The GEMex Project: Investigation of Acoculco (Mexico) as a Potential EGS Site

Abstract

The GEMex project is a Mexican-European research cooperation on developing concepts for the use of superhot and engineered geothermal systems for power generation. A major focus in the first stage of the project is the characterization of a potential EGS test site, which has been proposed for the Acoculco caldera in the Eastern Mexican Volcanic Belt. Two wells have shown high temperatures around 300 °C at 2km depth at Acoculco, but hardly any fluids were found. During the project we have used the full range of geological, geophysical and geochemical exploration methods to find out more about the geothermal system and to recommend EGS measures for the economic usage of the Acoculco reservoir. As a starting point, the geological characterization of the area and development of novel model approaches were used to build state-of-the-art models for simulation of both - the stimulation treatment and the lifetime performance of the EGS. The goal is to design an optimal stimulation treatment (including chemical stimulations, hydraulic fracturing, shear fracturing), reducing the potential negative impact of environmental effects such as induced seismicity. Dedicated simulation models are used to predict performance indicators related to economic performance, sustainability and environmental safety. Special attention will be paid to the mapping of seismically sensitive areas and the potential impact on drinking water aquifers. The paper will give an overview of the exploration strategy, selected results and interpretation. Based on the available data possible stimulation scenarios to connect the wells to a productive zone will be discussed.