CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 52,056	$ 52,652	$ 84,933		$ 173,608
Accounts receivable, net	19,478	20,770
Unbilled receivables	37,304	13,415
Inventories	14,508	15,241
Prepaid expenses and other current assets	7,643	9,559
Total current assets	130,989	111,637
Deferred income tax asset	1,753	0
Property, plant, equipment and seismic rental equipment, net	52,153	67,488
Multi-client data library, net	89,300	105,935
Goodwill	24,089	22,208	26,274
Intangible assets, net	1,666	3,103
Other assets	1,119	2,845
Total assets	301,069	313,216
Current liabilities:
Current maturities of long-term debt	40,024	14,581
Accounts payable	24,951	26,889
Accrued expenses	38,697	26,240
Accrued multi-client data library royalties	27,035	23,663
Deferred revenue	8,910	3,709
Total current liabilities	139,617	95,082
Long-term debt, net of current maturities	116,720	144,209
Other long-term liabilities	13,926	20,527
Total liabilities	270,263	259,818
Equity:
Common stock, $0.01 par value; authorized 26,666,667 shares; outstanding 12,019,701 and 11,792,447 shares at December 31, 2017 and 2016, respectively.	120	118
Additional paid-in capital	903,247	899,198
Accumulated deficit	(854,921)	(824,679)
Accumulated other comprehensive loss	(18,879)	(21,748)
Total stockholders’ equity	29,567	52,889
Noncontrolling interests	1,239	509
Total equity	30,806	53,398	$ 112,040	[1]	$ 135,712
Total liabilities and equity	$ 301,069	$ 313,216

[1] The figures for 2015, set forth in the tables above have been retroactively adjusted to reflect the one-for-fifteen reverse stock split completed on February 4, 2016.