Nanoscale confinement effects of pore radius and mineral type on shale oil component diffusion in porous media
Abstract
Shale oil plays an increasingly prominent role in compensating for the depletion of conventional hydrocarbon resources. While nanoscale confinement in shale nanopores can substantially alter hydrocarbon diffusivity, pore‑scale models capable of explicitly incorporating the combined effects of pore size and pore‑wall properties remain limited. In this study, molecular dynamics simulations of n‑octane confined in quartz and kerogen nanopores were conducted to establish pore‑radius‑dependent diffusion relationships for inorganic and organic pores. These relationships were incorporated into a modified OpenFOAM species‑transport solver, enabling the local diffusion coefficient to vary according to the pore radius and the pore type. Multi‑mineral shale porous structures were reconstructed using the Voronoi method combined with a stochastic algorithm, and pore‑scale simulations were performed to investigate the effects of heterogeneous diffusivity, pore radius and total organic carbon content on matrix‑fracture component transport. The results showed that nanoscale confinement suppresses n‑octane transport from the nanoporous matrix to the fracture and increases spatial heterogeneity in component distribution. A decreasing pore radius reduces the overall diffusion capacity, while an increasing organic matter content increases the proportion of low‑diffusivity organic pores and enhances component retention within the matrix. These findings demonstrate that spatial variations in molecular diffusivity should be explicitly considered when describing shale oil component transport. The proposed framework provides a practical bridge between molecular‑scale confined diffusion and pore‑scale transport modeling in heterogeneous shale porous media.
Document Type: Original article
Cited as: Lv, C., Yang, Y., Zhang, Q., Li, Y., Lisitsa, V., Yao, J. Nanoscale confinement effects of pore radius and mineral type on shale oil component diffusion in porous media. Advances in Geo‑Energy Research, 2026, 21(3): 205‑219. https://doi.org/10.46690/ager.2026.09.02
DOI:
https://doi.org/10.46690/ager.2026.09.02Keywords:
Shale oil, nanoscale conffnement effects, diffusion, porous mediaReferences
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Copyright (c) 2026 Changran Lv, Yongfei Yang, Qi Zhang, Yingwen Li, Jun Yao
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