Advanced Multiscale Modeling for Revealing Anomalous Fluid Transport Induced by Confinement Interfacial Layer Reconstruction in Sub-10 nm Space.

Fluid transportation in nanoconfined space is crucial for comprehensively understanding the distinctive flows in nano-porous media, particularly in shale and tight reservoirs. Nanoscale confinement induces substantial deviations in fluid apparent viscosity from the bulk state. These discrepancies are significantly influenced by interfacial layer effects, which have been widely recognized as the dominant contributors to viscosity amplification. However, existing theoretical models fail to adequately quantify the interfacial layer characteristics for confined fluids with dimensions less than 100 nm. By integrating the insights from experimental studies and molecular dynamics simulations, we developed an advanced mathematical model to characterize the interfacial properties of fluids confined in channels below 10 nm. Upon incorporating specific channel material properties, temperature conditions, and fluid characteristics into this model, it enables characterization of both the interfacial layer thickness and viscosity. Notably, the molecular interaction coefficient in this model demonstrates a strong linear correlation with alkane chain length, showing minimal dependence on channel dimensions but high sensitivity to temperature. The interfacial layer exhibits a 6.89-fold enhancement in viscosity compared to the bulk state at the channel height of 70 nm, establishing it as the predominant determinant of the anomalous transportation of nanoconfined fluid.