Finding the geothermal sweet spots of Germany by integrating the subsurface geological heterogeneity with process simulations

In Germany the heat demand distribution and operational geothermal production show limited spatial overlap and this is related to the geology in the subsurface. Most of the geothermal energy projects are located in the sedimentary areas of the Molasse Basin, the Upper Rhine Graben and the North German Basin. All these areas have in common that a thermal blanketing effect of young shallow sediments with high porosity keep the heat trapped beneath the insulating porous layer. The North German Basin has an additional heat controlling element - the mobilized Zechstein salt. Salt is thermally twice as conductive as clastic sediments and acts as a chimney for heat transport. The third controlling factor is the basal heat input that depends on the depth to the thermal LAB and the thickness of the upper crystalline crust producing ragiogenic heat, thus adding up to a half to the heat budget in the basins. Finally, the coupled transport of heat and fluid and the composition of the moving fluids add a last layer of complexity in defining geothermal sweet spots. As the fluids can move fast, they can take along their heat/cold, but also may transport solved material that can precipitate and destroy permeability if the PT-regime of the solution changes. The meanwhile increasing resolution of data and structural models of the subsurface open new opposrtunities to simulate heat transport considering the heterogenous physical property distribution as well as physical processes , thus enabling predictions far beyond the interpolation of a few temperatures measurements.