The influence of mineral wettability on the adsorption of shale gas
As an important carrier for shale gas adsorption,the surface properties of inorganic minerals have an important impact on the methane adsorption capacity,while wettability,as one of the important surface properties of solids,can not be ignored.In this paper,montmorillonite and quartz are taken as the research objects,and their wettability is changed by methylation(-CH3)and hydroxylation(-OH)on the mineral surface,so as to explore the effect of inorganic mineral surface wettability on methane adsorption capacity.The wettability of min-eral system was studied by molecular dynamics method,the wettability was quantitatively characterized by contact angle,and the nano slit was constructed.Combined with the grand canonical Monte Carlo method,the adsorp-tion changes of CH4 in minerals before and after the change of wettability were simulated.The results show that water droplets rupture rapidly on the surface of hydroxylated minerals and spread on the mineral surface,while the spread degree on the methylated surface is small and generally hemispherical.The wetting contact angles of hydroxylated montmorillonite and quartz are 12.7° and 26.5° respectively,which are less than those of methyla-ted surface 62.5° and 85.7°.The methane adsorption capacity of methylated minerals is higher than that of hy-droxylated minerals,and most of the gases are located on the pore wall in the adsorption state,with the weakening of mineral hydrophilicity,its adsorption capacity for methane increases.
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