Towards a multi-physics multi-scale approach of deep geothermal exploration

A wide range of geophysical methods is used for the exploration of deep geothermal resources. It aims at characterizing the deep fractured network and its capacity for fluid/heat extraction. This relies however on the capacity of geophysical techniques to 1) image the geometry of the fractured network but also 2) characterize the petro-physical properties of the fracture network and matrix. The challenge is however that the geophysical inverse problem is ill-posed and multi-scale. To overcome these challenges, we propose here to take a multi-physics and multi-scale approach of the geophysical/petro-physical inverse problem. To do so, we are developing iteratively petro-physical and geophysical models that can explain the observables at the different scales. In this paper, we report out the results of the first iteration phase of this research project that consists in building an initial petrophysical model from well logs and prior geological knowledge, and single-domain inversion of geophysical data. We applied this methodology to the Upper Rhine Graben where a wealth of knowledge and dataset on deep fractured formations are available.