Ramiriqui-1 Exploration Well Encounters Oil Shows, Testing to begin in AprilCALGARY, Feb. 21, 2012 /PRNewswire/ - Gran Tierra Energy Inc. (NYSE AMEX: GTE; TSX: GTE) (" Gran Tierra Energy") , a company focused on oil and gas exploration and production in South America, today announced a drilling update in the Putumayo and Llanos basins of Colombia, Recôncavo Basin of Brazil, and Noroeste Basin of Argentina. "Gran Tierra Energy's 2012 drilling campaign is now well underway, with a mix of exploration and development drilling in both Colombia and Brazil in progress, while planning continues for additional drilling through the year in those countries, and in Peru and Argentina," said Dana Coffield, President and CEO of Gran Tierra Energy. ColombiaLlanos-22 Block, Llanos Basin (45% working interest, subject to ANH approval; CEPSA 55% working interest and operator) Drilling operations continue on the Ramiriqui-1 exploration well in the Llanos-22 Block in the foothills of the Llanos Basin. The Mirador formation has been interpreted as oil bearing with up to 130 feet measured depth ("MD") gross thickness based on cuttings and logging while drilling. Casing is being set. Upon completion, drilling is expected to continue to evaluate deeper potential reservoir intervals and is expected to finish in March. Gran Tierra Energy expects testing of the Mirador formation, to confirm fluid content and reservoir productivity, to commence in April 2012. Chaza Block, Putumayo Basin (100% working interest and operator) The Pacayaco-1ST1 exploration well reached total true vertical depth of 5,343 feet. Approximately ten feet of oil column in the T-Sandstone was interpreted from cuttings and evaluation of wireline logs. It was determined that the formation did not contain economic quantities of hydrocarbons so the well was plugged and abandoned.