Identification of fluvio-deltaic facies in 3D-seismic: strategy to reduce geothermal exploration risk in North German Basin

Summary The geothermal potential of the North German Basin has been under evaluation since early 1970s. The fluvio-deltaic sandstones of the Upper Triassic Exter Formation has been target of several successful geothermal projects in North Germany. Nevertheless, the high exploration risk due to a lack of relevant information like reservoir geometry, have hampered the development of this reservoir at other sites. Previous studies have contributed to improve Rhaetian reservoir prediction by basin- to regional-scale subsurface mapping of facies based on sedimentological methods. However, a validated seismic methodology to delineate geometry and quality on the local scale is missing. The goal of this study is to propose a validated seismic facies analysis approach for the interpretation of 3D-seismic data to enable comprehensive Rhaetian reservoir predictions at individual localities. The obtained results confirm the presence of fluvio-deltaic channels in the middle Exter Formation in eastern Lower Saxony. The channel distribution found based on seismic attributes, evidences lateral shifting of individual channels contributing to the formation of channel belts within the Rhaetian system. These results significantly contribute to reduce the geothermal exploration risk in North German Basin by proposing a way to enhance the prediction of Rhaetian reservoirs based on seismic methods.