First EAGE Workshop on Geothermal Energy in Latin America

Helium as a noble gases can be successfully used as tracers of the different fluid components which make a geothermal water, namely magmatic, meteoric and fossil groundwater. Here, case histories from geothermal fields of Mexico are reported.

Low carbon renewable energy is required to support the energy transition away from hydrocarbons while meeting rising global energy demands. Geothermal energy is a proven system, capable of electricity production and direct heat, with over 95% availability. Normally geothermal energy requires a high geothermal gradient, however technological advances are improving the opportunities for deployment in lower gradient regions. In sedimentary basins the geothermal gradient is normally lower, however the presence of large salt deposits can provide localized regions with an increased gradient due to the unique characteristics of salt. Salt is able to mobilize and flow under suitable conditions, and form structures; it also has a thermal conductivity two to four times higher than clastics and carbonates. Therefore, sediments above salt structures are expected to have a higher geothermal gradient - positive temperature anomalies. This research focusses on assessing the geothermal potential associated with positive temperature anomalies above salt structures in selected areas of the Scotian and Maritime basins.

The Los Humeros geothermal field and the Acoculco geothermal prospect in Mexico are identified as two key locations to advance the understanding of unconventional geothermal resources. In the Los Humeros geothermal field, temperatures higher than 400C have been found, being a suitable case study of a super-hot system. In Acoculco area, there are two exploratory holes with temperature of 300C at 2000m depth with practically null permeability. Hence, representing an interesting case to develop an Enhanced Geothermal System (EGS). Both areas were study subjects in the project “Mexico-Europe Cooperation to investigate improved geothermal systems and super-hot geothermal systems” (GEMex). We conduct magnetotelluric (MT) surveys in both areas to provide information on the electrical resistivity distribution at depth. We measured 123 MT sites in Los Humeros and 68 in Acoculco. The observation sites were distributed with a high spatial density to provide well-constrained resistivity models. The models clearly detect a conductive zone between 500 and 1000m deep associated with a clay zone of hydrothermal alteration. In Los Humeros the clay-cap overlies an intermediate resistivity zone probably related to the reservoir. At Acoculco, the resistivity increases rapidly beneath the clay-cap, in agreement with the presence of impermeable metamorphic rocks.

Very low enthalpy geothermal energy is one of the least known NCRES in Colombia, but it has been widely used around the world in particular for space conditioning (heating and/or cooling) for domestic and industrial purposes, due to its great adaptability since all it needs is a GHP to directly exchange heat with subsoil and/or groundwater. This investigation evaluates the possibility of implementing a SWSHP system to cool at 3°C a preservation room for exportation flowers in La Virginia S.A.S located in La Ceja, at 41 km to the southeast of Medellin (Antioquia, Colombia). The temperature of two reservoirs belonging to the flower farm was monitored to analyze their potential as heat sinks for a SWSHP. The traditional and geothermal refrigeration systems were compared using empirical formulas based on the theoretical performance proposed by Carnot. It was found that the water temperature had a very little variation with respect to the ambient air temperature. The feasibility of using a surface water body as a heat sink of a SWSHP was evaluated. The coupling with other geothermal arrangements such as vertical and/or horizontal Ground Source Heat Pumps (GSHP) and even combining aerothermal is suggested.

Fluid inclusions studies have been undertaken in Berlín geothermal field, El Salvador since 2001 as part of the training given by IAEA. From then on, interest in this field has been focused. With the proper training from well-known institutions like Italy and USA, Lageo acquired its fluid inclusion system in 2012. Several temperature measurements (Th and Tf) were done and in collaboration with CNR of Italy, a petrological model was constructed in Berlín geothermal field. The model correlates well with geochemistry and reservoir models, where the hottest temperature is located at the TR-4 and TR-5 zones. The outflow zone was also delimited by fluid inclusion studies.

The growth in population and energy requirement is a challenge for stakeholders in huge cities such as Buenos Aires. Sustainably meeting this demand is the goal demanded by society for this new century. The shallow geothermal energy (SGE) is a renewable energy very valuable. However, it is a great unknown. To overcome this initial barrier and make it known, the geothermal potential of the Matanza-Riachuelo Basin, where the City of Buenos Aires is located, were calculated.

For the estimation of shallow geothermal potential, it is necessary to define the characteristics and behavior of the aquifers under exploitation. The heat transport equation in porous media was used on the basis of a geological and hydrogeological model. The input parameters necessary for this estimate were obtained from an exhaustive geological data base for the Matanza-Riachuelo Basin. The required parameters are mainly the groundwater velocity, the lithological description and the thickness of each hydrogeological formations and geothermal ground parameters (volumetric heat capacity and thermal conductivity).

As a result, maps of SGE potential were obtained for the Matanza-Riachuelo Basin. This map reflects the viability of the exploitation of SGE in the City of Buenos Aires, thanks to the high geothermal potential values calculated.

The purpose of this report is to present the geophysical characterization of the Berlin geothermal field reservoir, based on results of different methodologies carried out in different moment, such us: MT, passive seismic and gravity. From MT results, the reservoir corresponds to a resistivity range of 50–90 Ohm- m inside the resistive dome. Its estimated thickness varies from 600 to 800 m. From the 9 years seismic data collected, a seismic tomography modelling was built, this model shows that production zone has good correlation to a seismic waves speed ratio (Vp/Vs) lower than 1.7. The area of this anomaly correlates very well with that suggested by the MT method. Finally the gravity survey result suggests that the Berlin producer reservoir is associated to a high positive gravimetric anomaly which it extends toward the south and southwest of the actual production zone, beyond to the Berlin town.

Show a comparison of the relevant geochemical and thermohydraulic characteristics of the fluids of the geothermal fields in production Alfredo Mainieri Protti, Las Pailas I & II and the field in development Borinquen that have allowed their current productive development. Although geographically both volcanoes are very close, the volcanic activities resulting from their origin are different and affect the formation of geothermal reservoirs associated with the Miravalles and Rincon de la Vieja Volcanoes relative to each of the fields.