Hydrogen is arousing considerable interest in the global energy scene as energy vector for achieving the decarbonization targets. Hydrogen diffusion could contribute to improving the security of energy supply if combined with the development of cost-effective, large-scale and long-term storage solutions, which include underground storage. However, the feasibility and sustainability of this process have not yet been properly demonstrated.

Studies such as the one presented here are required to provide concrete tools for supporting the development of underground hydrogen storage systems. Saline aquifers and depleted hydrocarbon fields are one of the most promising solutions. These, in fact, worldwide have a significant storage capacity and geographical diffusion compared to salt caves.

The aim of the current activity is to evaluate the feasibility of the hydrogen’s geological storage process through the support of a modelling approach. To understand how the pore pressure variation due to the injection/production of hydrogen at the reservoir can affect the faults’ stability (and therefore the faults’ reactivation and earthquakes triggering) the following workflow has been developed: the creation of the 3D geological model; the execution of fluid dynamic simulations in order to compute the pore pressure variation over time related to the hydrogen injection/production processes; geomechanical simulations that allow to evaluate the effect of the injection/production in terms of deformations; finally, the faults stability analysis which is performed through the calculation of the faults slip tendency.

Furthermore, we configured some numerical simulations which will be executed in the next activity period. The numerical simulations are related both to a benchmark case that will be realized to check the performances of the RSE-developed code GeoSIAM and to some synthetic cases. Concerning the synthetic cases simulations, we will apply the developed methodology to compute a sensitivity analysis of some parameters which can impact on the faults’ stability. These numerical works are currently ongoing, and the results will be discussed in the next reports.

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