Residual oil evolution based on displacement characteristic curve

The purpose of this study was to determine the displacement and dynamic distribution characteristics of the remaining oil in the two development stages of water flooding and subsequent alkaline surfactant polymer (ASP) flooding. The well pattern types in the water and ASP flooding stages are a long-distance determinant well pattern and short-distance five-point well pattern, respectively. The type A displacement characteristic curve can be obtained using the production data, and the slope of the straight-line section of the curve can reflect the displacement strength of the oil displacement agent. A numerical simulation was carried out based on the geological model. The results revealed that the injected water advances steadily with a large-distance determinant water-flooding well pattern. The single-well water production rate increases monotonically during water flooding. There is a significant positive correlation between the cumulative water-oil ratio and the formation parameter. Differential seepage between the oil and water phases is the main factor causing residual oil formation after water flooding, while the residual oil is still relatively concentrated. The effect of the chemical oil-displacement agent on improving the oil-water two-phase seepage flow has distinct stages during ASP flooding. The remaining oil production is extremely sporadic after ASP flooding.