Asset Retirement Obligation (Tables)

12 Months Ended

Dec. 31, 2011

Asset Retirement Obligation [Abstract]

Changes in Asset Retirement Obligations

Changes in the carrying amounts of the asset retirement obligations associated with the Company's oil and natural gas properties were as follows:

	As at December 31,
(Thousands of U.S. Dollars)	2011			2010
Balance, beginning of year	$	4,807		$	4,708
Settlements		(345	)		(286	)
Disposal		(172	)		(720	)
Liability incurred		867			719
Liability assumed in a business combination (Note 3)		4,901			-
Foreign exchange		17			58
Accretion		673			328
Revisions in estimated liability		1,921			-
Balance, end of year	$	12,669		$	4,807
Asset retirement obligation - current	$	326		$	338
Asset retirement obligation - long term		12,343			4,469
Balance, end of year	$	12,669		$	4,807