Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net loss	$ (45,274)	$ (38,130)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization	39,486	36,162
Stock-based compensation	352	2,713
Stock-based payments	0	(601)
Deferred taxes	(11,688)	(6,432)
Loss on derivative financial instruments	26,724	36,620
Settlements of derivative financial instruments	(3,579)	(8,676)
Gain on disposal of property and equipment	(17)	0
Loss on abandoned property and equipment	0	170
Loss on sale of oil and gas properties	33,046	0
Non-cash interest expense	1,182	3,544
Change in fair value of warrants	(694)	2,615
Changes in operating assets and liabilities:
Accounts receivable	(3,379)	(254)
Prepaid expenses and other assets	(692)	(1,159)
Accounts payable and accrued expenses	2,720	12,179
Net cash provided by operating activities	38,187	38,751
Cash flows from investing activities
Acquisition of oil and gas properties	(3,025)	(2,862)
Development of oil and gas properties	(67,696)	(66,761)
Proceeds from sale of oil and gas properties	11,953	0
Purchases of other property and equipment	(3,267)	(1,498)
Net cash used in investing activities	(62,035)	(71,121)
Cash flows from financing activities
Proceeds from borrowings	54,000	290,744
Payments on borrowings	(32,167)	(255,452)
Net cash provided by financing activities	21,833	35,292
Net increase in cash and cash equivalents	(2,015)	2,922
Cash and cash equivalents, beginning of the period	5,355	2,538
Cash and cash equivalents, end of the period	3,340	5,460
Supplemental information:
Cash paid for taxes	0	1,147
Cash paid for interest	19,770	6,143
Non-cash investing and financing activities:
Change in asset retirement obligation	(455)	183
Change in liabilities for capital expenditures	$ 28,384	$ 12,425