Abstract: In order to accurately and simply predict volumetric sweep efficiency, based on the characteristics of water?drive oilfield and the previous studies, a new relationship between volumetric sweep efficiency (Ev) and water cut (fw) under the various oil?water viscosity ratios is proposed and analyzed using Yu’s water?drive curve. And then, the three types of water?drive curves such as Type?C curve, Zhang’scurve and Yu’s curve are correlated by case study. The results show that when b ranges from 0.1 to 10, the Ev?fw relationship curve gradually changes from concave type to linear type, and when the fw reaches over 60%, the Ev amplitude increases; when the fw reaches over 80%,Ev curve appears in upwarp?like increase with the fw curve. It is concluded that the calculation method for volumetric sweep efficiency based on Yu’s water drive curve is better than those based on the Type C and Zhang’s water drive curves in application and precision