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

TL;DR

This paper proposes a multi-physics, multi-scale approach to deep geothermal exploration, integrating geophysical and petrophysical models to better characterize fractured networks and improve inverse problem solutions.

Contribution

It introduces an iterative method combining petrophysical and geophysical models to address the ill-posed, multi-scale inverse problem in geothermal exploration.

Findings

Initial petrophysical model built from well logs and geological data

Single-domain inversion applied to geophysical data

Method applied to the Upper Rhine Graben with promising results

Abstract

A wide range of geophysical methods is used for the exploration of deep geothermal resources. It aimsat characterizing the deep fractured network and its capacity for fluid/heat extraction. This relieshowever on the capacity of geophysical techniques to 1) image the geometry of the fractured networkbut also 2) characterize the petro-physical properties of the fracture network and matrix. The challengeis 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 thegeophysical/petro-physical inverse problem. To do so, we are developing iteratively petro-physical andgeophysical models that can explain the observables at the different scales. In this paper, we report outthe 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 ofgeophysical data. We applied this methodology to the Upper Rhine Graben where a wealth ofknowledge and dataset on deep fractured formations are available.