World Geothermal Congress 2020+1
March - October, 2021

Modelling and Interpreting the Resistivity Structure of Borinquen Geothermal Area in Costa Rica: Analysis of 1D and 3D Resistivity Inversions

Diego BADILLA ELIZONDO, Gylfi Páll HERSIR, Ásdís BENEDIKTSDÓTTIR

[Instituto Costarricense de Electricidad, ICE, Costa Rica]

Modelling and interpreting the resistivity structure of Borinquen Geothermal Area in Costa Rica were achieved through both 1D and 3D inversion of the MT and TDEM resistivity data. The structure has been compared with well data and results from geological mapping which was done to better understand the geothermal system. A total of 100 co-located soundings were used to carry out the inversion where each TDEM/MT sounding pair was jointly 1D inverted by using the TEM data to correct the static shift of the MT data. Resistivity depth slices and cross sections were created based on resistivity models from the 1D and 3D inversion to compare both approaches and to identifying the main anomalies and structures that can suggest possible well targets and thereby, additional power to the Borinquen Geothermal Power plant. The main regional geoelectrical strike direction seems to have a NW-SE trend according to strike analyses of the MT data. Resistivity cross sections were created perpendicular to the main strike. From the models based on 1D inversion we can see in general a shallow, medium to high resistivity structure which is associated to unaltered rocks, a low resistivity layer that is related to the smectite clay cap and below this, a medium to high resistivity structure which is presumably associated with the geothermal resource. For some areas a deep conductor was found below the proposed reservoir suggesting what could be interpreted as the heat source of the geothermal system.

        Topic: Geophysics Paper Number: 13106

         Session 8P: Poster 2 [Tuesday 11th May 2021, 11:00 pm] (UTC-8)
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