Geochemical characterization and resource assessment of a low to medium temperature hydrothermal system within the Sabinas basin, Coahuila, Mexico

Abstract

Northeast of Mexico is known for the exploitation of hydrocarbons, moreover, the region also contains thermal manifestations that have not been studied a detailed to determine its characteristics, potential and to evaluate their possible use in the generation of electricity, and/or in direct uses. This work presents a preliminary geothermal prospecting study of thermal manifestations in the Escobedo area, Coahuila, within the Sabinas basin, known for the exploitation of natural gas and coal. The work considered a review and compilation of information of the area, including information from gas wells, as well as a first campaign to collect samples from different water bodies, including hot springs, rivers, and water wells, to the characterization of major elements and stable isotopes. This geochemical information was used to classify the fluids and determine their origin and likely producing reservoir temperatures. Preliminary results indicate the presence of two types of waters: thermal Ca2-SO4 waters and cold Ca2-HCO3 waters, which seem to indicate a meteoric origin and whose precipitation occurs at altitudes like those of the mountains that delimit the study area, discharging from fractures in the base of anticlines. Geothermometric temperatures estimated in hot waters (discharged from thermal springs and a gas well) indicate a low to medium temperature system, with equilibrium values of the order of 87.0 ± 17°C, consistent with those predicted by a silica-enthalpy mixing model. Probable reservoir would be in the La Virgen formation, according to available gas well information. The evidence found and integration of information led to propose a conceptual model of the system, which is the base for the resource assessment through the volumetric method and Monte Carlo simulations. These results allow the knowledge of the geothermal resources in the Sabinas basin and the possible synergies between the oil industry (Infrastructure and related studies) and the development of geothermal energy in Mexico.