REC-T-142 Block (Gran Tierra Energy 70% WI & Operator, Alvorada 30% WI)Drilling of the 1-GTE-01-BA oil exploration well began on October 7, 2011. The well is located in Block REC-T-142 in the prolific onshore Recôncavo Basin. This operation is commencing with the drilling of a vertical pilot hole from which core will be acquired from the prospective reservoir section. The pilot well is planned to reach a total measured depth of approximately 6,070 feet and take approximately 35 days to drill. Upon completion of the well and subsequent evaluation to determine if adequate reservoir is present, a drilling rig is planned to return late in 2011 to drill a horizontal sidetrack from the pilot hole at the optimum depth to test the productivity of the sandstone reservoir target. This will be the first of three horizontal wells Gran Tierra Energy plans to drill in late 2011 and continuing into the first quarter of 2012. REC-T-129 Block (Gran Tierra Energy 70% WI & Operator, Alvorada 30% WI) Drilling of the 1-GTE-02-BA oil exploration well is scheduled to begin in mid-October, 2011. This well is located in Block REC-T-129 in the Recôncavo Basin and is targeting two independent light oil reservoir targets. The well is expected to reach a total measured depth of approximately 6,400 feet and take approximately 35 days to drill. Colombia Rumiyaco Block (Gran Tierra Energy 100% WI and Operator) The Rumiyaco-1 oil exploration well began drilling on October 9, 2011. This prospect lies in the southern Putumayo Basin approximately 85 kilometers southwest of Gran Tierra Energy's existing producing properties, and between two existing oil producing trends. The well is expected to test a structural closure defined by 3-D seismic data at a total measured depth of approximately 10,700 feet and take approximately 45 days to drill. Chaza Block (Gran Tierra Energy 100% WI and Operator) The Moqueta-6ST1 delineation well in the 2010 Moqueta oil discovery reached total measured depth of 5,724 feet in basement after encountering oil shows in the Kg Sandstone, the U Sandstone, the T Sandstone and the Caballos reservoirs. The primary T Sandstone and Caballos reservoirs were encountered approximately 250 feet deeper than the equivalent reservoirs in Moqueta-5. Electric log interpretations and pressure gradient data indicate oil pay in the T Sandstone and Caballos reservoirs. A testing program is currently being designed to confirm the nature of the fluids and reservoir productivity of the sandstones.