Integrated Thermo-Haline Modeling to Constrain the Thermal Regime in the Upper Rhine Graben

The DEKAPALATIN–BERTHA joint research project aims to improve the understanding of deep geothermal systems in the central Upper Rhine Graben to support the decarbonization of the heating sector. As geothermal reservoirs are hosted in fault damage zones where highly saline brines circulate, integrated thermo-haline numerical modeling is required to reliably constrain the subsurface thermal regime and fluid circulation. This contribution presents a modeling framework that couples salinity-dependent fluid flow, heat transport, and fault-zone petrophysical heterogeneity to evaluate reservoir behavior. Application to representative fault damage zones in the Upper Rhine Graben demonstrates the key role of permeability contrasts and fluid density effects in controlling long-term temperature distribution and operational sustainability.