Annual report pursuant to Section 13 and 15(d)

Supplemental Information on Oil and Gas Producing Activities (Unaudited) - Proved reserves (Details)

v3.19.3.a.u2
Supplemental Information on Oil and Gas Producing Activities (Unaudited) - Proved reserves (Details)
12 Months Ended
Dec. 31, 2019
MMcfe
MMBbls
Bcf
Dec. 31, 2018
MMcfe
Bcf
MMBbls
Dec. 31, 2017
MMcfe
MMBbls
Bcf
Proved developed and undeveloped reserves:      
Balance at the beginning of the period | MMcfe 18,011,000 17,261,000 15,386,000
Revisions | MMcfe (1,648,000) (1,042,000) 176,000
Extensions, discoveries and other additions | MMcfe 3,705,000 2,781,000 2,148,000
Production | MMcfe (1,175,000) (989,000) (822,000)
Purchase of reserves | MMcfe     373,000
Proved Developed and Undeveloped Reserve, Net (Energy), Ending Balance | MMcfe 18,893,000 18,011,000 17,261,000
Oil and Gas Reserves      
Proved developed reserves | MMcfe 11,740 10,389 8,488
Proved undeveloped reserves | MMcfe 7,153 7,622 8,773
Natural gas      
Proved developed and undeveloped reserves:      
Balance at the beginning of the period | Bcf 11,425 11,098 9,414
Revisions | Bcf (1,735) (1,087) 342
Extensions, discoveries and other additions | Bcf 2,626 2,125 1,644
Production | Bcf (822) (711) (591)
Purchase of reserves | Bcf     289
Balance at the end of the period | Bcf 11,494 11,425 11,098
Oil and Gas Reserves      
Proved developed reserves | Bcf 7,229 6,669 5,587
Proved undeveloped reserves | Bcf 4,265 4,756 5,511
NGLS      
Proved developed and undeveloped reserves:      
Balance at the beginning of the period 1,052 989 957
Revisions 25 8 (22)
Extensions, discoveries and other additions 169 98 77
Production (55) (43) (36)
Purchase of reserves     13
Balance at the end of the period 1,191 1,052 989
Oil and Gas Reserves      
Proved developed reserves 731 600 467
Proved undeveloped reserves 460 452 522
Oil and condensate      
Proved developed and undeveloped reserves:      
Balance at the beginning of the period 46 38 38
Revisions (11) (1) (6)
Extensions, discoveries and other additions 11 12 7
Production (4) (3) (2)
Purchase of reserves     1
Balance at the end of the period 42 46 38
Oil and Gas Reserves      
Proved developed reserves 21 20 16
Proved undeveloped reserves 21 26 22