Gran Tierra has completed drilling and testing of the Jilguero-1 exploration well, a new field discovery on the Garibay Block in the Llanos Basin, Colombia. Gran Tierra Energy, through its wholly-owned subsidiary Solana Petroleum Exploration Colombia Limited (Solana), has a 50% working interest under the Garibay exploration and production contract executed with Colombia's National Hydrocarbon Agency (ANH). CEPSA Colombia S.A. (CEPCOLSA), a wholly owned subsidiary of Compania Espanola de Petroleos, S.A. is the operator of the Garibay block and has the other 50% working interest. Solana had previously entered into a sale agreement with respect to its interest in the Garibay Contract. The sale agreement terminated on October 8, 2010, when certain conditions to closing with respect to required contractual and regulatory approvals were not fulfilled.

Jilguero-1 CEPCOLSA has completed initial testing on the Jilguero-1 well by collecting reservoir data and fluid samples from four formations, including the Une, Gacheta, Guadalupe and Mirador.

The Une Formation's oil bearing interval was perforated and tested from 9,477 feet measured depth ("MD") to 9,484 MD and was interpreted as having 19 feet of total hydrocarbon pay subdivided into 12 feet of net oil pay in the Upper Une zone and 7 feet of net oil pay in the Lower Une zone. A variety of tests were performed resulting in up to 2,175 barrels of oil per day ("BOPD") of 39.9°API gravity oil with 11.5% watercut through a 52/64 inch choke. A second test was performed in the Upper Une zone from 9,445 feet to 9,451 feet MD and from 9,462 feet to 9,468 feet MD, which produced up to 862 BOPD of 39.9°API gravity oil with 0.3% watercut through a 28/64 inch choke.

The Gacheta Formation was interpreted as having 15 feet of total hydrocarbon pay. The interval was tested and perforated from 9,285 feet to 9,300 feet MD. The test produced up to 669 BOPD of 36.9°API gravity oil with 11% watercut through a 24/64 inch choke.

The Guadalupe Formation was interpreted as having 31 feet of total hydrocarbon pay. The lower interval was tested and perforated from 8,991 feet to 8,994 feet MD. The test produced 35 BOPD of 11.8°API gravity oil with 4% watercut.

The Mirador Formation was interpreted as having 46 feet of total hydrocarbon pay. The interval was tested and perforated from 8,852 feet to 8,898 feet MD. The test produced up to 1,015 BOPD of 24.7°API gravity oil with 0.11% watercut.

Plans for long term testing and crude sales are underway, with initial production expected to begin in December, 2010. Production from the Jilguero-1 well will be transported approximately 60 kilometers by truck to existing pipeline infrastructure.

Tags: Gran Tierra Energy Inc.