Numerical Modeling of Production Scenarios for Engineered Geothermal System (EGS) in Acoculco, Mexico

Abstract

Acoculco has been identified as a potential site for an EGS (Enhanced/Engineered Geothermal System) in Mexico. Within the Horizon 2020 project GEMex, it is investigated as an exploration field. In the present study, we describe the initial steady-state thermal modeling for Acoculco using stochastic forward simulations. We focus on the impact of uncertain input parameters such as thermal conductivity and porosity on the reservoir temperature at different target depths prior to production. Uncertainty is quantified in a Monte Carlo approach, using the algorithm of Sequential Gaussian Simulation (SGS). From the stochastically parametrized model, we extract the mean temperature of our target reservoir rocks from the ensembles of possible realizations. Following this, we analyze the likelihood of success of an EGS in this field by evaluating production scenarios from two different target reservoir rocks, skarn and granite. Simulations are performed using the existing wells as a geothermal doublet. These simulations investigate the impact in the temperature and pressure fields as a result of different injection rates, permeability, and volume of stimulated zone for a production period of 30 years. This study does not attempt to address the technicalities associated with designing a stimulation concept in this field, but rather focuses on the effect of production on the temperature and pressure field considering that a stimulation treatment has successfully resulted in a productive geothermal doublet.