GEMex – A Mexican-European Research Cooperation on Development of Superhot and Engineered Geothermal Systems

Abstract

Unconventional geothermal systems such as Engineered Geothermal Systems (EGS) have been in the focus of interest for geothermal exploitation for several decades. In addition, the development and exploitation of high-temperature geothermal fields with supercritical conditions are emerging as a new hot topic in various parts of the world. In the GEMex project, these two unconventional geothermal resources are investigated, building on previous efforts within the Mexican CeMIEGeo project (Centro Mexicano de Innovación en Energía Geotérmica). For this purpose, two sites have been selected in the eastern part of the Trans-Mexican Volcanic Belt (Los Humeros and Acoculco, Puebla) with the goal to develop transferable concepts for other high-temperature geothermal fields. Los Humeros is a geothermal field within a Quaternary volcanic complex with an existing geothermal power plant in operation since 1990. Temperatures around 380°C were found at depths below 2000 m; however, geothermal fluids at such high temperatures could only be used to some extent for energy production, due to their aggressive physicochemical characteristics. Focus of our research is on an improved and comprehensive understanding of the location and characteristics of the deeper superhot/supercritical geothermal reservoir and its connection to the known conventional geothermal system. Tests of different materials for the technical components, for downhole and surface installations, will address the special characteristics of the geothermal fluids and the very high temperatures. Acoculco is described as a high-temperature geothermal system within a Pliocene-Pleistocene volcanic complex. Two wells have been drilled and found temperatures above 300°C (EAC-1) at depths below 1800 m, but hardly any fluids. Preliminary geological studies consider Acoculco a candidate for the application of EGS technologies. In GEMex it will be evaluated if the existing wells can be hydraulically linked to permeable and fluid bearing fracture zones nearby.