Characterization of Crustal Fault Zones as Geothermal Reservoirs: A Multidisciplinary Approach

Summary As potential geothermal reservoirs, Crustal Fault Zones are still largely unexplored and unexploited (e.g. South Erzebirge deep fault zone, Germany (Achtziger-Zupancic, 2017), GraVisual Basic Expresserg, Sweden (Juhlin and Sandstedt 1989 , Lund and Zoback 1999 )). A multi-disciplinary approach has made it possible to estimate the position of the 150 °C isotherm at 2.5 km depth at the Pontgibaud Crustal Fault Zone (French Massif Central), highlighting its geothermal potential ( Duwiquet et al., 2019 ). Although consistent with field data, this estimate did not take the 3D distribution of permeability, the 3D geometry of fault networks, and the poroelastic effects on fluid flow, and the intensity and depth of temperature anomalies into account. With more measurements, observations, and 3D modeling based on thermo-hydro-mechanical (THM) coupling, this study proposes to better characterize the geothermal reservoir potential of the Pontgibaud Crustal Fault Zone.