Supplementary Data (Unaudited) | Supplementary Data (Unaudited) 1) Oil and Gas Producing Activities In accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification Topic 932, “Extractive Activities—Oil and Gas”, and regulations of the U.S. Securities and Exchange Commission (SEC), the Company is making certain supplemental disclosures about its oil and gas exploration and production operations. A. Estimated Proved Net After Royalty (“NAR”) Reserves The following table sets forth Gran Tierra’s estimated proved NAR reserves and total net proved developed and undeveloped reserves as of December 31, 2021, 2022, and 2023, and the changes in total net proved reserves during the three-year period ended December 31, 2023. The net proved reserves represent management’s best estimate of proved oil and natural gas reserves after royalties. Reserve estimates for each property are prepared internally each year and 100% of the reserves at December 31, 2023, have been evaluated by independent reservoir engineering specialist, McDaniel & Associates Consultants Ltd. The reserve estimation process requires us to use significant decisions and assumptions in the evaluation of available geological, geophysical, engineering and economic data for each property, and demonstrate reasonable certainty that they are recoverable from known reservoirs under economic and operating conditions that existed at year end. The determination of oil and natural gas reserves is complex and requires significant judgment. Assumptions used to estimate reserve information may significantly increase or decrease such reserves in future periods. The estimates of reserves are subject to continuing changes and, therefore, an accurate determination of reserves may not be possible for many years because of the time needed for development, drilling, testing, and studies of reservoirs. Liquids (1) Gas (Mbbl) (MMcf) Proved NAR Reserves, December 31, 2020 64,692 1,655 Improved recoveries 2,057 — Extensions (2) 7,475 — Technical revisions 1,009 133 Production (8,668) (119) Proved NAR Reserves, December 31, 2021 66,565 1,669 Extensions and discoveries (2) 6,273 — Technical revisions (2) 1,558 (208) Production (9,129) (15) Proved NAR Reserves, December 31, 2022 65,267 1,446 Extensions and discoveries (2) 17,808 — Technical revisions (2) 725 (1,446) Production (3) (9,504) — Proved NAR Reserves, December 31, 2023 74,296 — Proved Developed Reserves NAR, December 31, 2020 38,660 633 Proved Developed Reserves NAR, December 31, 2021 41,869 880 880 Proved Developed Reserves NAR, December 31, 2022 40,360 858 858 Proved Developed Reserves NAR, December 31, 2023 39,599 — Proved Undeveloped Reserves NAR, December 31, 2020 26,032 1,022 Proved Undeveloped Reserves NAR, December 31, 2021 24,696 789 Proved Undeveloped Reserves NAR, December 31, 2022 24,907 588 Proved Undeveloped Reserves NAR, December 31, 2023 34,697 — (1) At December 31, 2023, 2022, and 2021, liquids reserves are 100% oil. (2) Includes the following volumes related to Ecuador: 2023 - 1.5 MMbbl of extensions and 0.6 MMbbl of technical revisions; 2022 - 2.5 MMbbl of extensions and (0.2) MMbbl of technical revisions; 2021 - 0.5 MMbbl of extensions (3) Includes 0.2 MMbbl of production related to Ecuador for the year ended December 31, 2023 Changes in proved reserves during the years ended December 31, 2023, 2022 and 2021 shown in the table above primarily resulted from the following significant factors: Improved Recoveries. There were no improved recoveries for the years ended December 31, 2023 and 2022, respectively. There were 2.1 MMbbl of improved recoveries of heavy oil in the Acordionero field for the year ended December 31, 2021. Extensions and Discoveries. Added 17.8 MMbbl of proved reserves during the year ended December 31, 2023, of which 16.3 MMbbl were extensions in Colombia and 1.5 MMbbl were discoveries in Ecuador. In Colombia, we had 1.2, 3.5, 2.0 and 9.6 MMbbl of extensions in the Acordionero, Costayaco and Moqueta fields and Suroriente Block respectively, with a 1.5 MMbbl discovery in the Chanangue Block (2022 - 6.3 MMbbl due to reserve extensions in the Acordionero and Costayaco fields and the Charapa and Chanangue Blocks and a discovery in the Alea-1848 Block and 2021 - 7.5 MMbbl, due to reserve extensions in the Acordionero, Costayaco, Moqueta and Charapa fields). Technical and Economic Revisions. Added 0.7 MMbbl of proved oil reserves and removed all gas reserves during the year ended December 31, 2023. In Colombia this was primarily due to continued waterflood performance in the Costayaco and Acordionero fields as well as production type curve increases in the Ecuador Blocks (2022 - 1.6 MMBOE related to positive technical revisions based on increased drilling and continued waterflood performance in the Acordionero and Costayaco fields and 2021 - 1.0 MMBOE , related to positive technical revisions based on performance and waterflood response in the Acordionero and Costayaco fields). B. Capitalized Costs Capitalized costs for Gran Tierra’s oil and gas producing activities consisted of the following at the end of each of the years in the two-year period ended December 31, 2023: (Thousands of U.S. Dollars) Proved Properties Unproved Properties Accumulated Net Capitalized Costs Balance, December 31, 2023 $ 4,876,185 $ 54,116 $ (3,821,115) $ 1,109,186 Balance, December 31, 2022 $ 4,617,804 $ 74,471 $ (3,617,380) $ 1,074,895 C. Costs Incurred The following table presents costs incurred for Gran Tierra’s oil and gas property acquisitions and exploration and development for the respective years: (Thousands of U.S. Dollars) Colombia Ecuador Total Year Ended December 31, 2021 Property acquisition costs Proved $ — $ — $ — Unproved $ — $ — $ — Exploration costs $ 18,080 $ 2,330 $ 20,410 Development costs $ 142,461 $ — $ 142,461 Year Ended December 31, 2022 Property acquisition costs Proved $ — $ — $ — Unproved $ — $ — $ — Exploration costs $ 50,374 $ 39,524 $ 89,898 Development costs $ 160,933 $ — $ 160,933 Year Ended December 31, 2023 Property acquisition costs Proved $ — $ — $ — Unproved $ — $ — $ — Exploration costs $ 15,674 $ 14,188 $ 29,862 Development costs $ 199,240 $ 4,581 $ 203,821 D. Results of Operations for Oil and Gas Producing Activities (Thousands of U.S. Dollars) Colombia Ecuador Total December 31, 2023 Oil sales $ 621,297 $ 15,660 $ 636,957 Production costs (192,933) (8,477) (201,410) Exploration expenses — — — DD&A expenses (207,346) (8,018) (215,364) Inventory impairment — — — Income tax (expense) recovery (103,491) 90 (103,401) Results of Operations $ 117,527 $ (745) $ 116,782 December 31, 2022 Oil sales $ 711,388 $ — $ 711,388 Production costs (172,582) — (172,582) Exploration expenses — — — DD&A expenses (180,039) — (180,039) Inventory impairment — — — Income tax (expense) recovery (105,906) — (105,906) Results of Operations $ 252,861 $ — $ 252,861 December 31, 2021 Oil sales $ 473,722 $ — $ 473,722 Production costs (147,339) — (147,339) Exploration expenses — — — DD&A expenses (139,765) — (139,765) Inventory impairment — — — Income tax (expense) recovery 19,346 — 19,346 Results of Operations $ 205,964 $ — $ 205,964 E. Standardized Measure of Discounted Future Net Cash Flows and Changes The following disclosure is based on estimates of net proved reserves and the period during which they are expected to be produced. Future cash inflows are computed by applying the twelve month period unweighted arithmetic average of the price as of the first day of each month within that twelve month period, unless prices are defined by contractual arrangements, excluding escalations based on future conditions to Gran Tierra’s after royalty share of estimated annual future production from proved oil and gas reserves. Colombia Ecuador Twelve month period unweighted arithmetic average of the wellhead price as of the first day of each month within the twelve month period 2023 $ 69.91 $ 77.44 2022 $ 86.16 $ 91.53 2021 $ 58.07 $ 62.42 Weighted average production costs 2023 $ 18.54 $ 20.66 2022 $ 16.26 $ 19.55 2021 $ 15.55 $ 17.40 Future development and production costs to be incurred in producing and further developing the proved reserves are based on year end cost indicators. Future income taxes are computed by applying year end statutory tax rates. These rates reflect allowable deductions and tax credits, and are applied to the estimated pre-tax future net cash flows. Discounted future net cash flows are calculated using 10% mid-year discount factors. The calculations assume the continuation of existing economic, operating and contractual conditions. However, such prescribed assumptions have not proved to be the case in the past. Other assumptions could give rise to substantially different results. The Company believes this information does not in any way reflect the current economic value of its oil and gas producing properties or the present value of their estimated future cash flows as: • no economic value is attributed to probable and possible reserves; • use of a 10% prescribed discount rate; and • prices change constantly from the twelve-month period unweighted arithmetic average of the price as of the first day of each month within that twelve-month period. The standardized measure of discounted future net cash flows from Gran Tierra’s estimated proved oil and gas reserves is as follows: (Thousands of U.S. Dollars) Colombia Ecuador Total December 31, 2023 Future cash inflows $ 4,893,758 $ 358,421 $ 5,252,179 Future production costs $ (1,552,227) $ (158,643) $ (1,710,870) Future development costs $ (460,819) $ (89,639) $ (550,458) Future asset retirement obligations $ (82,314) $ (3,300) $ (85,614) Future income tax expense $ (954,973) $ (41,852) $ (996,825) Future net cash flows $ 1,843,425 $ 64,987 $ 1,908,412 10% discount $ (516,451) $ (22,924) $ (539,375) Standardized Measure of Discounted Future Net Cash Flows $ 1,326,974 $ 42,063 $ 1,369,037 December 31, 2022 Future cash inflows $ 5,410,256 $ 256,220 $ 5,666,476 Future production costs (1,298,198) (104,614) (1,402,812) Future development costs (334,560) (63,040) (397,600) Future asset retirement obligations (50,520) (2,700) (53,220) Future income tax expense (1,391,436) (33,058) (1,424,494) Future net cash flows 2,335,542 52,808 2,388,350 10% discount (659,092) (18,632) (677,724) Standardized Measure of Discounted Future Net Cash Flows $ 1,676,450 $ 34,176 $ 1,710,626 December 31, 2021 Future cash inflows $ 3,880,608 $ 30,573 $ 3,911,181 Future production costs (1,249,901) (13,502) (1,263,403) Future development costs (365,983) (12,175) (378,158) Future asset retirement obligations (47,580) (600) (48,180) Future income tax expense (514,231) (1,866) (516,097) Future net cash flows 1,702,913 2,430 1,705,343 10% discount (481,504) (2,062) (483,566) Standardized Measure of Discounted Future Net Cash Flows $ 1,221,409 $ 368 $ 1,221,777 Changes in the Standardized Measure of Discounted Future Net Cash Flows The following table summarizes changes in the standardized measure of discounted future net cash flows for Gran Tierra’s proved oil and gas reserves: (Thousands of U.S. Dollars) 2023 2022 2021 Balance, beginning of year $ 1,710,626 $ 1,221,777 $ 727,487 Sales and transfers of oil and gas produced, net of production costs (739,703) (433,676) (244,486) Net changes in prices and production costs related to future production (924,346) 1,373,950 1,217,785 Extensions, discoveries and improved recovery, less related costs 583,254 384,414 382,423 Previously estimated development costs incurred during the year (156,664) (136,856) (98,724) Revisions of previous quantity estimates 981,873 75,460 (191,738) Accretion of discount 171,063 122,178 72,748 Net change in income taxes 32,875 (739,879) (414,458) Changes in future development costs (289,941) (156,742) (229,260) Net (decrease) increase (341,589) 488,849 494,290 Balance, end of year $ 1,369,037 $ 1,710,626 $ 1,221,777 |