Costs Incurred for Property Acquisition, Exploration and Development

3 Months Ended

Mar. 31, 2013

Costs Incurred for Property Acquisition, Exploration and Development

(17) Costs Incurred for Property Acquisition, Exploration and Development (a)

	Three MonthsEnded March31, 2013	Year Ended December31, 2012
	(in thousands)
Acreage purchases	$9,394	$188,843
Development	309,240	1,049,129
Exploration:
Drilling	70,853	309,816
Expense	15,710	65,758
Stock-based compensation expense	1,070	4,049
Gas gathering facilities:
Development	6,789	41,035
Subtotal	413,056	1,658,630
Asset retirement obligations	1,690	57,982
Total costs incurred	$414,746	$1,716,612

(a)Includes cost incurred whether capitalized or expensed.