Prospective Gas Resources with Emphasis on Wet Gas in Onshore Colombian Basins

Abstract

Colombia is a gas producing country, which has allowed it to maintain a high level of self-sufficiency for the past 40 years, including Natural Gas (NG) and liquefied petroleum gas (LPG) in activities primarily related to residential consumption, industry, and transportation. According to official data from the National Hydrocarbons Agency (ANH by its Spanish acronym), the total gas discovered in Colombia reaches 27 Tcf (Original gas in place - OGIP). The estimation of gas prospective resources in the Colombian onshore basins with commercial hydrocarbon production, where the presence of discovered gas has been concentrated, contributes to guiding exploration and production activities. The selected method to estimate the gas resources was proposed by Zetaware, a leading company in petroleum system modeling, and is called SREPC (Source Rock Expulsion Potential Calculator). In this study, it is used for the first time in Colombia to discriminate prospective resource of oil and total gas. The statistical analysis of the gas composition samples representative of the evaluated basins was used to estimate the amount of wet gas (probable source of LPG) with the parameter C3+ greater than 5%. The gas prospective resource estimation shows an important potential related with the current hydrocarbon production areas; total gas (including dry and wet gas) is close to 39.6 Tcf (Trillion cubic feet) while wet gas is about 21.1 Tcf (approximately 60% of the total resources to be discovered). The largest gas resources are in the Middle Magdalena basin with 10.39 Tcf, the Cordillera basin with 7.54 Tcf, and the Llanos Basin-Foothills Domain with 6.15 Tcf. In terms of prospective wet gas resources, the most promising basins are Middle Magdalena (5.9 Tcf) and Llanos-Foothills Domain (5.9 Tcf).