Insights on structural deformation within the Münsterland, Germany, from legacy and newly acquired 2D seismic data for the development of conventional geothermal systems

The Münsterland Cretaceous Basin with its underlying coal-bearing Paleozoic strata has become one of the prolific areas in North-Rhine Westphalia, Germany, to develop conventional geothermal systems. The presence and structural deformation of four potential calcareous and siliciclastic geothermal reservoirs within the basin (Upper Cretaceous carbonates) and the basement (Lower Carboniferous carbonates, Upper Devonian sandstones, Upper/Middle Devonian carbonates) are only known from sparsely distributed boreholes and crustal seismic data (DEKORP). We aim at reducing the geological uncertainties by interpreting and analyzing legacy data of the DEKORP project, and recently acquired 2D seismic data from the central Münsterland. In addition, information from former research and hydrocarbon wells, now intersecting the newly acquired surveys, were integrated to guide and verify the interpretation. Our investigations contribute to the already existing knowledge of the Variscan folding and spatial distribution of the potential geothermal reservoirs within and below the Münsterland Cretaceous Basin. Further, we show previously undescribed local inversion structures in the Cretaceous section caused likely by the reactivation of post-Variscan transtensional faults in the center of the basin. The seismic data exhibits anomalies which will be analyzed if they are indicating areas of increased porosities through structural deformation or the presence of migrated hydrocarbons in these regions. The latter would imply a structural connection between coal-bearing Carboniferous strata and porous reservoirs in the Upper Cretaceous via deep-reaching reactivated faults. The presence of fault zones that have evidently been vertically permeable on a geological time scale demonstrate possible fluid pathways for conventional geothermal systems. Such geothermal systems could be future targets for drilling to produce local renewable district heating for the city of Munster.  Therefore, further investigations such as in-situ tests through drillings are required to quantify the current permeability of these damage zones.