Extra high water cut has been the main development stage of bottom⁃water reservoir, due to water cut highly with great escalating rate in the initial. At present, the relative permeability curve endpoint has become a serious distortion. This paper presents a method to calculate the performance of water cresting with two phases flowing using the streamlines theory, good for solving the existing problems in the common method, as no pertinence, ineffectiveness and less affecting factors considered. Meanwhile, optimized relative permeability curve was calculated based on the research coupling genetic algorithm with bottom⁃water drive model. The result of numerical calculation based on optimized relative permeability curve showed that the histogram of technical reserves was matched basically with the real practice. This research could provide some instructional meaning to the application of dynamic prediction and developing the oilfield in bottom⁃water reservoir.

Oil displacement efficiency is one of the important parameters affecting the oil reservoir recovery, and the pore volume injection rate is the decisive factor that directly affects the ultimate oil displacement efficiency in the sweep zone. The semi quantitative relationship between the displacement efficiency and the injection volume of pore volume is derived by using the percolation equation expressed by the phase permeability index, combining with the BL theory and the Welge equation. The relation curve satisfies the life cycle theory and the quantitative relation expression between them is deduced according to the law of Logistic growth. At the same time, the optimal pore volume injection ratio is determined by the twoorder derivative curve. With the oil field entering the high water cut stage, the quantitative evaluation method of oil displacement efficiency is of great significance for evaluating the development effect of water flooding reservoir and tap the potential of the reservoir.