Thermo-Hydraulic Modeling of the Northern Upper Rhine Graben using OpenGeoSys

Effective geothermal reservoirs are characterized by high permeability, elevated geothermal gradients and active hydrothermal fluid dynamics. Targeting zones with these features is essential to ensure sufficient temperature and flow rate at the wellhead, which is the key factor for the economic viability of geothermal projects. The Upper Rhine Graben (URG) is characterized by numerous positive temperature anomalies and abundant permeable fault zones that facilitate fluid movement, which could lead to the development of hydrothermal convection cells in the subsurface. Accurately identifying such zones can substantially reduce the risk associated with geothermal prospecting. To improve the reliability of predicting the location of hydrothermal convection cells, numerical simulation can be utilized to simulate the interactions of coupled thermo-hydraulic (TH) processes in the subsurface. This study presents a workflow for integrating a 3D geological model from Petrel into OpenGeoSys (OGS) to simulate coupled TH processes in the geothermal system of the Northern URG on a regional scale. The 3D geological model is based on the ArtemIS project, whichincorporates data from previous projects, including GeORG, Hessen 3D 1.0 & 2.0, and DGEROLLOUT. The results of the TH simulation indicate that hydrothermal convection cells develop within and around fault zones, enhancing both upward and downward fluid flow. These flow patterns lead to localized positive and negative temperature anomalies. The workflow developed in this study lays the groundwork for the ConvEx project, which aims to establish integrated exploration methods for mapping hydrothermal convection cells as key targets in deep geothermal energy exploration.