30 / 2025-11-19 00:14:56

Hydrogen Adsorption-induced strain in shale: Implications for Underground Hydrogen Storage

Key words: underground hydrogen storage, adsorption, hydrogen, shale, strain

Underground hydrogen storage (UHS) has been proposed as a promising option for large-scale hydrogen storage, and depleted shale gas reservoirs are considered as candidate sites because of their wide distribution, large capacity, and sealing integrity. Although recent research has reported hydrogen adsorption capacities in shale, systematic experimental data on adsorption-induced strain remains lacking. In this study, hydrogen adsorption and adsorption-induced strain in shale were systematically investigated under high-pressure conditions at 313.15, 333.15, and 353.15 K. Results show that hydrogen adsorption capacity increases with pressure but decreases with temperature, reaching 0.156 mmol g⁻¹ at 313.15 K and 16 MPa. The corresponding volumetric strain exhibits three stages with pressure—rapid increase, gradual growth, and final stabilization—with a maximum magnitude of 0.21‰, confirming that adsorption-induced deformation is extremely limited. Strain shows a stronger correlation with the adsorbed amount than with external pressure , and the relationship is well described by a Freundlich-type strain–adsorption model (R²= 0.978–0.989). Directional differences between axial and radial strains are small (R≈0.9–1.0 at 313.15 K), indicating that hydrogen adsorption causes only weakly anisotropic and nearly reversible deformation . In comparison, CH₄ and CO₂ adsorption in shale generally induces much larger swelling and permeability reduction, whereas hydrogen produces deformation one to two orders of magnitude smaller. It can therefore be inferred that hydrogen adsorption is unlikely to affect the injectivity or withdrawal capacity of shale reservoirs. These findings demonstrate that hydrogen adsorption in shale provides substantial storage potential without compromising reservoir efficiency, offering a scientific basis for evaluating the feasibility of depleted shale gas reservoirs for underground hydrogen storage.