Abstract

While traditional frameworks often simplify fluid dynamics, non-ideal thermodynamic characteristics, driven by intermolecular forces and spatial confinement, significantly alter bulk flow at the nanometer scale. To address this gap, we propose a novel transport model that rigorously couples nanoscale gas slippage with dynamic fluid properties. This approach uniquely integrates varying molecular interactions, seamlessly transitioning from attractive to repulsive regimes, alongside confinement-induced shifts in critical parameters. Taking the deep shale formation in the Sichuan Basin, China, as a representative geological context, accurately modeling methane transport is essential. Our analytical results reveal that incorporating non-ideal thermodynamics profoundly amplifies the predicted boundary slip. Specifically, the corrected mean free path is amplified by a factor of up to 4.7 relative to standard ideal gas assumptions. This enhancement scales strongly with elevated pressure but remains negligible near 1 MPa. Furthermore, we demonstrate that relying on ideal gas laws can inflate nanopore flow capacity estimates by more than 75%, an error primarily driven by density reductions and viscosity increases under high-pressure regimes. We also identify a specific thermodynamic window, sub-10 MPa pressures combined with temperatures below 290 K, where corrected transport metrics actually surpass conventional predictions, an anomaly governed predominantly by intensified slip dynamics. Ultimately, these findings highlight widespread inaccuracies in current permeability estimations, providing a more robust physical foundation for forecasting production and conducting numerical reservoir simulations.

IPC Classification

Keywords