2nd GEMex Side-event

GEMex researchers will present their results during the European Geothermal Workshop on 9-10 October 2019 in Karlsruhe, Germany.

GEMex researchers are invited to present their results during the EGW on:

  • Results from geological, geochemical and geophysical investigations in Los Humeros and Acoculco, Mexico

  • Results from geological, temperature and reservoir modelling

  • Results from technology development for super hot geothermal reservoirs

More info on this event here

Reservoir characterization studies ongoing in Los Humeros and Acoculco

To evaluate the physical properties of the rocks comprising the Los Humeros and Acoculco geothermal system, scientists from Europe conducted five field trips in cooperation with the Mexican scientists in these sites, collecting more than 330 outcrop analogues of representative lithology and drilling 70 plugs from cored sections of existing wells of Los Humeros. The petrophysical, thermal and mechanical properties of these plugs are being measured and will be used as calibrations for the measurements done in the outcrop samples. In general, petrophysical and rock mechanical data are needed for processing and interpreting the geophysical data and for parameterizing the geological models.

The metamorphic basement of Los Humeros and Acoculco geothermal system comprises of metamorphosed limestone and granitic intrusions. This project evaluates the potential of Acoculco as a possible Engineered (Enhanced) Geothermal System (EGS). Granite and skarn/marble samples were collected from Las Minas and Pueblo Nuevo Quarry for performing Hydraulic Stimulation experiments in laboratory scale. The samples were cut and polished and hydraulic fracturing experiments were performed on them. Results of the experiments will be reported in September 2018.

The research team is also working on analysing data from more than 50 wells received from CFE. These well data are crucial to understanding the physics of the geothermal system and provides the necessary details to support conceptual geological ideas. The biggest challenge faced by reservoir modelling group is the lack of conceptual understanding of the reservoir. In spite of several years of exploitation, Los Humeros is not yet completely understood due to lack of adequate geophysical measurements. However, the work carried out by the GEMex project, including geological, geochemical and geophysical investigations, might reveal important details towards the end of the project.

Read more: Deliverable 6.4: Report on the laboratory fracking experiment, its boundary conditions, and its flow rates and fracture apertures versus time curves.

Figure 5: Left-top - picture from the CFE core storage, left-bottom – plugs drilled from cores of CFE wells, right – sample preparation from different outcrop analogues for laboratory experiments Figure 6: Left - Pueblo Nuevo quarry from which the big skarn samples have been collected (center) were collected; Right - cut and polished sample before the experiment


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The site at Acoculco, foreseen for EGS development, has been explored by two deep wells drilled by the CFE (Comisión Federal de Electricidad). These wells found hardly any fluids but temperatures around 300°C at a depth of 2 km. The lack of fluids at depth is surprising, as this area of Mexico is subject to abundant precipitation. Nonetheless, the high temperature gradient makes it an interesting target for exploitation and the lack of a clear resource makes it an ideal region for testing our knowledge on how to constrain an area where EGS can be performed.

Los Humeros

The geothermal system at Los Humeros is currently exploited. The northern part of the area, however, is much hotter (>380°C) than the wells used for production today. The development of this part of the reservoir presents a challenge, both because of the high temperature and because of the water chemistry. In addition, the area has only been poorly characterised by geophysical and geological surveys. Therefore our understanding required for the development and exploitation of this super-hot resource is limited. The uncertainty about the potential of this resource and the technical challenges involved with the development of such a super-hot geothermal system currently prevent its economic development.