Adsorption-Induced Deformation in Microporous Kerogen by Hydrogen and Methane: Implications for Underground Hydrogen Storage
Saeed Babaei, Benoît Coasne, Mehdi Ostadhassan
Abstract
High Resolution Image Download MS PowerPoint Slide Accurately assessing the adsorption and diffusion behaviors of H 2, CH 4, and their mixtures are essential for estimating underground hydrogen storage (UHS). This understanding is critical for the safe and efficient storage of H 2 in depleted shale gas reservoirs. Although H 2 adsorption in kerogen has been extensively studied, adsorption-induced swelling remains unexplored in UHS. In this study, we investigate adsorption mechanisms using Lagrangian and Eulerian approaches and analyze diffusion in kerogen through molecular simulations. Our results reveal that in the presence of cushion gases like CH 4, which exhibit stronger adsorption than H 2, neglecting kerogen deformation can lead to an underestimation of storage capacity by approximately 40%. Furthermore, increasing pressure makes H 2 adsorption behavior deviate from the consistent swelling trend that is observed with CH 4, with kerogen either swelling or contracting depending on the pore size. Simulations also predict that H 2 self-diffusion coefficient in porous kerogen is 1 order of magnitude higher than CH 4 . These findings highlight the importance of incorporating kerogen flexibility into the modeling of UHS involving multiple gas species to improve the accuracy and safety of H 2 storage operations in shale reservoirs.