CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
Current assets:
Cash and cash equivalents	$ 44,349	$ 52,056	$ 43,272
Accounts receivable, net	15,375	19,478
Unbilled receivables	15,046	37,304
Inventories	14,925	14,508
Prepaid expenses and other current assets	5,961	7,643
Total current assets	95,656	130,989
Deferred income tax asset	3,614	1,753
Property, plant, equipment and seismic rental equipment, net	48,442	52,153
Multi-client data library, net	82,576	89,300
Goodwill	23,543	24,089
Intangible assets, net	1,082	1,666
Other assets	731	1,119
Total assets	255,644	301,069
Current liabilities:
Current maturities of long-term debt	459	40,024
Accounts payable	26,173	24,951
Accrued expenses	28,936	38,697
Accrued multi-client data library royalties	27,988	27,035
Deferred revenue	8,402	8,910
Total current liabilities	91,958	139,617
Long-term debt, net of current maturities	117,159	116,720
Other long-term liabilities	12,606	13,926
Total liabilities	221,723	270,263
Equity:
Common stock, $0.01 par value; authorized 26,666,667 shares; outstanding 14,002,999 and 12,019,701 shares at June 30, 2018 and December 31, 2017, respectively	140	120
Additional paid-in capital	951,349	903,247
Accumulated deficit	(899,213)	(854,921)
Accumulated other comprehensive loss	(19,634)	(18,879)
Total stockholders’ equity	32,642	29,567
Noncontrolling interest	1,279	1,239
Total equity	33,921	30,806
Total liabilities and equity	$ 255,644	$ 301,069