405
Income tax expense	0	0	[1]	(22,858)
Net income	215,231	147,752	[2]	72,547
Less: Net income prior to initial public offering	0	0	[1]	37,577
Less: Net income attributable to Delaware Predecessor	4,464	1,343	[1]	0
Less: Net income attributable to non-controlling interests	93,111	96,354	[1]	23,332
Net income attributable to OMP LP	$ 117,656	$ 50,055	[1]	$ 11,638
Common Units
Earnings per limited partner unit
Common units - basic and diluted (in usd per share)	$ 3.41	$ 1.82	[1]	$ 0.43
Weighted average number of limited partners units outstanding (Note 14)
Common units- Basic (shares)	20,024	14,504	[1]	13,566
Common units - Diluted (shares)	20,032	14,519	[1]	13,568
Midstream service
Revenues
Total revenues	$ 323,603	$ 252,967		$ 170,178
Midstream service | Oasis Petroleum
Revenues
Total revenues	317,072	250,363	[1]	168,205
Midstream service | Third parties
Revenues
Total revenues	6,531	2,604	[1]	1,973
Product sales
Revenues
Total revenues	86,588	20,803		12,038
Operating expenses
Costs of product sales	35,826	7,433	[1]	6,085
Product sales | Oasis Petroleum
Revenues
Total revenues	86,543	17,476	[1]	11,644
Product sales | Third parties
Revenues
Total revenues	45	3,327	[1]	394
General Partner
Operating expenses
Net income	2,472	112
Net income attributable to OMP LP	2,472	112	[1]	0
Limited Partners
Operating expenses
Net income attributable to OMP LP	115,184	49,943	[1]	11,638
Limited Partners | Common Units
Operating expenses
Net income	68,291	25,913
Net income attributable to OMP LP	$ 68,312	$ 26,416		$ 5,819
Weighted average number of limited partners units outstanding (Note 14)
Common units- Basic (shares)	20,024	14,504		13,566
Common units - Diluted (shares)	20,032	14,519		13,568
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Consolidated Statement of Chang

Consolidated Statement of Changes in Equity - USD ($) $ in Thousands		Total		Noncontrolling Interests	Limited PartnersCommon Units	Limited PartnersSubordinated Units	General Partner
Beginning predecessor balance at Dec. 31, 2016		$ 331,675
Increase (Decrease) in Partners' Capital [Roll Forward]
Capital contributions		65,145
Equity-based compensation		999
Net income		37,577
Ending predecessor balance at Sep. 25, 2017		435,337
Ending balance at Sep. 25, 2017				$ 0	$ 0	$ 0	$ 0
Beginning predecessor balance at Dec. 31, 2016		331,675
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income		0
Net income		72,547
Ending predecessor balance at Dec. 31, 2017		0
Ending balance at Dec. 31, 2017		560,020		313,446	167,401	79,173	0
Beginning predecessor balance at Sep. 25, 2017		435,337
Beginning balance at Sep. 25, 2017				0	0	0	0
Increase (Decrease) in Partners' Capital [Roll Forward]
Elimination of current and deferred tax liabilities		104,005
Net assets excluded from initial public offering		(50,726)
Allocation of net investment to unitholders		(488,616)		290,835	53,704	144,077
Net proceeds from initial public offering		134,185			134,185
Distributions to unitholders		(132,083)		(35,000)	(26,360)	(70,723)
Contributions from non-controlling interests		34,279		34,279
Equity-based compensation		53			53
Net income		34,970		23,332	5,819	5,819
Ending predecessor balance at Dec. 31, 2017		0
Ending balance at Dec. 31, 2017		560,020		313,446	167,401	79,173	0
Increase (Decrease) in Partners' Capital [Roll Forward]
Capital contributions		4,884
Distributions to unitholders		(44,918)			22,478	22,440
Contributions from non-controlling interests		147,453		147,453
Distributions to non-controlling interests		(128,903)		(128,903)
2018 Dropdown Acquisition				(115,535)	45,935	69,600
Distribution to Oasis Petroleum for contributed assets		(172,429)			(68,556)	(103,873)
Issuance of common units		44,503			44,503
Other		(1,046)			(493)	(553)
Equity-based compensation		356			356
Net income	[1]	1,343
Net income		147,752	[2]	96,354	25,913	24,030	112
Ending predecessor balance at Dec. 31, 2018	[3]	6,227
Ending balance at Dec. 31, 2018		557,672	[3]	312,815	192,581	45,937	112
Increase (Decrease) in Partners' Capital [Roll Forward]
Capital contributions		14,008
Elimination of current and deferred tax liabilities		104,000
Distributions to unitholders		(66,614)			(38,587)	(26,469)	(1,558)
Contributions from non-controlling interests		5,078		5,078
Distributions to non-controlling interests		(95,771)		(95,771)
2019 Delaware Acquisition		(24,699)
2019 Delaware Acquisition		(24,939)			(95)	(145)
Other		(415)		(2,975)	2,771	(211)
Equity-based compensation		378			378
Net income		4,464
Net income		215,231		93,111	68,291	46,893	2,472
Ending predecessor balance at Dec. 31, 2019		0
Ending balance at Dec. 31, 2019		$ 604,628		$ 312,258	$ 225,339	$ 66,005	$ 1,026
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[3]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 215,231		$ 147,752	[1]	$ 72,547
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	36,358		28,409	[2]	15,730
Deferred income taxes	0		0	[1]	5,240
Equity-based compensation expenses	378		356	[1]	1,052
Deferred financing costs amortization and other	946		(519)	[1]	127
Working capital and other changes:
Change in accounts receivable	(37)		3,194	[1]	(56,473)
Change in prepaid expenses	(505)		(640)	[1]	(304)
Change in accounts payable and accrued liabilities	(3,311)		27,814	[1]	24,400
Change in current income taxes payable	0		0	[1]	17,618
Change in other assets and liabilities, net	3,479		(22)	[1]	(94)
Net cash provided by operating activities	252,539		206,344	[1]	79,843
Cash flows from investing activities:
Capital expenditures	(225,832)		(283,026)	[1]	(181,424)
Acquisitions	(24,939)		0	[1]	(74,520)
Net cash used in investing activities	(250,771)		(283,026)	[1]	(255,944)
Cash flows from financing activities:
Capital contributions from parent prior to initial public offering	0		0	[1]	65,145
Capital contributions from non-controlling interests	5,078		140,277	[1]	33,875
Capital contributions from Delaware Predecessor, net	14,008		4,884	[1]	0
Proceeds from initial public offering, net of offering costs	0		0	[1]	134,185
Proceeds from sale of common units, net of offering costs	0		44,503	[1]	0
Distribution to Oasis Petroleum subsequent to initial public offering	0		0	[1]	(132,083)
Distributions to non-controlling interests	(95,771)		(128,903)	[1]	0
Distribution to Oasis Petroleum for contributed assets	0		(172,429)	[1]	0
Distributions to unitholders	(66,615)		(44,918)	[1]	0
Deferred financing costs	(973)		(966)	[1]	(2,138)
Proceeds from revolving credit facility	153,000		275,000	[1]	78,000
Principal payments on revolving credit facility	(12,500)		(35,000)	[1]	0
Other	(476)		0	[1]	0
Net cash provided by (used in) financing activities	(4,249)		82,448	[1]	176,984
Increase (decrease) in cash and cash equivalents	(2,481)		5,766	[1]	883
Beginning of period	6,649	[1]	883	[1]	0
End of period	4,168		6,649	[1]	883	[1]
Supplemental cash flow information:
Cash paid for interest, net of capitalized interest	16,592		2,054	[1]	0
Supplemental non-cash transactions:
Change in accrued capital expenditures	(12,945)		(1,794)	[1]	63,199
Change in asset retirement obligations	117		314	[1]	198
Installment notes from acquisition	0		0	[1]	4,875
Reimbursement of capital expenditures from Oasis Petroleum	0		7,176	[1]	0
Non-cash elimination of current and deferred tax liabilities	$ 0		$ 0	[1]	$ 104,005
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Organization and Nature of Oper

Organization and Nature of Operations	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Nature of Operations	Organization and Nature of Operations Organization. Oasis Midstream Partners LP (the “Partnership”) is a growth-oriented, fee-based master limited partnership formed by its sponsor, Oasis Petroleum Inc. (together with its subsidiaries, “Oasis Petroleum”) to own, develop, operate and acquire a diversified portfolio of midstream assets in North America that are integral to the crude oil and natural gas operations of Oasis Petroleum and are strategically positioned to capture volumes from other producers. The Partnership conducts its business through its ownership of the following development companies: Bighorn DevCo LLC (“Bighorn DevCo”), Bobcat DevCo LLC (“Bobcat DevCo”), Beartooth DevCo LLC (“Beartooth DevCo”) and Panther DevCo LLC (“Panther DevCo” and collectively with Bighorn DevCo, Bobcat DevCo and Beartooth DevCo, the “DevCos”), two of which are jointly-owned with Oasis Petroleum. Initial public offering. The Partnership completed its initial public offering in 2017. In connection with the Partnership’s initial public offering, Oasis Petroleum contributed to the Partnership a 100% ownership interest in Bighorn DevCo, a 10% ownership interest in Bobcat DevCo and a 40% ownership interest in Beartooth DevCo. 2018 Dropdown Acquisition. On November 19, 2018, the Partnership acquired an additional 15% ownership interest in Bobcat DevCo and an additional 30% ownership interest in Beartooth DevCo. See Note 4 — Acquisitions. 2019 Capital Expenditures Arrangement. On February 22, 2019, the Partnership entered into the 2019 Capital Expenditures Arrangement (defined below) pursuant to which the Partnership agreed to pay up to $80.0 million of expansion capital expenditures associated with Oasis Petroleum’s retained interest in Bobcat DevCo, in exchange for increasing ownership interest in Bobcat DevCo. During the year ended December 31, 2019, the Partnership made capital contributions to Bobcat DevCo pursuant to the 2019 Capital Expenditures Arrangement of $73.0 million. As a result, the Partnership’s ownership interest in Bobcat DevCo increased from 25% as of December 31, 2018 to 35.3% as of December 31, 2019. The 2019 Capital Expenditures Arrangement ended on December 31, 2019. See Note 5 — Transactions with Affiliates. 2019 Delaware Acquisition. On November 1, 2019, the Partnership entered into an agreement with Oasis Petroleum, pursuant to which Oasis Petroleum agreed to assign to Panther DevCo, a wholly-owned subsidiary of the Partnership, certain crude oil gathering and produced and flowback water gathering and disposal assets in the Delaware Basin (the “2019 Delaware Acquisition”). See Note 4 — Acquisitions. As of December 31, 2019, the Partnership’s assets and ownership interests in the DevCos were as follows: DevCos Areas Served Service Lines OMP Ownership Bighorn DevCo Wild Basin – Natural gas processing – Crude oil stabilization – Crude oil blending – Crude oil and NGL storage – Crude oil transportation 100% Bobcat DevCo Wild Basin – Natural gas gathering – Natural gas compression – Gas lift – Crude oil gathering – Produced and flowback water gathering – Produced and flowback water disposal 35.3% Beartooth DevCo Alger – Produced and flowback water gathering – Produced and flowback water disposal – Freshwater supply and distribution 70% Panther DevCo Delaware Basin – Crude oil gathering – Produced and flowback water gathering – Produced and flowback water disposal 100%

Summary of Significant Accounti

Summary of Significant Accounting Policies and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies and Basis of Presentation	Summary of Significant Accounting Policies and Basis of Presentation Basis of Presentation The accompanying consolidated financial statements of the Partnership include the accounts of Oasis Midstream Partners LP and its subsidiaries. All intercompany transactions have been eliminated in consolidation. These statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The 2019 Delaware Acquisition was accounted for as a transfer of net assets between entities under common control (see Note 4 — Acquisitions). As a result, the Partnership recorded the net assets acquired at historic carrying value and recast its financial statements to include such net assets from the date of common control. The Partnership recast its consolidated financial statements as of and for the year ended December 31, 2018, and prior to the effective date of November 1, 2019 for the year ended December 31, 2019. The consolidated financial statements for the year ended December 31, 2017 were not recast, since Oasis Petroleum first entered the Delaware Basin in 2018 following its acquisition of certain assets from Forge Energy, LLC. For those periods requiring recast, the consolidated financial statements for periods prior to the effective date were prepared from Oasis Petroleum’s historical cost-basis accounts and may not necessarily be indicative of the actual results had the Partnership owned the assets during the reported period. See Note 4 — Acquisitions. Delaware Predecessor. Prior to the 2019 Delaware Acquisition, Oasis Petroleum’s midstream services in the Delaware Basin were performed by OMS (the “Delaware Predecessor”). The consolidated financial statements include the results of the Delaware Predecessor for the year ended December 31, 2018 and prior to the effective date of the 2019 Delaware Acquisition for the year ended December 31, 2019. The Delaware Predecessor financial statements have been prepared from the separate records maintained by Oasis Petroleum and may not necessarily be indicative of the actual results of operations that might have occurred if the Delaware Predecessor assets had been operated by the Partnership during the periods reported. Predecessor. Prior to the initial public offering, Oasis Petroleum’s midstream services were performed by Oasis Midstream Services LLC (“OMS”), a wholly-owned subsidiary of Oasis Petroleum, which constitutes the predecessor to the Partnership for accounting purposes (the “Predecessor”). The consolidated financial statements include the results of the Predecessor for the periods presented prior to the initial public offering on September 25, 2017. Certain midstream infrastructure assets, liabilities, revenues and expenses included in the Predecessor’s historical financial statements have been excluded from the DevCos upon formation. These excluded assets are not included in the consolidated financial statements for the periods presented subsequent to the initial public offering on September 25, 2017. Substantially all of the services of the Predecessor were provided to Oasis Petroleum North America LLC (“OPNA”), a wholly-owned subsidiary of Oasis Petroleum that conducts Oasis Petroleum’s crude oil and natural gas exploration and production activities. The Predecessor financial statements have been prepared from the separate records maintained by Oasis Petroleum and may not necessarily be indicative of the actual results of operations that might have occurred if the Predecessor had been operated separately during the periods reported. Use of Estimates Preparation of the Partnership’s consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ significantly from those estimates. Management evaluates estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic and commodity price environment. Consolidation The Partnership’s consolidated financial statements include its accounts and the accounts of the DevCos, each of which is controlled by OMP GP LLC (the “General Partner”). All intercompany balances and transactions have been eliminated upon consolidation. Variable interest entity. The Partnership determined that Bobcat DevCo is a variable interest entity (“VIE”), since OMS’s equity at risk was established with non-substantive voting rights. As the Partnership has the authority to direct the activities that most significantly affect the economic performance of Bobcat DevCo, the Partnership is considered the primary beneficiary and consolidates Bobcat DevCo in its financial statements under the VIE consolidation model. The Partnership determined that Bighorn DevCo, Beartooth DevCo and Panther DevCo are not VIEs and consolidates these entities in its financial statements under the voting interest consolidation model. Non-controlling interests. The non-controlling interests represent Oasis Petroleum’s retained ownership interests in Bobcat DevCo and Beartooth DevCo of 64.7% and 30%, respectively, as of December 31, 2019. Significant Accounting Policies Cash and cash equivalents. The Partnership classifies all unrestricted cash on hand and investments with original maturity dates less than 90 days as cash equivalents. In the first quarter of 2019, the Partnership adopted Accounting Standards Update No. 2016-15, Statement of Cash Flows (“ASU 2016-15”), which is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. ASU 2016-15 was applied on a retrospective basis. The adoption of ASU 2016-15 did not result in a material impact to the Partnership’s financial position, cash flows, results of operations or financial statement disclosures. Transactions with affiliates. Transactions between Oasis Petroleum, its affiliates and the Partnership have been identified in the consolidated financial statements as transactions with affiliates. See Note 5 — Transactions with Affiliates. Property, plant and equipment. Property, plant and equipment consists primarily of pipelines, natural gas processing plants, produced and flowback water facilities and compressor stations. Property, plant and equipment is stated at the lower of historical cost less accumulated depreciation, or fair value, if impaired. The Partnership capitalizes a portion of its interest expense incurred on its outstanding debt. The amount capitalized is determined by multiplying the capitalization rate by the average amount of eligible accumulated capital expenditures and is limited to actual interest costs incurred during the period. The accumulated capital expenditures included in the capitalized interest calculation begin when the first costs are incurred and end when the asset is either placed into service or written off. The Partnership capitalized $0.9 million, $4.9 million and $1.2 million of interest costs for the years ended December 31, 2019, 2018 and 2017, respectively. These amounts are amortized over the useful life of the related assets once the assets are placed in-service. When assets are placed into service, management makes estimates with respect to useful lives and salvage values that management believes are reasonable. However, subsequent events could cause a change in estimates, thereby impacting future depreciation amounts. Uncertainties that may impact these estimates include, among others, changes in laws and regulations relating to environmental matters, including air and water quality, restoration and abandonment requirements, economic conditions and supply and demand in the area. Depreciation is computed over the asset’s estimated useful life using the straight line method based on estimated useful lives and asset salvage values. The weighted average life of each of the Partnership’s pipelines, natural gas processing plants, produced and flowback water facilities, compressor stations, and other long-lived assets is 30 years. When properties are retired or otherwise disposed of, the related cost and accumulated depreciation are removed from the respective accounts and any profit or loss on disposition is recognized as gain or loss. Impairment of long-lived assets. The Partnership evaluates the ability to recover the carrying amount of long-lived assets and determine whether such long-lived assets have been impaired. Impairment exists when the carrying amount of an asset exceeds estimates of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. An impairment analysis requires management to apply judgment in identifying impairment indicators and estimating future cash flows. When alternative courses of action to recover the carrying amount of a long-lived asset are under consideration, estimates of future undiscounted cash flows take into account possible outcomes and probabilities of their occurrence. If the carrying amount of the long-lived asset is not recoverable based on the estimated future undiscounted cash flows, the impairment loss is measured as the excess of the asset’s carrying amount over its estimated fair value, such that the asset’s carrying amount is adjusted to its estimated fair value with an offsetting charge to impairment expense. Fair value represents the estimated price between market participants to sell an asset in the principal or most advantageous market for the asset, based on assumptions a market participant would make. When warranted, management assesses the fair value of long-lived assets using commonly accepted techniques and may use more than one source in making such assessments. The factors used to determine fair value are subject to management’s judgment and expertise and include, but are not limited to, recent third-party comparable sales, internally developed discounted cash flow analysis and analysis from outside advisors. Significant changes, such as changes in contract rates or terms, the condition of an asset or management’s intent to utilize the asset, generally require management to reassess the cash flows related to long-lived assets. A reduction of the carrying value of fixed assets would represent a Level 3 fair value measurement. If actual results are not consistent with assumptions and estimates, or assumptions and estimates change due to new information, the Partnership may be exposed to additional impairment charges. Ultimately, a prolonged period of lower commodity prices may adversely affect the estimate of future operating results through lower throughput volumes on the Partnership’s assets, which could result in future impairment charges due to the potential impact on operations and cash flows. Asset retirement obligations (“ARO”). The Partnership records the fair value of a liability for a legal obligation to retire an asset in the period in which the liability is incurred, with the corresponding cost capitalized by increasing the carrying amount of the related long-lived asset. For produced and flowback water disposal wells, this is the period in which the well is drilled or acquired. The ARO represents the estimated amount the Partnership will incur to plug, abandon and remediate the produced and flowback water properties at the end of their useful lives, in accordance with applicable state laws. The liability is accreted to its present value each period and the capitalized costs are depreciated using the straight-line method. The accretion expense is recorded as a component of depreciation and amortization in the Consolidated Statements of Operations. Some assets, including certain pipelines and the Partnership’s natural gas processing plants, have contractual or regulatory obligations to perform remediation and, in some instances, dismantlement and removal activities when the assets are abandoned. The Partnership is not able to reasonably estimate the fair value of the ARO for these assets because the settlement dates are indeterminable given the expected continued use of the assets with proper maintenance. The Partnership will record an ARO for these assets in the periods in which the settlement dates become reasonably determinable. The Partnership determines the ARO, which represents a non-financial liability which is measured at fair value on a non-recurring basis, by calculating the present value of estimated cash flows related to the liability. Estimating the future ARO requires management to make estimates and judgments regarding timing and existence of a liability, as well as what constitutes adequate restoration. Inherent in the fair value calculation are numerous assumptions and judgments including the ultimate costs, inflation factors, credit adjusted discount rates, timing of settlement and changes in the legal, regulatory, environmental and political environments. These assumptions represent Level 3 inputs. To the extent future revisions to these assumptions impact the fair value of the existing ARO liability, a corresponding adjustment is made to the related asset. Deferred financing costs. The Partnership capitalizes directly attributable costs incurred in connection with obtaining debt financing. These costs are amortized over the term of the related financing using the straight-line method, which approximates the interest method. The amortization expense is recorded as a component of interest expense in the Partnership’s Consolidated Statements of Operations. The deferred financing costs related to the Partnership’s revolving credit facility are included in other assets on the Consolidated Balance Sheets. Equity-based compensation. The Partnership has granted phantom unit awards and restricted unit awards under the Oasis Midstream Partners LP 2017 Long Term Incentive Plan (“LTIP”). The Partnership accounts for phantom unit awards as liability-classified awards in accordance with GAAP, since the Partnership intends to settle these awards in cash. The Partnership will be reimbursed by Oasis Petroleum for the cash settlement amount of these awards. The Partnership accounts for restricted units granted to certain independent directors of the General Partner as equity-classified awards in accordance with GAAP, as the Partnership intends to settle these awards in common units. Forfeitures associated with awards granted under the LTIP are accounted for when they occur. In the first quarter of 2019, the Partnership adopted Accounting Standards Update No. 2017-09, Scope of Modification Accounting (“ASU 2017-09”), which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting. ASU 2017-09 was adopted on a prospective basis. The adoption of ASU 2017-09 did not result in a material impact to the Partnership’s financial position, cash flows, results of operations or financial statement disclosures. Income taxes. The Partnership is not a taxable entity for United States federal income tax purposes or for the majority of states that impose an income tax. Generally, each partner is separately taxed on its share of taxable income. During the fourth quarter of 2019, the Partnership commenced operations in the Delaware Basin, and as a result, is subject to the Texas margin tax, which is considered an income tax under GAAP. For periods prior to the initial public offering, the consolidated financial statements include a provision for income tax expense. Deferred federal and state income taxes were provided on temporary differences between the financial statement carrying amounts of recognized assets and liabilities and their respective tax bases as if the Partnership filed tax returns as a stand-alone entity. Revenue recognition. In the first quarter of 2018, the Partnership adopted Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers and a series of related accounting standards updates incorporated into GAAP as Accounting Standards Codification Topic 606 (“ASC 606”) using the modified retrospective method. The adoption of ASC 606 did not result in a material impact to the Partnership’s financial position, cash flows or results of operations. The Partnership has also modified current processes and controls to apply the requirements of the new standard and does not believe such modifications are material to its internal controls over financial reporting. Enhanced disclosures in accordance with the requirements of ASC 606 have been provided in Note 3 —Revenue Recognition. The unit of account in ASC 606 is a performance obligation, which is a promise in a contract to transfer to a customer either a distinct good or service (or bundle of goods or services) or a series of distinct goods or services provided over a period of time. ASC 606 requires that a contract’s transaction price, which is the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to a customer, is to be allocated to each performance obligation in the contract based on relative standalone selling prices and recognized as revenue when (point in time) or as (over time) the performance obligation is satisfied. The Partnership generates revenues primarily by charging fees for (i) crude oil gathering, stabilization, blending, storage and transportation, (ii) natural gas gathering, gas lift, compression and processing, (iii) produced and flowback water gathering and disposal and (iv) freshwater supply and distribution. The Partnership categorizes revenues as service revenues or product sales in its Consolidated Statements of Operations. For revenues generated under fee-based arrangements, the Partnership records the fees attributable to such arrangements as service revenues in its Consolidated Statements of Operations. Under fee-based arrangements, the Partnership does not take ownership of the volumes it handles for its customers and receives fees for midstream services it provides. Revenues are recognized based upon the transaction price at month-end under the right to invoice practical expedient. For revenues generated under purchase arrangements, the Partnership takes ownership of the product prior to sale and is the principal in the transaction. Revenues and expenses are recognized on a gross basis under Product sales and Costs of product sales, respectively, in the Consolidated Statements of Operations. Common control transactions. The Partnership accounts for assets acquired from Oasis Petroleum and its subsidiaries as common control transactions whereby the net assets acquired are recorded at historical carrying value at the date of transfer. Consideration transferred in excess of the carrying value of the net assets acquired is recorded to equity as a deemed distribution. Common control transactions involving the transfer of a business or the transfer of net assets result in a change in reporting entity and require prior periods to be retrospectively adjusted. To the extent such transactions require prior periods to be retrospectively adjusted, historical net equity amounts prior to the transaction date are reflected in predecessor equity. Business combinations (excluding common control transactions). The Partnership accounts for business combinations under the acquisition method of accounting. An income, market or cost valuation method may be utilized to estimate the fair value of the assets acquired, liabilities assumed, and non-controlling interest, if any, in a business combination. Fair value is determined on the acquisition date. Acquisition-related costs are expensed as incurred in connection with each business combination. If the initial accounting for the business combination is incomplete by the end of the reporting period in which the acquisition occurs, an estimate will be recorded. Subsequent to the acquisition, and not later than one year from the acquisition date, the Partnership will record any material adjustments to the initial estimate based on new information obtained about facts and circumstances that existed as of the acquisition date. The Partnership makes various assumptions in estimating the fair values of assets acquired and liabilities assumed. As fair value is a market-based measurement, it is determined based on the assumptions that market participants would use. The income valuation method represents the present value of future cash flows over the life of the asset using discrete financial forecasts. Such discrete financial forecasts rely on estimates and assumptions made by management. The most significant assumptions relate to management’s estimates of throughput volumes, future operating and development costs, long-term growth rates and a market-based weighted average cost of capital. The market valuation method uses prices paid for a reasonably similar asset by other purchasers in the market, with adjustments relating to any differences between the assets. The cost valuation method is based on the replacement cost of a comparable asset at prices at the time of the acquisition reduced for depreciation of the asset. Any excess of the acquisition price over the estimated fair value of net assets acquired is recorded as goodwill. Any excess of the estimated fair value of net assets acquired over the acquisition price is recorded in current earnings as a gain on bargain purchase. In the first quarter of 2019, the Partnership adopted Accounting Standards Update No. 2017-01, Clarifying the Definition of a Business (“ASU 2017-01”), which provides guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU 2017-01 was adopted on a prospective basis. The adoption of ASU 2017-01 did not result in a material impact to the Partnership’s financial position, cash flows, results of operations or financial statement disclosures. Leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016-02, Leases (“ASU 2016-02”), which established a right-of-use (“ROU”) model that requires a lessee to recognize an operating lease asset and lease liability on the balance sheet, with the exception of short-term leases. Accounting Standards Codification 842, Leases (“ASC 842”), was subsequently amended by ASU No. 2018-01, Land easement practical expedient for transition to Topic 842 (“ASU 2018-01”); ASU No. 2018-10, Codification Improvements to Topic 842; and ASU No. 2018-11, Targeted Improvements . The new standard is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The effective date and transition requirements for the amendments are the same as the effective date for ASU 2016-02. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. An entity may choose to use either (i) its effective date or (ii) the beginning of the earliest comparative period presented in the financial statements as its date of initial application. The Partnership adopted the new standard as of January 1, 2019, using the required modified retrospective approach and elected the option to recognize a cumulative effect adjustment of initially applying the guidance to the opening balance of retained earnings in the period of adoption. Prior period amounts were not adjusted. The Partnership elected the package of practical expedients under the transition guidance within the new standard, including the practical expedient to not reassess under the new standard any prior conclusions about lease identification, lease classification and initial direct costs; the use-of hindsight practical expedient; the practical expedient to not reassess the prior accounting treatment for existing or expired land easements; and the practical expedient pertaining to combining lease and non-lease components for all asset classes. In addition, the Partnership elected not to apply the recognition requirements of ASC 842 to short-term leases, and as such, recognition of lease payments for short-term leases are recognized in net income on a straight line basis. See Note 9 — Leases for the adoption impact and disclosures required by ASC 842. Concentrations of Market and Credit Risk The Partnership has limited direct exposure to risks associated with fluctuating commodity prices due to the nature of its business and its long-term, fixed-fee contractual arrangements with customers. However, to the extent that the future contractual arrangements with customers, including Oasis Petroleum or third parties, do not provide for fixed-fee structures, the Partnership may become subject to commodity price risk. Additionally, as substantially all of the Partnership’s revenues are derived from Oasis Petroleum, the Partnership is indirectly subject to risks associated with fluctuating commodity prices to the extent that lower commodity prices adversely affect Oasis Petroleum’s production, drilling schedule, financial condition, leverage, market reputation, liquidity, results of operations or cash flows. Recent Accounting Pronouncements Fair Value Measurement. In August 2018, the FASB issued Accounting Standards Update No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which improves the effectiveness of the disclosure requirements for fair value measurements. The changes affect all companies that are required to include fair value measurement disclosures. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those years. An entity is permitted to early adopt the removed or modified disclosures upon the issuance of ASU 2018-13 and may delay adoption of the additional disclosures until their effective date. The Partnership does not expect the adoption of this guidance to have an impact on its financial position, cash flows or results of operations, but it may result in changes to disclosures. Financial Instruments - Credit Losses. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information, including forecasts, to develop credit loss estimates. ASU 2016-13 requires entities to use the new methodology to measure impairment of financial instruments, including accounts receivable, and may result in earlier recognition of credit losses than under current GAAP. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019. Although the Partnership continues to evaluate ASU 2016-13, based on our current credit portfolio the Partnership does not expect the adoption of this standard to have a material impact on its financial position, cash flows or results of operations, but it may result in changes to disclosures.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition The Partnership categorizes revenues as service revenues or product sales under the following types of arrangements: Fee-based arrangements. Revenues generated under fee-based arrangements are reported as service revenues on the Consolidated Statements of Operations. Under fee-based arrangements, the Partnership receives a fee for midstream services provided to its customers, and revenues are recognized using the output method for measuring the satisfaction of performance obligations. Revenues earned under fee-based arrangements are generally directly related to the volume of crude oil, natural gas and produced and flowback water that flows through the Partnership’s systems, and the Partnership does not take ownership to the volumes it handles for its customers. Payments under fee-based arrangements are generally due 30 days after receipt of invoice. The Partnership generates revenues under fee-based arrangements as follows: • Crude oil and natural gas. The Partnership is party to certain contracts with customers for crude oil gathering, stabilization, blending, storage and transportation, as well as natural gas gathering, compression, processing and gas lift services. Under these customer contracts, the Partnership provides daily integrated midstream services on a stand ready basis over a period of time, which represents a single performance obligation since the customer simultaneously receives and consumes the benefits of these services on a daily basis. Satisfaction of the performance obligation is measured as each day of service is completed, which directly corresponds with its right to consideration from the customer. Revenues associated with these contracts are recognized based upon the transaction price at month-end under the right to invoice practical expedient. • Produced and flowback water. The Partnership is party to certain contracts with customers for produced and flowback water gathering and disposal services. Under these customer contracts, the Partnership provides daily integrated midstream services on a stand ready basis over a period of time, which represents a single performance obligation since the customer simultaneously receives and consumes the benefits of these services on a daily basis. Satisfaction of the performance obligation is measured as each day of service is completed, which directly corresponds with its right to consideration from the customer. Revenues associated with these contracts are recognized based upon the transaction price at month-end under the right to invoice practical expedient. Purchase arrangements. Revenues generated under purchase arrangements are reported as product sales on the Consolidated Statements of Operations. Under purchase arrangements, revenues and expenses are recognized on a gross basis since the Partnership takes control of the product prior to sale and is the principal in the transaction. The Partnership recognizes revenues using the output method for measuring the satisfaction of performance obligations based upon the volume of natural gas, natural gas liquids (“NGLs”) or freshwater delivered to its customers. Revenues associated with purchase arrangements are recognized at a point in time based upon the transaction price when title, control and risk of loss transfers to the customer, which occurs at the delivery point. Payments under purchase arrangements are generally due 30 days after receipt of invoice. The Partnership generates revenues under purchase arrangements as follows: • Natural gas and NGL. The Partnership is party to certain purchase arrangements pursuant to which the Partnership purchases natural gas from a third party at a connection point and obtains control prior to performing services. The Partnership gathers, compresses and/or processes the gas and then redelivers the residue gas and NGLs to a different counterparty at market-based prices. • Freshwater. The Partnership is party to certain contracts with customers for freshwater supply and distribution. Under these customer contracts, the Partnership supplies and distributes freshwater to its customers for hydraulic fracturing and production optimization. These contracts contain multiple distinct performance obligations since each freshwater barrel can be sold separately and is not dependent or highly interrelated with other barrels. Disaggregation of revenues The following table summarizes revenues associated with contracts with customers for crude oil, natural gas and water services for the periods presented: Year Ended December 31, 2019 (1) 2018 (1) 2017 (In thousands) Service revenues Crude oil and natural gas revenues $ 197,015 $ 134,562 $ 85,828 Produced and flowback water revenues 126,588 118,405 84,350 Total service revenues 323,603 252,967 170,178 Product revenues Natural gas and NGL revenues 65,154 1,445 — Freshwater revenues 21,434 19,358 12,038 Total product revenues 86,588 20,803 12,038 Total revenues $ 410,191 $ 273,770 $ 182,216 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions. Prior period performance obligations The Partnership records revenue when the performance obligations under the terms of its customer contracts are satisfied. The Partnership measures the satisfaction of its performance obligations using the output method based upon the volume of crude oil, natural gas or water that flows through its systems. In certain cases, the Partnership is required to estimate these volumes during a reporting period and record any differences between the estimated volumes and actual volumes in the following reporting period. Such differences have historically not been significant. For the years ended December 31, 2019, 2018 and 2017, revenue recognized related to performance obligations satisfied in prior reporting periods was not material. Contract balances Contract balances are the result of timing differences between revenue recognition, billings and cash collections. Contract liabilities are recorded for consideration received from customers primarily related to (i) temporary deficiency quantities under minimum volume commitments which are recognized as revenue when the customer makes up the volumes or the deficiency makeup period expires and (ii) aid in construction payments received from customers which are recognized as revenue over the expected period of future benefit. The Partnership does not recognize contract assets or contract liabilities under its customer contracts for which invoicing occurs once the Partnership’s performance obligations have been satisfied and payment is unconditional. Contract liabilities are classified as current or long-term based on the timing of when the Partnership expects to recognize revenue. As of December 31, 2018, there were no contract balances recorded. The following table summarizes the changes in contract liabilities for the year ended December 31, 2019: (In thousands) Beginning of period $ — Cash received 3,750 Revenue recognized (69) End of period $ 3,681 Remaining performance obligations ASC 606 requires presentation of information about partially and wholly unsatisfied performance obligations under contracts that exist as of the end of the period. The following table presents estimated revenue allocated to remaining performance obligations for contracted revenues that are unsatisfied (or partially satisfied) as of December 31, 2019: (In thousands) 2020 $ 20,648 2021 22,393 2022 19,244 2023 12,624 2024 11,870 Thereafter 2,768 Total $ 89,547 The partially and wholly unsatisfied performance obligations presented in the table above are generally limited to customer contracts which have fixed pricing and fixed volume terms and conditions, which generally include customer contracts with minimum volume commitment payment obligations. The Partnership has elected practical expedients, pursuant to ASC 606, to exclude from the presentation of remaining performance obligations: (i) contracts with index-based pricing or variable volume attributes in which such variable consideration is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct service that forms part of a series of distinct services and (ii) contracts with an original expected duration of one year or less.

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisitions	Acquisitions 2019 Delaware Acquisition. On November 1, 2019, the Partnership entered into an agreement with Oasis Petroleum, pursuant to which Oasis Petroleum agreed to assign to Panther DevCo certain crude oil gathering and produced and flowback water gathering and disposal assets in the Delaware Basin in exchange for cash consideration of approximately $24.9 million. The Partnership funded the cash consideration with borrowings under the Revolving Credit Facility. For the period from November 1, 2019 through December 31, 2019, the Partnership recognized $1.4 million in revenues and $0.7 million in net income related to the 2019 Delaware Acquisition. The 2019 Delaware Acquisition was accounted for as a transfer of net assets between entities under common control. Prior to the 2019 Delaware Acquisition, Oasis Petroleum’s midstream services in the Delaware Basin were performed by OMS and were not included in the consolidated financial statements of the Partnership. In accordance with FASB authoritative guidance under Accounting Standards Codification Topic 805-50 (“ASC 805-50”), the Partnership recorded the net assets acquired at historical carrying value and recast its financial statements to include such net assets from the date of common control. The Partnership recast its consolidated financial statements as of and for the year ended December 31, 2018, and prior to the effective date of November 1, 2019 for the year ended December 31, 2019. For those periods requiring recast, the consolidated financial statements for periods prior to the effective date were prepared from Oasis Petroleum’s historical cost-basis accounts. The following table summarizes the assets acquired, liabilities assumed and consideration paid: Effective November 1, 2019 (In thousands) Cash consideration paid to Oasis Petroleum $ 24,939 Property, plant and equipment $ 35,272 Accumulated depreciation and amortization (439) Accrued capital costs (9,256) Accrued operating expenses (746) Asset retirement obligations (132) Total net assets acquired $ 24,699 Consideration paid in excess of book value of net assets (1) $ 240 ___________________ (1) Consideration paid in excess of book value was recorded to Partnership equity as a deemed distribution in accordance with FASB authoritative guidance for common control transactions. The following tables present the Partnership’s financial position, results of operations and cash flows giving effect to the 2019 Delaware Acquisition as of and for the year ended December 31, 2018: December 31, 2018 As Previously Reported 2019 Delaware Acquisition As Recasted (In thousands) ASSETS Current assets Cash and cash equivalents $ 6,649 $ — $ 6,649 Accounts receivable 2,481 — 2,481 Accounts receivable – Oasis Petroleum 80,805 217 81,022 Prepaid expenses 1,418 — 1,418 Other current assets 22 — 22 Total current assets 91,375 217 91,592 Property, plant and equipment 933,155 9,423 942,578 Less: accumulated depreciation and amortization (62,730) — (62,730) Total property, plant and equipment, net 870,425 9,423 879,848 Other assets 2,452 — 2,452 Total assets $ 964,252 $ 9,640 $ 973,892 LIABILITIES AND EQUITY Current liabilities Accounts payable $ 2,180 $ — $ 2,180 Accounts payable – Oasis Petroleum 33,014 — 33,014 Accrued liabilities 57,657 3,297 60,954 Accrued interest payable 442 — 442 Total current liabilities 93,293 3,297 96,590 Long-term debt 318,000 — 318,000 Asset retirement obligations 1,514 116 1,630 Total liabilities 412,807 3,413 416,220 Equity Limited partners Common units 192,581 — 192,581 Subordinated units 45,937 — 45,937 General Partner 112 — 112 Total partners’ equity 238,630 — 238,630 Non-controlling interests 312,815 — 312,815 Delaware Predecessor — 6,227 6,227 Total equity 551,445 6,227 557,672 Total liabilities and equity $ 964,252 $ 9,640 $ 973,892 Year Ended December 31, 2018 As Previously Reported 2019 Delaware Acquisition As Recasted (In thousands, except per unit data) Revenues Midstream services – Oasis Petroleum $ 248,216 $ 2,147 $ 250,363 Midstream services – third parties 2,604 — 2,604 Product sales – Oasis Petroleum 17,476 — 17,476 Product sales – third parties 3,327 — 3,327 Total revenues 271,623 2,147 273,770 Operating expenses Costs of product sales 7,433 — 7,433 Operating and maintenance 63,123 562 63,685 Depreciation and amortization 28,404 5 28,409 General and administrative 23,897 — 23,897 Total operating expenses 122,857 567 123,424 Operating income 148,766 1,580 150,346 Other income (expense) Interest expense, net of capitalized interest (2,343) (237) (2,580) Other income (expense) (14) — (14) Total other expense, net (2,357) (237) (2,594) Income before income taxes 146,409 1,343 147,752 Income tax expense — — — Net income 146,409 1,343 147,752 Less: Net income attributable to Delaware Predecessor — 1,343 1,343 Less: Net income attributable to non-controlling interests 96,354 — 96,354 Net income attributable to OMP LP 50,055 — 50,055 Less: Net income attributable to General Partner 112 — 112 Net income attributable to limited partners $ 49,943 $ — $ 49,943 Earnings per limited partner unit (Note 14) Common units – basic and diluted $ 1.82 $ — $ 1.82 Weighted average number of limited partners units outstanding (Note 14) Common units – basic 14,504 — 14,504 Common units – diluted 14,519 — 14,519 Year Ended December 31, 2018 As Previously Reported 2019 Delaware Acquisition As Recasted (In thousands) Cash flows from operating activities: Net income $ 146,409 $ 1,343 $ 147,752 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 28,404 5 28,409 Equity-based compensation expenses 356 — 356 Deferred financing costs amortization and other (519) — (519) Working capital and other changes: Change in accounts receivable 3,411 (217) 3,194 Change in prepaid expenses (640) — (640) Change in accounts payable and accrued liabilities 27,613 201 27,814 Change in other assets and liabilities, net (22) — (22) Net cash provided by operating activities 205,012 1,332 206,344 Cash flows from investing activities: Capital expenditures (276,810) (6,216) (283,026) Net cash used in investing activities (276,810) (6,216) (283,026) Cash flows from financing activities: Capital contributions from non-controlling interests 140,277 — 140,277 Capital contributions from Delaware Predecessor, net — 4,884 4,884 Proceeds from sale of common units, net of offering costs 44,503 — 44,503 Distributions to non-controlling interests (128,903) — (128,903) Distribution to Oasis Petroleum for contributed assets (172,429) — (172,429) Distributions to unitholders (44,918) — (44,918) Deferred financing costs (966) — (966) Proceeds from revolving credit facility 275,000 — 275,000 Principal payments on revolving credit facility (35,000) — (35,000) Net cash provided by financing activities 77,564 4,884 82,448 Increase in cash and cash equivalents 5,766 — 5,766 Cash: Beginning of period 883 — 883 End of period $ 6,649 $ — $ 6,649 Supplemental cash flow information: Cash paid for interest, net of capitalized interest $ 1,817 $ 237 $ 2,054 Supplemental non-cash transactions: Change in accrued capital expenditures $ (4,890) $ 3,096 $ (1,794) Change in asset retirement obligations 198 116 314 Reimbursement of capital expenditures from Oasis Petroleum 7,176 — 7,176 2018 Dropdown Acquisition. On November 19, 2018, the Partnership completed transactions contemplated by a contribution agreement (the “Contribution Agreement”) dated as of November 7, 2018, with OMS Holdings LLC (“OMS Holdings”), OMS, OMP GP LLC, OMP Operating, and for certain limited purposes set forth therein, Oasis Petroleum. Pursuant to the Contribution Agreement, Oasis Petroleum caused OMS to contribute to OMP Operating, as the Partnership’s designee, (a) an additional 15% limited liability company interest in Bobcat DevCo, and (b) an additional 30% limited liability company interest in Beartooth DevCo (collectively, the “Contributed Assets”) for consideration of approximately $251.4 million (the “Purchase Price”), consisting of approximately $172.4 million in cash and 3,950,000 common units, representing limited partner interests

Transactions with Affiliates

Transactions with Affiliates	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Transactions with Affiliates	Transactions with Affiliates Revenues. The Partnership generates substantially all of its revenues through 15-year, fee-based contractual arrangements with wholly-owned subsidiaries of Oasis Petroleum for midstream services. These services include (i) gas gathering, compression, processing and gas lift services; (ii) crude gathering, stabilization, blending, storage and transportation services; (iii) produced and flowback water gathering and disposal services; and (iv) freshwater supply and distribution services. The revenue earned from these services is generally directly related to the volume of crude oil, natural gas, and produced and flowback water and freshwater that flows through the Partnership’s systems, and the Partnership does not take ownership of the crude oil or natural gas that it handles for Oasis Petroleum. Expenses. Oasis Petroleum provides substantial labor and overhead support for the Partnership pursuant to a 15-year services and secondment agreement (the “Services and Secondment Agreement”). Oasis Petroleum performs centralized corporate, general and administrative services for the Partnership, such as legal, corporate recordkeeping, planning, budgeting, regulatory, accounting, billing, business development, treasury, insurance administration and claims processing, risk management, health, safety and environmental, information technology, human resources, investor relations, cash management and banking, payroll, internal audit, tax and engineering. Oasis Petroleum has also seconded to the Partnership certain of its employees to operate, construct, manage and maintain its assets. The Partnership reimburses Oasis Petroleum for direct and allocated general and administrative expenses incurred by Oasis Petroleum for the provision of these services. The expenses of executive officers and non-executive employees of Oasis Petroleum are allocated to the Partnership based on the amount of time spent managing its business and operations. For the periods prior to the initial public offering, shared services and direct labor were allocated to the Predecessor primarily based on headcount and direct usage during the respective years. Management believes that these allocations are reasonable and reflect the utilization of services provided and benefits received, but may differ from the cost that would have been incurred had the Predecessor operated as a stand-alone company for the periods presented prior to the initial public offering. Additionally, for the periods prior to the initial public offering and the 2019 Delaware Acquisition, interest expense was recognized by the Predecessor and Delaware Predecessor related to its funding activity with Oasis Petroleum based on capital expenditures for the period using the weighted average effective interest rate for Oasis Petroleum’s long-term indebtedness. The Partnership’s general and administrative expenses include $28.0 million, $21.1 million and $12.8 million from affiliate transactions with Oasis Petroleum for the years ended December 31, 2019, 2018 and 2017, respectively. Interest expense, net of capitalized interest, includes $0.6 million and $0.2 million related to the funding activity of the Delaware Predecessor with Oasis Petroleum for the years ended December 31, 2019 and 2018, respectively. In addition, interest expense, net of capitalized interest, includes $6.9 million related to funding activity of the Predecessor prior to the initial public offering for the year ended December 31, 2017. 2019 Capital Expenditures Arrangement. On February 22, 2019, the Partnership entered into a memorandum of understanding (the “MOU”) with Oasis Petroleum regarding the funding of Bobcat DevCo’s capital expenditures for the 2019 calendar year (the “2019 Capital Expenditures Arrangement”). Pursuant to the Amended and Restated Limited Liability Company Agreement of Bobcat DevCo LLC, as amended (the “First A&R Bobcat LLCA”), the Partnership and Oasis Petroleum are each required to make pro-rata capital contributions to Bobcat DevCo in accordance with their respective percentage ownership interests in Bobcat DevCo. Pursuant to the MOU, the Partnership agreed to make up to $80.0 million of capital expenditures to Bobcat DevCo that Oasis Petroleum would otherwise be required to contribute under the First A&R Bobcat LLCA. In connection with execution of the MOU, the Partnership and Oasis Petroleum amended the First A&R Bobcat LLCA and entered into the Second Amended and Restated Limited Liability Company Agreement of Bobcat DevCo LLC (the “Second A&R Bobcat LLCA”). The Second A&R Bobcat LLCA includes provisions applicable to the disproportionate capital contributions that the Partnership made to Bobcat

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Accrued Liabilities	Accrued Liabilities Accrued liabilities consist of the following: December 31, 2019 2018 (1) (In thousands) Accrued capital costs $ 33,105 $ 46,049 Accrued operating expenses 12,149 13,740 Other accrued liabilities 4,956 1,165 Total accrued liabilities $ 50,210 $ 60,954 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment consists of the following: December 31, 2019 2018 (1) (In thousands) Pipelines $ 523,576 $ 395,087 Natural gas processing plants 296,609 278,680 Produced and flowback water facilities 121,797 103,572 Compressor stations 143,276 126,019 Other property and equipment 34,231 33,829 Construction in progress 36,014 5,391 Total property, plant and equipment 1,155,503 942,578 Less: accumulated depreciation and amortization (98,982) (62,730) Total property, plant and equipment, net $ 1,056,521 $ 879,848 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt On September 25, 2017, the Partnership entered into a credit agreement (the “Credit Agreement”) for a revolving credit facility with OMP Operating as borrower (the “Revolving Credit Facility”), which has a maturity date of September 25, 2022. The Revolving Credit Facility is available to fund working capital and to finance acquisitions and other capital expenditures of the Partnership. On May 6, 2019, the Partnership entered into the Second Amendment to the Credit Agreement to (i) increase the aggregate amount of commitments from $400.0 million to $475.0 million; (ii) provide for the ability to further increase commitments to $675.0 million; and (iii) add a new lender to the bank group. On August 16, 2019, the Partnership entered into the Third Amendment to the Credit Agreement to (i) increase the aggregate amount of commitments from $475.0 million to $575.0 million and (ii) provide for the ability to further increase commitments to $775.0 million. As of December 31, 2019, the aggregate amount of commitments under the Revolving Credit Facility were $575.0 million. The Revolving Credit Facility includes a letter of credit sublimit of $10.0 million and a swingline loans sublimit of $10.0 million. All obligations of OMP Operating, as the borrower under the Revolving Credit Facility, are unconditionally guaranteed on a joint and several basis by the Partnership, Bighorn DevCo and Panther DevCo. The Revolving Credit Facility is collateralized by mortgages and other interests on substantially all of the Partnership’s and its subsidiaries’ properties and assets, including the equity interests in all present and future subsidiaries (subject to certain exceptions). Some or all of the collateral owned by Bobcat DevCo and Beartooth DevCo is subject to an intercreditor agreement between Wells Fargo, National Association (“Wells Fargo”), as administrative agent for the Revolving Credit Facility, and Wells Fargo as the administrative agent for the revolving credit facility of Oasis Petroleum, and acknowledged by OMS, Bobcat DevCo and Beartooth DevCo. The Revolving Credit Facility provides for customary representations, warranties and covenants, including, among other things, covenants relating to financial and collateral reporting, notices of material events, maintenance of the existence of the business and its properties, payment of obligations, the Partnership’s ability to enter into certain hedging agreements, limitations on the Partnership’s ability to sell or acquire properties and limitations on indebtedness and liens, dividends and distributions, transactions with affiliates and certain fundamental transactions. Borrowings under the Revolving Credit Facility bear interest at a rate per annum equal to the applicable margin (as described below) plus (i) with respect to Eurodollar Loans, the Adjusted LIBO Rate (as defined in the Credit Agreement) or (ii) with respect to ABR Loans, the greatest of (A) the Prime Rate in effect on such day, (B) the Federal Funds Effective Rate in effect on such day plus 1/2 of 1.00% or (C) the Adjusted LIBO Rate for a one-month interest period on such day plus 1.00% (each as defined in the Credit Agreement). The unused portion of the Revolving Credit Facility is subject to a commitment fee ranging from 0.375% to 0.500%. As of December 31, 2019 and 2018, the weighted average interest rate on the Revolving Credit Facility was 3.8% and 4.2%, respectively. The applicable margin for borrowings under the Revolving Credit Facility is determined in accordance with the Credit Agreement as follows: Consolidated Total Leverage Ratio Applicable Margin Applicable Margin Commitment Fee Rate Less than or equal to 3.00 to 1.00 1.75 % 0.75 % 0.375 % Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00 2.00 % 1.00 % 0.375 % Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00 2.25 % 1.25 % 0.500 % Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00 2.50 % 1.50 % 0.500 % Greater than 4.50 to 1.00 2.75 % 1.75 % 0.500 % The Revolving Credit Facility also requires the Partnership to maintain the following financial covenants as of the end of each fiscal quarter: • Consolidated Total Leverage Ratio: Prior to the date on which one or more of the credit parties have issued an aggregate principal amount of at least $150.0 million of senior notes (as permitted under the Revolving Credit Facility) (such date the “Covenant Changeover Date”) and commencing with the fiscal quarter ended December 31, 2018, the Partnership and OMP Operating’s ratio of Total Debt to EBITDA (each as defined in the Credit Agreement) on a quarterly basis may not exceed 4.50 to 1.00 (or during an Acquisition Period (as defined in the Credit Agreement), 5.00 to 1.00). On a quarterly basis following the Covenant Changeover Date, the Partnership and OMP Operating’s ratio of Total Debt to EBITDA may not exceed 5.25 to 1.00. • Consolidated Senior Secured Leverage Ratio: On a quarterly basis, commencing with the date the Covenant Changeover Date occurs, the Partnership and OMP Operating’s ratio of Consolidated Senior Secured Funded Debt to EBITDA (each as defined in the Credit Agreement) may not exceed 3.75 to 1.00. • Consolidated Interest Coverage Ratio: On a quarterly basis prior to the Covenant Changeover Date and commencing with the fiscal quarter ended December 31, 2018, the Partnership and OMP Operating’s ratio of EBITDA to Consolidated Interest Expense (each as defined in the Credit Agreement) may not be less than 3.00 to 1.00 and on a quarterly basis following the Covenant Changeover Date, the Partnership and OMP Operating’s ratio of EBITDA to Consolidated Interest Expense may not be less than 2.50 to 1.00. The Partnership was in compliance with the financial covenants under the Revolving Credit Facility as of December 31, 2019.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases As discussed in Note 2 — Summary of Significant Accounting Policies and Basis of Presentation, the Partnership adopted ASC 842 as of January 1, 2019 using the modified retrospective method, which resulted in the Partnership recognizing offsetting operating lease ROU assets and lease liabilities of $4.1 million. The Partnership did not have any finance leases as of the date of adoption. There was no impact to the opening equity balance as a result of the adoption of ASC 842. Prior period amounts were not adjusted and continue to be reported in accordance with previous guidance, Accounting Standards Codification 840 (“ASC 840”). In accordance with the adoption of ASC 842, management determines whether an arrangement is a lease at its inception. The Partnership’s operating and finance leases consist primarily of equipment and land easements. The operating lease ROU asset also includes any lease incentives in the recognition of the present value of future lease payments. The Partnership considers renewal and termination options in determining the lease term used to establish its ROU assets and lease liabilities to the extent the Partnership is reasonably certain to exercise the renewal or termination. The Partnership’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. As most of the Partnership’s leases do not provide an implicit rate, the Partnership uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future lease payments. The Partnership has determined the respective incremental borrowing rates based upon the rate of interest that would have been paid on a collateralized basis over similar tenors to that of the leases. The Partnership’s components of lease costs were as follows for the year ended December 31, 2019: (In thousands) Operating lease costs $ 3,204 Variable lease costs (1) 414 Short-term lease costs 144 Finance lease costs: Amortization of ROU assets 26 Interest on lease liabilities 20 Total lease costs $ 3,808 __________________ (1) Based on payments made by the Partnership to lessors for the right to use an underlying asset that vary because of changes in circumstances occurring after the commencement date, other than the passage of time, such as property taxes, operating and maintenance costs, which do not depend on an index or rate. The operating lease costs disclosed above are included in operating and maintenance expenses on the Partnership’s Consolidated Statements of Operations. The finance lease costs for the amortization of ROU assets and the interest on lease liabilities disclosed above are included in depreciation and amortization and interest expense, net of capitalized interest, respectively, on the Partnership’s Consolidated Statements of Operations. As of December 31, 2019, maturities of the Partnership’s lease liabilities were as follows: Operating Leases Finance Leases (In thousands) 2020 $ 3,150 $ 11 2021 1,530 45 2022 743 45 2023 — 45 2024 — 45 Thereafter — 639 Total future lease payments 5,423 830 Less: Imputed interest 202 273 Present value of future lease payments $ 5,221 $ 557 As of December 31, 2018, future minimum annual rental commitments under non-cancelable leases under ASC 840 were as follows: (In thousands) 2019 $ 736 2020 — 2021 — 2022 — 2023 — Thereafter — Total future minimum lease payments $ 736 Supplemental balance sheet information related to the Partnership’s leases are as follows: Balance Sheet Location As of December 31, 2019 (In thousands) Assets Operating lease assets Operating lease right-of-use assets $ 5,207 Finance lease assets (1) Other assets 602 Total lease assets $ 5,809 Liabilities Current Operating lease liabilities Current operating lease liabilities $ 3,005 Finance lease liabilities Other current liabilities 5 Long-term Operating lease liabilities Operating lease liabilities 2,216 Finance lease liabilities Other liabilities 552 Total lease liabilities $ 5,778 ___________________ (1) Finance lease ROU assets recorded net of accumulated amortization of $0.03 million as of December 31, 2019. Supplemental cash flow information and non-cash transactions related to the Partnership’s leases are as follows: December 31, 2019 (In thousands) Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 3,107 Operating cash flows from finance leases 20 Financing cash flows from finance leases 59 ROU assets obtained in exchange for lease obligations Operating leases $ 4,109 Finance leases 660 Weighted-average remaining lease terms and discount rates for the Partnership’s leases are as follows: As of December 31, 2019 Operating Leases Weighted average remaining lease term 2.0 years Weighted average discount rate 4.1 % Finance Leases Weighted average remaining lease term 19.2 years Weighted average discount rate 4.3 %
Leases	Leases As discussed in Note 2 — Summary of Significant Accounting Policies and Basis of Presentation, the Partnership adopted ASC 842 as of January 1, 2019 using the modified retrospective method, which resulted in the Partnership recognizing offsetting operating lease ROU assets and lease liabilities of $4.1 million. The Partnership did not have any finance leases as of the date of adoption. There was no impact to the opening equity balance as a result of the adoption of ASC 842. Prior period amounts were not adjusted and continue to be reported in accordance with previous guidance, Accounting Standards Codification 840 (“ASC 840”). In accordance with the adoption of ASC 842, management determines whether an arrangement is a lease at its inception. The Partnership’s operating and finance leases consist primarily of equipment and land easements. The operating lease ROU asset also includes any lease incentives in the recognition of the present value of future lease payments. The Partnership considers renewal and termination options in determining the lease term used to establish its ROU assets and lease liabilities to the extent the Partnership is reasonably certain to exercise the renewal or termination. The Partnership’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. As most of the Partnership’s leases do not provide an implicit rate, the Partnership uses its incremental borrowing rate based on the information available at commencement date in determining the present value of future lease payments. The Partnership has determined the respective incremental borrowing rates based upon the rate of interest that would have been paid on a collateralized basis over similar tenors to that of the leases. The Partnership’s components of lease costs were as follows for the year ended December 31, 2019: (In thousands) Operating lease costs $ 3,204 Variable lease costs (1) 414 Short-term lease costs 144 Finance lease costs: Amortization of ROU assets 26 Interest on lease liabilities 20 Total lease costs $ 3,808 __________________ (1) Based on payments made by the Partnership to lessors for the right to use an underlying asset that vary because of changes in circumstances occurring after the commencement date, other than the passage of time, such as property taxes, operating and maintenance costs, which do not depend on an index or rate. The operating lease costs disclosed above are included in operating and maintenance expenses on the Partnership’s Consolidated Statements of Operations. The finance lease costs for the amortization of ROU assets and the interest on lease liabilities disclosed above are included in depreciation and amortization and interest expense, net of capitalized interest, respectively, on the Partnership’s Consolidated Statements of Operations. As of December 31, 2019, maturities of the Partnership’s lease liabilities were as follows: Operating Leases Finance Leases (In thousands) 2020 $ 3,150 $ 11 2021 1,530 45 2022 743 45 2023 — 45 2024 — 45 Thereafter — 639 Total future lease payments 5,423 830 Less: Imputed interest 202 273 Present value of future lease payments $ 5,221 $ 557 As of December 31, 2018, future minimum annual rental commitments under non-cancelable leases under ASC 840 were as follows: (In thousands) 2019 $ 736 2020 — 2021 — 2022 — 2023 — Thereafter — Total future minimum lease payments $ 736 Supplemental balance sheet information related to the Partnership’s leases are as follows: Balance Sheet Location As of December 31, 2019 (In thousands) Assets Operating lease assets Operating lease right-of-use assets $ 5,207 Finance lease assets (1) Other assets 602 Total lease assets $ 5,809 Liabilities Current Operating lease liabilities Current operating lease liabilities $ 3,005 Finance lease liabilities Other current liabilities 5 Long-term Operating lease liabilities Operating lease liabilities 2,216 Finance lease liabilities Other liabilities 552 Total lease liabilities $ 5,778 ___________________ (1) Finance lease ROU assets recorded net of accumulated amortization of $0.03 million as of December 31, 2019. Supplemental cash flow information and non-cash transactions related to the Partnership’s leases are as follows: December 31, 2019 (In thousands) Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 3,107 Operating cash flows from finance leases 20 Financing cash flows from finance leases 59 ROU assets obtained in exchange for lease obligations Operating leases $ 4,109 Finance leases 660 Weighted-average remaining lease terms and discount rates for the Partnership’s leases are as follows: As of December 31, 2019 Operating Leases Weighted average remaining lease term 2.0 years Weighted average discount rate 4.1 % Finance Leases Weighted average remaining lease term 19.2 years Weighted average discount rate 4.3 %

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Partnership is not a taxable entity for U.S. federal income tax purposes, and taxes are generally borne by unitholders through the allocation of taxable income. In connection with the initial public offering, Predecessor current and deferred tax liabilities of $104.0 million were eliminated upon consummation of the Partnership. The Partnership recorded a de minimis state income tax provision for the year ended December 31, 2019 associated with the Texas margin tax. As of December 31, 2019, the reported amounts of the Partnership’s assets and liabilities exceeded the tax basis by $122.7 million. The provision for income taxes included in the Consolidated Statements of Operations for the periods presented relates to the Predecessor. The Predecessor is not a separate taxable entity for U.S. federal and certain states purposes, and its results are included in the consolidated income tax returns of Oasis Petroleum. The provision for income taxes recorded by the Predecessor was determined as if the Predecessor was a stand-alone taxpayer for the period prior to the initial public offering on September 25, 2017. The Predecessor’s income tax expense consists of the following for the year ended December 31, 2017: (In thousands) Current: Federal $ 15,571 State 2,047 Total current income tax expense 17,618 Deferred: Federal 4,631 State 609 Total deferred income tax expense 5,240 Total income tax expense $ 22,858 The reconciliation of income taxes calculated at the U.S. federal statutory rate to the Predecessor’s effective tax rate for the year ended December 31, 2017 is as follows: (%) (In thousands) U.S. federal statutory rate 35.00 % $ 33,392 Earnings not subject to tax subsequent to the initial public offering (12.83) % (12,239) State income taxes, net of federal income tax benefit 1.81 % 1,727 Other (0.02) % (22) Annual effective tax rate 23.96 % $ 22,858

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesIncluded below is a description of the Partnership’s various future commitments as of December 31, 2019. The commitments under these arrangements are not recorded in the accompanying Consolidated Balance Sheets in accordance with GAAP. The amounts disclosed represent undiscounted cash flows on a gross basis and no inflation elements have been applied. Volume commitment agreements. As of December 31, 2019, the Partnership had certain agreements with an aggregate requirement to either deliver or purchase a minimum quantity of approximately 13.1 million barrels of water, prior to any applicable volume credits, within specified timeframes, all of which are ten years or less. The estimable future commitments under these volume commitment agreements as of December 31, 2019 were as follows: (In thousands) 2020 $ 3,600 2021 2,759 2022 876 2023 — 2024 — Thereafter 838 Total $ 8,073 Subsequent to December 31, 2019, the Partnership entered into new agreements to deliver, transport or purchase additional volumes of produced water within specified timeframes, all of which are ten years or less. The estimable future commitments under these volume commitment agreements were approximately $3.8 million. Litigation. The Partnership is party to various legal and/or regulatory proceedings from time to time arising in the ordinary course of business. When the Partnership determines that a loss is probable of occurring and is reasonably estimable, the Partnership accrues an undiscounted liability for such contingencies based on its best estimate using information available at the time. The Partnership discloses contingencies where an adverse outcome may be material, or where in the judgment of management, the matter should otherwise be disclosed. Mirada litigation. On March 23, 2017, Mirada Energy, LLC, Mirada Wild Basin Holding Company, LLC and Mirada Energy Fund I, LLC (collectively, “Mirada”) filed a lawsuit against Oasis Petroleum, Oasis Petroleum North America LLC (“OPNA”), and OMS, seeking monetary damages in excess of $100 million, declaratory relief, attorneys’ fees and costs ( Mirada Energy, LLC, et al. v. Oasis Petroleum North America LLC, et al. ; in the 334th Judicial District Court of Harris County, Texas; Case Number 2017-19911). Mirada asserts that it is a working interest owner in certain acreage owned and operated by Oasis Petroleum in Wild Basin. Specifically, Mirada asserts that Oasis Petroleum has breached certain agreements by: (1) failing to allow Mirada to participate in Oasis Petroleum’s midstream operations in Wild Basin; (2) refusing to provide Mirada with information that Mirada contends is required under certain agreements and failing to provide information in a timely fashion; (3) failing to consult with Mirada and failing to obtain Mirada’s consent prior to drilling more than one well at a time in Wild Basin; and (4) overstating the estimated costs of proposed well operations in Wild Basin. Mirada seeks a declaratory judgment that Oasis Petroleum be removed as operator in Wild Basin at Mirada’s election and that Mirada be allowed to elect a new operator; certain agreements apply to Oasis Petroleum and Mirada and Wild Basin with respect to this dispute; Oasis Petroleum be required to provide all information within its possession regarding proposed or ongoing operations in Wild Basin; and Oasis Petroleum not be permitted to drill, or propose to drill, more than one well at a time in Wild Basin without obtaining Mirada’s consent. Mirada also seeks a declaratory judgment with respect to Oasis Petroleum’s current midstream operations in Wild Basin. Specifically, Mirada seeks a declaratory judgment that Mirada has a right to participate in Oasis Petroleum’s Wild Basin midstream operations, consisting of produced and flowback water disposal, crude oil gathering and natural gas gathering and processing; that, upon Mirada’s election to participate, Mirada is obligated to pay its proportionate costs of Oasis Petroleum’s midstream operations in Wild Basin; and that Mirada would then be entitled to receive a share of revenues from the midstream operations and would not be charged any amount for its use of these facilities for production from the “Contract Area.” On June 30, 2017, Mirada amended its original petition to add a claim that Oasis Petroleum has breached certain agreements by charging Mirada for midstream services provided by its affiliates and to seek a declaratory judgment that Mirada is entitled to be paid its share of total proceeds from the sale of hydrocarbons received by OPNA or any affiliate of OPNA without deductions for midstream services provided by OPNA or its affiliates. On February 2, 2018 and February 16, 2018, Mirada filed a second and third amended petition, respectively. In these filings, Mirada alleged new legal theories for being entitled to enforce the underlying contracts, and added Bighorn DevCo, Bobcat DevCo and Beartooth DevCo as defendants, asserting that these entities were created in bad faith in an effort to avoid contractual obligations owed to Mirada. On March 2, 2018, Mirada filed a fourth amended petition that described Mirada’s alleged ownership and assignment of interests in assets purportedly governed by agreements at issue in the lawsuit. On August 31, 2018, Mirada filed a fifth amended petition that added the Partnership as a defendant, asserting that it was created in bad faith in an effort to avoid contractual obligations owed to Mirada. On July 2, 2019, Oasis Petroleum, OPNA, OMS, the Partnership, Bighorn DevCo, Bobcat DevCo and Beartooth DevCo (collectively “Oasis Entities”) counterclaimed against Mirada for a judgment declaring that Oasis Entities are not obligated to purchase, manage, gather, transport, compress, process, market, sell or otherwise handle Mirada’s proportionate share of oil and gas produced from OPNA-operated wells. The counterclaim also seeks attorney’s fees, costs and expenses. On November 1, 2019, Mirada filed a sixth amended petition that stated that Mirada seeks in excess of $200 million in damages and asserted that OMS is an agent of OPNA and OPNA, OMS, the Partnership, Bighorn DevCo, Bobcat DevCo and Beartooth DevCo are agents of Oasis Petroleum. Mirada also changed its allegation that it may elect a new operator for the subject wells to instead allege that Mirada may remove Oasis Petroleum as operator. On November 1, 2019, the Oasis Entities amended their counterclaim against Mirada for a judgment declaring that a provision in one of the agreements does not incorporate by reference any provisions in a certain participation agreement and joint operating agreement. The additional counterclaim also seeks attorney’s fees, costs and expenses. On the same day, the Oasis Entities filed an amended answer asserting additional defenses against Mirada’s claims. Oasis Petroleum and the Partnership believe that Mirada’s claims are without merit, that Oasis Petroleum has complied with its obligations under the applicable agreements and that some of Mirada’s claims are grounded in agreements that do not apply to Oasis Petroleum. Oasis Petroleum filed answers denying all of Mirada’s claims and intends and continues to vigorously defend against Mirada’s claims. Discovery is ongoing, and each of the parties has made a number of procedural filings and motions, and additional filings and motions can be expected over the course of the claim. Trial is scheduled for May 2020. Neither the Partnership nor Oasis Petroleum can predict or guarantee the ultimate outcome or resolution of such matter. If such matter were to be determined adversely to the Partnership’s or Oasis Petroleum’s interests, or if the Partnership or Oasis Petroleum were forced to settle such matter for a significant amount, such resolution or settlement could have a material adverse effect on the Partnership's business, financial condition, results of operations and cash flows. Such an adverse determination could materially impact Oasis Petroleum’s ability to operate its properties in Wild Basin or develop its identified drilling locations in Wild Basin on its current development schedule. A determination that Mirada has a right to participate in Oasis Petroleum’s midstream operations could materially reduce the interests of Oasis Petroleum and the Partnership in the Partnership’s current assets and future midstream opportunities and related revenues in Wild Basin. Under the Omnibus Agreement the Partnership entered into with Oasis Petroleum in connection with the closing of the initial public offering, Oasis Petroleum agreed to indemnify the Partnership for any losses resulting from this litigation. However, the Partnership cannot guarantee that such indemnity will fully protect the Partnership from the adverse consequences of any adverse ruling. Solomon litigation. On or about August 28, 2019, Oasis Petroleum LLC, a wholly-owned subsidiary of Oasis Petroleum (“OP LLC”), was named as a defendant in the lawsuit styled Andrew Solomon, on behalf of himself and those similarly situated vs. Oasis Petroleum, LLC , pending in the United States District Court for the District of North Dakota. The lawsuit alleged violations of the federal Fair Labor Standards Act (the “FLSA”) and Title 29 of the North Dakota Century Code (“Title 29”) as the result of OP LLC’s alleged practice of paying the plaintiff and similarly situated current and former employees overtime at rates less than required by applicable law, or failing to pay for certain overtime hours worked. The lawsuit requested that: (i) its federal claims be advanced as a collective action, with a class of all operators, technicians and all other employees in substantially similar positions employed by OP LLC who were paid hourly for at least one week during the three year period prior to the commencement of the lawsuit, who worked 40 or more hours in at least one workweek and/or eight or more hours on at least one workday; and (ii) its state claims be advanced as a class action, with a class of all operators, technicians, and all other employees in substantially similar positions employed by OP LLC in North Dakota during the two year period prior to the commencement of the lawsuit, who worked 40 or more hours in at least one workweek and/or worked eight or more hours in a day on at least one workday. No motion has been filed for class certification, and the Partnership cannot predict whether such motion will be filed or a class certified. Oasis Petroleum believes that Mr. Solomon’s claims are without merit and that OP LLC has complied with its obligations under the FLSA and Title 29. OP LLC has filed an answer denying all of Mr. Solomon’s claims and intends to vigorously defend against the claims. The Partnership cannot predict or guarantee the ultimate outcome or resolutions of such matter. If such matter were to be determined adversely to Oasis Petroleum’s interests, or if Oasis Petroleum were forced to settle such matter for a significant amount, such resolution or settlement could have a material adverse effect on the Partnership’s business, financial condition, results of operations or cash flows.

Equity-Based Compensation

Equity-Based Compensation	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Equity-Based Compensation	Equity-Based Compensation The LTIP provides for the grant, at the discretion of the board of directors of the General Partner, of options, unit appreciation rights, restricted units, phantom units, and other unit or cash-based awards. The purpose of awards under the LTIP is to provide additional incentive compensation to individuals providing services to the Partnership, and to align the economic interests of such individuals with the interests of the Partnership’s unitholders. As of December 31, 2019, the aggregate number of common units that may be issued pursuant to any and all awards under the LTIP is equal to 2,455,408 common units, subject to adjustment due to recapitalization or reorganization, or related to forfeitures or expiration of awards, as provided under the LTIP. On January 1 of each calendar year following the adoption and prior to the expiration of the LTIP, the total number of common units that may be issued pursuant to the LTIP automatically increases by a number of common units equal to one percent of the number of common units outstanding on a fully diluted basis as of the close of business on the immediately preceding December 31 (calculated by adding to the number of common units outstanding, all outstanding securities convertible into common units on such date on an as converted basis). As a result of this adjustment, an additional 337,952 common units were reserved for issuance pursuant to awards under the LTIP on January 1, 2020. Phantom unit awards. On October 19, 2017, the Partnership granted under its LTIP 101,500 phantom unit awards to certain employees of Oasis Petroleum who are non-employees of the Partnership. Each phantom unit represents the right to receive a cash payment equal to the fair market value of one common unit on the day prior to the date it vests. Award recipients are also entitled to distribution equivalent rights, which represent the right to receive a cash payment equal to the value of the distributions paid on one common unit between the grant date and the vesting date. The phantom units vest in equal amounts each year over a three The following table summarizes information related to phantom units issued under the LTIP and held by certain employees of Oasis Petroleum for the periods presented: Phantom Units Weighted Average Grant Date Fair Value per Unit Non-vested units outstanding at December 31, 2018 58,379 $ 16.40 Granted — — Vested (22,112) 16.40 Forfeited (14,198) 16.40 Non-vested units outstanding at December 31, 2019 22,069 $ 16.40 Equity-based compensation recorded for phantom unit awards was $0.1 million and $0.1 million as of December 31, 2019 and 2018, respectively, and is included in the Consolidated Balance Sheets in Accounts Receivable from Oasis Petroleum, for the portion reimbursed from Oasis Petroleum, and Accrued Liabilities, for the portion to be paid to award holders. The Partnership did not record any equity-based compensation expense related to these awards for the year ended December 31, 2017 because these awards were first granted during the fourth quarter of 2017. The fair value of awards vested was $0.4 million for the year ended December 31, 2019 and $0.6 million for the year ended December 31, 2018. No awards vested during the year ended December 31, 2017. The weighted average grant date fair value of phantom units granted was $16.40 per unit for the year ended December 31, 2017. No phantom units were granted under the LTIP for the years ended December 31, 2019 or 2018. Unrecognized equity-based compensation as of December 31, 2019 for all outstanding phantom unit awards was $0.4 million and will be recognized over a weighted average period of 0.9 year. Restricted unit awards. The Partnership has granted to independent directors of the General Partner restricted unit awards under the LTIP, which vest over a one year period. These awards are accounted for as equity-classified awards since the awards will settle in common units upon vesting. Under the fair value method for equity-classified awards, equity-based compensation expense is measured at the grant date based on the fair value of the award and is recognized over the service period. The following table summarizes information related to restricted units issued under the LTIP and held by certain directors of the General Partner for the periods presented: Restricted Units Weighted Average Grant Date Fair Value per Unit Non-vested units outstanding at December 31, 2018 17,260 $ 17.55 Granted 16,170 18.57 Vested (17,260) 17.55 Forfeited — — Non-vested units outstanding at December 31, 2019 16,170 $ 18.57 Equity-based compensation expense recorded for restricted unit awards was $0.4 million, $0.4 million and $0.1 million for the years ended December 31, 2019, 2018 and 2017, respectively, and is included in general and administrative expenses on the Consolidated Statements of Operations. The fair value of awards vested was $0.3 million for each of the years ended December 31, 2019 and 2018. No awards vested during the year ended December 31, 2017. The weighted average grant date fair value of restricted unit awards granted was $18.57 per unit, $17.55 per unit and $17.00 per unit for the years ended December 31, 2019, 2018 and 2017, respectively. Unrecognized equity-based compensation as of December 31, 2019 for all outstanding restricted unit awards was $0.01 million and will be recognized over a weighted average period of 0.1 year. Restricted stock awards (Predecessor). Prior to the initial public offering, certain employees of Oasis Petroleum were granted restricted stock awards under its Amended and Restated 2010 Long Term Incentive Plan, the majority of which vest over a three In accordance with its indirect shared service expense allocation from Oasis Petroleum, the Predecessor recorded equity-based compensation expense associated with these awards of approximately $1.0 million for the year ended December 31, 2017 and is included in general and administrative expenses on the Consolidated Statements of Operations. The weighted average grant date fair value of restricted stock awards granted was $14.95 per share and the fair value of awards vested was $0.8 million for the year ended December 31, 2017. As of December 31, 2019, there was no unrecognized expense associated with these awards attributable to the Partnership.

Partnership Equity and Distribu

Partnership Equity and Distributions	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Partnership Equity and Distributions	Partnership Equity and Distributions On November 14, 2018, the Partnership completed a public offering of 2,300,000 common units (including 300,000 common units issued pursuant to the underwriters’ option to purchase additional common units), representing limited partnership interests, at a purchase price to the public of $20.00 per common unit. Net proceeds from the offering were $44.5 million, after deducting underwriting discounts, commissions and offering costs. The Partnership used the net proceeds to fund a portion of the 2018 Dropdown Acquisition (see Note 4 — Acquisitions). This public offering was made pursuant to an effective shelf registration statement on Form S-3 filed with the SEC on October 1, 2018. Cash distributions. On January 30, 2020, the board of directors of the General Partner declared the quarterly distribution for the fourth quarter of $0.54 per unit. In addition, the General Partner will receive a cash distribution of $1.0 million attributable to its incentive distribution rights (“IDRs”) related to earnings for the fourth quarter. These distributions will be paid on February 27, 2020 to unitholders of record as of February 13, 2020. The following table details the distributions paid in respect of each period in which the distributions were earned: Distributions Limited Partners General Partner Period Record Date Distribution Date Distribution per limited partner unit Common units Subordinated units IDRs (In thousands) Q1 2018 May 17, 2018 May 29, 2018 $ 0.3925 $ 5,406 $ 5,397 $ — Q2 2018 August 16, 2018 August 28, 2018 0.4100 5,649 5,638 — Q3 2018 November 9, 2018 November 27, 2018 0.4300 5,925 5,913 — Q4 2018 February 15, 2019 February 28, 2019 0.4500 9,020 6,188 112 Q1 2019 May 17, 2019 May 29, 2019 0.4700 9,421 6,463 238 Q2 2019 August 16, 2019 August 28, 2019 0.4900 9,822 6,738 463 Q3 2019 November 15, 2019 November 27, 2019 0.5150 10,323 7,081 745 Q4 2019 February 13, 2020 February 27, 2020 0.5400 10,833 7,425 1,027 Minimum quarterly distribution. The partnership agreement requires that all of the Partnership’s available cash be distributed quarterly. Under the current cash distribution policy, the Partnership intends to distribute to the holders of common units and subordinated units on a quarterly basis at least the minimum quarterly distribution of $0.3750 per unit, or $1.50 on an annualized basis, to the extent the Partnership has sufficient cash after establishment of cash reserves and payment of fees and expenses, including payments to the General Partner and its affiliates. Subordinated units. Oasis Petroleum owns all of the Partnership’s subordinated units. The partnership agreement provides that, during the subordination period, the common units have the right to receive distributions of available cash from operating surplus each quarter in an amount equal to the minimum quarterly distribution, plus any arrearages in the payment of the minimum quarterly distribution on the common units from prior quarters, before any distributions of available cash from operating surplus may be made on the subordinated units. No arrearages will accrue or be payable on the subordinated units. When the subordination period ends, each outstanding subordinated unit will convert into one common unit and will thereafter participate pro rata with the other common units in distributions of available cash. The subordination period will end on December 31, 2020 if each of the following tests are met: • for each of the three consecutive, non-overlapping four-quarter periods immediately preceding that date, aggregate distributions from operating surplus equaled or exceeded the sum of the minimum quarterly distribution multiplied by the total number of common units and subordinated units outstanding in each quarter in each period; • for the same three consecutive, non-overlapping four-quarter periods, the “adjusted operating surplus” (as defined in the partnership agreement) equaled or exceeded the sum of the minimum quarterly distribution multiplied by the total number of common units and subordinated units outstanding during each quarter on a fully diluted weighted average basis; and • there are no arrearages in payment of the minimum quarterly distribution on the common units. Notwithstanding the foregoing, the subordination period will automatically terminate, and all of the subordinated units will convert into common units on a one-for-one basis, on the first business day after the distribution to unitholders in respect of any quarter, beginning with the quarter ended December 31, 2018, if each of the following has occurred: • for one four-quarter period immediately preceding that date, aggregate distributions from operating surplus exceeded 150.0% of the minimum quarterly distribution multiplied by the total number of common units and subordinated units outstanding in each quarter in the period; • for the same four-quarter period, the “adjusted operating surplus” (as defined in the Partnership’s Amended and Restated Agreement of Limited Partnership) equaled or exceeded 150.0% of the sum of the minimum quarterly distribution multiplied by the total number of common and subordinated units outstanding during each quarter on a fully diluted weighted average basis, plus the related distribution on the IDRs; and • there are no arrearages in payment of the minimum quarterly distributions on the common units. Incentive distribution rights. The General Partner owns all of the Partnership’s IDRs, which entitle it to receive increasing percentages, up to a maximum of 50.0% of the cash the Partnership distributes in excess of $0.4313 per unit per quarter. The maximum distribution of 50.0% does not include any distributions that Oasis Petroleum may receive on common units or subordinated units that it owns. Percentage allocations of available cash from operating surplus. For any quarter in which the Partnership has distributed cash from operating surplus to the common and subordinated unitholders in an amount equal to the minimum distribution, the Partnership will distribute any additional available cash from operating surplus for that quarter among the unitholders and the IDRs holders in the following manner: Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Minimum Quarterly Distribution up to $0.3750 100 % — % First Target Distribution above $0.3750 up to $0.4313 100 % — % Second Target Distribution above $0.4313 up to $0.4688 85 % 15 % Third Target Distribution above $0.4688 up to $0.5625 75 % 25 % Thereafter above $0.5625 50 % 50 %

Earnings Per Limited Partner Un

Earnings Per Limited Partner Unit	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Limited Partner Unit	Earnings Per Limited Partner Unit Earnings per limited partner unit is computed by dividing the respective limited partners’ interest in earnings attributable to the Partnership by the weighted average number of common and subordinated units outstanding. Because there is more than one class of participating securities, the Partnership uses the two-class method when calculating earnings per limited partner unit. The classes of participating securities include common units, subordinated units and IDRs. Diluted earnings per limited partner unit reflects the potential dilution that could occur if securities or agreements to issue common units, such as awards under the LTIP, were exercised, settled or converted into common units. When it is determined that potential common units should be included in diluted net income per limited partner unit calculation, the impact is reflected by applying the treasury stock method. There are no adjustments made to income attributable to the Partnership in the calculation of diluted earnings per limited partner unit. The following is a calculation of the basic and diluted weighted average units outstanding for the periods presented: December 31, 2019 2018 2017 (In thousands) Basic weighted average common units outstanding 20,024 14,504 13,566 Dilutive effect of restricted awards 8 15 2 Diluted weighted average common units outstanding 20,032 14,519 13,568 Net income related to the 2018 Dropdown Acquisition was recorded prospectively from the closing date. Net income related to the 2019 Delaware Acquisition was recast to prior periods, and earnings for the period prior to the effective date were allocated to the Delaware Predecessor. See Note 4 — Acquisitions for further information on these transactions. The following table presents the calculation of earnings per limited partner unit under the two-class method: Year ended December 31, 2019 General Partner Limited Partners IDRs Common units Subordinated units Total (In thousands, except per unit data) Net income attributable to OMP LP: Distribution declared $ 2,472 $ 40,400 $ 27,706 $ 70,578 Undistributed earnings attributable to OMP LP — 27,912 19,166 47,078 Net income attributable to OMP LP $ 2,472 $ 68,312 $ 46,872 $ 117,656 Weighted average limited partner units outstanding Basic 20,024 Diluted 20,032 Net income attributable to OMP LP per limited partner unit Basic $ 3.41 Diluted 3.41 Anti-dilutive restricted units 13 Year ended December 31, 2018 General Partner Limited Partners IDRs Common units Subordinated units Total (In thousands, except per unit data) Net income attributable to OMP LP: Distribution declared $ 112 $ 26,001 $ 23,134 $ 49,247 Undistributed earnings attributable to OMP LP — 415 393 808 Net income attributable to OMP LP $ 112 $ 26,416 $ 23,527 $ 50,055 Weighted average limited partner units outstanding Basic 14,504 Diluted 14,519 Net income attributable to OMP LP per limited partner unit Basic $ 1.82 Diluted 1.82 Anti-dilutive restricted units 6 Year ended December 31, 2017 General Partner Limited Partners IDRs Common units Subordinated units Total (In thousands, except per unit data) Net income attributable to OMP LP: Distribution declared $ — $ 5,498 $ 5,493 $ 10,991 Undistributed earnings attributable to OMP LP — 321 326 647 Net income attributable to OMP LP $ — $ 5,819 $ 5,819 $ 11,638 Weighted average limited partner units outstanding Basic 13,566 Diluted 13,568 Net income attributable to OMP LP per limited partner unit Basic $ 0.43 Diluted 0.43 Anti-dilutive restricted units 10

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Partnership has evaluated the period after the balance sheet date, noting no subsequent events or transactions that required recognition or disclosure in the financial statements, other than as previously disclosed.

Quarterly Financial Data - Unau

Quarterly Financial Data - Unaudited	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data - Unaudited	Quarterly Financial Data - Unaudited The Partnership’s results of operations, by quarter, for the years ended December 31, 2019 and 2018 were as follows: Year Ended December 31, 2019 First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per unit data) Revenues (1) $ 93,852 $ 100,403 $ 103,550 $ 112,386 Operating income (1) 48,383 54,580 61,732 68,077 Net income (1) 44,414 50,246 57,120 63,451 Net income attributable to OMP LP 21,543 26,198 31,436 38,479 Earnings per limited partner unit - Basic and Diluted Common units $ 0.63 $ 0.76 $ 0.91 $ 1.11 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions. Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per unit data) Revenues (1) $ 61,693 $ 67,106 $ 72,105 $ 72,866 Operating income (1) 32,032 38,068 39,416 40,830 Net income (1) 31,770 37,868 39,160 38,954 Net income attributable to OMP LP 9,954 12,444 12,376 15,281 Earnings per limited partner unit - Basic and Diluted Common units $ 0.36 $ 0.45 $ 0.45 $ 0.54 __________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies and Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of the Partnership include the accounts of Oasis Midstream Partners LP and its subsidiaries. All intercompany transactions have been eliminated in consolidation. These statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The 2019 Delaware Acquisition was accounted for as a transfer of net assets between entities under common control (see Note 4 — Acquisitions). As a result, the Partnership recorded the net assets acquired at historic carrying value and recast its financial statements to include such net assets from the date of common control. The Partnership recast its consolidated financial statements as of and for the year ended December 31, 2018, and prior to the effective date of November 1, 2019 for the year ended December 31, 2019. The consolidated financial statements for the year ended December 31, 2017 were not recast, since Oasis Petroleum first entered the Delaware Basin in 2018 following its acquisition of certain assets from Forge Energy, LLC. For those periods requiring recast, the consolidated financial statements for periods prior to the effective date were prepared from Oasis Petroleum’s historical cost-basis accounts and may not necessarily be indicative of the actual results had the Partnership owned the assets during the reported period. See Note 4 — Acquisitions. Delaware Predecessor. Prior to the 2019 Delaware Acquisition, Oasis Petroleum’s midstream services in the Delaware Basin were performed by OMS (the “Delaware Predecessor”). The consolidated financial statements include the results of the Delaware Predecessor for the year ended December 31, 2018 and prior to the effective date of the 2019 Delaware Acquisition for the year ended December 31, 2019. The Delaware Predecessor financial statements have been prepared from the separate records maintained by Oasis Petroleum and may not necessarily be indicative of the actual results of operations that might have occurred if the Delaware Predecessor assets had been operated by the Partnership during the periods reported.
Use of Estimates	Use of Estimates Preparation of the Partnership’s consolidated financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ significantly from those estimates. Management evaluates estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic and commodity price environment.
Consolidation	Consolidation The Partnership’s consolidated financial statements include its accounts and the accounts of the DevCos, each of which is controlled by OMP GP LLC (the “General Partner”). All intercompany balances and transactions have been eliminated upon consolidation. Variable interest entity. The Partnership determined that Bobcat DevCo is a variable interest entity (“VIE”), since OMS’s equity at risk was established with non-substantive voting rights. As the Partnership has the authority to direct the activities that most significantly affect the economic performance of Bobcat DevCo, the Partnership is considered the primary beneficiary and consolidates Bobcat DevCo in its financial statements under the VIE consolidation model. The Partnership determined that Bighorn DevCo, Beartooth DevCo and Panther DevCo are not VIEs and consolidates these entities in its financial statements under the voting interest consolidation model.
Cash and Cash Equivalents	Cash and cash equivalents. The Partnership classifies all unrestricted cash on hand and investments with original maturity dates less than 90 days as cash equivalents. In the first quarter of 2019, the Partnership adopted Accounting Standards Update No. 2016-15, Statement of Cash Flows (“ASU 2016-15”), which is intended to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. ASU 2016-15 was applied on a retrospective basis. The adoption of ASU 2016-15 did not result in a material impact to the Partnership’s financial position, cash flows, results of operations or financial statement disclosures.
Transactions with affiliates	Transactions with affiliates. Transactions between Oasis Petroleum, its affiliates and the Partnership have been identified in the consolidated financial statements as transactions with affiliates.
Property, plant and equipment	Property, plant and equipment. Property, plant and equipment consists primarily of pipelines, natural gas processing plants, produced and flowback water facilities and compressor stations. Property, plant and equipment is stated at the lower of historical cost less accumulated depreciation, or fair value, if impaired. The Partnership capitalizes a portion of its interest expense incurred on its outstanding debt. The amount capitalized is determined by multiplying the capitalization rate by the average amount of eligible accumulated capital expenditures and is limited to actual interest costs incurred during the period. The accumulated capital expenditures included in the capitalized interest calculation begin when the first costs are incurred and end when the asset is either placed into service or written off. The Partnership capitalized $0.9 million, $4.9 million and $1.2 million of interest costs for the years ended December 31, 2019, 2018 and 2017, respectively. These amounts are amortized over the useful life of the related assets once the assets are placed in-service. When assets are placed into service, management makes estimates with respect to useful lives and salvage values that management believes are reasonable. However, subsequent events could cause a change in estimates, thereby impacting future depreciation amounts. Uncertainties that may impact these estimates include, among others, changes in laws and regulations relating to environmental matters, including air and water quality, restoration and abandonment requirements, economic conditions and supply and demand in the area. Depreciation is computed over the asset’s estimated useful life using the straight line method based on estimated useful lives and asset salvage values. The weighted average life of each of the Partnership’s pipelines, natural gas processing plants, produced and flowback water facilities, compressor stations, and other long-lived assets is 30 years. When properties are retired or otherwise disposed of, the related cost and accumulated depreciation are removed from the respective accounts and any profit or loss on disposition is recognized as gain or loss.
Impairment of long-lived assets	Impairment of long-lived assets. The Partnership evaluates the ability to recover the carrying amount of long-lived assets and determine whether such long-lived assets have been impaired. Impairment exists when the carrying amount of an asset exceeds estimates of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. An impairment analysis requires management to apply judgment in identifying impairment indicators and estimating future cash flows. When alternative courses of action to recover the carrying amount of a long-lived asset are under consideration, estimates of future undiscounted cash flows take into account possible outcomes and probabilities of their occurrence. If the carrying amount of the long-lived asset is not recoverable based on the estimated future undiscounted cash flows, the impairment loss is measured as the excess of the asset’s carrying amount over its estimated fair value, such that the asset’s carrying amount is adjusted to its estimated fair value with an offsetting charge to impairment expense. Fair value represents the estimated price between market participants to sell an asset in the principal or most advantageous market for the asset, based on assumptions a market participant would make. When warranted, management assesses the fair value of long-lived assets using commonly accepted techniques and may use more than one source in making such assessments. The factors used to determine fair value are subject to management’s judgment and expertise and include, but are not limited to, recent third-party comparable sales, internally developed discounted cash flow analysis and analysis from outside advisors. Significant changes, such as changes in contract rates or terms, the condition of an asset or management’s intent to utilize the asset, generally require management to reassess the cash flows related to long-lived assets. A reduction of the carrying value of fixed assets would represent a Level 3 fair value measurement. If actual results are not consistent with assumptions and estimates, or assumptions and estimates change due to new information, the Partnership may be exposed to additional impairment charges. Ultimately, a prolonged period of lower commodity prices may adversely affect the estimate of future operating results through lower throughput volumes on the Partnership’s assets, which could result in future impairment charges due to the potential impact on operations and cash flows.
Asset retirement obligations	Asset retirement obligations (“ARO”). The Partnership records the fair value of a liability for a legal obligation to retire an asset in the period in which the liability is incurred, with the corresponding cost capitalized by increasing the carrying amount of the related long-lived asset. For produced and flowback water disposal wells, this is the period in which the well is drilled or acquired. The ARO represents the estimated amount the Partnership will incur to plug, abandon and remediate the produced and flowback water properties at the end of their useful lives, in accordance with applicable state laws. The liability is accreted to its present value each period and the capitalized costs are depreciated using the straight-line method. The accretion expense is recorded as a component of depreciation and amortization in the Consolidated Statements of Operations. Some assets, including certain pipelines and the Partnership’s natural gas processing plants, have contractual or regulatory obligations to perform remediation and, in some instances, dismantlement and removal activities when the assets are abandoned. The Partnership is not able to reasonably estimate the fair value of the ARO for these assets because the settlement dates are indeterminable given the expected continued use of the assets with proper maintenance. The Partnership will record an ARO for these assets in the periods in which the settlement dates become reasonably determinable. The Partnership determines the ARO, which represents a non-financial liability which is measured at fair value on a non-recurring basis, by calculating the present value of estimated cash flows related to the liability. Estimating the future ARO requires management to make estimates and judgments regarding timing and existence of a liability, as well as what constitutes adequate restoration. Inherent in the fair value calculation are numerous assumptions and judgments including the ultimate costs, inflation factors, credit adjusted discount rates, timing of settlement and changes in the legal, regulatory, environmental and political environments. These assumptions represent Level 3 inputs. To the extent future revisions to these assumptions impact the fair value of the existing ARO liability, a corresponding adjustment is made to the related asset.
Deferred financing costs	Deferred financing costs. The Partnership capitalizes directly attributable costs incurred in connection with obtaining debt financing. These costs are amortized over the term of the related financing using the straight-line method, which approximates the interest method. The amortization expense is recorded as a component of interest expense in the Partnership’s Consolidated Statements of Operations. The deferred financing costs related to the Partnership’s revolving credit facility are included in other assets on the Consolidated Balance Sheets.
Equity-based compensation	Equity-based compensation. The Partnership has granted phantom unit awards and restricted unit awards under the Oasis Midstream Partners LP 2017 Long Term Incentive Plan (“LTIP”). The Partnership accounts for phantom unit awards as liability-classified awards in accordance with GAAP, since the Partnership intends to settle these awards in cash. The Partnership will be reimbursed by Oasis Petroleum for the cash settlement amount of these awards. The Partnership accounts for restricted units granted to certain independent directors of the General Partner as equity-classified awards in accordance with GAAP, as the Partnership intends to settle these awards in common units. Forfeitures associated with awards granted under the LTIP are accounted for when they occur. In the first quarter of 2019, the Partnership adopted Accounting Standards Update No. 2017-09, Scope of Modification Accounting
Income taxes	Income taxes. The Partnership is not a taxable entity for United States federal income tax purposes or for the majority of states that impose an income tax. Generally, each partner is separately taxed on its share of taxable income. During the fourth quarter of 2019, the Partnership commenced operations in the Delaware Basin, and as a result, is subject to the Texas margin tax, which is considered an income tax under GAAP. For periods prior to the initial public offering, the consolidated financial statements include a provision for income tax expense. Deferred federal and state income taxes were provided on temporary differences between the financial statement carrying amounts of recognized assets and liabilities and their respective tax bases as if the Partnership filed tax returns as a stand-alone entity.
Revenue recognition	Revenue recognition. In the first quarter of 2018, the Partnership adopted Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers and a series of related accounting standards updates incorporated into GAAP as Accounting Standards Codification Topic 606 (“ASC 606”) using the modified retrospective method. The adoption of ASC 606 did not result in a material impact to the Partnership’s financial position, cash flows or results of operations. The Partnership has also modified current processes and controls to apply the requirements of the new standard and does not believe such modifications are material to its internal controls over financial reporting. Enhanced disclosures in accordance with the requirements of ASC 606 have been provided in Note 3 —Revenue Recognition. The unit of account in ASC 606 is a performance obligation, which is a promise in a contract to transfer to a customer either a distinct good or service (or bundle of goods or services) or a series of distinct goods or services provided over a period of time. ASC 606 requires that a contract’s transaction price, which is the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to a customer, is to be allocated to each performance obligation in the contract based on relative standalone selling prices and recognized as revenue when (point in time) or as (over time) the performance obligation is satisfied. The Partnership generates revenues primarily by charging fees for (i) crude oil gathering, stabilization, blending, storage and transportation, (ii) natural gas gathering, gas lift, compression and processing, (iii) produced and flowback water gathering and disposal and (iv) freshwater supply and distribution. The Partnership categorizes revenues as service revenues or product sales in its Consolidated Statements of Operations. For revenues generated under fee-based arrangements, the Partnership records the fees attributable to such arrangements as service revenues in its Consolidated Statements of Operations. Under fee-based arrangements, the Partnership does not take ownership of the volumes it handles for its customers and receives fees for midstream services it provides. Revenues are recognized based upon the transaction price at month-end under the right to invoice practical expedient. For revenues generated under purchase arrangements, the Partnership takes ownership of the product prior to sale and is the principal in the transaction. Revenues and expenses are recognized on a gross basis under Product sales and Costs of product sales, respectively, in the Consolidated Statements of Operations.
Common control transactions	Common control transactions. The Partnership accounts for assets acquired from Oasis Petroleum and its subsidiaries as common control transactions whereby the net assets acquired are recorded at historical carrying value at the date of transfer. Consideration transferred in excess of the carrying value of the net assets acquired is recorded to equity as a deemed distribution. Common control transactions involving the transfer of a business or the transfer of net assets result in a change in reporting entity and require prior periods to be retrospectively adjusted. To the extent such transactions require prior periods to be retrospectively adjusted, historical net equity amounts prior to the transaction date are reflected in predecessor equity.
Business combinations	Business combinations (excluding common control transactions). The Partnership accounts for business combinations under the acquisition method of accounting. An income, market or cost valuation method may be utilized to estimate the fair value of the assets acquired, liabilities assumed, and non-controlling interest, if any, in a business combination. Fair value is determined on the acquisition date. Acquisition-related costs are expensed as incurred in connection with each business combination. If the initial accounting for the business combination is incomplete by the end of the reporting period in which the acquisition occurs, an estimate will be recorded. Subsequent to the acquisition, and not later than one year from the acquisition date, the Partnership will record any material adjustments to the initial estimate based on new information obtained about facts and circumstances that existed as of the acquisition date. The Partnership makes various assumptions in estimating the fair values of assets acquired and liabilities assumed. As fair value is a market-based measurement, it is determined based on the assumptions that market participants would use. The income valuation method represents the present value of future cash flows over the life of the asset using discrete financial forecasts. Such discrete financial forecasts rely on estimates and assumptions made by management. The most significant assumptions relate to management’s estimates of throughput volumes, future operating and development costs, long-term growth rates and a market-based weighted average cost of capital. The market valuation method uses prices paid for a reasonably similar asset by other purchasers in the market, with adjustments relating to any differences between the assets. The cost valuation method is based on the replacement cost of a comparable asset at prices at the time of the acquisition reduced for depreciation of the asset. Any excess of the acquisition price over the estimated fair value of net assets acquired is recorded as goodwill. Any excess of the estimated fair value of net assets acquired over the acquisition price is recorded in current earnings as a gain on bargain purchase. In the first quarter of 2019, the Partnership adopted Accounting Standards Update No. 2017-01, Clarifying the Definition of a Business (“ASU 2017-01”), which provides guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. ASU 2017-01 was adopted on a prospective basis. The adoption of ASU 2017-01 did not result in a material impact to the Partnership’s financial position, cash flows, results of operations or financial statement disclosures.
Leases	Leases. In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016-02, Leases (“ASU 2016-02”), which established a right-of-use (“ROU”) model that requires a lessee to recognize an operating lease asset and lease liability on the balance sheet, with the exception of short-term leases. Accounting Standards Codification 842, Leases (“ASC 842”), was subsequently amended by ASU No. 2018-01, Land easement practical expedient for transition to Topic 842 (“ASU 2018-01”); ASU No. 2018-10, Codification Improvements to Topic 842; and ASU No. 2018-11, Targeted Improvements . The new standard is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The effective date and transition requirements for the amendments are the same as the effective date for ASU 2016-02. A modified retrospective transition approach is required, applying the new standard to all leases existing at the date of initial application. An entity may choose to use either (i) its effective date or (ii) the beginning of the earliest comparative period presented in the financial statements as its date of initial application.
Concentrations of Credit Risk	Concentrations of Market and Credit RiskThe Partnership has limited direct exposure to risks associated with fluctuating commodity prices due to the nature of its business and its long-term, fixed-fee contractual arrangements with customers. However, to the extent that the future contractual arrangements with customers, including Oasis Petroleum or third parties, do not provide for fixed-fee structures, the Partnership may become subject to commodity price risk.
Concentrations of Market Risk	Additionally, as substantially all of the Partnership’s revenues are derived from Oasis Petroleum, the Partnership is indirectly subject to risks associated with fluctuating commodity prices to the extent that lower commodity prices adversely affect Oasis Petroleum’s production, drilling schedule, financial condition, leverage, market reputation, liquidity, results of operations or cash flows.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Fair Value Measurement. In August 2018, the FASB issued Accounting Standards Update No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which improves the effectiveness of the disclosure requirements for fair value measurements. The changes affect all companies that are required to include fair value measurement disclosures. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those years. An entity is permitted to early adopt the removed or modified disclosures upon the issuance of ASU 2018-13 and may delay adoption of the additional disclosures until their effective date. The Partnership does not expect the adoption of this guidance to have an impact on its financial position, cash flows or results of operations, but it may result in changes to disclosures. Financial Instruments - Credit Losses. In June 2016, the FASB issued Accounting Standards Update No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information, including forecasts, to develop credit loss estimates. ASU 2016-13 requires entities to use the new methodology to measure impairment of financial instruments, including accounts receivable, and may result in earlier recognition of credit losses than under current GAAP. ASU 2016-13 is effective for fiscal years beginning after December 15, 2019. Although the Partnership continues to evaluate ASU 2016-13, based on our current credit portfolio the Partnership does not expect the adoption of this standard to have a material impact on its financial position, cash flows or results of operations, but it may result in changes to disclosures.

Organization and Nature of Op_2

Organization and Nature of Operations (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Ownership Interests in DevCos	As of December 31, 2019, the Partnership’s assets and ownership interests in the DevCos were as follows: DevCos Areas Served Service Lines OMP Ownership Bighorn DevCo Wild Basin – Natural gas processing – Crude oil stabilization – Crude oil blending – Crude oil and NGL storage – Crude oil transportation 100% Bobcat DevCo Wild Basin – Natural gas gathering – Natural gas compression – Gas lift – Crude oil gathering – Produced and flowback water gathering – Produced and flowback water disposal 35.3% Beartooth DevCo Alger – Produced and flowback water gathering – Produced and flowback water disposal – Freshwater supply and distribution 70% Panther DevCo Delaware Basin – Crude oil gathering – Produced and flowback water gathering – Produced and flowback water disposal 100%

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table summarizes revenues associated with contracts with customers for crude oil, natural gas and water services for the periods presented: Year Ended December 31, 2019 (1) 2018 (1) 2017 (In thousands) Service revenues Crude oil and natural gas revenues $ 197,015 $ 134,562 $ 85,828 Produced and flowback water revenues 126,588 118,405 84,350 Total service revenues 323,603 252,967 170,178 Product revenues Natural gas and NGL revenues 65,154 1,445 — Freshwater revenues 21,434 19,358 12,038 Total product revenues 86,588 20,803 12,038 Total revenues $ 410,191 $ 273,770 $ 182,216 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
Summary of Changes in Contract Liabilities	The following table summarizes the changes in contract liabilities for the year ended December 31, 2019: (In thousands) Beginning of period $ — Cash received 3,750 Revenue recognized (69) End of period $ 3,681
Expected Satisfaction Period for Remaining Performance Obligation	The following table presents estimated revenue allocated to remaining performance obligations for contracted revenues that are unsatisfied (or partially satisfied) as of December 31, 2019: (In thousands) 2020 $ 20,648 2021 22,393 2022 19,244 2023 12,624 2024 11,870 Thereafter 2,768 Total $ 89,547

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Summary of Asset Acquired and Liabilities Assumed	The following table summarizes the assets acquired, liabilities assumed and consideration paid: Effective November 1, 2019 (In thousands) Cash consideration paid to Oasis Petroleum $ 24,939 Property, plant and equipment $ 35,272 Accumulated depreciation and amortization (439) Accrued capital costs (9,256) Accrued operating expenses (746) Asset retirement obligations (132) Total net assets acquired $ 24,699 Consideration paid in excess of book value of net assets (1) $ 240 ___________________ (1) Consideration paid in excess of book value was recorded to Partnership equity as a deemed distribution in accordance with FASB authoritative guidance for common control transactions.
Schedule of Acquisitions	The following tables present the Partnership’s financial position, results of operations and cash flows giving effect to the 2019 Delaware Acquisition as of and for the year ended December 31, 2018: December 31, 2018 As Previously Reported 2019 Delaware Acquisition As Recasted (In thousands) ASSETS Current assets Cash and cash equivalents $ 6,649 $ — $ 6,649 Accounts receivable 2,481 — 2,481 Accounts receivable – Oasis Petroleum 80,805 217 81,022 Prepaid expenses 1,418 — 1,418 Other current assets 22 — 22 Total current assets 91,375 217 91,592 Property, plant and equipment 933,155 9,423 942,578 Less: accumulated depreciation and amortization (62,730) — (62,730) Total property, plant and equipment, net 870,425 9,423 879,848 Other assets 2,452 — 2,452 Total assets $ 964,252 $ 9,640 $ 973,892 LIABILITIES AND EQUITY Current liabilities Accounts payable $ 2,180 $ — $ 2,180 Accounts payable – Oasis Petroleum 33,014 — 33,014 Accrued liabilities 57,657 3,297 60,954 Accrued interest payable 442 — 442 Total current liabilities 93,293 3,297 96,590 Long-term debt 318,000 — 318,000 Asset retirement obligations 1,514 116 1,630 Total liabilities 412,807 3,413 416,220 Equity Limited partners Common units 192,581 — 192,581 Subordinated units 45,937 — 45,937 General Partner 112 — 112 Total partners’ equity 238,630 — 238,630 Non-controlling interests 312,815 — 312,815 Delaware Predecessor — 6,227 6,227 Total equity 551,445 6,227 557,672 Total liabilities and equity $ 964,252 $ 9,640 $ 973,892 Year Ended December 31, 2018 As Previously Reported 2019 Delaware Acquisition As Recasted (In thousands, except per unit data) Revenues Midstream services – Oasis Petroleum $ 248,216 $ 2,147 $ 250,363 Midstream services – third parties 2,604 — 2,604 Product sales – Oasis Petroleum 17,476 — 17,476 Product sales – third parties 3,327 — 3,327 Total revenues 271,623 2,147 273,770 Operating expenses Costs of product sales 7,433 — 7,433 Operating and maintenance 63,123 562 63,685 Depreciation and amortization 28,404 5 28,409 General and administrative 23,897 — 23,897 Total operating expenses 122,857 567 123,424 Operating income 148,766 1,580 150,346 Other income (expense) Interest expense, net of capitalized interest (2,343) (237) (2,580) Other income (expense) (14) — (14) Total other expense, net (2,357) (237) (2,594) Income before income taxes 146,409 1,343 147,752 Income tax expense — — — Net income 146,409 1,343 147,752 Less: Net income attributable to Delaware Predecessor — 1,343 1,343 Less: Net income attributable to non-controlling interests 96,354 — 96,354 Net income attributable to OMP LP 50,055 — 50,055 Less: Net income attributable to General Partner 112 — 112 Net income attributable to limited partners $ 49,943 $ — $ 49,943 Earnings per limited partner unit (Note 14) Common units – basic and diluted $ 1.82 $ — $ 1.82 Weighted average number of limited partners units outstanding (Note 14) Common units – basic 14,504 — 14,504 Common units – diluted 14,519 — 14,519 Year Ended December 31, 2018 As Previously Reported 2019 Delaware Acquisition As Recasted (In thousands) Cash flows from operating activities: Net income $ 146,409 $ 1,343 $ 147,752 Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization 28,404 5 28,409 Equity-based compensation expenses 356 — 356 Deferred financing costs amortization and other (519) — (519) Working capital and other changes: Change in accounts receivable 3,411 (217) 3,194 Change in prepaid expenses (640) — (640) Change in accounts payable and accrued liabilities 27,613 201 27,814 Change in other assets and liabilities, net (22) — (22) Net cash provided by operating activities 205,012 1,332 206,344 Cash flows from investing activities: Capital expenditures (276,810) (6,216) (283,026) Net cash used in investing activities (276,810) (6,216) (283,026) Cash flows from financing activities: Capital contributions from non-controlling interests 140,277 — 140,277 Capital contributions from Delaware Predecessor, net — 4,884 4,884 Proceeds from sale of common units, net of offering costs 44,503 — 44,503 Distributions to non-controlling interests (128,903) — (128,903) Distribution to Oasis Petroleum for contributed assets (172,429) — (172,429) Distributions to unitholders (44,918) — (44,918) Deferred financing costs (966) — (966) Proceeds from revolving credit facility 275,000 — 275,000 Principal payments on revolving credit facility (35,000) — (35,000) Net cash provided by financing activities 77,564 4,884 82,448 Increase in cash and cash equivalents 5,766 — 5,766 Cash: Beginning of period 883 — 883 End of period $ 6,649 $ — $ 6,649 Supplemental cash flow information: Cash paid for interest, net of capitalized interest $ 1,817 $ 237 $ 2,054 Supplemental non-cash transactions: Change in accrued capital expenditures $ (4,890) $ 3,096 $ (1,794) Change in asset retirement obligations 198 116 314 Reimbursement of capital expenditures from Oasis Petroleum 7,176 — 7,176

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consist of the following: December 31, 2019 2018 (1) (In thousands) Accrued capital costs $ 33,105 $ 46,049 Accrued operating expenses 12,149 13,740 Other accrued liabilities 4,956 1,165 Total accrued liabilities $ 50,210 $ 60,954 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property, plant and equipment consists of the following: December 31, 2019 2018 (1) (In thousands) Pipelines $ 523,576 $ 395,087 Natural gas processing plants 296,609 278,680 Produced and flowback water facilities 121,797 103,572 Compressor stations 143,276 126,019 Other property and equipment 34,231 33,829 Construction in progress 36,014 5,391 Total property, plant and equipment 1,155,503 942,578 Less: accumulated depreciation and amortization (98,982) (62,730) Total property, plant and equipment, net $ 1,056,521 $ 879,848 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Applicable Debt Margins	The applicable margin for borrowings under the Revolving Credit Facility is determined in accordance with the Credit Agreement as follows: Consolidated Total Leverage Ratio Applicable Margin Applicable Margin Commitment Fee Rate Less than or equal to 3.00 to 1.00 1.75 % 0.75 % 0.375 % Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00 2.00 % 1.00 % 0.375 % Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00 2.25 % 1.25 % 0.500 % Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00 2.50 % 1.50 % 0.500 % Greater than 4.50 to 1.00 2.75 % 1.75 % 0.500 %

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lease Costs	The Partnership’s components of lease costs were as follows for the year ended December 31, 2019: (In thousands) Operating lease costs $ 3,204 Variable lease costs (1) 414 Short-term lease costs 144 Finance lease costs: Amortization of ROU assets 26 Interest on lease liabilities 20 Total lease costs $ 3,808 __________________ (1) Based on payments made by the Partnership to lessors for the right to use an underlying asset that vary because of changes in circumstances occurring after the commencement date, other than the passage of time, such as property taxes, operating and maintenance costs, which do not depend on an index or rate.
Summary of Finance Leases by Maturity	As of December 31, 2019, maturities of the Partnership’s lease liabilities were as follows: Operating Leases Finance Leases (In thousands) 2020 $ 3,150 $ 11 2021 1,530 45 2022 743 45 2023 — 45 2024 — 45 Thereafter — 639 Total future lease payments 5,423 830 Less: Imputed interest 202 273 Present value of future lease payments $ 5,221 $ 557
Summary of Operating Leases by Maturity	As of December 31, 2019, maturities of the Partnership’s lease liabilities were as follows: Operating Leases Finance Leases (In thousands) 2020 $ 3,150 $ 11 2021 1,530 45 2022 743 45 2023 — 45 2024 — 45 Thereafter — 639 Total future lease payments 5,423 830 Less: Imputed interest 202 273 Present value of future lease payments $ 5,221 $ 557
Schedule of Future Minimum Rental Payments	As of December 31, 2018, future minimum annual rental commitments under non-cancelable leases under ASC 840 were as follows: (In thousands) 2019 $ 736 2020 — 2021 — 2022 — 2023 — Thereafter — Total future minimum lease payments $ 736
Supplemental Balance Sheet Information	Supplemental balance sheet information related to the Partnership’s leases are as follows: Balance Sheet Location As of December 31, 2019 (In thousands) Assets Operating lease assets Operating lease right-of-use assets $ 5,207 Finance lease assets (1) Other assets 602 Total lease assets $ 5,809 Liabilities Current Operating lease liabilities Current operating lease liabilities $ 3,005 Finance lease liabilities Other current liabilities 5 Long-term Operating lease liabilities Operating lease liabilities 2,216 Finance lease liabilities Other liabilities 552 Total lease liabilities $ 5,778 ___________________ (1) Finance lease ROU assets recorded net of accumulated amortization of $0.03 million as of December 31, 2019.
Supplemental Cash Flow Information	Supplemental cash flow information and non-cash transactions related to the Partnership’s leases are as follows: December 31, 2019 (In thousands) Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 3,107 Operating cash flows from finance leases 20 Financing cash flows from finance leases 59 ROU assets obtained in exchange for lease obligations Operating leases $ 4,109 Finance leases 660
Schedule of Weighted Average Remaining Lease Term and Discount Rate	Weighted-average remaining lease terms and discount rates for the Partnership’s leases are as follows: As of December 31, 2019 Operating Leases Weighted average remaining lease term 2.0 years Weighted average discount rate 4.1 % Finance Leases Weighted average remaining lease term 19.2 years Weighted average discount rate 4.3 %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	The Predecessor’s income tax expense consists of the following for the year ended December 31, 2017: (In thousands) Current: Federal $ 15,571 State 2,047 Total current income tax expense 17,618 Deferred: Federal 4,631 State 609 Total deferred income tax expense 5,240 Total income tax expense $ 22,858
Schedule of Effective Income Tax Rate Reconciliation	The reconciliation of income taxes calculated at the U.S. federal statutory rate to the Predecessor’s effective tax rate for the year ended December 31, 2017 is as follows: (%) (In thousands) U.S. federal statutory rate 35.00 % $ 33,392 Earnings not subject to tax subsequent to the initial public offering (12.83) % (12,239) State income taxes, net of federal income tax benefit 1.81 % 1,727 Other (0.02) % (22) Annual effective tax rate 23.96 % $ 22,858

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments	As of December 31, 2018, future minimum annual rental commitments under non-cancelable leases under ASC 840 were as follows: (In thousands) 2019 $ 736 2020 — 2021 — 2022 — 2023 — Thereafter — Total future minimum lease payments $ 736
Schedule of Future Minimum Commitments	The estimable future commitments under these volume commitment agreements as of December 31, 2019 were as follows: (In thousands) 2020 $ 3,600 2021 2,759 2022 876 2023 — 2024 — Thereafter 838 Total $ 8,073

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Phantom Units Held by Certain Non-employees of the Partnership	The following table summarizes information related to phantom units issued under the LTIP and held by certain employees of Oasis Petroleum for the periods presented: Phantom Units Weighted Average Grant Date Fair Value per Unit Non-vested units outstanding at December 31, 2018 58,379 $ 16.40 Granted — — Vested (22,112) 16.40 Forfeited (14,198) 16.40 Non-vested units outstanding at December 31, 2019 22,069 $ 16.40
Schedule of Nonvested Share Activity	The following table summarizes information related to restricted units issued under the LTIP and held by certain directors of the General Partner for the periods presented: Restricted Units Weighted Average Grant Date Fair Value per Unit Non-vested units outstanding at December 31, 2018 17,260 $ 17.55 Granted 16,170 18.57 Vested (17,260) 17.55 Forfeited — — Non-vested units outstanding at December 31, 2019 16,170 $ 18.57

Partnership Equity and Distri_2

Partnership Equity and Distributions (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of Percentage Allocations of Available Cash from Operating Surplus	The following table details the distributions paid in respect of each period in which the distributions were earned: Distributions Limited Partners General Partner Period Record Date Distribution Date Distribution per limited partner unit Common units Subordinated units IDRs (In thousands) Q1 2018 May 17, 2018 May 29, 2018 $ 0.3925 $ 5,406 $ 5,397 $ — Q2 2018 August 16, 2018 August 28, 2018 0.4100 5,649 5,638 — Q3 2018 November 9, 2018 November 27, 2018 0.4300 5,925 5,913 — Q4 2018 February 15, 2019 February 28, 2019 0.4500 9,020 6,188 112 Q1 2019 May 17, 2019 May 29, 2019 0.4700 9,421 6,463 238 Q2 2019 August 16, 2019 August 28, 2019 0.4900 9,822 6,738 463 Q3 2019 November 15, 2019 November 27, 2019 0.5150 10,323 7,081 745 Q4 2019 February 13, 2020 February 27, 2020 0.5400 10,833 7,425 1,027 Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Minimum Quarterly Distribution up to $0.3750 100 % — % First Target Distribution above $0.3750 up to $0.4313 100 % — % Second Target Distribution above $0.4313 up to $0.4688 85 % 15 % Third Target Distribution above $0.4688 up to $0.5625 75 % 25 % Thereafter above $0.5625 50 % 50 %

Earnings Per Limited Partner _2

Earnings Per Limited Partner Unit (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Earnings per Common and Subordinated Units	The following is a calculation of the basic and diluted weighted average units outstanding for the periods presented: December 31, 2019 2018 2017 (In thousands) Basic weighted average common units outstanding 20,024 14,504 13,566 Dilutive effect of restricted awards 8 15 2 Diluted weighted average common units outstanding 20,032 14,519 13,568 The following table presents the calculation of earnings per limited partner unit under the two-class method: Year ended December 31, 2019 General Partner Limited Partners IDRs Common units Subordinated units Total (In thousands, except per unit data) Net income attributable to OMP LP: Distribution declared $ 2,472 $ 40,400 $ 27,706 $ 70,578 Undistributed earnings attributable to OMP LP — 27,912 19,166 47,078 Net income attributable to OMP LP $ 2,472 $ 68,312 $ 46,872 $ 117,656 Weighted average limited partner units outstanding Basic 20,024 Diluted 20,032 Net income attributable to OMP LP per limited partner unit Basic $ 3.41 Diluted 3.41 Anti-dilutive restricted units 13 Year ended December 31, 2018 General Partner Limited Partners IDRs Common units Subordinated units Total (In thousands, except per unit data) Net income attributable to OMP LP: Distribution declared $ 112 $ 26,001 $ 23,134 $ 49,247 Undistributed earnings attributable to OMP LP — 415 393 808 Net income attributable to OMP LP $ 112 $ 26,416 $ 23,527 $ 50,055 Weighted average limited partner units outstanding Basic 14,504 Diluted 14,519 Net income attributable to OMP LP per limited partner unit Basic $ 1.82 Diluted 1.82 Anti-dilutive restricted units 6 Year ended December 31, 2017 General Partner Limited Partners IDRs Common units Subordinated units Total (In thousands, except per unit data) Net income attributable to OMP LP: Distribution declared $ — $ 5,498 $ 5,493 $ 10,991 Undistributed earnings attributable to OMP LP — 321 326 647 Net income attributable to OMP LP $ — $ 5,819 $ 5,819 $ 11,638 Weighted average limited partner units outstanding Basic 13,566 Diluted 13,568 Net income attributable to OMP LP per limited partner unit Basic $ 0.43 Diluted 0.43 Anti-dilutive restricted units 10

Quarterly Financial Data - Un_2

Quarterly Financial Data - Unaudited (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data - Unaudited	The Partnership’s results of operations, by quarter, for the years ended December 31, 2019 and 2018 were as follows: Year Ended December 31, 2019 First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per unit data) Revenues (1) $ 93,852 $ 100,403 $ 103,550 $ 112,386 Operating income (1) 48,383 54,580 61,732 68,077 Net income (1) 44,414 50,246 57,120 63,451 Net income attributable to OMP LP 21,543 26,198 31,436 38,479 Earnings per limited partner unit - Basic and Diluted Common units $ 0.63 $ 0.76 $ 0.91 $ 1.11 ___________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions. Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter (In thousands, except per unit data) Revenues (1) $ 61,693 $ 67,106 $ 72,105 $ 72,866 Operating income (1) 32,032 38,068 39,416 40,830 Net income (1) 31,770 37,868 39,160 38,954 Net income attributable to OMP LP 9,954 12,444 12,376 15,281 Earnings per limited partner unit - Basic and Diluted Common units $ 0.36 $ 0.45 $ 0.45 $ 0.54 __________________ (1) Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Organization and Nature of Op_3

Organization and Nature of Operations (Details) - USD ($)	Feb. 22, 2019	Dec. 31, 2018	Nov. 19, 2018	Dec. 31, 2019	Dec. 31, 2017
Oasis Midstream Partners, LP | Bighorn DevCo
Limited Partners' Capital Account [Line Items]
Ownership interest (percent)				100.00%	100.00%
Oasis Midstream Partners, LP | Bobcat DevCo
Limited Partners' Capital Account [Line Items]
Ownership interest (percent)		25.00%		35.30%	10.00%
Limited liability company interest (percent)			15.00%
Oasis Midstream Partners, LP | Beartooth DevCo
Limited Partners' Capital Account [Line Items]
Ownership interest (percent)				70.00%	40.00%
Limited liability company interest (percent)			30.00%
Oasis Midstream Partners, LP | Panther DevCo
Limited Partners' Capital Account [Line Items]
Ownership interest (percent)				100.00%
Oasis | 2019 Capital Expenditures Arrangement
Limited Partners' Capital Account [Line Items]
Amount under capital contributions agreement	$ 80,000,000
Capital contribution	$ 73,000,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies and Basis of Presentation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Interest costs capitalized	$ 0.9	$ 4.9	$ 1.2
Weighted average useful life of long-lived assets	30 years
Bobcat DevCo | Oasis Petroleum
Variable Interest Entity [Line Items]
Non-controlling interest (percent)	64.70%
Beartooth DevCo | Oasis Petroleum
Variable Interest Entity [Line Items]
Non-controlling interest (percent)	30.00%

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 112,386,000	$ 103,550,000	$ 100,403,000	$ 93,852,000	$ 72,866,000	$ 72,105,000	$ 67,106,000	$ 61,693,000	$ 410,191,000	$ 273,770,000	[1]	$ 182,216,000
Contract liability	$ 3,681,000				$ 0				3,681,000	0
Midstream service
Disaggregation of Revenue [Line Items]
Total revenues									323,603,000	252,967,000		170,178,000
Product sales
Disaggregation of Revenue [Line Items]
Total revenues									86,588,000	20,803,000		12,038,000
Crude oil and natural gas revenues | Midstream service
Disaggregation of Revenue [Line Items]
Total revenues									197,015,000	134,562,000		85,828,000
Produced and flowback water revenues | Midstream service
Disaggregation of Revenue [Line Items]
Total revenues									126,588,000	118,405,000		84,350,000
Natural gas and NGL revenues | Product sales
Disaggregation of Revenue [Line Items]
Total revenues									65,154,000	1,445,000		0
Freshwater revenues | Product sales
Disaggregation of Revenue [Line Items]
Total revenues									$ 21,434,000	$ 19,358,000		$ 12,038,000
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Revenue Recognition - Summary o

Revenue Recognition - Summary of Contract Liability Activity (Details)	12 Months Ended
	Dec. 31, 2019USD ($)
Change in Contract with Customer, Liability [Abstract]
Beginning of period	$ 0
Cash received	3,750,000
Revenue recognized	(69,000)
End of period	$ 3,681,000

Revenue Recognition - Remaining

Revenue Recognition - Remaining Performance Obligations (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Revenue from Contract with Customer [Abstract]
Timing of satisfaction of performance obligation and payment	The partially and wholly unsatisfied performance obligations presented in the table above are generally limited to customer contracts which have fixed pricing and fixed volume terms and conditions, which generally include customer contracts with minimum volume commitment payment obligations. The Partnership has elected practical expedients, pursuant to ASC 606, to exclude from the presentation of remaining performance obligations: (i) contracts with index-based pricing or variable volume attributes in which such variable consideration is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct service that forms part of a series of distinct services and (ii) contracts with an original expected duration of one year or less.
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 89,547
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 20,648
Expected satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 22,393
Expected satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 19,244
Expected satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 12,624
Expected satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 11,870
Expected satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 2,768
Expected satisfaction period

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - Delaware Acquisition $ in Thousands	Nov. 01, 2019USD ($)
Business Acquisition [Line Items]
Cash consideration paid to Oasis Petroleum	$ 24,939
Revenue since acquisition date	1,400
Net income since acquisition date	$ 700

Acquisitions - Assets Acquired

Acquisitions - Assets Acquired and Liabilities Assumed (Details) - Delaware Acquisition $ in Thousands	Nov. 01, 2019USD ($)
Business Acquisition [Line Items]
Cash consideration paid to Oasis Petroleum	$ 24,939
Property, plant and equipment	35,272
Accumulated depreciation and amortization	(439)
Accrued capital costs	(9,256)
Accrued operating expenses	(746)
Asset retirement obligations	(132)
Total net assets acquired	24,699
Consideration paid in excess of book value of net assets	$ 240

Acquisitions - Balance Sheet Fo

Acquisitions - Balance Sheet Following Acquisition (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017	Sep. 25, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Cash and cash equivalents	$ 4,168	$ 6,649	[1]
Accounts receivable	5,969	2,481	[1]
Accounts receivable – Oasis Petroleum	77,571	81,022	[1]
Prepaid expenses	1,923	1,418	[1]
Other current assets	138	22	[1]
Total current assets	89,769	91,592	[1]
Property, plant and equipment	1,155,503	942,578	[1]
Less: accumulated depreciation and amortization	(98,982)	(62,730)	[1]
Total property, plant and equipment, net	1,056,521	879,848	[1]
Other assets	3,172	2,452	[1]
Total assets	1,154,669	973,892	[1]
Accounts payable	2,478	2,180	[1]
Accounts payable – Oasis Petroleum	27,139	33,014	[1]
Accrued liabilities	50,210	60,954	[1]
Accrued interest payable	508	442	[1]
Total current liabilities	83,934	96,590	[1]
Long-term debt	458,500	318,000	[1]
Asset retirement obligations	1,747	1,630	[1]
Total liabilities	550,041	416,220	[1]
General Partner	1,026	112	[1]
Total partners’ equity	292,370	238,630	[1]
Non-controlling interests	312,258	312,815	[1]
Delaware Predecessor	0	6,227	[1]	$ 0	$ 435,337	$ 331,675
Total equity	604,628	557,672	[1]	$ 560,020
Total liabilities and equity	1,154,669	973,892	[1]
Previously Reported
Business Acquisition [Line Items]
Cash and cash equivalents		6,649
Accounts receivable		2,481
Accounts receivable – Oasis Petroleum		80,805
Prepaid expenses		1,418
Other current assets		22
Total current assets		91,375
Property, plant and equipment		933,155
Less: accumulated depreciation and amortization		(62,730)
Total property, plant and equipment, net		870,425
Other assets		2,452
Total assets		964,252
Accounts payable		2,180
Accounts payable – Oasis Petroleum		33,014
Accrued liabilities		57,657
Accrued interest payable		442
Total current liabilities		93,293
Long-term debt		318,000
Asset retirement obligations		1,514
Total liabilities		412,807
General Partner		112
Total partners’ equity		238,630
Non-controlling interests		312,815
Delaware Predecessor		0
Total equity		551,445
Total liabilities and equity		964,252
Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Cash and cash equivalents		0
Accounts receivable		0
Accounts receivable – Oasis Petroleum		217
Prepaid expenses		0
Other current assets		0
Total current assets		217
Property, plant and equipment		9,423
Less: accumulated depreciation and amortization		0
Total property, plant and equipment, net		9,423
Other assets		0
Total assets		9,640
Accounts payable		0
Accounts payable – Oasis Petroleum		0
Accrued liabilities		3,297
Accrued interest payable		0
Total current liabilities		3,297
Long-term debt		0
Asset retirement obligations		116
Total liabilities		3,413
General Partner		0
Total partners’ equity		0
Non-controlling interests		0
Delaware Predecessor		6,227
Total equity		6,227
Total liabilities and equity		9,640
Common Units
Business Acquisition [Line Items]
Limited partners	225,339	192,581	[1]
Common Units | Previously Reported
Business Acquisition [Line Items]
Limited partners		192,581
Common Units | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Limited partners		0
Subordinated Units
Business Acquisition [Line Items]
Limited partners	$ 66,005	45,937	[1]
Subordinated Units | Previously Reported
Business Acquisition [Line Items]
Limited partners		45,937
Subordinated Units | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Limited partners		$ 0
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Acquisitions - Statement of Ope

Acquisitions - Statement of Operations Following Acquisition (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended									9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 25, 2017	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Business Acquisition [Line Items]
Total revenues	$ 112,386	$ 103,550	$ 100,403	$ 93,852	$ 72,866	$ 72,105	$ 67,106	$ 61,693			$ 410,191	$ 273,770	[1]	$ 182,216
Operating and maintenance											74,226	63,685	[1]	39,441
Depreciation and amortization											36,358	28,409	[1]	15,730
General and administrative											31,009	23,897	[1]	18,597
Total operating expenses											177,419	123,424	[1]	79,853
Operating income	68,077	61,732	54,580	48,383	40,830	39,416	38,068	32,032			232,772	150,346	[1]	102,363
Interest expense, net of capitalized interest											(17,538)	(2,580)	[1]	(6,965)
Other income (expense)											(3)	(14)	[1]	7
Total other expense, net											(17,541)	(2,594)	[1]	(6,958)
Income before income taxes											215,231	147,752	[1]	95,405
Income tax expense											0	0	[1]	(22,858)
Net income	63,451	57,120	50,246	44,414	38,954	39,160	37,868	31,770	$ 34,970	$ 37,577	215,231	147,752	[2]	72,547
Less: Net income attributable to Delaware Predecessor											4,464	1,343	[1]	0
Less: Net income attributable to non-controlling interests											93,111	96,354	[1]	23,332
Net income attributable to OMP LP	$ 38,479	$ 31,436	$ 26,198	$ 21,543	$ 15,281	$ 12,376	$ 12,444	$ 9,954			117,656	50,055	[1]	11,638
Previously Reported
Business Acquisition [Line Items]
Total revenues												271,623
Operating and maintenance												63,123
Depreciation and amortization												28,404
General and administrative												23,897
Total operating expenses												122,857
Operating income												148,766
Interest expense, net of capitalized interest												(2,343)
Other income (expense)												(14)
Total other expense, net												(2,357)
Income before income taxes												146,409
Income tax expense												0
Net income												146,409
Less: Net income attributable to Delaware Predecessor												0
Less: Net income attributable to non-controlling interests												96,354
Net income attributable to OMP LP												50,055
Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Total revenues												2,147
Operating and maintenance												562
Depreciation and amortization												5
General and administrative												0
Total operating expenses												567
Operating income												1,580
Interest expense, net of capitalized interest												(237)
Other income (expense)												0
Total other expense, net												(237)
Income before income taxes												1,343
Income tax expense												0
Net income												1,343
Less: Net income attributable to Delaware Predecessor												1,343
Less: Net income attributable to non-controlling interests												0
Net income attributable to OMP LP												0
General Partner
Business Acquisition [Line Items]
Net income											2,472	112
Net income attributable to OMP LP											2,472	112	[1]	0
General Partner | Previously Reported
Business Acquisition [Line Items]
Net income attributable to OMP LP												112
General Partner | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Net income attributable to OMP LP												0
Oasis
Business Acquisition [Line Items]
Net income attributable to OMP LP											$ 115,184	49,943	[1]	$ 11,638
Oasis | Previously Reported
Business Acquisition [Line Items]
Net income attributable to OMP LP												49,943
Oasis | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Net income attributable to OMP LP												$ 0
Common Units
Business Acquisition [Line Items]
Basic and Diluted (in usd per share)	$ 1.11	$ 0.91	$ 0.76	$ 0.63	$ 0.54	$ 0.45	$ 0.45	$ 0.36			$ 3.41	$ 1.82	[1]	$ 0.43
Common units- Basic (shares)											20,024	14,504	[1]	13,566
Common units - Diluted (shares)											20,032	14,519	[1]	13,568
Common Units | Previously Reported
Business Acquisition [Line Items]
Basic and Diluted (in usd per share)												$ 1.82
Common units- Basic (shares)												14,504
Common units - Diluted (shares)												14,519
Common Units | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Basic and Diluted (in usd per share)												$ 0
Common units- Basic (shares)												0
Common units - Diluted (shares)												0
Common Units | Oasis
Business Acquisition [Line Items]
Net income									$ 5,819		$ 68,291	$ 25,913
Net income attributable to OMP LP											$ 68,312	$ 26,416		$ 5,819
Common units- Basic (shares)											20,024	14,504		13,566
Common units - Diluted (shares)											20,032	14,519		13,568
Midstream service
Business Acquisition [Line Items]
Total revenues											$ 323,603	$ 252,967		$ 170,178
Product sales
Business Acquisition [Line Items]
Total revenues											86,588	20,803		12,038
Costs of product sales											35,826	7,433	[1]	6,085
Product sales | Previously Reported
Business Acquisition [Line Items]
Costs of product sales												7,433
Product sales | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Costs of product sales												0
Oasis Petroleum | Midstream service
Business Acquisition [Line Items]
Total revenues											317,072	250,363	[1]	168,205
Oasis Petroleum | Midstream service | Previously Reported
Business Acquisition [Line Items]
Total revenues												248,216
Oasis Petroleum | Midstream service | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Total revenues												2,147
Oasis Petroleum | Product sales
Business Acquisition [Line Items]
Total revenues											86,543	17,476	[1]	11,644
Oasis Petroleum | Product sales | Previously Reported
Business Acquisition [Line Items]
Total revenues												17,476
Oasis Petroleum | Product sales | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Total revenues												0
Third parties | Midstream service
Business Acquisition [Line Items]
Total revenues											6,531	2,604	[1]	1,973
Third parties | Midstream service | Previously Reported
Business Acquisition [Line Items]
Total revenues												2,604
Third parties | Midstream service | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Total revenues												0
Third parties | Product sales
Business Acquisition [Line Items]
Total revenues											$ 45	3,327	[1]	$ 394
Third parties | Product sales | Previously Reported
Business Acquisition [Line Items]
Total revenues												3,327
Third parties | Product sales | Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Total revenues												$ 0
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Acquisitions - Statement of Cas

Acquisitions - Statement of Cash Flows Following Acquisition (Details) - USD ($) $ in Thousands	Nov. 14, 2018	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018		Dec. 31, 2017		Sep. 25, 2017	Dec. 31, 2019		Dec. 31, 2018		Dec. 31, 2017
Business Acquisition [Line Items]
Net income		$ 63,451	$ 57,120	$ 50,246	$ 44,414		$ 38,954		$ 39,160	$ 37,868	$ 31,770		$ 34,970		$ 37,577	$ 215,231		$ 147,752	[1]	$ 72,547
Depreciation and amortization																36,358		28,409	[2]	15,730
Equity-based compensation expenses																378		356	[1]	1,052
Deferred financing costs amortization and other																946		(519)	[1]	127
Change in accounts receivable																(37)		3,194	[1]	(56,473)
Change in prepaid expenses																(505)		(640)	[1]	(304)
Change in accounts payable and accrued liabilities																(3,311)		27,814	[1]	24,400
Change in other assets and liabilities, net																(3,479)		22	[1]	94
Net cash provided by operating activities																252,539		206,344	[1]	79,843
Capital expenditures																(225,832)		(283,026)	[1]	(181,424)
Net cash used in investing activities																(250,771)		(283,026)	[1]	(255,944)
Capital contributions from non-controlling interests																5,078		140,277	[1]	33,875
Capital contributions from Delaware Predecessor, net																14,008		4,884	[1]	0
Proceeds from sale of common units, net of offering costs	$ 44,500															0		44,503	[1]	0
Distributions to non-controlling interests																(95,771)		(128,903)	[1]	0
Distribution to Oasis Petroleum for contributed assets																0		(172,429)	[1]	0
Distributions to unitholders																(66,615)		(44,918)	[1]	0
Deferred financing costs																(973)		(966)	[1]	(2,138)
Proceeds from revolving credit facility																153,000		275,000	[1]	78,000
Principal payments on revolving credit facility																(12,500)		(35,000)	[1]	0
Net cash provided by (used in) financing activities																(4,249)		82,448	[1]	176,984
Increase (decrease) in cash and cash equivalents																(2,481)		5,766	[1]	883
Beginning of period					6,649	[1]					883	[1]			$ 0	6,649	[1]	883	[1]	0
End of period		$ 4,168					6,649	[1]					883	[1]		4,168		6,649	[1]	883	[1]
Cash paid for interest, net of capitalized interest																16,592		2,054	[1]	0
Change in accrued capital expenditures																(12,945)		(1,794)	[1]	63,199
Change in asset retirement obligations																117		314	[1]	198
Reimbursement of capital expenditures from Oasis Petroleum																0		7,176	[1]	0
Previously Reported
Business Acquisition [Line Items]
Net income																		146,409
Depreciation and amortization																		28,404
Equity-based compensation expenses																		356
Deferred financing costs amortization and other																		(519)
Change in accounts receivable																		3,411
Change in prepaid expenses																		(640)
Change in accounts payable and accrued liabilities																		27,613
Change in other assets and liabilities, net																		22
Net cash provided by operating activities																		205,012
Capital expenditures																		(276,810)
Net cash used in investing activities																		(276,810)
Capital contributions from non-controlling interests																		140,277
Capital contributions from Delaware Predecessor, net																		0
Proceeds from sale of common units, net of offering costs																		44,503
Distributions to non-controlling interests																		(128,903)
Distribution to Oasis Petroleum for contributed assets																		(172,429)
Distributions to unitholders																		(44,918)
Deferred financing costs																		(966)
Proceeds from revolving credit facility																		275,000
Principal payments on revolving credit facility																		(35,000)
Net cash provided by (used in) financing activities																		77,564
Increase (decrease) in cash and cash equivalents																		5,766
Beginning of period					6,649						883					6,649		883
End of period							6,649						883					6,649		883
Cash paid for interest, net of capitalized interest																		1,817
Change in accrued capital expenditures																		(4,890)
Change in asset retirement obligations																		198
Reimbursement of capital expenditures from Oasis Petroleum																		7,176
Restatement Adjustment
Business Acquisition [Line Items]
Capital expenditures																		(6,216)
Net cash used in investing activities																		(6,216)
Restatement Adjustment | Delaware Acquisition
Business Acquisition [Line Items]
Net income																		1,343
Depreciation and amortization																		5
Equity-based compensation expenses																		0
Deferred financing costs amortization and other																		0
Change in accounts receivable																		(217)
Change in prepaid expenses																		0
Change in accounts payable and accrued liabilities																		201
Change in other assets and liabilities, net																		0
Net cash provided by operating activities																		1,332
Capital contributions from non-controlling interests																		0
Capital contributions from Delaware Predecessor, net																		4,884
Proceeds from sale of common units, net of offering costs																		0
Distributions to non-controlling interests																		0
Distribution to Oasis Petroleum for contributed assets																		0
Distributions to unitholders																		0
Deferred financing costs																		0
Proceeds from revolving credit facility																		0
Principal payments on revolving credit facility																		0
Net cash provided by (used in) financing activities																		4,884
Increase (decrease) in cash and cash equivalents																		0
Beginning of period					$ 0						$ 0					$ 0		0
End of period							$ 0						$ 0					0		$ 0
Cash paid for interest, net of capitalized interest																		237
Change in accrued capital expenditures																		3,096
Change in asset retirement obligations																		116
Reimbursement of capital expenditures from Oasis Petroleum																		$ 0
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Acquisitions (Details)

Acquisitions (Details) - Oasis Midstream Partners, LP shares in Thousands, $ in Millions	Nov. 19, 2018USD ($)shares
Business Acquisition [Line Items]
Consideration paid to acquire additional interest	$ 251.4
Cash consideration paid to acquire additional interest	$ 172.4
Beartooth DevCo
Business Acquisition [Line Items]
Limited liability company interest (percent)	30.00%
Bobcat DevCo
Business Acquisition [Line Items]
Limited liability company interest (percent)	15.00%
Oasis
Business Acquisition [Line Items]
Common units paid as consideration to acquire additional interest (shares) | shares	3,950
Post-effective date purchase price adjustments	$ 1.4

Transactions with Affiliates (D

Transactions with Affiliates (Details) - Oasis - USD ($)	Feb. 22, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
General and administrative		$ 28,000,000	$ 21,100,000	$ 12,800,000
Interest expense, net of capitalized interest		$ 600,000	$ 200,000	$ 6,900,000
Commercial Agreements with OPNA, Oasis Petroleum Marketing LLC (“OPM”) and OMS
Related Party Transaction [Line Items]
Term of contractual arrangements		15 years
2019 Capital Expenditures Arrangement
Related Party Transaction [Line Items]
Amount under capital contributions agreement	$ 80,000,000
Capital contribution	$ 73,000,000
Centralized Corporate, General and Administrative Services | Commercial Agreements with OPNA, Oasis Petroleum Marketing LLC (“OPM”) and OMS
Related Party Transaction [Line Items]
Term of contractual arrangements		15 years

Accrued Liabilities (Details)

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued capital costs	$ 33,105	$ 46,049
Accrued operating expenses	12,149	13,740
Other accrued liabilities	4,956	1,165
Total accrued liabilities	$ 50,210	$ 60,954	[1]
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 1,155,503	$ 942,578	[1]
Less: accumulated depreciation and amortization	(98,982)	(62,730)	[1]
Total property, plant and equipment, net	1,056,521	879,848	[1]
Pipelines
Property, Plant and Equipment [Line Items]
Property, plant and equipment	523,576	395,087
Natural gas processing plants
Property, Plant and Equipment [Line Items]
Property, plant and equipment	296,609	278,680
Produced and flowback water facilities
Property, Plant and Equipment [Line Items]
Property, plant and equipment	121,797	103,572
Compressor stations
Property, Plant and Equipment [Line Items]
Property, plant and equipment	143,276	126,019
Other property and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	34,231	33,829
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 36,014	$ 5,391
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Long-Term Debt (Details)

Long-Term Debt (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Aug. 16, 2019	May 06, 2019	May 05, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Maximum consolidated senior secured leverage ratio	3.75
Covenant Period One
Line of Credit Facility [Line Items]
Maximum consolidated total leverage ratio	4.50
Minimum consolidated interest coverage ratio	3
Covenant Period Two
Line of Credit Facility [Line Items]
Maximum consolidated total leverage ratio	5
Minimum consolidated interest coverage ratio	2.50
Covenant Period Three
Line of Credit Facility [Line Items]
Maximum consolidated total leverage ratio	5.25
Revolving Credit Facility
Line of Credit Facility [Line Items]
Minimum aggregate principal amount threshold under covenant	$ 150,000,000
The Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum aggregate commitment amount	$ 575,000,000	$ 575,000,000	$ 475,000,000	$ 400,000,000
Borrowing capacity increase limit		775,000,000	$ 675,000,000
Weighted average interest rate (percent)	3.80%				4.20%
Amounts outstanding under credit facility	$ 458,500,000				$ 318,000,000
Letters of credit outstanding	1,700,000
Unused borrowing capacity	$ 114,800,000				$ 82,000,000
The Credit Agreement | Revolving Credit Facility | Minimum
Line of Credit Facility [Line Items]
Commitment fee rate (percent)	0.375%
The Credit Agreement | Revolving Credit Facility | Maximum
Line of Credit Facility [Line Items]
Commitment fee rate (percent)	0.50%
The Credit Agreement | Swingline Loans
Line of Credit Facility [Line Items]
Maximum aggregate commitment amount		$ 10,000,000
ABR Loans | Revolving Credit Facility | Adjusted (LIBOR) Rate
Line of Credit Facility [Line Items]
Spread on variable rate (percent)	1.00%
ABR Loans | Revolving Credit Facility | Federal Funds Effective Rate
Line of Credit Facility [Line Items]
Spread on variable rate (percent)	0.50%

Long-Term Debt - Debt Marginal

Long-Term Debt - Debt Marginal Rates (Details)	12 Months Ended
	Dec. 31, 2019
Less than or equal to 3.00 to 1.00 | Maximum
Debt Instrument [Line Items]
Consolidated total leverage ratio	3
Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00 | Minimum
Debt Instrument [Line Items]
Consolidated total leverage ratio	3
Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00 | Maximum
Debt Instrument [Line Items]
Consolidated total leverage ratio	3.50
Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00 | Minimum
Debt Instrument [Line Items]
Consolidated total leverage ratio	3.50
Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00 | Maximum
Debt Instrument [Line Items]
Consolidated total leverage ratio	4
Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00 | Minimum
Debt Instrument [Line Items]
Consolidated total leverage ratio	4
Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00 | Maximum
Debt Instrument [Line Items]
Consolidated total leverage ratio	4.50
Greater than 4.50 to 1.00 | Minimum
Debt Instrument [Line Items]
Consolidated total leverage ratio	4.50
OMP Revolving Line of Credit | Less than or equal to 3.00 to 1.00
Debt Instrument [Line Items]
Commitment fee rate (percent)	0.375%
OMP Revolving Line of Credit | Less than or equal to 3.00 to 1.00 | Eurodollar Loans
Debt Instrument [Line Items]
Applicable margin (percent)	1.75%
OMP Revolving Line of Credit | Less than or equal to 3.00 to 1.00 | Alternate Based Rate (ABR)
Debt Instrument [Line Items]
Applicable margin (percent)	0.75%
OMP Revolving Line of Credit | Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00
Debt Instrument [Line Items]
Commitment fee rate (percent)	0.375%
OMP Revolving Line of Credit | Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00 | Eurodollar Loans
Debt Instrument [Line Items]
Applicable margin (percent)	2.00%
OMP Revolving Line of Credit | Greater than 3.00 to 1.00 but less than or equal to 3.50 to 1.00 | Alternate Based Rate (ABR)
Debt Instrument [Line Items]
Applicable margin (percent)	1.00%
OMP Revolving Line of Credit | Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00
Debt Instrument [Line Items]
Commitment fee rate (percent)	0.50%
OMP Revolving Line of Credit | Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00 | Eurodollar Loans
Debt Instrument [Line Items]
Applicable margin (percent)	2.25%
OMP Revolving Line of Credit | Greater than 3.50 to 1.00 but less than or equal to 4.00 to 1.00 | Alternate Based Rate (ABR)
Debt Instrument [Line Items]
Applicable margin (percent)	1.25%
OMP Revolving Line of Credit | Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00
Debt Instrument [Line Items]
Commitment fee rate (percent)	0.50%
OMP Revolving Line of Credit | Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00 | Eurodollar Loans
Debt Instrument [Line Items]
Applicable margin (percent)	2.50%
OMP Revolving Line of Credit | Greater than 4.00 to 1.00 but less than or equal to 4.50 to 1.00 | Alternate Based Rate (ABR)
Debt Instrument [Line Items]
Applicable margin (percent)	1.50%
OMP Revolving Line of Credit | Greater than 4.50 to 1.00
Debt Instrument [Line Items]
Commitment fee rate (percent)	0.50%
OMP Revolving Line of Credit | Greater than 4.50 to 1.00 | Eurodollar Loans
Debt Instrument [Line Items]
Applicable margin (percent)	2.75%
OMP Revolving Line of Credit | Greater than 4.50 to 1.00 | Alternate Based Rate (ABR)
Debt Instrument [Line Items]
Applicable margin (percent)	1.75%

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease assets	$ 5,207
Present value of future lease payments	$ 5,221
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease assets		$ 4,100
Present value of future lease payments		$ 4,100

Leases - Schedule of lease cost

Leases - Schedule of lease costs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease costs	$ 3,204
Variable lease costs	414
Short-term lease costs	144
Amortization of ROU assets	26
Interest on lease liabilities	20
Total lease costs	$ 3,808

Leases - Maturities of the Part

Leases - Maturities of the Partnership's lease liabilities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Operating Leases
2020	$ 3,150
2021	1,530
2022	743
2023	0
2024	0
Thereafter	0
Total future lease payments	5,423
Less: Imputed interest	202
Present value of future lease payments	5,221
Finance Leases
2020	11
2021	45
2022	45
2023	45
2024	45
Thereafter	639
Total future lease payments	830
Less: Imputed interest	273
Present value of future lease payments	$ 557

Leases - Schedule of future min

Leases - Schedule of future minimum rental commitments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 736
2020	0
2021	0
2022	0
2023	0
Thereafter	0
Total future minimum lease payments	$ 736

Leases - Schedule of supplement

Leases - Schedule of supplemental balance sheet information (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating lease assets	$ 5,207
Finance lease assets	602
Total lease assets	5,809
Operating lease liabilities	3,005
Finance lease liabilities	5
Operating lease liabilities	2,216
Finance lease liabilities	552
Total lease liabilities	5,778
Finance lease ROU asset accumulated amortization	$ 30

Leases - Schedule of lease co_2

Leases - Schedule of lease costs, supplemental cash flow information and non-cash transactions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 3,107
Operating cash flows from finance leases	20
Financing cash flows from finance leases	59
Operating leases	4,109
Finance leases	$ 660

Leases - Schedule of weighted a

Leases - Schedule of weighted average remaining lease term and discount rates (Details)	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	2 years
Operating Lease, Weighted Average Discount Rate, Percent	4.10%
Finance Lease, Weighted Average Remaining Lease Term	19 years 2 months 12 days
Finance Lease, Weighted Average Discount Rate, Percent	4.30%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Predecessor net tax liabilities eliminated	$ 104,005	$ 104,000
Difference between tax bases and reported amounts of Partnership's assets and liabilities		$ 122,700

Income Taxes - Components of Pr

Income Taxes - Components of Predecessor's Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Current:
Federal				$ 15,571
State				2,047
Total current income tax expense				17,618
Deferred:
Federal				4,631
State				609
Total deferred income tax expense	$ 0	$ 0	[1]	5,240
Total income tax expense	$ 0	$ 0	[2]	$ 22,858
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Effective Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	[1]	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent [Abstract]
U.S. federal statutory rate (percent)				35.00%
Earnings not subject to tax subsequent to the Offering (percent)				(12.83%)
State income taxes, net of federal income tax benefit (percent)				1.81%
Other (percent)				(0.02%)
Annual effective tax rate (percent)				23.96%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
U.S. federal statutory rate				$ 33,392
Earnings not subject to tax subsequent to the initial public offering				(12,239)
State income taxes, net of federal income tax benefit				1,727
Other				(22)
Total income tax expense	$ 0	$ 0		$ 22,858
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Commitments and Contingencies_2

Commitments and Contingencies (Details) bbl in Millions	Nov. 01, 2019USD ($)	Mar. 23, 2017USD ($)	Dec. 31, 2019bbl	Feb. 28, 2020USD ($)
Mirada Litigation
Loss Contingencies [Line Items]
Damages sought	$ 200,000,000	$ 100,000,000
Water Volume Commitment Agreements
Loss Contingencies [Line Items]
Additional volumes of produced water under agreement | bbl			13.1
Term of contractual arrangements			10 years
Water Volume Commitment Agreements | Subsequent Event
Loss Contingencies [Line Items]
Unrecorded commitments				$ 3,800,000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Purchase Commitments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 3,600
2021	2,759
2022	876
2023	0
2024	0
Thereafter	838
Total	$ 8,073

Equity-Based Compensation (Deta

Equity-Based Compensation (Details) - Long Term Incentive Plan (LTIP) - USD ($)	Jan. 01, 2020	Oct. 19, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate number of common units that were reserved for issuance under LTIP (shares)			2,455,408
Percentage of number of common units outstanding (percent)			1.00%
Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted unit awards granted (shares)			0
Vesting period			3 years
Stock-based compensation expense			$ 100,000	$ 100,000
Vested awards (shares)			22,112
Weighted average grant date per share (in dollars per share)			$ 0
Restricted Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted unit awards granted (shares)			16,170
Vesting period			1 year
Stock-based compensation expense			$ 400,000	400,000	$ 100,000
Fair value of vested awards			$ 300,000	$ 300,000
Vested awards (shares)			17,260		0
Weighted average grant date per share (in dollars per share)			$ 18.57	$ 17.55	$ 17
Unrecognized compensation cost			$ 10,000
Expected recognition period			1 month 6 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Stock-based compensation expense					$ 1,000,000
Fair value of vested awards					$ 800,000
Weighted average grant date per share (in dollars per share)					$ 14.95
Unrecognized compensation cost			$ 0
Oasis Midstream Partners, LP | Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted unit awards granted (shares)		101,500	0	0
Fair value of vested awards			$ 400,000	$ 600,000
Vested awards (shares)				0
Weighted average grant date per share (in dollars per share)			$ 16.40
Unrecognized compensation cost			$ 400,000
Expected recognition period			10 months 24 days
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional number of common units that were reserved for issuance under LTIP (shares)	337,952

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Equity Units Activity (Details) - Long Term Incentive Plan (LTIP) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (shares)	58,379
Granted (shares)	0
Vested (shares)	(22,112)
Forfeited (shares)	(14,198)
Outstanding at end of period (shares)	22,069	58,379
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date per share, outstanding (in dollars per share)	$ 16.40
Weighted average grant date per share, granted (in dollars per share)	0
Weighted average grant date per share, vested (in dollars per share)	16.40
Weighted average grant date per share, forfeited (in dollars per share)	16.40
Weighted average grant date per share, outstanding (in dollars per share)	$ 16.40	$ 16.40
Restricted Units
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (shares)	17,260
Granted (shares)	16,170
Vested (shares)	(17,260)		0
Forfeited (shares)	0
Outstanding at end of period (shares)	16,170	17,260
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date per share, outstanding (in dollars per share)	$ 17.55
Weighted average grant date per share, granted (in dollars per share)	18.57	$ 17.55	$ 17
Weighted average grant date per share, vested (in dollars per share)	17.55
Weighted average grant date per share, forfeited (in dollars per share)	0
Weighted average grant date per share, outstanding (in dollars per share)	$ 18.57	$ 17.55

Partnership Equity and Distri_3

Partnership Equity and Distributions (Details) $ / shares in Units, $ in Thousands	Feb. 27, 2020USD ($)	Jan. 30, 2020$ / shares	Nov. 14, 2018USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Sep. 30, 2019USD ($)$ / shares	Jun. 30, 2019USD ($)$ / shares	Mar. 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)$ / shares	Sep. 30, 2018USD ($)$ / shares	Jun. 30, 2018USD ($)$ / shares	Mar. 31, 2018USD ($)$ / shares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)		Dec. 31, 2017USD ($)
Distribution Made to Limited Partner [Line Items]
Proceeds from sale of common units, net of offering costs | $			$ 44,500									$ 0	$ 44,503	[1]	$ 0
Quarterly cash distribution declared (in usd per share)				$ 0.5400	$ 0.5150	$ 0.4900	$ 0.4700	$ 0.4500	$ 0.4300	$ 0.4100	$ 0.3925
Distribution declared | $												$ 70,578	49,247		10,991
Number of common units each subordinated unit can be converted into upon subordination (shares) | shares				1								1
Subordination conversion ratio				1								1
General Partner
Distribution Made to Limited Partner [Line Items]
Distribution declared | $				$ 1,027	$ 745	$ 463	$ 238	$ 112	$ 0	$ 0	$ 0	$ 2,472	112		0
Cash Distribution
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												$ 0.3750
Target annualized distributions (in usd per unit)												$ 1.50
Termination threshold as percentage of sum of minimum distribution multiplied by total number of units outstanding (percent)												150.00%
Cash Distribution | Target Distribution up to $0.375
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												$ 0.375
Cash Distribution | Target Distribution above $0.375 up to $0.4313 | Minimum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												0.375
Cash Distribution | Target Distribution above $0.375 up to $0.4313 | Maximum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												0.4313
Cash Distribution | Target Distribution above $0.4313 up to $0.4688 | Minimum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												0.4313
Cash Distribution | Target Distribution above $0.4313 up to $0.4688 | Maximum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												0.4688
Cash Distribution | Target Distribution above $$0.4688 up to 0.5625 | Minimum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												0.4688
Cash Distribution | Target Distribution above $$0.4688 up to 0.5625 | Maximum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												0.5625
Cash Distribution | Target Distribution above $0.5625 | Minimum
Distribution Made to Limited Partner [Line Items]
Partners periodic distribution (in dollars per share)												$ 0.5625
Cash Distribution | Limited Partners | Target Distribution up to $0.375
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				100.00%								100.00%
Cash Distribution | Limited Partners | Target Distribution above $0.375 up to $0.4313
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				100.00%								100.00%
Cash Distribution | Limited Partners | Target Distribution above $0.4313 up to $0.4688
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				85.00%								85.00%
Cash Distribution | Limited Partners | Target Distribution above $$0.4688 up to 0.5625
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				75.00%								75.00%
Cash Distribution | Limited Partners | Target Distribution above $0.5625
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				50.00%								50.00%
Cash Distribution | General Partner
Distribution Made to Limited Partner [Line Items]
Termination threshold as percentage of sum of minimum distribution multiplied by total number of units outstanding (percent)												50.00%
Basis for General Partners' interest in distributions (in dollars per share)												$ 0.4313
Cash Distribution | General Partner | Target Distribution up to $0.375
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				0.00%								0.00%
Cash Distribution | General Partner | Target Distribution above $0.375 up to $0.4313
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				0.00%								0.00%
Cash Distribution | General Partner | Target Distribution above $0.4313 up to $0.4688
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				15.00%								15.00%
Cash Distribution | General Partner | Target Distribution above $$0.4688 up to 0.5625
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				25.00%								25.00%
Cash Distribution | General Partner | Target Distribution above $0.5625
Distribution Made to Limited Partner [Line Items]
Marginal percentage interest in distributions (percent)				50.00%								50.00%
Subsequent Event
Distribution Made to Limited Partner [Line Items]
Quarterly cash distribution declared (in usd per share)		$ 0.54
Subsequent Event | General Partner
Distribution Made to Limited Partner [Line Items]
Distribution declared | $	$ 1,000
Common Units | Limited Partners
Distribution Made to Limited Partner [Line Items]
Distribution declared | $				$ 10,833	10,323	9,822	9,421	9,020	5,925	5,649	5,406	$ 40,400	26,001		5,498
Subordinated Units | Limited Partners
Distribution Made to Limited Partner [Line Items]
Distribution declared | $				$ 7,425	$ 7,081	$ 6,738	$ 6,463	$ 6,188	$ 5,913	$ 5,638	$ 5,397	$ 27,706	$ 23,134		$ 5,493
Oasis Midstream Partners, LP | Partnership Interest | Common Units
Distribution Made to Limited Partner [Line Items]
Common units sold in public offering (shares) | shares			2,300,000
Price of common units sold, net of underwriting discounts and commission (in usd per share)			$ 20
Oasis Midstream Partners, LP | Partnership Interest | Over-Allotment Option | Common Units
Distribution Made to Limited Partner [Line Items]
Common units sold in public offering (shares) | shares			300,000
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Earnings Per Limited Partner _3

Earnings Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distribution declared									$ 70,578	$ 49,247		$ 10,991
Undistributed earnings attributable to OMP LP									47,078	808		647
Net income attributable to OMP LP	$ 38,479	$ 31,436	$ 26,198	$ 21,543	$ 15,281	$ 12,376	$ 12,444	$ 9,954	$ 117,656	$ 50,055	[1]	$ 11,638
Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Basic weighted average common units outstanding									20,024	14,504	[1]	13,566
Diluted weighted average common units outstanding									20,032	14,519	[1]	13,568
Weighted average limited partner units outstanding
Common units- Basic (shares)									20,024	14,504	[1]	13,566
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Common units - Diluted (shares)									20,032	14,519	[1]	13,568
General Partner
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distribution declared	1,027	745	463	238	112	0	0	0	$ 2,472	$ 112		$ 0
Undistributed earnings attributable to OMP LP									0	0		0
Net income attributable to OMP LP									2,472	112	[1]	0
Limited Partners
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to OMP LP									$ 115,184	$ 49,943	[1]	$ 11,638
Limited Partners | Common Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Basic weighted average common units outstanding									20,024	14,504		13,566
Dilutive effect of restricted awards (in shares)									8	15		2
Diluted weighted average common units outstanding									20,032	14,519		13,568
Distribution declared	10,833	10,323	9,822	9,421	9,020	5,925	5,649	5,406	$ 40,400	$ 26,001		$ 5,498
Undistributed earnings attributable to OMP LP									27,912	415		321
Net income attributable to OMP LP									$ 68,312	$ 26,416		$ 5,819
Weighted average limited partner units outstanding
Common units- Basic (shares)									20,024	14,504		13,566
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Common units - Diluted (shares)									20,032	14,519		13,568
Net Income (Loss), Per Outstanding Limited Partnership Unit, Diluted, Other Disclosures [Abstract]
Earnings per limited partner units - basic (in usd per share)									$ 3.41	$ 1.82		$ 0.43
Earnings per limited partner units - diluted (in usd per share)									$ 3.41	$ 1.82		$ 0.43
Antidilutive restricted units (in shares)									13	6		10
Limited Partners | Subordinated Units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Distribution declared	$ 7,425	$ 7,081	$ 6,738	$ 6,463	$ 6,188	$ 5,913	$ 5,638	$ 5,397	$ 27,706	$ 23,134		$ 5,493
Undistributed earnings attributable to OMP LP									19,166	393		326
Net income attributable to OMP LP									$ 46,872	$ 23,527		$ 5,819
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Quarterly Financial Data - Un_3

Quarterly Financial Data - Unaudited (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									9 Months Ended	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 25, 2017	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 112,386	$ 103,550	$ 100,403	$ 93,852	$ 72,866	$ 72,105	$ 67,106	$ 61,693			$ 410,191	$ 273,770	[1]	$ 182,216
Operating income(1)	68,077	61,732	54,580	48,383	40,830	39,416	38,068	32,032			232,772	150,346	[1]	102,363
Net income	63,451	57,120	50,246	44,414	38,954	39,160	37,868	31,770	$ 34,970	$ 37,577	215,231	147,752	[2]	72,547
Net income attributable to Oasis Midstream Partners LP	$ 38,479	$ 31,436	$ 26,198	$ 21,543	$ 15,281	$ 12,376	$ 12,444	$ 9,954			$ 117,656	$ 50,055	[1]	$ 11,638
Common Units
Condensed Financial Statements, Captions [Line Items]
Basic and Diluted (in usd per share)	$ 1.11	$ 0.91	$ 0.76	$ 0.63	$ 0.54	$ 0.45	$ 0.45	$ 0.36			$ 3.41	$ 1.82	[1]	$ 0.43
[1]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.
[2]	Retrospectively adjusted for the transfer of net assets between entities under common control. See Note 4 — Acquisitions.

Uncategorized Items - omp-20191

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (59,000)