Exploratory Well Costs (Tables)

12 Months Ended

Dec. 31, 2020

Capitalized Exploratory Well Costs, Roll Forward [Table Text Block]

The changes in capitalized exploratory well cost are as follows:


	Year Ended December 31,
	2020		2019
	(in millions)
Beginning capitalized exploratory well costs	$	660	$	509
Additions to exploratory well costs pending the determination of proved reserves	1,163		2,172
Reclassification due to determination of proved reserves	(1,325)		(2,011)
Disposition of assets	—		(6)

Exploratory well costs charged to exploration and abandonment expense	—		(4)
Ending capitalized exploratory well costs	$	498	$	660

Capitalized exploratory costs and the number of projects for which exploratory costs have been capitalized

Aging of capitalized exploratory costs and the number of projects for which exploratory well costs have been capitalized for a period greater than one year, based on the date of drilling was completed, are as follows:


	Year Ended December 31,
	2020		2019		2018
	(in millions, except well counts)
Capitalized exploratory well costs that have been suspended:

One year or less	$	495	$	660	$	509
More than one year	3		—		—
	$	498	$	660	$	509
Number of projects with exploratory well costs that have been suspended for a period greater than one year (a)	1		—		—