Gas prospectivity in the foothills domine Cordillera basin in the western foreland Llanos Orientales basin, Colombia

Abstract

Colombia is a gas producing country that has managed to maintain a high level of self-sufficiency of this energy resource during the last 40 years, however the drastic decrease in reserves poses a worrying picture. The gas prospectivity study in the foothills domain (Cordillera basin) and the western foreland area of the Eastern Llanos basin aims to support exploration and production effort to increase gas reserves in Colombia. The geochemical characterization of gasses and the focus on the C3+ variable (propane (C3) + butane (C4) + pentane (C5)), indicates that 96% of the gas produced in the study area is of wet character (C3+ above 5%) and is a source of both natural gas (NG-Methane) and liquefied petroleum gas (LPG- propane-butane). The combination associated the source rock potential, thermal maturity level of the source rocks and the origin of the gas associated to primary cracking processes, allowed ideal conditions for the trapping and production of light oil, condensates, wet gas (LPG source) and dry gas (NG). Based on the integration of the results, four prospectivity play fairways are proposed: foothills, where the largest gas production in Colombia is located (NG and LPG), foredeep (deep zone of the foreland basin). In all the play fairways there are discovered oil and gas fields with production histories of more than 30 years and in the process of decline, which have a well-developed oil infrastructure. Since most of the gas is associated with oil, the increase of gas reserves in the foothills domain and the foreland of the Llanos Orientales basin depends on an integrated exploration strategy that includes both oil and gas.