Hydro-Geomechanical Reservoir Modelling of Underground Hydrogen Storage in a Saline Aquifer of the North German Basin

To manage seasonal fluctuations in renewable energy, hydrogen can be produced from excess electricity and stored in geological formations. Saline aquifers, due to their large capacity and widespread presence in sedimentary basins, show strong potential for underground hydrogen storage (UHS). However, their viability in porous formations remains largely unproven. This study focuses on the Triassic Stuttgart Formation near Ketzin in the North German Basin, a former CO₂ storage site. Its heterogeneous lithology and anticlinal structure offer structural trapping potential, but a fault zone at the reservoir top presents a risk of gas migration, potentially intensified by geomechanical effects from cyclic hydrogen injection.

Previous UHS models have emphasised hydrodynamic behaviour, focusing less on geomechanical effects. However, understanding these effects is crucial for safe, long-term storage. This study presents a coupled hydro-geomechanical reservoir model to evaluate risks such as fault reactivation (assessed using slip tendency analysis of major faults near the wellbore) and ground deformation due to hydrogen injection and withdrawal. Site-specific simulations using CMG GEM indicate that faults remain stable and vertical displacements are within a small to moderate range.

The results provide valuable insight into flow and geomechanical behaviour during UHS in a saline aquifer setting. While based on a specific site, the analysis enhances understanding of reservoir integrity and supports the broader development of hydrogen storage technologies. The findings contribute to assessing the feasibility of UHS and aid in the design of a potential hydrogen storage demonstrator in the North German Basin.