f Effect Of Water Saturation On Diffusion Of Ions And Membrane Efficiency Of Reservoir Shale

In this paper, the characteristics of shale water saturation are considered. Based on the triple-layer model of clay-water interfaces, a computational model of unsaturated shale membrane efficiency is established in this paper by using the coupling constitutive equations of heterogeneous porous media. Taking water saturation into account, the change law of the membrane efficiency and diffusion coefficients of ions of clay-rich porous media is analyzed by numerical calculation. Diffusion coefficients of ions and membrane efficiency of unsaturated shale depend on the excess charge density of the surface of the solid in different water saturations. The analysis of factors influencing shale membrane efficiency in unsaturated reservoirs shows that the shale membrane efficiency decreases with the increase of water saturation under unsaturated conditions. The effective diffusion coefficients of ions will increase with the increase of water saturation. Cation exchange capacity (CEC) and solute concentration in pore fluid will affect the membrane efficiency and diffusion coefficients of ions of unsaturated shale.