Molecular dynamics study of H₂-oil mixture behavior in shale nanopores
Keywords:
Underground hydrogen storage, residual pore oil, H2 self-diffusion, molecular dynamics simulationAbstract
With growing hydrogen demand and production, large-scale H2 storage technologies are becoming increasingly essential. Depleted shale reservoirs, with their extensive pore space and existing subsurface infrastructure, offer a promising option for large-scale H2 storage. In this study, the behavior of H2 in shale nanopores in the presence of residual oil, which has not been well explored, is systematically investigated. It is observed that at 353 K and 30 MPa, residual oil weakens but does not completely prevent H2 accumulation on pore surfaces, which may contribute to H2 loss. Furthermore, decreasing pore size enhances H2 surface accumulation due to nano-confinement effect, while increased oil saturation and smaller apertures reduce H2 self-diffusion by restricting transport pathways. In addition, the phase of oil also plays a key role: supercritical methane mixes readily with H2, whereas liquid n-butane, n-octane, and n-dodecane form clusters or oil bridges, further limiting H2 mobility in nanopores. These findings provide molecular-scale insights into H2-oil interactions and highlight the combined effects of residual oil saturation, pore size, and oil composition on H2 retention and transport, which are critical for assessing the feasibility of underground H2 storage in depleted shale reservoirs.
Document Type: Original article
Cited as: Chang, Q., Wu, Y., Tian, Z. Molecular dynamics study of H2-oil mixture behavior in shale nanopores. Computational Energy Science, 2025, 2(3): 55-62. https://doi.org/10.46690/compes.2025.03.01
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