List of criteria for the geothermal survey of deep-reaching faults in Germany

Disruptive deformations create deep subsurface faults, which may result in the formation of hydrothermal fluid pathways. Deep-reaching faults are promising targets for geothermal exploration. In Germany, the hydraulic properties of faults are usually not known when geothermal wells are planned. However, there are documented and plausible criteria to assess the geothermal potential of faults in advance. Experience gained from geologic exploration of faults confirms an empirical correlation between fault geometry and the distribution of geothermal resources. Geothermal surveys indicate that damage zones at fault terminations and interfering faults (e.g. relay ramps, crossing faults etc.) could represent favourable settings for exploration in critically stressed areas. Besides fault geometry and stress regime, additional criteria are outlined for the assessment of the geothermal potential of faults.