THERMAL DIFFUSION AND FLOW PROPERTY OF CO2/CH4 IN ORGANIC NANOPORES WITH FRACTAL ROUGH SURFACE

The kerogen is rich in complex pore networks with a random rough surface, which is a factor controlling the thermal diffusion and flow property of gases. In this work, we construct organic-rich nanopore with fractal surfaces by inserting and deleting carbon atoms. The adsorption ability, thermal diffusion property, and flow velocity of CO2/CH4 in the nanopore are analyzed using with molecular simulations. The results showed that the adsorption capacity of CO2 is nearly twice that of CH4, which is decided by adsorption enthalpy, whereas the maximum thermal diffusion ability of CO2 is only 23.7% that of CH4. With external pressure gradients imposed on the system, the flow speed of CO2 was lower than that of CH4 for nanopores with different roughness. These findings provide a theoretical basis for the feasibility of CO2 exploitation of shale gas.