Simulation methods for shale gas adsorption: fundamentals and applications at the molecular and mesoscopic scales

Shale gas, regarded as a vital unconventional energy resource, plays a key role in sustaining the global energy supply and advancing a low-carbon economy. Considering that a significant portion of shale gas exists as adsorbed molecules within nanopores, a comprehensive understanding of its adsorption behavior and the development of accurate predictive models are crucial. These insights facilitate scientific evaluation of gas in place (GIP) and enhance understanding of diffusion and flow mechanisms. Microscopic and mesoscopic numerical simulations are powerful tools for studying the adsorption behavior of shale gas, since they elucidate the adsorption processes of gas inside the nanopores of the shale matrix. This review discusses recent advancements in isothermal adsorption models and numerical simulations of adsorption mechanisms at microscopic and mesoscopic scales. Special emphasis is placed on the development of molecular simulations and lattice Boltzmann method (LBM) in adsorption mechanism research. A comprehensive assessment of the benefits and drawbacks of each approach is provided. Finally, the challenges faced in shale gas adsorption research and the future directions are discussed, with the aim of providing reference for future studies in this field.