Seismic Exploration for Geothermal Development in Toulouse: An Integrated Exploration Program Effectively Mitigate the Risks

This paper presents an integrated exploration program designed to mitigate risks associated with geothermal resource development in Toulouse, France. In response to a call for tenders by Toulouse Métropole for a district heating network, Engie Solutions proposed an energy mix incorporating geothermal energy. The targeted geothermal reservoir, located in the Eocene infra-molassic sands, was characterized through an innovative seismic acquisition approach due to the limited available seismic data in the area.

Given the sparse seismic coverage and lack of detailed well data, a Frugal 3D seismic acquisition campaign was developed to address the geological uncertainties. This campaign, which utilized inline shooting along urban roads and tracks, resulted in a full-fold migrated surface area of 15 km², complemented by a 10-km 2D profile to connect existing geothermal wells. Seismic data acquisition was conducted during the night to minimize urban noise.

The data were processed using advanced techniques, including noise attenuation, signal processing, and 5D regularization, to obtain accurate subsurface images. The results revealed previously unmapped fault systems, highlighting the importance of these new data in optimizing wells design and minimizing exploration risks. This study contributes to advancing geothermal energy projects and their integration into sustainable energy solutions for the Occitanie region.