InterPore2025

Complex Interactions and Flow Mechanisms of Shale Oil in Nanopores: Insights from Molecular Dynamics Simulations

21 May 2025, 10:05

1h 30m

Poster Presentation (MS13) Fluids in Nanoporous Media Poster

Speaker

Dr Tianhao Li (China University of Petroleum (East China))

Description

Understanding the occurrence and flow mechanisms of shale oil in nanopores is critical for advancing knowledge of fluid behavior in porous media. Previous studies have often overlooked key factors such as the multi-component nature of shale oil, the realistic properties of nanopore walls, and nanopore flexibility, resulting in limited understanding of shale oil's behavior in nanoconfined spaces. In this study, molecular dynamics simulations were used to systematically investigate the occurrence and flow mechanisms of fluids in graphene, hydroxylated quartz, and rough kerogen nanopores. By comparing the flow of single-component and multi-component shale oil in relatively smooth quartz and rough kerogen nanopores, we found that slip flow only occurs under idealized conditions (single-component oil and smooth surfaces), whereas realistic shale oil in actual nanopores exhibits no slip flow. By studying the changes in fluid velocity profiles under different pressure gradients, we identified the critical pressure gradient for fluid flow regime transitions. Above this critical pressure gradient, the velocity profile changes from parabolic to plug-like. This phenomenon occurs because the increasing pressure gradient causes fluid near the wall to desorb and aggregate into clusters in the center of the pore. Through statistical analysis of the interaction forces between the fluid and the pore wall, we observed an increase in the vertical force exerted by the wall on the fluid, suggesting that the pressure inside the nanopores increases. To address this, we further investigated the flow of n-octane in rigid and flexible graphene nanopores. The results revealed that fluid flow in nanopores induces changes in pore pressure and pore deformation. In rigid nanopores, pore pressure increases with the rise in the pressure gradient, whereas in flexible nanopores, pore width increases with the pressure gradient. The increase in nanopore pressure or expansion of nanopores is attributed to enhanced collisions between fluid-fluid atoms and fluid-wall atoms caused by fluid flow. This study unveils the complex interactions of shale oil within nanopores, providing theoretical support for understanding the flow of shale oil in porous media and contributing to the efficient extraction of shale oil in unconventional reservoirs.