Property, Plant and Equipment (Tables)

9 Months Ended

Sep. 30, 2021

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant and Equipment

(Thousands of U.S. Dollars)	As at September 30, 2021		As at December 31, 2020
Oil and natural gas properties
Proved	$	4,236,548	$	4,106,768
Unproved	158,483		161,763
	4,395,031		4,268,531
Other(1)	32,779		32,135
	4,427,810		4,300,666
Accumulated depletion and depreciation and impairment	(3,433,173)		(3,336,184)
	$	994,637	$	964,482

(1) The "other" category includes right-of-use assets for operating and finance leases of $11.7 million, which had a net book value of $2.5 million as at September 30, 2021 (December 31, 2020 - $11.4 million which had a net book value of $4.4 million).