Molecular Simulation of Multi-Factor Coupling Effects on Nanopore Wettability of Typical Shale Minerals

Shale reservoirs feature widely developed nanopores, and the diverse crystal structures and surface functional groups of constituent minerals induce pronounced wettability heterogeneity, rendering conventional experimental methods incapable of characterizing nanoscale interfacial evolution. This work aims to reveal the multi-factor regulated wettability mechanisms of typical shale minerals at the molecular scale. Coupled molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations are performed on four shale minerals (hydroxylated graphene, quartz, calcite, kaolinite) under single-factor conditions (313–373 K, 10–40 MPa, 4–10 nm pores) and coupled pressure–pore deformation scenarios (15–35 MPa, 4–9.1 nm), with wetting mechanisms elucidated from hydrogen bond evolution, water molecular packing, nanoconfinement effect, and mineral crystal structure. The results show that rising temperature linearly reduces contact angles (average 0.33–0.35°/K) by strengthening hydrogen bonding; elevated pressure impairs wettability, with calcite exhibiting the highest-pressure sensitivity; nanoconfinement dominates pore scale wetting; and quartz presents the strongest pore size dependence. Synchronous pressure–pore expansion generates a superimposed wettability deterioration effect. This study quantifies the wettability evolution laws of shale minerals under diverse conditions, providing microscopic theoretical support for reservoir stimulation and enhanced oil recovery.