Investigations of the impact of wettability heterogeneity on trapping and relative permeability using pore-scale simulations

Abstract:

Wettability is one of the most important factors influencing the multi-phase fluid flow behavior in porous media. However, the role of wettability at pore-scale still remains poorly understood. In this study, we carried out a series of pore-scale simulations of multiphase displacement process to investigate the impact of wettability heterogeneity on trapping, sweep efficiency and relative permeability using lattice Boltzmann method. We first artificially generated mixed-wet bead pack models with varying degree of wettability by introducing spatial heterogeneity. Based on these models, we then calculated the relative permeability curves and performed the drainage and imbibition simulations to obtain the residual non-wetting phase distributions. The results indicate that strong wettability heterogeneity results in a decrease of non-wetting phase permeability due to the pinned interfaces at wettability discontinuities. The wetting phase permeability as well as the sweep efficiency are largely influenced by the degree of wettability rather than the wettability heterogeneity. The non-wetting phase is observed to be less trapped with strong heterogeneity conditions.