Multiphase hydraulic properties of reservoir rock in geologic H₂ storage

The feasibility of geologic hydrogen (H2) storage in saline aquifers necessitates a thorough analysis of multiphase fluid flow and fluid distribution. This study investigates Berea sandstone as a proxy for hydrogen injection into porous rock. An experimental setup has been developed to examine the water-hydrogen flow mechanism under representative in-situ stress conditions. The direct measurements demonstrate an exponential decrease in fluid permeability with saturation, with exponent values of 2.0 for water and 3.3 for hydrogen. The tests under different effective mean stresses reveal that the hydrogen relative permeability significantly changes, whereas the water permeability remains unaffected. Moreover, the relative permeability is predicted based on the capillary pressure curve and semi-empirical relative permeability models, indicating an underestimation of the fluid permeability at a given saturation. This research contributes unique insights into water and hydrogen relative permeability in potential reservoir for H2 storage. Although the pore structure-based estimation serves as a valuable pre-assessment tool, the direct measurements are crucial for accurately assessing the multiphase flow mechanism.