Experimental investigation on shale gas transport characteristics in nanopores under high temperature and high pressure

In this paper, we carried-out shale gas diffusion behaviour experiments under high temperature and pressure conditions (HPHT). Molecular membranes samples with a uniform pore size replacing shale cores are used in this experiment for the first time. The results show that: 1) the equation of shale gas diffusion coefficient and pore size was established. As the pore diameter increases, the diffusion coefficient increases exponentially. 2) The concentration gradient of shale gas in a nanoporous medium also has an impact on the diffusion capacity. 3) The greater the pressure, the smaller the diffusion coefficient in the confined pores. The diffusion coefficient increases as the temperature increases. 4) A new diffusion coefficient calculation method was proposed. The results provide theoretical guidance for the microscopic transport mechanism of methane transfer in the porous media of shale gas and tight sandstone reservoirs.