Effect of CO2 injection on adsorption of methane on shale from the Sichuan Basin in China

Abstract

In order to understand the change of adsorption capacity of methane (CH4) after carbon dioxide (CO2) injection into shale at high pressure condition. The pore structure character and adsorption capacity of CH4 were analysed via low-pressure N2 adsorption and isothermal adsorption measurements for original and supercritical CO2 (ScCO2) treated shale samples from Jiaoshiba area in the Sichuan Basin. The results show that the ScCO2 treated samples have lower specific surface areas, less micropore and mesopore, and more macropore compare to original one. For ScCO2 treated shale samples, specific surface area and micropore decrease with increasing temperature. Furthermore, the absolute adsorption capacity of CH4 in original shale is higher than that in ScCO2 treated ones, indicating that micropore specific surface area is probably the main factor controlling adsorption capacity of CH4 on shale. For all samples, the absolute adsorption capacity of CH4 increase with increasing pressure from 0 MPa to 43 MPa and then tended to be stable.