Molecular simulation of CH 4 adsorption behavior in slit nanopores: Verification of simulation methods and models

The aim of this study is to select an appropriate method for CH 4 adsorption in organic nanopores for shale‐gas development. Molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations were performed. Three comparison studies were included: (i) comparison of the adsorption behavior in kerogen nanopores using different schemes for dispersion correction, (ii) comparison of the adsorption behavior in graphite nanopores using MD and GCMC simulations, and (iii) comparison of the adsorption behavior in kerogen and graphite nanopores using MD simulations. The result was reliable when using a particle‐mesh Ewald scheme or a cut‐off ≥1.5 nm without dispersion correction. The simulation results were essentially identical for the MD and GCMC simulations. The free‐gas CH 4 density inside the nanopores started to deviate from the bulk density at ~2 nm for the graphite model and at ~7–10 nm for the kerogen model, whereas the total CH 4 density deviates from the bulk density at ~20 nm.