Passage lines of the seismic survey done around the Etang de Berre in southeastern France

 The Géoscan Arc project, focused on assessing geothermal resource potential in southeastern France near the Étang de Berre, has completed its geophysical data acquisition. This phase involved gathering over 320 km of modern broadband 2D reflection seismic data across land and the Étang de Berre during autumn 2024. The data is now under processing and will be combined with findings from other geoscientific studies. A presentation of the integrated results is scheduled before summer 2025. The initiative receives funding from ADEME, BRGM, Région Sud, Département des Bouches du Rhône, and Aix-Marseille-Provence metropole.

France currently operates 80 deep geothermal plants, generating 2 TWh of heat as of 2023. These facilities are primarily located in the Paris Basin and Aquitaine Basin, while southeastern France remains untapped despite its geothermal potential and need for sustainable heat in residential and industrial sectors. To address this, the Géoscan Arc project launched an exploration effort covering roughly 1,000 km² around the Étang de Berre, an area historically recognized for lignite and previously explored for oil and gas without success, based on wells and seismic data from before 1980. However, uncertainties persist about the deep geothermal resource, including the structure and depth of target reservoirs—specifically lower Cretaceous carbonates—as well as their properties and water resource dynamics, such as presence, recharge, and flow.

To tackle these unknowns, a detailed exploration program was designed and is now in progress. The recent seismic data collection enhances older records to support the development of a structural model for the region. Public funding backs this geophysical effort, noted in “La gazette des communes.” Alongside this, geological fieldwork is underway, gathering structural details and rock samples from analogous sites, paired with a study of karstification. These activities aim to clarify reservoir characteristics and fluid circulation at depth. By the end of 2025, a geological model incorporating all data will be finalized, with project completion and delivery of results to the public, authorities, and industry expected by mid-2026.

The project seeks to lay the groundwork for deep geothermal development in southeastern France, responding to the region's energy needs while leveraging its natural resources. The combined geophysical and geological efforts aim to provide a clearer picture of the subsurface, guiding future decisions on sustainable energy development.