Speaker
Description
As hydrogen becomes increasingly central to the energy transition, rock salt—with its exceptional sealing capacity and operational safety—has emerged as one of the most promising media for underground hydrogen storage. Reliable quantification of gas transport in rock salt is essential for the safe design and performance assessment of subsurface hydrogen storage caverns. Using an explosion-proof gas-permeability system, this study develops a pressure-inversion testing framework and measures the apparent permeability of H₂, He, N₂, and CH₄ under confining pressures of 5–40 MPa. The approach enables systematic analysis of how confining stress, injection pressure, and molecular properties jointly shape gas-flow behavior. The results reveal a distinct three-stage “U-shaped” evolution of permeability with increasing injection pressure. Slip flow and Knudsen diffusion dominate at low pressures, viscous flow and weak adsorption control the mid-pressure regime, and micro-fracture reconnection combined with effective-stress relaxation leads to permeability recovery at high pressures. The permeability ranking He ≥ H2 > N2> CH4 is governed primarily by molecular size and viscosity. An extended Klinkenberg-based model is proposed to jointly capture low-pressure slip attenuation and high-pressure permeability rebound within a unified semi-analytical framework. A stress–pressure operating criterion defined by χ= Pinj/ σc identifies an optimal hydrogen-storage operating window of 0.40–0.60. The integrated experimental–theoretical framework provides a quantitative understanding of gas migration in rock salt and offers practical guidance for the safety assessment and operational optimization of underground hydrogen storage.
Keywords：Rock salt permeability; Underground hydrogen storage; Klinkenberg effect; Gas transport mechanism; Operational safety evaluation
| Country | China |
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