NOTE J—OIL AND GAS INFORMATION

Costs related to the oil and gas activities of the Company were incurred as follows for the years ended December 31:

	2015		2014
	(in thousands)
Property acquisition—unproved	$	—	$	184,410
Property acquisition—proved		18,626		172,264
Exploration costs		3		32
Development costs		17,359		108,676

	$	35,988	$	465,382

Asset retirement cost included in oil and gas property costs increased by approximately $8,700 in 2015 and $2.1 million in 2014.

The Company had the following aggregate capitalized costs relating to the Company's oil and gas activities at December 31:

	2015		2014
	(in thousands)
Unproved oil and gas properties	$	14,658	$	204,627
Proved oil and gas properties		1,125,297		1,091,063

		1,139,955		1,295,690
Less accumulated depreciation, depletion, amortization and impairment expense		977,270		542,194

	$	162,685	$	753,496

The following table sets forth the Company's results of operations from oil and natural gas producing activities for the years ended December 31:

	2015			2014
	(in thousands)
Revenues	$	83,734		$	145,385
Production costs		(49,557	)		(48,357	)
Accretion of asset retirement obligation		(2,857	)		(2,521	)
Impairment		(562,151	)		—
Depreciation, depletion, amortization		(59,729	)		(50,686	)

Income (loss) from oil and gas producing activities	$	(590,560	)	$	43,821

In the presentation above, no deduction has been made for indirect costs such as corporate overhead or interest expense. No income taxes are reflected above due to the Company's tax loss carryforwards.

The following is a summary of Warren's oil and gas properties not subject to amortization as of December 31, 2015:

	Costs incurred in
	Fiscal year 2015		Fiscal year 2014		Fiscal year 2013		Prior to 2013		Total
	(in thousands)
Acquisition costs	$	—	$	—	$	—	$	—	$	—
Exploration costs		—		—		—		—		—
Development costs(1)		365		1,127		126		13,040		14,658

Total oil and gas properties not subject to amortization	$	365	$	1,127	$	126	$	13,040	$	14,658


(1)	The Company's development costs primarily reflect investment in well cellars and facilities in its Wilmington oil field to facilitate the development of future oil wells. These costs will be allocated to future wells drilled, the majority of these wells are expected to be drilling during the next five to eight years.