Permeability is a first order factor in controlling fluid circulations into the crust and the location of geothermal reservoirs. X-ray micro-tomography allows for imaging the geometry of permeable structures in 3D down to a 0.2 μm resolution. These observations can then be integrated into dynamic and multiphysical 3D numerical models allowing the estimation of the depth and intensity of temperature anomalies within geological targets such as Crustal Fault Zones.