Pore-scale analysis and modeling of heterogeneous wettability in immiscible two-phase flow inside natural porous media

The modeling of in-situ wettability is vital to accurately understand and predict two-phase flow in natural porous media. In this paper, the analysis of in-situ wettability in the pore-scale two-phase flow is implemented based on the automatic measurement of in-situ contact angle. The modeling method of the in-situ wettability in the porescale two-phase flow is developed by combining the measured in-situ contact angle and the volume of fluid method (VOF). The effect of heterogeneous wettability on pore-scale gas-water two-phase flow is also simulated and discussed. The results show that: (1) The in-situ contact angles of rock show a strong heterogeneity and present statistical Gaussian distribution. (2) Compared with the experimental result, the modeling method of insitu wettability proposed in this paper is more effective in predicting the pore-scale two-phase flow than that of the traditional method. (3) With the pore-scale displacement events such as Haines jumps and lateral and vertical-alternating growth of capillary fingers, the displacements under the heterogeneous weak water-wetting conditions with mean contact angles of 70 degrees and 80 degrees show the latest breakthrough times, as well as the highest breakthrough and final displacement efficiency.