An analytical method for modeling and analysis gas-water relative permeability in nanoscale pores with interfacial effects

•Two analytical single phase permeability and gas-water relative permeability models were established in Nano scale porous.•The influences of surface diffusion and wettability were analysis quantitatively.•Surface diffusion and hydrophobic of surfaces play positive roles to promote fluid flow.•Hydrophilic properties of solid interface show negative effects to the fluid flow.

This paper provides an analytical method for modeling and analyzing gas-water relative permeability in nanoscale pores with interfacial effects in terms of Hagen Poiseuille formula and capillary pressure curve. The flow models considering the interfacial effects in nanoporous shows good agreements with experimental data comparing with other models. The changing characteristics of gas-water relative permeability were analyzed under different conditions such as nanotube radius, film thickness, surface diffusion and contact angle. The results show that the larger the nanotube radius, the greater the relative permeability values because of decreasing both interfacial microstructure effect and the resistance of fluid flow. With the increasing of film thickness, surface diffusion which is positive for flow decreases in nanoscale pores. When the contact angle > 90° solid interface repel water and the hydrophobic of surfaces reduce the resistance to fluid flow, and the gas-water relative permeability increases with increasing contact angle. On the contrary when contact angle < 90°, the solid interface shows hydrophilic properties which play a negative effect to the fluid flow. This study has provided a new insight and theoretical basis for development of shale gas reservoirs with nanoscale pores.