Accounting for Suspended Exploratory Wells (Tables)

12 Months Ended

Dec. 31, 2018

Accounting for Suspended Exploratory Wells [Abstract]

Changes in company's suspended exploratory well costs

The following table indicates the changes to the company’s suspended exploratory well costs for the three years ended December 31, 2018:



	2018			2017			2016
Beginning balance at January 1	$	3,702		$	3,540		$	3,312
Additions to capitalized exploratory well costs pending the determination of proved reserves	207			323			465
Reclassifications to wells, facilities and equipment based on the determination of proved reserves	(13		)	(113		)	(119		)
Capitalized exploratory well costs charged to expense	(333		)	(39		)	(118		)
Other reductions^*	—			(9		)	—
Ending balance at December 31	$	3,563		$	3,702		$	3,540

^*Represents property sales.

Aging of capitalized well costs and number of project

The following table provides an aging of capitalized well costs and the number of projects for which exploratory well costs have been capitalized for a period greater than one year since the completion of drilling.



	At December 31
	2018		2017		2016
Exploratory well costs capitalized for a period of one year or less	$	202	$	307	$	445
Exploratory well costs capitalized for a period greater than one year	3,361		3,395		3,095
Balance at December 31	$	3,563	$	3,702	$	3,540
Number of projects with exploratory well costs that have been capitalized for a period greater than one year^*	30		32		35

^*Certain projects have multiple wells or fields or both.

Aging of Costs on Well and Project Basis

The $3,361 of suspended well costs capitalized for a period greater than one year as of December 31, 2018, represents 153 exploratory wells in 30 projects. The tables below contain the aging of these costs on a well and project basis:



Aging based on drilling completion date of individual wells:	Amount		Number of wells
1998-2007	$	410	31
2008-2012	1,076		61
2013-2017	1,875		61
Total	$	3,361	153

Aging based on drilling completion date of last suspended well in project:	Amount		Number of projects
2003-2010	$	338	5
2011-2014	894		10
2015-2018	2,129		15
Total	$	3,361	30