Speaker
Description
This contribution examines the long-term mechanical response of salt caverns operated for underground hydrogen storage, emphasizing how pore-fluid effects can alter integrity assessments. Salt is often idealized as a nearly impermeable, homogeneous viscoplastic solid; however, even limited porosity can enable pore-pressure diffusion and fluid–solid coupling that become relevant under repeated injection–withdrawal cycles.
We develop an axisymmetric finite element framework that couples cavern-scale deformation with Darcy flow in the surrounding salt and is solved using a fully coupled strategy. The approach allows a direct comparison between a conventional viscoplastic model and a poro-viscoplastic formulation in which pore pressure evolves by diffusion and contributes to effective stress, thereby influencing deformation. Simulations consider two operating strategies—long storage cycles and shorter, more frequent cycling—over multi-decade horizons.
Results show that pore-pressure diffusion systematically changes stress paths and deformation patterns. The coupled formulation generally smooths stress redistribution and reduces localized strain peaks near the cavern boundary, yet it may also lower stability indicators under deeper conditions and more demanding cycling by modifying effective stress levels and reshaping stress relaxation in critical regions. Consequently, viscoplastic-only simulations can yield overly optimistic predictions of cavern resilience when porous effects are non-negligible.
Overall, these findings highlight the importance of coupled flow–deformation poromechanics to produce more reliable long-term integrity evaluations and to support operational design for hydrogen storage in salt formations.
| Country | Spain |
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