CAPITALIZED EXPLORATORY WELL COSTS

The following summarizes the changes in capitalized exploratory well costs for each of the last three years ended December 31, 2018, 2017, and 2016. Additions pending the determination of proved reserves excludes amounts capitalized and subsequently charged to expense within the same year.



	2018			2017			2016
	(In millions)
Balance at January 1	$	350		$	264		$	245
Additions pending determination of proved reserves	602			477			249
Divestitures and other	(82		)	(3		)	—
Reclassifications to proved properties	(647		)	(373		)	(211		)
Charged to exploration expense	(64		)	(15		)	(19		)
Balance at December 31	$	159		$	350		$	264

The following provides an aging of capitalized exploratory 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:



	2018		2017		2016
	(In millions)
Exploratory well costs capitalized for a period of one year or less	$	126	$	160	$	119
Exploratory well costs capitalized for a period greater than one year	33		190		145
Balance at December 31	$	159	$	350	$	264

Number of projects with exploratory well costs capitalized for a period greater than one year	2		4		3

The following summarizes a further aging by geographic area of those exploratory well costs that have been capitalized for a period greater than one year since the completion of drilling at December 31, 2018:



								2015 and
		Total		2017		2016		Prior
	(In millions)
Suriname		28		—		—		28
Other Regions		5		5		—		—
		$	33	$	5	$	—	$	28

Projects with suspended exploratory well costs capitalized for a period greater than one year since the completion of drilling are those identified by management as exhibiting sufficient quantities of hydrocarbons to justify potential development. Management is actively pursuing efforts to assess whether reserves can be attributed to these projects.

Suspended exploratory well costs capitalized at December 31, 2018 for a period greater than one year since the completion of drilling primarily relate to exploratory drilling in Suriname. Suriname well costs have been suspended pending ongoing activities, including analysis of well results and geologic and geophysical studies of nearby blocks. Remaining activities required to classify the associated reserves as proved include additional exploratory and appraisal drilling, geologic and geophysical studies, reservoir modeling and simulation, economic modeling, pre-development studies, approval of development plans, and project sanctioning. Exploratory well costs as of December 31, 2017 were $190 million, of which $160 million related to three separate projects in the North Sea. The Seagull assets with exploratory costs of $82 million were divested during 2018, and the remaining two projects were reclassified to proved properties or charged to exploration expense based on management’s assessment and development efforts through year-end.