Experiments on Methane Adsorption of Common Clay Minerals in Shale

In order to reveal the main control factors of natural gas adsorption capacity of clay minerals,the methane adsorption isotherm experiments of common clay minerals selected from different sources were performed.The analysis shows that differences of gas adsorption capacity are significant among different types of clay minerals,and the order of methane adsorption capacity of various clay minerals is smectite illite and smectite mixed-layers kaolinite chlorite illite siltstone quartzite.The crystal structure of clay mineral determines the shape and size of pore spaces between polymer particles and interlayer spaces between crystal layers,and accordingly determines its surface area and gas adsorption capability.Methane adsorption capacities of clay minerals are highly consistent to the development degrees of micro-pores supplied by scanning electron microscopy.The study indicates that the gas adsorption capacity of clay minerals not only depends on the type of clay mineral,but also is significantly influenced by diagenesis and petrogenesis.In addition,the gas adsorption capacity of clay minerals slightly increases with the decrease of particle size due to the enlargement of pore connectivity and surface area.