Annual report pursuant to Section 13 and 15(d)

Supplemental Information on Oil and Natural Gas Properties (Unaudited) (Proved Developed and Undeveloped Oil and Gas Reserve Quantities) (Details)

v3.10.0.1
Supplemental Information on Oil and Natural Gas Properties (Unaudited) (Proved Developed and Undeveloped Oil and Gas Reserve Quantities) (Details)
MMcf in Thousands, MBoe in Thousands, MBbls in Thousands
12 Months Ended
Dec. 31, 2018
MBoe
MMcf
MBbls
Dec. 31, 2017
MBoe
MMcf
MBbls
Dec. 31, 2016
MBoe
MMcf
MBbls
Proved developed and undeveloped reserves (Energy):      
Beginning of period | MBoe 136,974 91,580 54,271
Purchase of reserves in place | MBoe 39,683 10,507 31,133
Sale of reserves in place | MBoe 0 0 (2,179)
Extensions and discoveries | MBoe 84,955 47,375 17,345
Revisions to previous estimates | MBoe   1,472 (1,737)
Reclassifications due to changes in development plan | MBoe (9,065) (5,587) (1,680)
Production | MBoe (12,018) (8,373) (5,573)
End of period | MBoe 238,508 136,974 91,580
Proved undeveloped reserves:      
Beginning of period, MBOE proved developed | MBoe 69,318 43,232 28,617
End of period, MBOE proved developed | MBoe 128,605 69,318 43,232
Beginning of periodic, MBOE proved developed | MBoe 67,656 48,348 25,654
End of period, MBOE proved developed | MBoe 109,903 67,656 48,348
Oil      
Proved developed and undeveloped reserves:      
Beginning of period | MBbls 107,072 71,145 43,348
Purchase of reserves in place | MBbls 30,756 8,388 25,054
Sale of reserves in place | MBbls 0 0 (1,718)
Extensions and discoveries | MBbls 67,763 39,267 14,479
Revisions to previous estimates | MBbls (8,982) (1,548) (4,544)
Reclassifications due to changes in development plan | MBbls (7,069) (3,623) (1,194)
Production | MBbls (9,443) (6,557) (4,280)
End of period | MBbls 180,097 107,072 71,145
Proved undeveloped reserves:      
Beginning of period, proved developed | MBbls 51,920 32,920 22,257
End of period, proved developed | MBbls 92,202 51,920 32,920
Beginning of period, proved undeveloped | MBbls 55,152 38,225 21,091
End of period, proved undeveloped | MBbls 87,895 55,152 38,225
Proved Developed and Undeveloped Reserves (Volume) | MBbls 107,072 71,145 43,348
Proved Developed and Undeveloped Reserves (Volume) | MBbls 180,097 107,072 71,145
Natural gas      
Proved developed and undeveloped reserves:      
Beginning of period | MMcf 179,410 122,611 65,537
Purchase of reserves in place | MMcf 53,563 12,711 36,474
Sale of reserves in place | MMcf 0 0 (2,765)
Extensions and discoveries | MMcf 103,149 48,648 17,194
Revisions to previous estimates | MMcf 41,767 18,121 16,842
Reclassifications due to changes in development plan | MMcf (11,976) (11,785) (2,913)
Production | MMcf (15,447) (10,896) (7,758)
End of period | MMcf 350,466 179,410 122,611
Proved undeveloped reserves:      
Beginning of period, proved developed | MMcf 104,389 61,871 38,157
End of period, proved developed | MMcf 218,417 104,389 61,871
Beginning of period, proved undeveloped | MMcf 75,021 60,740 27,380
End of period, proved undeveloped | MMcf 132,049 75,021 60,740
Proved Developed and Undeveloped Reserves (Volume) | MMcf 179,410 122,611 65,537
Proved Developed and Undeveloped Reserves (Volume) | MMcf 350,466 179,410 122,611