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. ("Ryder Scott") prepared reserve estimates for properties comprising approximately 99% , 99% , and 99% of the Company’s discounted future net cash flows (PV-10) as of December 31, 2016 , 2015 , and 2014 , respectively. Properties comprising 99% , 98% , and 98% of total proved reserves were evaluated by Ryder Scott as of December 31, 2016 , 2015 , and 2014 , 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 as of December 31, 2016 , 2015 , and 2014 . 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 to the 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, 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, 2016 , 2015 and 2014 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, 2016 , 2015 and 2014 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, 2013 737,788 2,078,020 1,084,125 Revisions of previous estimates (67,151 ) (244,783 ) (107,949 ) Extensions, discoveries and other additions 239,526 1,206,569 440,621 Production (44,530 ) (114,295 ) (63,579 ) Sales of minerals in place (123 ) (18,623 ) (3,227 ) Purchases of minerals in place 850 1,498 1,100 Proved reserves as of December 31, 2014 866,360 2,908,386 1,351,091 Revisions of previous estimates (246,840 ) (302,143 ) (297,198 ) Extensions, discoveries and other additions 134,764 710,453 253,173 Production (53,517 ) (164,454 ) (80,926 ) Sales of minerals in place (253 ) (456 ) (329 ) Purchases of minerals in place — — — Proved reserves as of December 31, 2015 700,514 3,151,786 1,225,811 Revisions of previous estimates (99,966 ) (63,057 ) (110,474 ) Extensions, discoveries and other additions 97,587 911,062 249,430 Production (46,850 ) (195,240 ) (79,390 ) Sales of minerals in place (8,057 ) (14,733 ) (10,513 ) Purchases of minerals in place — — — Proved reserves as of December 31, 2016 643,228 3,789,818 1,274,864 Revisions of previous estimates. Revisions represent changes in previous reserve estimates, either upward or downward, resulting from new information normally obtained from development drilling and production history or resulting from a change in economic factors, such as commodity prices, operating costs or development costs. Downward revisions to proved reserves in 2016 resulted in part from decreases in average commodity prices during the year. The 12-month average price for crude oil decreased 15% from $50.28 per Bbl for 2015 to $42.75 per Bbl for 2016, while the 12-month average price for natural gas decreased 3% from $2.58 per MMBtu for 2015 to $2.49 per MMBtu for 2016. These decreases shortened the economic lives of certain producing properties and caused certain exploration and development projects to become uneconomic which had an adverse impact on the Company's proved reserve estimates, resulting in downward revisions of 20 MMBo and 50 Bcf (totaling 28 MMBoe) in 2016. In response to the prolonged decrease in commodity prices throughout the majority of 2016, the Company further refined its capital program to focus on areas that provide the greatest opportunities to convert undeveloped acreage to acreage held by production, achieve operating efficiencies and cost reductions through multi-well pad drilling, and improve recoveries, cash flows and rates of return using enhanced completions. As part of this effort, the Company shifted a significant portion of its 2016 spending away from the Bakken to areas in Oklahoma that offered more advantageous opportunities. This shift, a longer and more severe decrease in crude oil prices than anticipated, and the Company's increased emphasis on balancing capital spending with cash flows have altered the timing and extent of previous development plans in certain areas and resulted in the removal of 51 MMBo and 118 Bcf (totaling 70 MMBoe) of proved undeveloped reserves no longer scheduled to be developed within five years from the date of initial booking, primarily in the Bakken. Additionally, changes in anticipated production performance on certain properties resulted in 37 MMBo of downward revisions to crude oil proved reserves and 166 Bcf of upward revisions to natural gas proved reserves (netting to 9 MMBoe of downward revisions) in 2016. Further, changes in ownership interests, operating costs, and other factors during 2016 resulted in 7 MMBo of upward revisions to crude oil proved reserves and 61 Bcf of downward revisions to natural gas proved reserves (netting to 3 MMBoe of downward revisions). Extensions, discoveries and other additions . These are additions to proved reserves resulting from (1) extension of the proved acreage of previously discovered reservoirs through additional drilling in periods subsequent to discovery and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields. Extensions, discoveries and other additions for each of the three years reflected in the table above were primarily due to increases in proved reserves associated with our successful drilling activity in the Bakken, SCOOP, and STACK plays. Proved reserve additions in the Bakken totaled 55 MMBo and 105 Bcf (totaling 73 MMBoe) and reserve additions in SCOOP totaled 18 MMBo and 475 Bcf (totaling 97 MMBoe) for the year ended December 31, 2016 . Additionally, 2016 extensions and discoveries were significantly impacted by successful drilling results in the STACK play, resulting in proved reserve additions of 24 MMBo and 331 Bcf (totaling 79 MMBoe) in 2016 . Sales of minerals in place. These are reductions to proved reserves resulting from the disposition of properties during a period. See Note 14. Property Dispositions for a discussion of notable dispositions. Purchases of minerals in place. These are additions to proved reserves resulting from the acquisition of properties during a period. There were no notable acquisitions 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, 2016 , 2015 and 2014 : December 31, 2016 2015 2014 Proved Developed Reserves Crude oil (MBbl) 290,210 326,798 342,137 Natural Gas (MMcf) 1,370,620 1,190,343 962,051 Total (MBoe) 518,646 525,188 502,479 Proved Undeveloped Reserves Crude oil (MBbl) 353,018 373,716 524,223 Natural Gas (MMcf) 2,419,198 1,961,443 1,946,335 Total (MBoe) 756,218 700,623 848,612 Total Proved Reserves Crude oil (MBbl) 643,228 700,514 866,360 Natural Gas (MMcf) 3,789,818 3,151,786 2,908,386 Total (MBoe) 1,274,864 1,225,811 1,351,091 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. 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 the Company’s proved crude oil and natural gas reserves as of December 31, 2016 , 2015 and 2014 . December 31, In thousands 2016 2015 2014 Future cash inflows $ 31,008,587 $ 36,551,672 $ 90,867,459 Future production costs (9,175,410 ) (10,869,493 ) (25,799,221 ) Future development and abandonment costs (6,452,647 ) (6,935,958 ) (12,842,174 ) Future income taxes (3,018,839 ) (3,717,612 ) (13,800,737 ) Future net cash flows 12,361,691 15,028,609 38,425,327 10% annual discount for estimated timing of cash flows (6,851,468 ) (8,552,325 ) (19,992,293 ) Standardized measure of discounted future net cash flows $ 5,510,223 $ 6,476,284 $ 18,433,034 The weighted average crude oil price (adjusted for location and quality differentials) utilized in the computation of future cash inflows was $35.57 , $41.63 , and $84.54 per barrel at December 31, 2016 , 2015 and 2014 , respectively. The weighted average natural gas price (adjusted for location and quality differentials) utilized in the computation of future cash inflows was $2.14 , $2.35 , and $6.06 per Mcf at December 31, 2016 , 2015 and 2014 , 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 the Company’s proved crude oil and natural gas reserves are presented below for each of the past three years. December 31, In thousands 2016 2015 2014 Standardized measure of discounted future net cash flows at January 1 $ 6,476,284 $ 18,433,034 $ 16,295,767 Extensions, discoveries and improved recoveries, less related costs 786,587 1,091,283 5,516,528 Revisions of previous quantity estimates (794,785 ) (2,156,028 ) (1,755,366 ) Changes in estimated future development and abandonment costs 1,651,218 5,008,731 476,665 Sales of minerals in place, net (90,390 ) (7,768 ) (3,196 ) Net change in prices and production costs (2,003,163 ) (16,111,142 ) (1,925,349 ) Accretion of discount 798,597 1,843,303 1,629,576 Sales of crude oil and natural gas produced, net of production costs (1,595,281 ) (2,002,997 ) (3,500,790 ) Development costs incurred during the period 454,983 1,394,584 2,466,748 Change in timing of estimated future production and other (538,665 ) (3,844,259 ) (309,902 ) Change in income taxes 364,838 2,827,543 (457,647 ) Net change (966,061 ) (11,956,750 ) 2,137,267 Standardized measure of discounted future net cash flows at December 31 $ 5,510,223 $ 6,476,284 $ 18,433,034 |