Property, Plant and Equipment (Tables)

9 Months Ended

Sep. 30, 2011

Net Changes in Capitalized Exploratory Well Costs

The following table reflects the net changes in capitalized exploratory well costs during the nine-month periods ended September 30, 2011 and 2010.

(Thousands of dollars)	2011		2010
Beginning balance at January 1	$	497,765		369,862
Additions pending the determination of proved reserves		31,481		89,797
Reclassifications to proved properties based on the determination of proved reserves		0		0
Balance at September 30	$	529,246		459,659

Aging of Capitalized Exploratory Well Costs

The following table provides an aging of capitalized exploratory well costs based on the date the drilling was completed for each individual well and the number of projects for which exploratory well costs have been capitalized. The projects are aged based on the last well drilled in the project.

	September 30,
	2011						2010
(Thousands of dollars)	Amount		No. of Wells		No. of Projects		Amount		No. of Wells		No. of Projects
Aging of capitalized well costs:
Zero to one year	$	92,752		15		5	$	83,642		13		5
One to two years		69,591		9		1		118,776		12		3
Two to three years		115,924		8		3		50,604		4		4
Three years or more		250,979		37		7		206,637		32		3
	$	529,246		69		16	$	459,659		61		15