Supplemental Crude Oil and Natural Gas Information (Unaudited) | Supplemental Crude Oil and Natural Gas Information (Unaudited) The table below shows estimates of proved reserves prepared by the Company’s internal technical staff and independent external reserve engineers in accordance with SEC definitions. Ryder Scott Company, L.P. prepared reserve estimates for properties comprising approximately 91% , 98% , and 96% of the Company's total proved reserves as of December 31, 2019 , 2018 , and 2017 , respectively. Remaining reserve estimates were prepared by the Company’s internal technical staff. All proved reserves stated herein are located in the United States. No proved reserves have been included for the Company’s Canadian operations for the periods presented. Proved reserves attributable to noncontrolling interests are not material relative to the Company's consolidated reserves and are not separately presented in the tables below. Proved reserves are estimated quantities of crude oil and natural gas which geological and engineering data demonstrate with reasonable certainty to be economically producible in future periods from known reservoirs under existing economic conditions, operating methods, and government regulations prior to the time at which contracts providing the right to operate expire, unless evidence indicates renewal is reasonably certain. There are numerous uncertainties inherent in estimating quantities of proved crude oil and natural gas reserves. Crude oil and natural gas reserve engineering is a subjective process of estimating underground accumulations of crude oil and natural gas that cannot be precisely measured, and estimates of engineers other than the Company’s might differ materially from the estimates set forth herein. The accuracy of any reserve estimate is a function of the quality of available data and of engineering and geological interpretation and judgment. Periodic revisions or removals of estimated reserves and future cash flows may be necessary as a result of a number of factors, including reservoir performance, new drilling, crude oil and natural gas prices, changes in costs, technological advances, new geological or geophysical data, changes in business strategies, or other economic factors. Accordingly, reserve estimates may differ significantly from the quantities of crude oil and natural gas ultimately recovered. Reserves at December 31, 2019 , 2018 and 2017 were computed using the 12-month unweighted average of the first-day-of-the-month commodity prices as required by SEC rules. Natural gas imbalance receivables and payables for each of the three years ended December 31, 2019 , 2018 and 2017 were not material and have not been included in the reserve estimates. Proved crude oil and natural gas reserves Changes in proved reserves were as follows for the periods presented: Crude Oil Natural Gas Total Proved reserves as of December 31, 2016 643,228 3,789,818 1,274,864 Revisions of previous estimates (77,779 ) (25,390 ) (82,012 ) Extensions, discoveries and other additions 129,895 661,867 240,206 Production (50,536 ) (228,159 ) (88,562 ) Sales of minerals in place (4,365 ) (64,989 ) (15,197 ) Purchases of minerals in place 506 7,134 1,696 Proved reserves as of December 31, 2017 640,949 4,140,281 1,330,995 Revisions of previous estimates (76,994 ) (1,153,555 ) (269,253 ) Extensions, discoveries and other additions 253,066 1,871,777 565,030 Production (61,384 ) (284,730 ) (108,839 ) Sales of minerals in place (2,154 ) (35,142 ) (8,011 ) Purchases of minerals in place 3,613 52,983 12,443 Proved reserves as of December 31, 2018 757,096 4,591,614 1,522,365 Revisions of previous estimates (88,307 ) (363,239 ) (148,848 ) Extensions, discoveries and other additions 162,710 1,213,947 365,034 Production (72,267 ) (311,865 ) (124,244 ) Sales of minerals in place (803 ) (6,224 ) (1,840 ) Purchases of minerals in place 1,758 30,238 6,798 Proved reserves as of December 31, 2019 760,187 5,154,471 1,619,265 Revisions of previous estimates. Revisions for 2019 are comprised of (i) the removal of 17 MMBo and 108 Bcf (totaling 35 MMBoe) of PUD reserves no longer scheduled to be drilled within five years of initial booking due to the continual refinement of the Company's drilling programs and reallocation of capital to areas providing the greatest opportunities to improve efficiencies, recoveries, and rates of return, (ii) downward revisions of 38 MMBo and 278 Bcf (totaling 85 MMBoe) from the removal of PUD reserves due to changes in economics, performance, and other factors, (iii) downward price revisions of 24 MMBo and 118 Bcf (totaling 43 MMBoe) due to a decrease in average crude oil and natural gas prices in 2019 compared to 2018, and (iv) net downward revisions for oil reserves of 9 MMBo and net upward revisions for natural gas reserves of 139 Bcf (netting to 14 MMBoe of upward revisions) due to changes in ownership interests, operating costs, anticipated production, and other factors. Revisions for 2018 are comprised of (i) the removal of 74 MMBo and 960 Bcf (totaling 234 MMBoe) of PUD reserves no longer scheduled to be drilled within five years of initial booking due to changes in development plans, (ii) downward revisions of 21 MMBo and 216 Bcf (totaling 57 MMBoe) from the removal of PUD reserves due to changes in anticipated well densities and other factors, (iii) upward price revisions of 21 MMBo and 31 Bcf (totaling 26 MMBoe) due to an increase in average crude oil and natural gas prices in 2018 compared to 2017, and (iv) net downward revisions of 2 MMBo and 11 Bcf (totaling 4 MMBoe) due to changes in ownership interests, operating costs, anticipated production, and other factors. Revisions for 2017 are comprised of (i) the removal of 89 MMBoe of PUD reserves not scheduled to be drilled within five years of initial booking due to changes in development plans, (ii) upward price revisions of 42 MMBoe due to an increase in average crude oil and natural gas prices in 2017 compared to 2016, (iii) downward revisions of 30 MMBoe due to changes in anticipated production performance, and (iv) net downward revisions of 5 MMBoe due to changes in ownership interests, operating costs, and other factors. Extensions, discoveries and other additions . Extensions, discoveries and other additions for each of the three years reflected in the table above were due to successful drilling and completion activities and continual refinement of our drilling programs in the Bakken, SCOOP, and STACK plays. For 2019, proved reserve additions in the Bakken totaled 113 MMBo and 283 Bcf (totaling 160 MMBoe) and reserve additions in SCOOP totaled 47 MMBo and 830 Bcf (totaling 186 MMBoe). Additionally, 2019 proved reserve additions in STACK totaled 2 MMBo and 101 Bcf (totaling 19 MMBoe). Sales of minerals in place. See Note 16. Property Dispositions for a discussion of notable dispositions in 2019 , 2018 and 2017 , none of which involved significant volumes of proved reserves. Purchases of minerals in place. There were no individually significant acquisitions of proved reserves in the three years reflected in the table above. The following reserve information sets forth the estimated quantities of proved developed and proved undeveloped crude oil and natural gas reserves of the Company as of December 31, 2019 , 2018 and 2017 : December 31, 2019 2018 2017 Proved Developed Reserves Crude oil (MBbl) 336,405 347,825 318,707 Natural Gas (MMcf) 2,226,117 1,964,289 1,699,161 Total (MBoe) 707,424 675,206 601,901 Proved Undeveloped Reserves Crude oil (MBbl) 423,782 409,271 322,242 Natural Gas (MMcf) 2,928,354 2,627,325 2,441,120 Total (MBoe) 911,841 847,159 729,094 Total Proved Reserves Crude oil (MBbl) 760,187 757,096 640,949 Natural Gas (MMcf) 5,154,471 4,591,614 4,140,281 Total (MBoe) 1,619,265 1,522,365 1,330,995 Proved developed reserves are reserves expected to be recovered through existing wells with existing equipment and operating methods. Proved undeveloped reserves are reserves expected to be recovered from new wells on undrilled acreage or from existing wells that require relatively major capital expenditures to recover, including most wells where drilling has occurred but the wells have not been completed. Natural gas is converted to barrels of crude oil equivalent using a conversion factor of six thousand cubic feet per barrel of crude oil based on the average equivalent energy content of natural gas compared to crude oil. Standardized measure of discounted future net cash flows relating to proved crude oil and natural gas reserves The standardized measure of discounted future net cash flows presented in the following table was computed using the 12-month unweighted average of the first-day-of-the-month commodity prices, the costs in effect at December 31 of each year and a 10% discount factor. The Company cautions that 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 available information, the development and production of the crude oil and natural gas reserves may not occur in the periods assumed. Actual prices realized, costs incurred and production quantities may vary significantly from those used. Therefore, the 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. The following table sets forth the standardized measure of discounted future net cash flows attributable to proved crude oil and natural gas reserves as of December 31, 2019 , 2018 and 2017 . Discounted future net cash flows attributable to noncontrolling interests are not material relative to the Company's consolidated amounts and are not separately presented below. December 31, In thousands 2019 2018 2017 Future cash inflows $ 49,893,470 $ 61,510,432 $ 42,574,897 Future production costs (15,309,672 ) (16,139,001 ) (11,159,362 ) Future development and abandonment costs (10,033,887 ) (9,706,114 ) (6,487,097 ) Future income taxes (1) (3,351,657 ) (6,012,439 ) (3,488,755 ) Future net cash flows 21,198,254 29,652,878 21,439,683 10% annual discount for estimated timing of cash flows (10,736,613 ) (13,968,061 ) (10,969,506 ) Standardized measure of discounted future net cash flows $ 10,461,641 $ 15,684,817 $ 10,470,177 (1) Estimated future income taxes were calculated by applying existing statutory tax rates, including any known future changes, to the estimated pre-tax net cash flows related to proved crude oil and natural gas reserves, giving effect to any permanent taxable differences and tax credits, less the tax basis of the properties involved. The U.S. federal statutory tax rate utilized in estimating future income taxes was 21% at December 31, 2019, 2018, and 2017. The weighted average crude oil price (adjusted for location and quality differentials) utilized in the computation of future cash inflows was $51.95 , $61.20 , and $47.03 per barrel at December 31, 2019 , 2018 and 2017 , respectively. The weighted average natural gas price (adjusted for location and quality differentials) utilized in the computation of future cash inflows was $2.02 , $3.22 , and $3.00 per Mcf at December 31, 2019 , 2018 and 2017 , respectively. Future cash flows are reduced by estimated future costs to develop and produce the proved reserves, as well as certain abandonment costs, based on year-end cost estimates assuming continuation of existing economic conditions. The expected tax benefits to be realized from the utilization of net operating loss carryforwards and tax credits are used in the computation of future income tax cash flows. The changes in the aggregate standardized measure of discounted future net cash flows attributable to proved crude oil and natural gas reserves are presented below for each of the past three years. December 31, In thousands 2019 2018 2017 Standardized measure of discounted future net cash flows at January 1 $ 15,684,817 $ 10,470,177 $ 5,510,223 Extensions, discoveries and improved recoveries, less related costs 1,649,322 5,162,635 1,462,629 Revisions of previous quantity estimates (1,564,503 ) (3,522,428 ) (1,004,355 ) Changes in estimated future development and abandonment costs 1,401,513 1,063,089 743,657 Purchases (sales) of minerals in place, net 49,330 (9,192 ) (41,077 ) Net change in prices and production costs (6,591,347 ) 4,224,473 3,808,116 Accretion of discount 1,865,034 1,183,347 665,507 Sales of crude oil and natural gas produced, net of production costs (3,486,103 ) (3,743,572 ) (2,450,474 ) Development costs incurred during the period 1,557,121 1,134,153 1,045,875 Change in timing of estimated future production and other (1,690,779 ) 1,324,365 948,519 Change in income taxes 1,587,236 (1,602,230 ) (218,443 ) Net change (5,223,176 ) 5,214,640 4,959,954 Standardized measure of discounted future net cash flows at December 31 $ 10,461,641 $ 15,684,817 $ 10,470,177 |