2011-03-31-2011-01-17-2011-03-21

Acquired company with an interest in 11 E&P blocks in Colombia, Peru & Argentina covering more than 5 million acres.

Gran Tierra Energy Inc., Calgary, (NYSE Amex: GTE; Toronto: GTE) has completed the acquisition of all the issued and outstanding common shares and warrants of Petrolifera Petroleum Ltd. by way of statutory plan of arrangement for US$195 million in equity.

Petrolifera shareholders received, for each Petrolifera share held, 0.1241 of a share of Gran Tierra Energy common stock, and Petrolifera warrant holders received, for each Petrolifera warrant held, 0.1241 of a warrant to purchase a share of Gran Tierra Energy common stock at $9.67 per share. The Gran Tierra Energy warrants expire on Aug. 28.

The arrangement was approved at a special meeting of Petrolifera shareholders on March 17, and by the Court of Queen's Bench of Alberta on March 18. Approximately 72% of the Petrolifera shareholders voted, with over 99% of the votes cast by Petrolifera shareholders voting in favor of the arrangement. Gran Tierra Energy has acquired all the issued and outstanding Petrolifera shares and warrants through the issuance of approximately 18.2 million Gran Tierra Energy shares and approximately 4.1 million Gran Tierra Energy warrants.

Petrolifera owns an interest in 11 exploration and production blocks; three are in Colombia, three are in Peru and five are in Argentina. The Colombian blocks, comprising approximately 850,000 acres, are in the Lower and Middle Magdalena Basins and are characterized by high quality light crude oil and gas. One crude oil discovery, La Pinta and one natural gas discovery, Brilliante, have been made in the Sierra Nevada Block in the Lower Magdalena Basin. Petrolifera is the operator of and currently owns a 100% working interest, subject to recent agreement pursuant to which Petrolifera agreed to transfer a 25% working interest to Gran Tierra Energy, upon receipt of approval from Colombia's National Hydrocarbon Agency.

The Peruvian blocks encompass approximately 4 million acres. Block 106 is in the prolific Marañon Basin adjacent to the Corrientes Field, which according to industry reports, is the largest field in the Basin. This Block is immediately west to Gran Tierra Energy's existing acreage within Peru. Blocks 107 and 133 are located in the Ucayali Basin north-west of the Camisea Field. Numerous leads and prospects have been identified on this acreage with indications the region has proven petroleum systems generating light crude oil and natural gas, with evidence of reservoir quality sandstones.

In Argentina, there are more than 220,000 net acres in five contiguous blocks operated by Petrolifera in the prolific Neuquen Basin. Working interest in the blocks range from 25% to 100%. In the Puesto Morales/Rinconada Concession, which accounts for the majority of production, Petrolifera is operator and has a 100% working interest. Recently, these producing assets have received limited investment due to capital constraints, but with Gran Tierra Energy's strong balance sheet, increased activity is contemplated as steadily increasing regional commodity prices through 2009 and 2010 may facilitate the potential to realize additional shareholder value through reinvestment of internally generated cash flow from operations in Argentina.

"The successful closing of this transaction represents a milestone for Gran Tierra Energy as we have now added substantially to our asset base in Colombia, Peru and Argentina," says Dana Coffield, president and chief executive of Gran Tierra Energy.

"The acquisition adds undeveloped oil and gas reserve potential in Colombia, exploration opportunities in Colombia and Peru and additional oil production and reserves in a rising oil price environment in Argentina. Gran Tierra Energy has retained its strong balance sheet and cash position to further develop the assets acquired in this transaction."

Petrolifera shares and warrants are expected to be de-listed from the Toronto Stock Exchange.

Gran Tierra Energy expects to announce a revised 2011 work program and budget shortly once final internal approvals are obtained.