Pore-scale modeling of a water/oil two-phase flow in hot water flooding for enhanced oil recovery

An attempt was made to investigate the hot water displacement process inside a two-dimensional pore-throat structure by a computational fluid dynamics (CFD) method. The VOF (volume of fluid) method implemented in the CFD software FLUNT was used and a model for two-phase flow and heat transfer was developed. Hot water injection was compared with conventional water injection and it exhibited a higher oil recovery factor and a lower displacement pressure. Then, the behaviors of hot water flooding in a pore with different wettability were investigated. For the oil-wet case, the contact angle and original oil saturation affected the displacement behavior and the oil recovery factor significantly. However, in the water-wet system, the oil phase was surrounded by water, and all the oil could then be driven out of the pore. For the intermediate wet system, three cases with different initial oil/water distribution patterns were simulated, also taking into consideration the effects of droplet size and the symmetry. The results show that the initial oil/water distribution patterns play a more important role in the hot water displacement behavior than the contact angle and oil viscosity.