UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 18,702	$ 49,704
Restricted cash	325	325
Accounts receivable	22,836	29,514
Short-term derivative instruments	5,919	18,813
Prepaid expenses and other current assets	9,304	7,241
Total current assets	57,086	105,597
Property and equipment, at cost:
Oil and natural gas properties, successful efforts method	619,748	598,331
Support equipment and facilities	125,721	108,760
Other	6,831	6,625
Accumulated depreciation, depletion and impairment	(109,614)	(85,535)
Property and equipment, net	642,686	628,181
Long-term derivative instruments	7,485	2,469
Restricted investments	4,606	94,467
Operating lease - long term right-of-use asset	5,096	0
Other long-term assets	5,725	6,129
Total assets	722,684	836,843
Current liabilities:
Accounts payable	6,933	2,345
Revenues payable	22,386	24,779
Accrued liabilities (see Note 13)	31,360	23,155
Short-term derivative instruments	151	139
Total current liabilities	60,830	50,418
Long-term debt (see Note 8)	175,000	294,000
Asset retirement obligations	78,417	75,867
Long-term derivative instruments	275	0
Operating lease liability	2,986	0
Other long-term liabilities	89	0
Total liabilities	317,597	420,285
Commitments and contingencies (see Note 15)
Stockholders' equity:
Preferred stock, $0.0001 par value: 45,000,000 shares authorized; no shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	0	0
Warrants, 2,173,913 warrants issued and outstanding at June 30, 2019 and December 31, 2018, respectively	4,788	4,788
Common stock, $0.0001 par value: 300,000,000 shares authorized; 22,305,256 and 22,181,881 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	357,237	355,872
Accumulated earnings	43,059	55,895
Total stockholders' equity	405,087	416,558
Total liabilities and equity	$ 722,684	$ 836,843