Exhibit 12.1

Ratio of Earnings to Fixed Charges

The following table sets forth our ratios of consolidated earnings to fixed charges for the periods presented:

	Year Ended December 31,															Nine Months  Ended September 30, 2011
	2006			2007			2008			2009			2010
	(in thousands, except ratios)
	(unaudited)
Income before income taxes	$	306,354		$	215,759		$	(828,482	)	$	(262,030	)	$	129,793		$	195,593
Add: Fixed charges		30,561			62,438			54,213			46,974			43,304			37,056
Add: Amortization of capitalized interest		689			1,265			1,273			2,667			1,353			676
Less: Capitalized interest		(13,238	)		(25,100	)		(19,292	)		(6,662	)		(5,395	)		(6,654	)
Earnings before fixed charges	$	324,366		$	254,362		$	(792,288	)	$	(219,051	)	$	169,055		$	226,671
Fixed charges:
Interest expense, net of capitalized interest	$	17,180		$	37,088		$	34,709		$	40,087		$	37,706		$	30,259
Capitalized interest		13,238			25,100			19,292			6,662			5,395			6,654
Portion of rental expense representative of an interest factor		143			250			212			225			203			143
Total fixed charges	$	30,561		$	62,438		$	54,213		$	46,974		$	43,304		$	37,056
Ratio of earnings to fixed charges		10.6			4.1			—	(1)		—	(2)		3.9			6.1

(1) Earnings were inadequate to cover fixed charges for the year ended December 31, 2008 by $846.5 million. Earnings for the year ended December 31, 2008 included an impairment write down of $1,182.8 million.

(2) Earnings were inadequate to cover fixed charges for the year ended December 31, 2009 by $266.0 million. Earnings for the year ended December 31, 2009 included an impairment write down of $218.9 million.