Property, Plant and Equipment (Tables)

9 Months Ended

Sep. 30, 2012

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, 2012 and 2011.

(Thousands of dollars)	2012			2011
Beginning balance at January 1	$	556,412			497,765
Additions pending the determination of proved reserves		143,863			31,481
Reclassifications to proved properties based on the determination of proved reserves		(76,633	)		0
Capitalized exploratory well costs charged to expense		(51,866	)		0
Balance at September 30	$	571,776			529,246

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,
	2012						2011
(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	$	82,521		8		5	$	92,752		15		5
One to two years		90,390		7		3		69,591		9		1
Two to three years		114,532		6		1		115,924		8		3
Three years or more		284,333		26		6		250,979		37		7
	$	571,776		47		15	$	529,246		69		16