Supplemental Oil and Gas Disclosures (Unaudited) | Note 13 — Suppl emental Oil and Gas Disclosures (Unaudited) Capitalized Costs Aggregate amounts of capitalized costs relating to oil, natural gas and NGL activities and the aggregate amount of related accumulated depletion and amortization as of the dates indicated are presented below (in thousands): Year Ended December 31, 2021 2020 Proved properties $ 5,232,479 $ 4,945,550 Unproved oil and gas properties, not subject to amortization (1) 219,055 254,994 Total oil and gas properties 5,451,534 5,200,544 Less: Accumulated depletion 3,072,907 2,680,254 Net capitalized costs $ 2,378,627 $ 2,520,290 Depletion and amortization rate (Per MBoe) (2) $ 16.71 $ 31.42 (1) Amount includes $ 110.3 million and $ 121.7 million of unproved properties, not subject to amortization, related to the Company’s operations in offshore Mexico for the years ended December 31, 2021 and 2020, respectively. (2) Year ended December 31, 2020 includes the impact of a write-down of its U.S. oil and natural gas properties as result of the Company's ceiling test computations. See Note 4 — Property, Plant and Equipment for additional information. Included in the depletable basis of proved oil and gas properties is the estimate of the Company’s proportionate share of asset retirement costs relating to these properties which are also reflected as “Asset retirement obligations” on the accompanying Consolidated Balance Sheets. See Note 4 — Property, Plant and Equipment for additional information. Costs Incurred for Property Acquisition, Exploration and Development Activities The following table reflects the costs incurred in oil, natural gas and NGL property acquisition, exploration and development activities during the years indicated (in thousands). Costs incurred also include new asset retirement obligations established in the current year, as well as increases or decreases to the asset retirement obligations resulting from changes to estimates during the year. Year Ended December 31, 2021 2020 2019 Property acquisition costs: Proved properties $ 210 $ 422,833 $ 27,660 Unproved properties, not subject to amortization — 95,242 16,062 Total property acquisition costs 210 518,075 43,722 Exploration costs (1) 23,844 59,422 209,161 Development costs 245,058 362,011 292,547 Total costs incurred $ 269,112 $ 939,508 $ 545,430 (1) Amount includes $ 6.6 million, $ 14.6 million and $ 74.2 million of exploration costs related to the Company’s operations in offshore Mexico for the year ended December 31, 2021, 2020 and 2019 , respectively. Estimated Quantities of Proved Oil, Natural Gas and NGL Reserves The Company employs full-time experienced reserve engineers and geologists who are responsible for determining proved reserves in compliance with SEC guidelines. There are numerous uncertainties inherent in estimating quantities of proved reserves and projecting future rates of production and timing of development expenditures. The reserve data in the following tables only represent estimates and should not be construed as being exact. Engineering reserve estimates were prepared based upon interpretation of production performance data and sub-surface information obtained from the drilling of existing wells. The Company’s Director of Reserves, internal reservoir engineers and geologists analyzed and prepared reserve estimates on all oil and natural gas fields. All of the Company’s proved oil, natural gas and NGL reserves are located in the U.S. Gulf of Mexico. At, December 31, 2021, 2020 and 2019 , 100 % of proved oil, natural gas and NGL reserves attributable to all of the Company’s oil and natural gas properties were estimated and compiled for reporting purposes by the Company’s reservoir engineers and audited by Netherland, Sewell & Associates, Inc. (“NSAI”), independent petroleum engineers and geologists. The following table presents the Company’s estimated proved reserves at its net ownership interest: Oil (MBbls) Gas (MMcf) NGL (MBbls) Oil Total proved reserves at December 31, 2018 112,539 171,024 10,696 151,739 Revision of previous estimates ( 5,553 ) ( 15,898 ) ( 1,237 ) ( 9,440 ) Production ( 13,844 ) ( 23,306 ) ( 1,228 ) ( 18,956 ) Purchases of reserves 2,094 2,626 130 2,662 Extensions and discoveries 11,518 21,552 620 15,730 Total proved reserves at December 31, 2019 106,754 155,998 8,981 141,735 Revision of previous estimates ( 14,633 ) ( 56,358 ) ( 168 ) ( 24,195 ) Production (1) ( 13,665 ) ( 28,652 ) ( 1,559 ) ( 19,999 ) Purchases of reserves 26,903 181,872 3,528 60,743 Extensions and discoveries 3,948 4,348 76 4,749 Total proved reserves at December 31, 2020 109,307 257,208 10,858 163,033 Revision of previous estimates 13,619 8,979 5,137 20,252 Production ( 16,159 ) ( 32,795 ) ( 1,875 ) ( 23,500 ) Extensions and discoveries 997 2,961 315 1,806 Total proved reserves at December 31, 2021 107,764 236,353 14,435 161,591 Total proved developed reserves as of: December 31, 2019 72,016 115,381 6,733 97,979 December 31, 2020 85,007 204,054 8,104 127,120 December 31, 2021 93,420 186,442 11,792 136,286 Total proved undeveloped reserves as of: December 31, 2019 34,738 40,617 2,248 43,756 December 31, 2020 24,300 53,154 2,754 35,913 December 31, 2021 14,344 49,911 2,643 25,305 (1) Excludes approximately 3.0 MBoe of Mexico well test production . During 2021, proved reserves decreased by 1.4 MMBoe primarily due to a decrease of 23.5 MMBoe of production. The decrease was partially offset by revision to previous estimates of 20.3 MMBoe due to increase in commodity prices as well as 1.8 MMBoe of estimated proved reserves from extensions and discoveries primarily from an evaluation of Crown and Anchor Field located in the Mississippi Canyon core area. During 2020 , proved reserves decreased by 21.3 MMBoe primarily due to a decrease of 20.0 MMBoe of production and revision to previous estimates of 24.2 MMBoe due to decrease in commodity prices. The decrease was partially offset by the addition of 60.7 MMBoe added through purchases from the ILX and Castex Acquisition, Castex Energy 2005 Acquisition and LLOG Acquisition as well as 4.7 MMBoe of estimated proved reserves from extensions and discoveries primarily from an evaluation of Green Canyon 18 and Claiborne Fields. During 2019 , proved reserves decreased by 10.0 MMBoe primarily due to a decrease of 19.0 MMBoe of production and revision to previous estimates of 9.7 MMBoe due to the Phoenix and Ram Powell Fields. The decrease was partially offset by the addition of 15.7 MMBoe of estimated proved reserves from extensions and discoveries primarily from an evaluation of Green Canyon 21, Pompano, and Ewing Bank 305 as well as 3.0 MMBoe added through purchases from the Gunflint Acquisition. Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil, Natural Gas and NGL Reserves The following table reflects the standardized measure of discounted future net cash flows relating to the Company’s interest in proved oil, natural gas and NGL reserves (in thousands): Year Ended December 31, 2021 2020 2019 Future cash inflows $ 8,496,005 $ 4,927,497 $ 7,151,875 Future costs: Production ( 1,868,818 ) ( 1,105,211 ) ( 1,633,432 ) Development and abandonment ( 1,422,507 ) ( 1,236,874 ) ( 1,464,270 ) Future net cash flows before income taxes 5,204,680 2,585,412 4,054,173 Future income tax expense ( 676,778 ) ( 141,515 ) ( 662,317 ) Future net cash flows after income taxes 4,527,902 2,443,897 3,391,856 Discount at 10% annual rate ( 1,087,291 ) ( 538,963 ) ( 854,261 ) Standardized measure of discounted future net cash flows $ 3,440,611 $ 1,904,934 $ 2,537,595 Future cash inflows are computed by applying SEC Pricing to year-end quantities of proved reserves. The discounted future cash flow estimates do not include the effects of derivative instruments. See the following table for base prices used in determining the standardized measure: Year Ended December 31, 2021 2020 2019 Oil price per Bbl $ 67.14 $ 39.47 $ 61.01 Natural gas price per Mcf $ 3.71 $ 1.97 $ 2.59 NGL price per Bbl $ 26.62 $ 9.89 $ 26.17 Future net cash flows are discounted at the prescribed rate of 10 %. Actual future net cash flows may vary considerably from these estimates. Although the Company’s estimates of total proved reserves, development costs and production rates were based on the best information available, the development and production of oil and gas reserves may not occur in the periods assumed. Actual prices realized, costs incurred and production quantities may vary significantly from those used. Therefore, such estimated future net cash flow computations should not be considered to represent the Company’s estimate of the expected revenues or the current value of existing proved reserves. Changes in Standardized Measure of Discounted Future Net Cash Flows Principal changes in the standardized measure of discounted future net cash flows attributable to the Company’s proved oil, natural gas and NGL reserves are as follows (in thousands): Year Ended December 31, 2021 2020 2019 Standardized measure, beginning of year $ 1,904,934 $ 2,537,595 $ 3,340,246 Sales and transfers of oil, net gas and NGLs produced during the period ( 957,576 ) ( 339,557 ) ( 665,226 ) Net change in prices and production costs 2,049,980 ( 1,468,304 ) ( 849,696 ) Changes in estimated future development costs ( 57,876 ) 32,589 ( 75,564 ) Previously estimated development costs incurred 69,125 46,143 117,049 Accretion of discount 199,849 299,302 392,526 Net change in income taxes ( 391,834 ) 361,875 129,590 Purchases of reserves — 730,611 75,009 Extensions and discoveries 45,485 71,589 306,515 Net change due to revision in quantity estimates 426,357 ( 309,338 ) ( 199,576 ) Changes in production rates (timing) and other 152,167 ( 57,571 ) ( 33,278 ) Standardized measure, end of year $ 3,440,611 $ 1,904,934 $ 2,537,595 |