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SUPPLEMENTARY OIL & GAS INFORMATION (Unaudited) - Proved and Proved Developed Oil and Natural Gas Reserves, Net of Royalties (Details) - MMBbls | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Crude Oil, Synthetic Crude Oil, Bitumen, Natural Gas, Natural Gas Liquids |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 7,919 | 7,091 | 4,514 |
Extensions and discoveries (in MMbbl) | 364 | 912 | 45 |
Improved recovery (in MMbbl) | 181 | 64 | 27 |
Purchases of reserves in place (in MMbbl) | 668 | 16 | 2,336 |
Sales of reserves in place (in MMbbl) | 0 | (4) | 0 |
Production (in MMbbl) | (285) | (274) | (229) |
Economic revisions due to prices (in MMbbl) | (285) | (51) | 54 |
Revisions of prior estimates (in MMbbl) | (19) | 165 | 344 |
Proved reserves, net, ending balance | 8,544 | 7,919 | 7,091 |
Net proved developed reserves (in MMbbl) | 6,543 | 6,571 | 5,825 | 3,307
Change in proved developed and undeveloped reserves, net (in MMbbl) | 625 | 828 | 2,577 |
North America | Synthetic Crude Oil |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 5,661 | 4,956 | 2,542 |
Extensions and discoveries (in MMbbl) | 334 | 744 | 0 |
Improved recovery (in MMbbl) | 0 | 0 | 0 |
Purchases of reserves in place (in MMbbl) | 0 | 0 | 2,232 |
Sales of reserves in place (in MMbbl) | 0 | 0 | 0 |
Production (in MMbbl) | (137) | (148) | (100) |
Economic revisions due to prices (in MMbbl) | (288) | 0 | 0 |
Revisions of prior estimates (in MMbbl) | (17) | 109 | 282 |
Proved reserves, net, ending balance | 5,554 | 5,661 | 4,956 |
Net proved developed reserves (in MMbbl) | 5,452 | 5,661 | 4,967 | 2,527
North America | Bitumen |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 1,469 | 1,365 | 1,301 |
Extensions and discoveries (in MMbbl) | 18 | 151 | 28 |
Improved recovery (in MMbbl) | 169 | 10 | 7 |
Purchases of reserves in place (in MMbbl) | 666 | 2 | 37 |
Sales of reserves in place (in MMbbl) | 0 | (4) | 0 |
Production (in MMbbl) | (81) | (64) | (70) |
Economic revisions due to prices (in MMbbl) | 3 | (45) | 18 |
Revisions of prior estimates (in MMbbl) | (27) | 54 | 44 |
Proved reserves, net, ending balance | 2,216 | 1,469 | 1,365 |
Net proved developed reserves (in MMbbl) | 661 | 461 | 410 | 384
North America | Crude Oil and NGLs |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 604 | 594 | 504 |
Extensions and discoveries (in MMbbl) | 12 | 17 | 17 |
Improved recovery (in MMbbl) | 12 | 50 | 19 |
Purchases of reserves in place (in MMbbl) | 2 | 7 | 67 |
Sales of reserves in place (in MMbbl) | 0 | 0 | 0 |
Production (in MMbbl) | (49) | (47) | (44) |
Economic revisions due to prices (in MMbbl) | 0 | (18) | 17 |
Revisions of prior estimates (in MMbbl) | 17 | 1 | 14 |
Proved reserves, net, ending balance | 598 | 604 | 594 |
Net proved developed reserves (in MMbbl) | 354 | 378 | 399 | 353
North America | Crude Oil, Synthetic Crude Oil, Bitumen, Natural Gas, Natural Gas Liquids |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 7,734 | 6,915 | 4,347 |
Extensions and discoveries (in MMbbl) | 364 | 912 | 45 |
Improved recovery (in MMbbl) | 181 | 60 | 26 |
Purchases of reserves in place (in MMbbl) | 668 | 9 | 2,336 |
Sales of reserves in place (in MMbbl) | 0 | (4) | 0 |
Production (in MMbbl) | (267) | (259) | (214) |
Economic revisions due to prices (in MMbbl) | (285) | (63) | 35 |
Revisions of prior estimates (in MMbbl) | (28) | 164 | 340 |
Proved reserves, net, ending balance | 8,368 | 7,734 | 6,915 |
Net proved developed reserves (in MMbbl) | 6,466 | 6,500 | 5,776 | 3,264
North Sea | Crude Oil and NGLs |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 114 | 107 | 93 |
Extensions and discoveries (in MMbbl) | 0 | 0 | 0 |
Improved recovery (in MMbbl) | 0 | 1 | 1 |
Purchases of reserves in place (in MMbbl) | 0 | 7 | 0 |
Sales of reserves in place (in MMbbl) | 0 | 0 | 0 |
Production (in MMbbl) | (10) | (9) | (9) |
Economic revisions due to prices (in MMbbl) | (1) | 11 | 18 |
Revisions of prior estimates (in MMbbl) | 3 | (3) | 4 |
Proved reserves, net, ending balance | 105 | 114 | 107 |
Net proved developed reserves (in MMbbl) | 38 | 37 | 28 | 12
Offshore Africa | Crude Oil and NGLs |  |  |  |
Proved Developed And Undeveloped Reserves [Roll Forward] |  |  |  |
Proved reserves, net, beginning balance | 71 | 69 | 74 |
Extensions and discoveries (in MMbbl) | 0 | 0 | 0 |
Improved recovery (in MMbbl) | 0 | 3 | 0 |
Purchases of reserves in place (in MMbbl) | 0 | 0 | 0 |
Sales of reserves in place (in MMbbl) | 0 | 0 | 0 |
Production (in MMbbl) | (7) | (6) | (6) |
Economic revisions due to prices (in MMbbl) | 1 | 1 | 1 |
Revisions of prior estimates (in MMbbl) | 6 | 4 | 0 |
Proved reserves, net, ending balance | 70 | 71 | 69 |
Net proved developed reserves (in MMbbl) | 39 | 34 | 21 | 31

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- Definition Additions to proved reserves that result from (1) extension of the proved acreage of previously discovered (old) reservoirs through additional drilling in periods after discovery and (2) discovery of new fields with proved reserves or of new reservoirs of proved reserves in old fields. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Form 20-F -Section Item 18 -Subsection Instruction 2 + Details
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- Definition The net quantity of proved reserves as of the balance sheet date. Proved oil reserves are the estimated quantities of crude oil and natural gas liquids which geological and engineering data demonstrate with reasonable certainty to be recoverable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Form 20-F -Section Item 18 -Subsection Instruction 2 + Details
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- Definition Net quantities of an enterprise's interests in proved developed reserves of either crude oil (including condensate and natural gas liquids), natural gas, synthetic oil and gas, or other nonrenewable natural resource that is intended to be upgraded into synthetic oil and gas as of the beginning and the end of the year. "Net" quantities of reserves include those relating to the enterprise's operating and nonoperating interests in properties. Quantities of reserves relating to royalty interests owned are included in "net" quantities if the necessary information is available to the enterprise. "Net" quantities does not include reserves relating to interests of others in properties owned by the enterprise. The unit of measure for reserve quantities is defined as "barrels" for oil and synthetic oil reserves or "cubic feet" or "cubic meters" for natural gas and synthetic gas reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher SEC -Name Form 20-F -Section Item 18 -Subsection Instruction 2 + Details
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