High technical and economic risks stemming from the lack of detailed knowledge of the subsurface hold back large-scale investments in geothermal energy. In a survey conducted on nine use cases from diverse geological settings across Europe and with different purposes (electricity/heating and cooling) and project objectives (scientific/commercial), we identify the “common practice” and the aspiration for the “state of the art” in geothermal exploration. For each use case, the survey investigates what workflows have been adopted and what data acquired by which methods at different stages of exploration. This provided a benchmark for exploration in a range geothermal play types. The survey shows that this industry-standard base-case can be adapted to improve exploration success and efficiency by (1) applying numerical modelling in early stages of exploration to guide strategic data collection, (2) novel application of innovative technologies and (3) closer integration of software tools for static geological interpretation and dynamic heat flow simulation.

This study evaluates the geothermal potential in an Area of Interest (AOI) in the southeast of Gran Canaria, focusing on location selection near the rift zone and NW-SE vertical fracture zones.

Via a 3D resistivity model nine conductive bodies were identified in the AOI. Then interpretations of the location of these bodies were constructed based on magnetetelluric (MT), density, and S-wave velocity data with geochemical analyses of gas emissions, groundwater chemistry, temperature gradients and the geological history of the AOI. Eventually the geothermal potential of these locations within the AOI was assessed via six criteria: degree of hydrothermal alteration, depth, hydrothermal activity, marine intrusion, top-down area size and fracture density.

Finally a conceptual geological model of the most promising location was made with a sub-vertical fracture system. Several scenarios were tested as part of a sensitivity analysis, all of which are plausible and therefore not irrelevant. In these scenarios key parameters such as porosity, permeability, geothermal gradients, and the permeability ratio (kz/kx/ky) within the fracture zone were varied. One of the main findings was that the 10/10/1 permeability ratio, considered the most realistic for sub-vertical fractures, showed minimal impact on production performance.