PEPR Project – Subsurface, a Common Good – PC13 Massif Central Program – High-temperature geothermal energy in the Limagne – Subtask 2.2.2

Explanations of the PEPR Project – Subsurface, a Common Good – PC13 Massif Central Program – High-temperature geothermal energy in the Limagne – Subtask 2.2.2
(ANR-22-EXSS-0014)

Geothermal energy, as a new low-environmental-impact energy source, requires improved identification of the impact of heat transfer related to hydrothermal circulation and volcanism, and therefore a better characterization of the permeability of the fractured Variscan basement and the Cenozoic sediments.

We will also consider the potential of co-products such as lithium (Li) contained in hydrothermal fluids.

This project aims to explore deep geothermal reservoirs in the Limagne half-graben (Auvergne region, France), which formed during the rifting phase of the European Cenozoic Rift System (ECRIS).

This asymmetric graben shows, in its western part (Riom area), a thick sedimentary succession (>2000 m) ranging from the Eocene to the Early Miocene, progressively thinning toward the east.

This basin overlies a Paleozoic basement affected by a series of NE–SW-oriented faults, which may have been reactivated during the rifting phase and therefore probably played a major role in fluid transfer.

To characterize this geothermal potential, a multidisciplinary study focuses on two main themes:

Subsurface characterization using geophysical tools and existing borehole data to identify the structural network affecting the Limagne d’Allier area as well as the geometry of the associated geological bodies.
Geochemistry of geothermal waters in the same area and, based on the structural framework developed in (1), the development of a 3D geothermal model using numerical modeling tools.

These two aspects, carried out by two 12-month postdoctoral research assistants (Bastien Huet – BRGM and Emmy Penhoët – GeoRessources, Nancy), are complemented by studies conducted by Master’s students, including:

1. Organic matter geochemistry (GeoRessources – Nancy)
2. Analysis of well data in the eastern part of the Limagne half-graben (Louis Gauthier – Géosciences Rennes)
3. Petrological characterization of volcanic and/or volcanoclastic rocks (“peperites”) (Laboratoire Magmas et Volcans – Clermont-Ferrand)
4. Paleo-altimetry estimates using stable isotopes (GeoRessources – Nancy)
5. Geochemistry of geothermal waters (GeoRessources – Nancy)

This subtask 2.2.2 complements subtask 2.2.3, which focuses on deep geothermal systems in the Sancy and Mont-Dore areas (led by Laurent Arbaret, ISTO), as well as studies aiming to better understand the perception of local stakeholders regarding this energy resource, conducted within subtask 2.2.1 (led by Sylvie Huet, INRAE).

Project start Date : 2024
Project end Date : 2029
Project duration : 72 month
Bearer of the sub-task : GEBELIN A. (GeoRessources)
Research team GEM
Link to the project site
Contact GeoRessources : GEBELIN Aude