Basin-scale 3D modelling of the northern Upper Rhine Graben: insights into basement fault-related geothermal flow pathways

Abstract

A regional assessment of the potential for geothermal heat production, power generation and also heat storage requires an evaluation of the heat in place and its recharge. Both are controlled by the flow properties and natural fluid flow through the reservoir at the present day, which must be thoroughly analysed based on the understanding and modelling of the architecture of deep reservoirs. In the Upper Rhine Graben, well known for its vast geothermal potential, a characterization of the structural organization at the basin scale and an understanding of mass and heat transfer are, therefore, useful for correctly estimating the technical and economic potential for geothermal energy. The distribution of the resources can be quantified based on the basin analysis approach. This is classically used for hydrocarbon resources and is applied in this study to predict the geothermal fluid-flow paths. The role of faults and their hydraulic regime on temperature field heterogeneities is investigated. Several scenarios with or without rift basin internal faults and various transmissivity ranges along these faults are analysed and compared. The measured temperature field is used for the calibration of the different model scenarios results. The scenario with the most significant role for internal faults as fluid-flow pathways in the western Upper Rhine Graben is the one that provides the most accurate reproduction of the temperature field. Such output highlights the importance of quantifying the hydraulic behaviour of faults and associated fracture networks in space and time. Supplementary material: dataset containing geometry, facies distribution and main results of scenario 4 is available at https://doi.org/10.6084/m9.figshare.c.6628506