6. Property, Plant and Equipment

	As at December 31, 2011
(Thousands of U.S. Dollars)	Cost		Accumulated DD&A				Net Book Value
Oil and natural gas properties
Proved	$	1,181,503		$	(562,521	)		$	618,982
Unproved		417,868			-				417,868
		1,599,371			(562,521	)			1,036,850
Furniture and fixtures and leasehold improvements		6,973			(4,002	)			2,971
Computer equipment		8,443			(4,174	)			4,269
Automobiles		1,295			(543	)			752
Total Property, Plant and Equipment	$	1,616,082		$	(571,240	)		$	1,044,842

	As at December 31, 2010
(Thousands of U.S. Dollars)	Cost		Accumulated DD&A				Net Book Value
Oil and natural gas properties
Proved	$	777,262		$	(334,858	)		$	442,404
Unproved		278,753			-				278,753
		1,056,015			(334,858	)			721,157
Furniture and fixtures and leasehold improvements		5,233			(2,831	)			2,402
Computer equipment		5,521			(2,358	)			3,163
Automobiles		779			(477	)			302
Total Property, Plant and Equipment	$	1,067,548		$	(340,524	)		$	727,024

On August 26, 2010, the Company entered into an agreement to acquire a 70% participating interest in four blocks in Brazil. With the exception of one block which has a producing well, the remaining blocks are unproved properties. The agreement was effective September 1, 2010, subject to regulatory approvals, and the transaction was completed on June 15, 2011. Purchase consideration was $40.1 million and was recorded in the All Other category of capital expenditures in 2011 and 2010. The 70% share of all benefits and costs with respect to the period between the effective date and the completion of the transaction were an adjustment to the consideration paid for the four blocks.

In March 2011, the Company recorded proceeds of $3.3 million from the farm out of a 50% interest in the Santa Victoria Block in Argentina to Apache Corporation. The Company also recorded $1.2 million from the sale of a blow-out preventer in Argentina in September 2011. In October 2010, the Company recorded proceeds of $6.4 million for the sale of an overriding interest in the Garibay Block in Colombia. In April 2009, Gran Tierra closed the sale of the Company's interests in the Guachiria Norte, Guachiria, and Guachiria Sur blocks in Colombia. Principal terms included consideration of $7.0 million comprising an initial cash payment of $4.0 million at closing, followed by 15 monthly installments of $200,000 each which began on June 1, 2009 and ended on August 3, 2010. The Company recorded proceeds of $1.6 million and $5.4 million in 2010 and 2009, respectively. Gran Tierra retained a 10% overriding royalty interest on the Guachiria Sur Block, which, in the event of a discovery, is designed to reimburse 200% of the Company's costs for previously acquired seismic data.

Depreciation, depletion and amortization was $163.5 million in 2011 (2010 - $140 million; 2009 - $134.0 million). In 2011, we recorded ceiling test impairment losses in the Company's Peru and Argentina cost centers of $42.0 million and $25.7 million, respectively. The 2011 impairment charge in the Peru cost center related to seismic and drilling costs from two blocks which were relinquished. The 2011 impairment charge in the Argentina cost center related to an increase in estimated future operating and capital costs to produce our remaining Argentine proved reserves and a decrease in reserve volumes. In 2010, we recorded a $23.6 million ceiling test impairment loss in the Company's Argentina cost center as compared with a $1.9 million impairment loss for December 31, 2009. Of the 2010 impairment loss, $17.9 million related to the abandonment of the Valle Morado sidetrack operations and the remaining $5.7 million resulted from a decrease in reserves combined with higher forecasted operating costs to produce the remaining proved reserves. The 2009 impairment loss resulted from higher forecasted operating costs to produce the remaining proved reserves in Argentina.

The amounts capitalized in each of the Company's cost centers during the years ended December 31, 2011 and 2010 were as follows:

	Year ended December 31, 2011
(Thousands of U.S. Dollars)	Colombia		Argentina		Peru		Brazil		Total
Capitalized G&A, including stock-based compensation	$	7,996	$	3,189	$	1,183	$	1,985	$	14,353
Capitalized stock-based compensation	$	456	$	266	$	-	$	234	$	956

	Year ended December 31, 2010
(Thousands of U.S. Dollars)	Colombia		Argentina		Peru		Brazil		Total
Capitalized G&A, including stock-based compensation	$	4,127	$	1,171	$	287	$	-	$	5,585
Capitalized stock-based compensation	$	308	$	150	$	-	$	-	$	458

	Year ended December 31, 2009
(Thousands of U.S. Dollars)	Colombia		Argentina		Peru		Brazil		Total
Capitalized G&A, including stock-based compensation	$	1,600	$	600	$	30	$	-	$	2,230
Capitalized stock-based compensation	$	198	$	117	$	-	$	-	$	315

Unproved oil and natural gas properties consist of exploration lands held in Colombia, Argentina, Peru and Brazil. The Company had $274.8 million (December 31, 2010 - $228.8 million) in unproved assets in Colombia, $57.0 million (December 31, 2010 - $9.4 million) of unproved assets in Argentina and $33.7 million (December 31, 2010 - $28.2 million) of unproved assets in Peru, and $52.4 million (December 31, 2010 – $12.4 million) of unproved assets in Brazil for a total of $417.9 million (December 31, 2010 - $278.8 million). These properties are being held for their exploration value and are not being depleted pending determination of the existence of proved reserves. Gran Tierra will continue to assess the unproved properties over the next several years as proved reserves are established and as exploration dictates whether or not future areas will be developed.

The following is a summary of Gran Tierra's oil and natural gas properties not subject to depletion as at December 31, 2011:

	Costs Incurred in
(Thousands of U.S. Dollars)	2011		2010		2009		Prior to 2009		Total
Acquisition costs - Colombia	$	76,346		-		-		159,045	$	235,391
Acquisition costs - Argentina		45,015		-		-		-		45,015
Acquisition costs - Peru		23,423		2,000		-		-		25,423
Acquisition costs - Brazil		22,891		12,395		-		-		35,286
Exploration costs - Colombia		19,233		12,427		3,311		487		35,458
Exploration costs - Argentina		181		683		163		229		1,256
Exploration costs - Peru		7,389		301		372		189		8,251
Exploration costs - Brazil		17,155		-		-		-		17,155
Development costs - Colombia		3,929		-		-		-		3,929
Development costs - Argentina		5,683		5,021		-				10,704
Total oil and natural gas properties not subject to depletion	$	221,245		32,827	$	3,846	$	159,950	$	417,868