A three-dimensional (3D) numerical model is proposed for natural state simulation of the Las Tres Virgenes (LTV) geothermal system from emplacement and cooling of the heat source. A conceptual model of the LTV volcanic system was developed considering tectonic regime, structural geology, out-cropping geology, eruptive events and geochronology. The model includes the emplacement of two magma chambers, lateral variations of physical properties and the topography of the geographic area. Model calibration was carried out for several chamber volumes and depths, as well as thermal diffusivity of lithological units. Static formation temperatures (SFT) and homogenization temperatures were used as references. Chamber depths between 3000 and 3500 m below sea level with total chamber volumes of 429 and 563 km(3), respectively, were inferred from the simulation results. The exergy of the reservoir was consistent with the current installed capacity of the power plant (10 MWe); however, an increase of at least 4 MWe would be attained with optimized power cycles. (C) 2013 Elsevier Ltd. All rights reserved.