Using graphene to simplify the adsorption of methane on shale in MD simulations

In this paper we explored material similarity between graphene and shale for methane (CH4) adsorption in the shale gas recovery simulations. The reasons of choosing graphene to model shale have been clarified. Through theoretical analysis we obtained the attenuation law of interaction potential between CH4 and multilayer graphene. It indicates the adsorption energy of CH4 on monolayer graphene is closest to that on shale. The limiting heat of adsorption of CH4 on graphene was calculated by molecular dynamics (MD) simulation. The adsorption isotherms and adsorption heats on the monolayer graphene whose width of the slit pore ranges from 2 nm to 11 nm were calculated by using grand canonical Monte Carlo (GCMC) simulations at different temperatures. The computed adsorption heat is validated by experimental data which indicates that the adsorption properties of CH4 on shale are quite similar with that of CH4 on graphene. Our study may provide a direct evidence of using graphene in modeling shale in simulating the shale gas adsorption/ desorption. (C) 2017 Elsevier B.V. All rights reserved