Abstract: Prediction accuracy of residual oil distribution in late development stage depends mainly on whether numerical models reflect reservoir heterogeneity. This paper presents the analytical methods, classification and mapping of the reservoir seepage now units in shuanghe oilfield and researches their distribution features. The distribution of the seepage flow units is very complex with different types of seepage flow units alternating with each other and strong heterogeneity existed in the distribution ranges and shapes. The numerical modeling grids could be divided according to the distribution features of the seepage flow units to develop highly accurate residual oil distribution maps.