ThermoBase: Characterization of the Thermal Field in the Sedimentary Sub-Areas of Germany

For the assessment of the long-term safety of heat-generating waste in deep geological formations, knowledge of the current temperature field, thermophysical rock parameters and their spatial distribu-tion, as well as the heat flow distribution, is essential. The ThermoBase project aims to improve the understanding of the thermal field in the sedimentary basins of Germany that are, in principle, under consideration for waste disposal. However, a systematic collection of thermophysical rock properties for relevant sedimentary rocks is still lacking. Previous studies—particularly those focused on rock salt—have been limited in terms of methodology and geographical scope. Furthermore, there is a shortage of reliable heat flow data and investigations into the influence of in-situ conditions and glacial overprints on the temperature field.

ThermoBase integrates interdisciplinary methods to enable a comprehensive, multi-scale characteriza-tion. The project addresses four key aspects:

• Analysis of borehole temperature data to identify temporal and process-related influences,
• Mineralogical and facies analyses of selected drill core samples,
• Systematic determination of thermal rock properties through laboratory analyses and core-log interpretation, and
• Acquisition of new heat flow data at selected sites and quantification of the paleoclimatic influ-ence.

Numerical temperature models supplement the characterization of the subsurface temperature field down to a depth of 2 km using 3D transient conductive models based on borehole data, by physically simulating heat transport processes. By comparing these models with geophysical measurements and the geostatistical temperature model GeotIS, vertical and lateral variability in thermophysical parame-ters is accounted for to reduce uncertainties in temperature calculation.