Pore-Scale Lattice Boltzmann Simulation of Blind-End Oil Retention

Currently, a large number of simulation studies on multiphase flow at the pore scale are conducted based on complex porous media. As a microstructure that constitutes the porous media of reservoir, the blind-end can efficiently trap crude oil. However, the research on the multiphase flow within a blind-end is still lacking. In this paper, we used the color-gradient model to simulate the dynamic process that occurs when the oil–water interface passes through a blind-end based on the waterflooding. Furthermore, the effect of influencing factors on the oil in a blind-end (residual oil) after the oil–water interface passes the blind-end were investigated. The results show that the displacement of the water phase from a blind-end full of the oil phase can be categorized into three stages. First, the oil–water interface moves towards the blind-end. Second, when the oil–water interface reaches the blind-end, a portion the of toil phase in the blind-end can be displaced by the water phase. Third, after the oil–water interface passes through the blind-end, a portion of the oil phase (residual oil) is trapped in the blind-end. The residual oil saturation of a blind-end is defined as the ratio of the area of residual oil in a blind-end to the total area of a blind-end. The residual oil saturation in the blind-end increases with the increase in the water velocity, the oil-to-water viscosity ratio, the main channel width, and the blind-end depth. Conversely, it decreases with the increase in blind-end width. The findings provide critical insights into the oil retention mechanism in the blind-end.