A FRACTAL-BASED MODEL FOR RELATIVE PERMEABILITY IN NANOSCALE PORES WITH INTERFACIAL EFFECTS

摘要

The application of relative permeability plays an important role in the development of shale gas reservoirs with nanoscale pores. An analytical model of relative permeability in nanoscale pores with interfacial effects has been developed accord-ing to the fractal theory. We verified our model with the classical models and experimental data and the results show good agreement with them. The proposed model considers the influence of surface diffusion and wettability, and estab-lishes relationships between the relative permeability and the nanotube radius, fractal dimension, and contact angle. The results show that with an increase in film thickness, the fluid velocity in the spreading solid surface is decreased such that the surface diffusion coefficient is decreased and the flow resistance is increased in the nanoscale pores. Surface dif-fusion plays a positive role in promoting fluid flow, and the wettability effect has different influences with changes in the solid interfacial properties. This study has provided a new theoretical basis for gas-water two-phase flow in nanoscale pores and may be beneficial in shale gas reservoir development.