Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2011

We recognized total stock-based compensation expense as follows:

	Year Ended December 31,
	2011			2010			2009
(millions)
Stock-Based Compensation Expense Included in
General and Administrative Expense	$	42		$	39		$	36
Exploration Expense and Other		16			15			13
Total Stock-Based Compensation Expense	$	58		$	54		$	49
Tax Benefit Recognized	$	(20	)	$	(19	)	$	(17	)

Share-based compensation awards

The assumptions used in valuing stock options granted were as follows:

	Year Ended December 31,
	2011			2010			2009
(weighted averages)
Expected Term (in Years)		5.7			5.6			5.5
Expected Volatility		36.2	%		35.4	%		43.0	%
Risk-Free Rate		2.2	%		2.6	%		2.0	%
Expected Dividend Yield		1.1	%		1.1	%		1.2	%
Weighted Average Grant-Date Fair Value	$	30.17		$	25.05		$	19.14

Stock option activity was as follows:

	Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
				(per share)		(in years)	(in millions)
Outstanding at December 31, 2010		6,266,960		$	52.87
Granted		992,488			90.34
Exercised		(837,096	)		45.59
Forfeited		(56,536	)		75.01
Outstanding at December 31, 2011		6,365,816		$	59.47	6.1	$	223
Exercisable at December 31, 2011		4,315,415		$	51.13	5.1	$	187

The total intrinsic value of options exercised was $40 million in 2011, $68 million in 2010, and $19 million in 2009.

As of December 31, 2011, $30 million of compensation cost related to unvested stock options granted under the Plans remained to be recognized. The cost is expected to be recognized over a weighted-average period of 1.3 years. We issue new shares of our common stock to settle option exercises. Dividends are not paid on unexercised options.

Restricted Stock Awards Restricted stock activity was as follows:

	Shares Subject to Service Conditions			Weighted Average Award Date Fair Value
				(per share)
Outstanding at December 31, 2010		1,232,867		$	66.11
Awarded		407,336			90.32
Vested		(633,312	)		67.84
Forfeited		(27,634	)		73.26
Outstanding at December 31, 2011		979,257		$	74.87