Preliminary resource assessment of El Galpón area (Salta, Northwest Argentina) from fluid geochemistry studies and the Volumetric Method

Abstract

 Within a global warming scenario in searching the energy transition from fossil fuels to free-CO₂ energy sources, as well as the improvement in energy efficiency and diversification, geothermal energy is positioned as a promising energy source. This paper presents new geochemical and isotopic data of the fluids related to the El Galpón geothermal system with the aim to:  investigate the physicochemical conditions of the fluids within the geothermal reservoir, present a conceptual model of the geothermal system, and carry out an evaluation of the geothermal potential of the area. The geochemical characterization was carried out by direct sampling of water and subsequent analysis of its chemical and isotopic composition, while the 3D geological modeling was carried out by using the LeapfrogGeo software. The deep geothermal reservoir, hosted within with the Pirgua Subgroup, has sodium bicarbonate composition and temperatures of ~111 °C, while the deposits of the Balbuena Subgroup would constitute the seal of the system. Recharging meteoric water could reach depths of up to 6 km, acquiring the temperatures estimated by geothermometers in an area of normal geothermal gradient. During the ascent to the surface, favored by the structures, the geothermal water undergoes mixing processes with more superficial aquifers, sodium sulfate chloride in composition, hosted in the Orán Group. The geothermal potential of the modeled area, expressed as heat stored both in the rock and in the fluids, would be 4.33 * 10¹⁷ J.