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 geologicalgeochemical and geophysical investigations in Los Humeros and Acoculco, Mexico

  • Results from geologicaltemperature and reservoir modelling

  • Results from technology development for super hot geothermal reservoirs

More info on this event here

Qué Hacemos

Geothermal reservoirs


Geothermal reservoirs are hot deep waterbearing systems (hydrothermal systems) or systems without or with limited amount of water (petrothermal systems). Hydrothermal systems include geologic formations with naturally sufficient hydraulic permeability, i.e. the capacity of the geological medium to transport fluids. Crucial for the economic operation of hydrothermal systems is a sufficient temperature of the aquifer, and a high hot water production rate.


EGS – Enhanced Geothermal Systems

Enhanced geothermal systems are geothermal reservoirs which have promising high temperatures but the rock permeability or the abundance of fluids in the rock is not high enough for the production of electricity. EGS are also referred to as Hot Dry Rocks.


In EGS, stimulation techniques are used to generate an artificially higher hydraulic permeability in initially low-permeability rocks. Such stimulation techniques are hydraulic, thermal, or chemical stimulation, advanced well configurations, or soft stimulation techniques such as cyclic/fatigue stimulation or multi-stage stimulation. EGS technologies represent the sum of the engineering measures that are required for the transfer of heat and to optimize the exploitation of the reservoir. Therefore, the concept of EGS is designed to make geothermal energy utilization feasible in most environments and thus offers an enormous untapped potential.


In GEMex we aim to explore the EGS in Acoculco. Two wells have shown high temperatures around 300 °C at 2km depth, but hardly any fluids were found. During the project we are going to use 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.


SHGS – Super Hot Geothermal Systems

Super Hot geothermal systems are geothermal reservoirs with an exceptional high geothermal gradient. In SHGS temperatures of more than 380 °C can be reached. This makes them ideal candidates for the exploitation of geothermal energy and geothermal electricity production.


However, we often also find exceptional fluid chemistry in SHGS - the aggressive fluid and the high temperature pose a challenge to the methods and materials used for drilling and well completion. That is why SHGS are up to now rarely used for geothermal energy production.


In GEMex, we will investigate the SHGS in Los Humeros. The northern part of the geothermal field, which shows the super hot temperatures, will be characterized by geological, geochemical and geophysical methods and numerical models will permit the simulation of reservoir characteristics. At the end, GEMex will provide a list of suitable materials to be used in SHGS and recommend designs for drilling, well completion, and sustainable usage of the reservoir.


Acronym GEMex
Title Cooperation in Geothermal energy research Europe-Mexico for development of Enhanced Geothermal Systems and Superhot Geothermal Systems
Topic LCE-23-2016
Call identifier H2020-LCE-2016-RES-CCS-RIA
Grant Agreement number 727550
Duration 44 Months
Start date 01/10/2016
Estimated project cost 9'999'792.50 €
Requested EU contribution 9'999'792.50 €


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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.