Gran Tierra Finds Oil at Popa-1 in Colombia

Gran Tierra Energy has successfully completed the first phase of testing of a new field wildcat well in the Rio Magdalena Block, located in the Middle Magdalena Basin of Colombia. The testing of Popa-1 has established the presence of a new light oil accumulation in the Middle Magdalena Basin of Colombia.

Popa-1 was drilled to a final depth of 9,285 feet on July 14, 2006. Significant light oil and gas shows were encountered during drilling from 8,700 feet to final depth, and subsequent logging of the well indicated that hydrocarbons were present.

A drill-stem testing program was designed and executed in two of the most prospective sandstone intervals of the Monserrate Formation. Stabilized oil flow was attained in two flow periods. The produced fluid consists of light oil of 34 degree API with a relatively high gas/oil ratio and no water. This testing program was constrained by the physical limits of the surface equipment available on location and the use of the drilling rig for testing.

Plans are now to suspend operations while bringing in a service rig to complete and test the full production capability of the existing perforated zones, and to test secondary zones deeper in the well that were not tested with the current operations.

The Popa-1 is the first oil accumulation discovered in the Rio Magdalena Block and establishes a new light oil play trend for future exploration and production drilling. Gran Tierra Energy is now initiating plans for acquiring 3-D seismic that will be used for future exploration and development drilling on the Block.

Popa-1 is a commitment well in the third phase of the Rio Magdalena Association Contract. Gran Tierra is the operator of the Block via its acquisition of Argosy Energy International, which was completed on June 20, 2006. The Company currently holds a 100% working interest in the Block. Ecopetrol, the state company, has a right to 30% participation subject to commerciality, and a sliding scale royalty applies.

Dana Coffield, President and Chief Executive Officer of Gran Tierra, stated, "Gran Tierra Energy is very excited with these early testing results. This was the highest risk prospect in our drilling portfolio for the coming year; we are very pleased with these positive results. We are eager to move forward in quickly evaluating this discovery, and creating additional value through the active drilling program we have scheduled for the coming year in both Colombia and Argentina."