Supplemental Oil and Natural Gas Disclosures (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2011

Oil and Gas Exploration and Production Industries Disclosures [Abstract]

Cost incurred in oil and natural gas activities

Costs incurred in oil and natural gas activities were as follows:

				Year Ended December 31,
In thousands				2011		2010		2009
Property acquisitions:
	Proved		$	86,465	$	3,373,450	$	585,637
	Unevaluated			17,858		1,297,695		104,772
Exploration				31,483		8,728		4,635
Development				1,144,243		658,758		292,545
		Total costs incurred (1)	$	1,280,049	$	5,338,631	$	987,589
(1)		Capitalized general and administrative costs that directly relate to exploration and development activities were $35.0 million, $20.1 million and $14.0 million for the years ended December 31, 2011, 2010 and 2009, respectively.

Results of operations from oil and natural gas producing activities excluding corporate overhead and interest costs

Results of operations from oil and natural gas producing activities, excluding corporate overhead and interest costs, were as follows:

			Year Ended December 31,
In thousands, except per BOE data			2011		2010		2009
Oil, natural gas and related product sales			$	2,269,151	$	1,793,292	$	866,709
Lease operating costs				507,397		470,364		314,689
Marketing expenses				26,047		31,036		16,890
Taxes other than income				138,419		114,569		37,037
Depletion, depreciation and amortization				369,075		391,782		206,999
CO2 depletion, depreciation and amortization (1)				24,460		29,206		29,076
Commodity derivative expense (income)				(52,497)		(21,414)		236,226
	Net operating income			1,256,250		777,749		25,792
Income tax provision				477,375		295,545		9,927
		Results of operations from oil and natural gas producing activities	$	778,875	$	482,204	$	15,865
Depletion, depreciation and amortization per BOE			$	16.42	$	15.82	$	13.39
(1)		Represents an allocation of the depletion, depreciation and amortization of our CO2 properties and pipelines associated with our tertiary oil producing activities.

Estimated quantities of reserves

		Year Ended December 31,
		2011			2010			2009
		Oil	Gas	Total	Oil	Gas	Total	Oil	Gas	Total
		(MBbl)	(MMcf)	(MBOE)	(MBbl)	(MMcf)	(MBOE)	(MBbl)	(MMcf)	(MBOE)
Balance at beginning of year		338,276	357,893	397,925	192,879	87,975	207,542	179,126	427,955	250,452
Revisions of previous estimates		(4,478)	(14,058)	(6,821)	3,538	16,171	6,233	(69)	(1,298)	(285)
Revisions due to price changes		2,558	485	2,639	2,780	811	2,915	4,557	(2,079)	4,211
Extensions and discoveries		42,936	52,339	51,658	26,313	130,245	48,021	334	11,785	2,298
Improved recovery(1)		264	-	264	30,173	-	30,173	13,875	-	13,875
Production		(22,169)	(10,783)	(23,966)	(21,870)	(28,491)	(26,619)	(13,495)	(24,764)	(17,622)
Acquisition of minerals in place		346	239,332	40,235	155,021	622,984	258,852	28,379	2,317	28,765
Sales of minerals in place		-	-	-	(50,558)	(471,802)	(129,192)	(19,828)	(325,941)	(74,152)
Balance at end of year		357,733	625,208	461,934	338,276	357,893	397,925	192,879	87,975	207,542
Proved Developed Reserves:
	Balance at beginning of year	219,077	110,516	237,496	116,192	69,513	127,778	96,746	298,114	146,432
	Balance at end of year	239,741	125,970	260,736	219,077	110,516	237,496	116,192	69,513	127,778
(1) Improved recovery additions result from the application of secondary recovery methods such as water flooding, or tertiary recovery methods such as CO2 flooding.

Oil and natural gas prices

The following representative oil and natural gas prices were used in the Standardized Measure. These prices were adjusted by field to arrive at the appropriate corporate net price.

	December 31,
	2011		2010		2009
Oil (NYMEX)	$	96.19	$	79.43	$	61.18
Natural Gas (Henry Hub)		4.16		4.40		3.87

Discounted future net cash inflows after income taxes

		December 31,
In thousands		2011		2010		2009
Future cash inflows		$	38,165,122	$	26,698,819	$	11,579,159
Future production costs			(12,570,015)		(9,702,896)		(5,034,393)
Future development costs			(3,026,898)		(1,912,457)		(836,455)
Future income taxes			(7,379,972)		(4,700,023)		(1,257,844)
	Future net cash flows		15,188,237		10,383,443		4,450,467
10% annual discount for estimated timing of cash flows			(8,180,632)		(5,465,516)		(1,993,082)
	Standardized measure of discounted future net cash flows	$	7,007,605	$	4,917,927	$	2,457,385

Analysis of changes in the Standardized Measure of Discounted Future Net Cash Flows from proved oil and natural gas reserves

The following table sets forth an analysis of changes in the Standardized Measure of Discounted Future Net Cash Flows from proved oil and natural gas reserves:

		Year Ended December 31,
In thousands		2011		2010		2009
Beginning of year		$	4,917,927	$	2,457,385	$	1,415,498
Sales of oil and natural gas produced, net of production costs			(1,597,288)		(1,177,322)		(498,093)
Net changes in sales prices			4,646,086		2,062,181		1,263,346
Extensions and discoveries, less applicable future development and production costs			762,370		295,074		6,735
Improved recovery(1)			15,708		623,622		202,145
Previously estimated development costs incurred			354,228		193,947		98,659
Revisions of previous estimates, including revised estimates of development costs, reserves and rates of production			(1,673,283)		(285,158)		(63,044)
Accretion of discount			729,234		307,546		192,686
Acquisition of minerals in place			29,737		3,671,439		365,771
Sales of minerals in place			-		(1,474,443)		(419,601)
Net change in income taxes			(1,177,114)		(1,756,344)		(106,717)
End of year		$	7,007,605	$	4,917,927	$	2,457,385
(1)	Improved recovery additions result from the application of secondary recovery methods such as water flooding or tertiary recovery methods such as CO2 flooding.