Exhibit 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

(in thousands, except ratios)

	Three Months Ended March 31, 2012			12/31/2011				12/31/2010			12/31/2009			12/31/2008			12/31/2007
Pre-tax income from continuing operations	$	54,514		$	(370,291	)		$	136,492		$	67,888		$	190,193		$	195,616
Interest expense	20,104			72,807				66,541			50,738			26,209			17,287
Amortization of capitalized interest	411			1,813
Capitalized interest	5,190			29,117				28,321			30,107			23,209			18,104
Earnings	$	75,029		$	(295,671	)		$	203,033		$	118,626		$	216,402		$	212,903
Ratio of earnings to fixed charges	3.0		x	—			(1)	2.1		x	1.5		x	4.4		x	6.0		x

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(1) For the year ended December 31, 2011, earnings were deficient by $397.6 million, which was due primarily to a pre-tax, non-cash charge to earnings of $625.0 million related to the impairment of our E. Texas natural gas properties.

For purposes of this table, “earnings” consists of earnings before income taxes from continuing operations plus fixed charges (excluding capitalized interest).  “Fixed charges” consists of interest expense and capitalized interest (for both continuing and discontinued operations).