Preliminary Front End Engineering Design Initiated for Bretaña Norte Field Development in PeruCALGARY, April 17, 2013 /PRNewswire/ - Gran Tierra Energy Inc. ("Gran Tierra Energy") (NYSE MKT: GTE, TSX: GTE), a company focused on oil exploration and production in South America, today provided updates for its production and exploration drilling in Colombia, Peru and Brazil. "Gran Tierra Energy is pleased to start the year with record levels of production as we continue to successfully mitigate transportation disruptions in Colombia," commented Dana Coffield, President and Chief Executive Officer of Gran Tierra Energy. "Operationally, we believe the northern boundary of the Moqueta field has now been successfully delineated with the Moqueta-9 appraisal well. The balance of this year will focus on increasing water injection for pressure support and increasing production capacity from the field. Once permits are in place, we can then direct our attention to appraising the eastern flank of the Moqueta structure, which remains undrilled. In Peru, the evaluation of our Bretaña Norte oil discovery continues, with initial testing of our well extension expected in the coming month, preliminary field development planning initiated, and long term testing expected to begin within a year. Our exploration program in the onshore Recôncavo Basin in Brazil, testing a new play with horizontal drilling and multi-stage fracture stimulation, is ongoing with results expected mid-year," concluded Coffield. Production Average daily consolidated light and medium crude oil and natural gas production net after royalty (NAR) before inventory adjustments for the three months ended March 31, 2013, increased 21% to approximately 21,860 barrels of oil equivalent per day ("BOEPD") NAR compared with 18,148 BOEPD NAR for the corresponding period in 2012. Approximately 97% was oil and natural gas liquids. First quarter production reflects increased production in all countries in which we are producing with the largest contribution to the increase from the Costayaco, Moqueta, and Surubi oil discoveries. This increase was partially offset by approximately 44 days of oil delivery restrictions due to disruptions in the Ecopetrol-operated Trans-Andean oil pipeline (the "OTA pipeline") in Colombia. Gran Tierra Energy continued production while the OTA pipeline was down, selling oil through an alternative pipeline and trucking and storing excess oil. Average daily Colombian production of light and medium crude oil and natural gas for the three months ended March 31, 2013 increased 18% to approximately 17,850 BOEPD NAR before inventory adjustments, compared with 15,163 BOEPD NAR before inventory adjustments for the comparable period in 2012. The production is primarily from the Costayaco and Moqueta fields in the Chaza Block in which Gran Tierra Energy has a 100% working interest. Additionally, preliminary indications show approximately 139,800 barrels NAR net liquidation of inventory during the quarter. Inventory volumes will be finalized near the end of April 2013 and, as such, this figure is subject to change. ColombiaChaza Block (100% working interest and operator) In Colombia, the Moqueta-9D appraisal well was spud on January 20, 2013 to test the northwest extent of the Moqueta field. It discovered hydrocarbons in a different fault block, separate from the main Moqueta oil accumulation. The T-Sandstone tested gas and the combined Caballos and U-Sandstone formations tested oil and water. Further isolation testing on the Caballos and U-Sandstone formations will be conducted to define their hydrocarbon potential. These results, integrated with seismic and other wells drilled to date, indicate the well has defined the northern margin of the main Moqueta oil accumulation. The down-dip extent of the oil column to the west, south and east, and the lateral extent of the structure to the east, have not yet been defined by drilling, with this additional resource potential to be defined with our ongoing drilling campaign. The Moqueta-10 well has begun drilling. This well will be used as a water injection well to assist with pressure support in the Moqueta field to support production growth from existing and future planned production wells. This well is being drilled to the far western flank of the field, and may provide additional information on the down-dip extent of the oil column in the primary reservoirs in the main block, which has not yet been determined. This well will be followed by Moqueta-11, which is planned to be a production well.