Molecular simulation study on adsorption and diffusion molecular of CO2 and CH4 in shale nanopores
To further reveal the molecular dynamics behavior of multi-component gases in shale nanopores,the model of shale nanopores was constructed by using graphene,and the microscopic mechanism of competitive adsorption and diffusion of CO2 and CH4 at different temperatures in the shale nanopores were studied based on the Grant Canonical Monte Carlo(GCMC)and Molecular Dynamics(MD),and the adsorption isotherm,adsorption selectivity,radial distribution function and gas diffusion coefficients were investigated.The re-sults showed that CO2 adsorption was always higher than CH4,the CO2 and CH4 adsorption selectivity coefficient was greater than 1,that is,injecting CO2 into shale can displace CH4.CO2 and CH4 had peaks with shale at 0.389 nm and 0.761 nm,respectively,and the peak size relationship was gab(CO2)＞gab(CH4),indicating a stronger interaction between CO2 and shale;the diffusion coefficient relation-ship was D(CO2)＞D(CH4).The research results can provide some theoretical guidance for gas injection replacement and efficient shale gas development from a microscopic perspective.
shale gasadsorptiondiffusionCO2 and CH4molecular dynamics
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