Gran Tierra Energy to Complete Costayaco-7 as Water Injector

Pipeline Repairs to Trans Andean Pipeline Continuing

Gran Tierra Energy Inc. (NYSE Amex: GTE, TSX: GTE), a company focused on oil exploration and production in South America, today announced that testing of Costayaco-7 has been completed. In addition, production operations are continuing at a reduced level while repairs continue with the Ecopetrol-operated Trans Andean Pipeline west of Orito.

Costayaco-7

The Costayaco-7 well is located at the northern end of the Costayaco Field in the Chaza Block, Putumayo Basin of southern Colombia. Following the well's initial results, further testing demonstrated that only formation water, and no oil, was present in the top of the Villeta T Reservoir where well logs and pressure data had indicated a potential thin oil column. This well will now be completed as a water injector to dispose of produced water from the Costayaco field, and to provide pressure support for the Villeta T reservoir.

Production Operations

Repairs on the Ecopetrol-operated Trans Andean Pipeline west of Orito are continuing. Since the pipeline was shut in on July 10, Gran Tierra Energy has produced crude at a reduced level of approximately 6,000 barrels of oil per day (BOPD) net after royalty in Colombia using available trucking capacity. The company expects to continue producing at approximately these levels until repairs are completed.

Argentina production has been averaging approximately 860 BOPD net after royalty during this period. Production in Argentina has since risen to approximately 1,200 BOPD net after royalty following recent completion of well workover activity.

"We expect to be able to return to normal production levels immediately following the completion of repairs," said Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy. "Production from the recently drilled Costayaco-8, with a production capacity of 3,500-4,500 BOPD, is ready to be tied in, and drilling operations at Costayaco-9 are proceeding normally with completion expected in late August."