Microscopic CT Images Based Percolation Characteristics Analysis on Hot Water Flooding for Offshore Heavy Oil

In this study, CT core samples from oil sands of an LD 5-2 oilfield were prepared to conduct CT scanning experiments to obtain core pore images, and digital image processing techniques were used for the pore structure modeling of rock cores. A microscopic numerical model of hot water flooding was established, based on the actual physical process of hot water flooding, conducting pore-scale hot water throughput to hot water flooding numerical simulations and analyzing the influence law of water injection rate and temperature on hot water flooding. Through the quantification of oil and water phase mass fraction and water saturation data, hot water-driven phase infiltration curves were obtained for different temperatures. The results show limited scope for utilization during the throughput phase, a ripple coefficient below 0.4, an extraction level below 5%, an improvement of the wave coefficient after conversion to hot water to more than 0.75, an increase in extraction level by more than 15%, and greatly improved oil driving efficiency. With increasing injection temperature, the level of extraction was progressively higher throughout the simulation, but after the injection temperature increased to 110°C, the change in the magnitude of the increase in the level of extraction in the simulation was smaller. As the rate of water injection increased, the level of extraction also gradually increased. The highest degree of extraction was achieved at an injection rate of 35 μm/s. Increased water injection temperature favors hot water oil drive, a temperature increase from 80°C to 130°C, an increased saturation of bound water, a reduced residual oil saturation, and an increased oil and water transportation capacity. The results of the study provide some references for the design of an offshore heavy oil hot water flooding program.