Building and Application of a Water-Drive Curve Based on Relative Permeability Following Power Function

The water drive curve is one of the most important methods for development evaluation and recovery ration prediction in waterflooding oilfields. Currently, widely used water drive characteristic curves such as Type A and Type B are mainly based on statistical relationships of production dynamics like output and water cut, often leading to certain errors in recovery prediction for different types of reservoirs. This study relies on the Buckley-Leverett non-piston waterflooding theory, uses the flow rate equation, and performs regression fitting on the relationship between phase permeability curves measured in laboratory tests and water saturation, effectively incorporating reservoir and fluid property factors. By combining the Welge average water saturation equation and using the general solution method for initial conditions of ordinary differential equations, a new relationship curve between water cut and recovery degree, as well as a water drive characteristic curve, are derived. During the derivation, the ratio of oil-water relative permeability satisfies a power function relationship, which significantly differs from traditional water drive curve derivation methods. This method considers the influence of the water-free oil production period on the water drive curve during waterflooding and has good adaptability due to different parameters in the corresponding relationships for different reservoirs. Applications in actual oilfields in Kazakhstan show that this method is close to numerical simulation results, conforms to production dynamics characteristics, and is reasonable and effective for dynamic analysis and effect evaluation of oilfield waterflooding development.