The Acoculco High Temperature Area in Mexico: Resistivity Survey (TEM and MT); Data Acquisition, Processing and Inversion - Geological Significance

GEMex (Cooperation in Geothermal energy research Europe-Mexico for development of Enhanced Geothermal Systems and Superhot Geothermal Systems) is a joint geothermal project of a European and Mexican consortium which began in late 2016 with the purpose to develop geothermal energy in the easternmost region of the Trans-Mexican Volcanic Belt. Two sites that belong to the Comisión Federal de Electricidad (CFE) have been investigated. One of them, the Los Humeros high-temperature area is a superhot geothermal system. The other one, Acoculco high-temperature geothermal area has been proposed to develop an Enhanced Geothermal System (EGS). To characterize an EGS development site in Acoculco, extensive geological, geochemical and geophysical studies were carried out. Already existing regional gravity and magnetic maps were analysed, and gravity was measured on a dense grid. A total of 18 micro-seismic stations were set up which collected data for about a year. Finally, 68 colocated MT and TEM soundings were measured in 2017-2019 through a joint effort by the European and Mexican partners. Their location was based on the interpretation of already existing resistivity measurements as well as a recent geological model of the area. The TEM was measured using TerraTEM equipment and the MT data were collected using instruments from the Metronix manufacturer. The Bounded Influence Remote Reference Processing method (BIRRP) was used for processing the MT time-series. Each TEM/MT pair was jointly inverted in 1D, using the TEM data to static shift correct the MT data. The authors wish to thank the Comisión Federal de Electricidad (CFE) for their assistance and support. This paper presents results of the GEMex Project, funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No. 727550, and by the Mexican Energy Sustainability Fund CONACYT-SENER, Project 2015-04-268074. More information can be found on the GEMex Website: http://www.gemex-h2020.eu.