Slip-tendency analysis of a potential CO2 storage site in the central German North Sea

Underground CO 2 storage operations may lead to induced seismicity, which may in part be related to nearby faults affected by injection. Considering the storage potential in the Middle Buntsandstein sandstone formation on the West Schleswig Block within the German North Sea, we investigate the reactivation and seismicity potential of existing faults in the vicinity of a selected study area. To this end, we develop a 3D fault dataset based on roughly 80 2D seismic lines, combining 60 years of exploration history. Contextual details regarding the geological features and the lithological description of the area are presented. Using the fault dataset and a previously developed 3D numerical stress model of Germany, a slip-tendency analysis is performed to assess the susceptibility of existing faults to reactivation and reveal critical focal mechanisms, which are precursors for further wave propagation simulations. Normal-faulting and strike-slip stress regimes are examined, whereas uncertainties in stress magnitudes, friction coefficients, fault geometry, dynamic weakening factor, and clustering tolerances are treated as variables in stochastic simulations. Furthermore, we extend the procedure to estimate the sustainable pore pressure window and the potential moment magnitude in the event of reactivation. The results show that the NW/SE- and NNW/SSE-oriented faults exhibit a higher slip tendency. Among these faults, those with a combination of above-average slip tendency and potential moment magnitude are identified and discussed.