Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2020

Property, Plant and Equipment [Abstract]

Net Changes in Capitalized Exploratory Well Costs

The following table reflects the net changes in capitalized exploratory well costs during the six-month periods ended June 30, 2020 and 2019.

(Thousands of dollars)	2020		2019
Beginning balance at January 1	$	217,326	207,855
Additions pending the determination of proved reserves	2,328		50,307
Capitalized exploratory well costs charged to expense	(39,519)		(13,145)
Balance at June 30	$	180,135	245,017

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.

	June 30,
	2020				2019
(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	$	24,429	3	3	33,125	3	2
One to two years	30,691		2	2	61,293	1	1
Two to three years	—		—	—	27,266	1	1
Three years or more	125,015		6	—	123,333	5	—
	$	180,135	11	5	245,017	10	4

Schedule of Recognized Impairments

The following table reflects the recognized impairments for the six months ended June 30, 2020.

	Six Months Ended
(Thousands of dollars)	June 30, 2020
U.S.	$	947,437
Other Foreign	39,709
	$	987,146