Property, Plant and Equipment (Tables)

9 Months Ended

Sep. 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 nine-month periods ended September 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	9,941		86,025
Capitalized exploratory well costs charged to expense	(39,408)		(13,145)
Balance at September 30	$	187,859	280,735

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.

	September 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	$	8,000	1	—	64,711	5	5
One to two years	54,334		5	5	63,615	1	1
Two to three years	—		—	—	27,500	1	—
Three years or more	125,525		6	—	124,909	5	—
	$	187,859	12	5	280,735	12	6

Schedule of Recognized Impairments

The following table reflects the recognized impairments for the nine months ended September 30, 2020.

	Nine Months Ended
(Thousands of dollars)	September 30, 2020
U.S.	$	1,152,515
Other Foreign	39,709
Corporate	14,060
	$	1,206,284