Capitalized Exploratory Well Costs and Undeveloped Leasehold Costs

9 Months Ended

Sep. 30, 2019

Capitalized Exploratory Well Costs and Undeveloped Leasehold Costs

Note 5. Capitalized Exploratory Well Costs and Undeveloped Leasehold Costs

Capitalized Exploratory Well Costs There were no significant changes to our capitalized exploratory well costs during the period. The following table provides an aging of capitalized exploratory well costs based on the date that drilling commenced:



(millions, except number of projects)	September 30, 2019		December 31, 2018
Exploratory Well Costs Capitalized for a Period of One Year or Less	$	15	$	6
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	354		348
Capitalized Exploratory Well Costs, End of Period	$	369	$	354
Number of Projects with Exploratory Well Costs That Have Been Capitalized for a Period Greater Than One Year Since Commencement of Drilling	7		7

Undeveloped Leasehold Costs Changes in undeveloped leasehold costs are as follows:



(millions)	Nine Months Ended September 30, 2019
Undeveloped Leasehold Costs, Beginning of Period	$	2,306
Additions to Undeveloped Leasehold Costs	63
Transfers to Proved Properties	(20		)
Undeveloped Leasehold Costs, End of Period	$	2,349

As of September 30, 2019, undeveloped leasehold costs included $2.1 billion, $100 million, $76 million, and $59 million attributable to the Delaware Basin, Eagle Ford Shale, other US onshore properties, and international properties, respectively. Certain of these costs pertain to acquired leases or licenses that are subject to expiration over the next several years unless production is established on the acreage. Other costs pertain to acreage that is being held by production.