Speaker
Description
The growing need for large-scale, flexible energy storage has increased the interest in using porous geological formations for hydrogen storage, but the associated geomechanical risks are still not well understood, particularly in structurally complex saline aquifers. This study presents a fully coupled hydro-geomechanical analysis of cyclic hydrogen injection and production in a fault-bounded reservoir, the Stuttgart Formation at Ketzin (North German Basin). It previously served for a successfully completed benchmark CO$_2$ storage pilot project. Using a compositional reservoir simulator (CMG-GEM), we evaluate the development of pore pressure, gas saturation, fault stress state, slip tendency and vertical displacement over multiple operational hydrogen injection cycles. The model incorporates facies-dependent elastic and strength properties, fault-specific mechanical behaviour and poroelastic coupling between pressure and deformation.
Simulation results show that pore pressure exhibits strong cyclic fluctuations near the well and attenuates towards the opening of the eastern fault, while the hydrogen plume remains largely confined between two bounding faults. Gas saturation is strongly influenced by facies-related permeability differences, with higher saturations in high-permeability sandy channel deposits and significantly reduced values in the lower-permeability floodplain facies. No evidence of uncontrolled plume migration or cross-fault leakage is observed.
The results indicate that the fault network remains geomechanically stable throughout all cycles. Slip-tendency values remain well below critical thresholds ($ST < 0.13$), and only minor stress redistribution is observed. Localised zones of increased shear stress occur at fault segments exhibiting a slight dip, demonstrating that geometric factors exert a strong control on resolved stresses. Time-series analysis shows that slip tendency increases during injection and decreases during production, driven primarily by pore-pressure-induced variations in effective normal stress. Results of the cyclic loading reveal that vertical displacements are small but measurable with magnitudes that fall well below typical detection thresholds and several orders of magnitude below levels known to affect infrastructure. The temporal evolution of displacement shows a consistent elastic response, with only a minor cumulative compaction trend (<0.02 mm per cycle) near the well.
Overall, we could demonstrate that hydrogen storage at the Ketzin site under the tested operational conditions induces modest hydraulic and mechanical perturbations and poses a low risk of fault reactivation or significant deformation. However, we emphasise that uncertainties in fault friction, cohesion and stress-dependent permeability remain important and should be addressed through targeted laboratory testing and sensitivity analysis. The findings support the mechanical feasibility of underground hydrogen storage in structurally complex saline aquifers while underscoring the need for continued monitoring and evaluation of higher-pressure operating scenarios.
| Country | Germany |
|---|---|
| Acceptance of the Terms & Conditions | Click here to agree |
