CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 73,876	$ 22,130
Restricted cash - other	2,639	6,136
Accounts receivable, net	18,963	19,576
Prepaid expenses	2,841	2,890
Other current assets	80	80
Total current assets	98,399	50,812
Oil and natural gas properties, using full cost method of accounting
Proved	1,443,508	1,463,950
Unproved	13,341	17,964
Less: accumulated depreciation, depletion and impairment	(1,376,754)	(1,375,692)
Net oil and natural gas properties	80,095	106,222
Other property, plant and equipment, net	101,057	103,118
Other assets	703	680
Total assets	280,254	260,832
Current liabilities
Accounts payable and accrued expenses	42,280	51,426
Asset retirement obligation	15,937	16,467
Other current liabilities	364	984
Total current liabilities	58,581	68,877
Long-term debt	20,000	20,000
Asset retirement obligation	35,934	40,701
Other long-term obligations	2,413	3,188
Total liabilities	116,928	132,766
Commitments and contingencies (Note 9)
Stockholders’ Equity
Common stock, $0.001 par value; 250,000 shares authorized; 36,135 issued and outstanding at March 31, 2021 and 35,928 issued and outstanding at December 31, 2020	36	36
Warrants	88,520	88,520
Additional paid-in capital	1,062,437	1,062,220
Accumulated deficit	(987,667)	(1,022,710)
Total stockholders’ equity	163,326	128,066
Total liabilities and stockholders’ equity	$ 280,254	$ 260,832