The use of numerical modelling for characterising deep geothermal reservoirs: A case study of the Upper Rhine Graben

Abstract

Over the last few decades, numerous numerical models of deep geothermal reservoirs in the Upper Rhine Graben (URG) have been developed to study natural hydrothermal circulation and the effects of industrial exploitation. However, there is a lack of numerical methods that incorporate multi-physical and multi-scale measurements. This research examines a natural, large-scale hydrothermal circulation and its associated multi-physical and multi-scale data through a homogenized thermo-hydro-mechanical (THM) model. The aim of this research is to develop a THM model that provides useful engineering tools for the exploration of future geothermal sites. To validate this approach, inversion of key rock physical properties has been conducted using observed temperature and stress depth profiles. The model provides new insights into the relationship between geophysical data and hydrothermal circulation. It also highlights the crucial impact of brine viscosity on circulation. Furthermore, the model provides a practical tool for linking measurable surface thermal gradients with reservoir temperature in relation to cap-rock depth. This method could be very useful for exploring future geothermal reservoirs in New Zealand.