Estuary bar sandstone body is also one of the most important types of oil and gas reservoirs in China,and its internal interlayers control the distribution and movement of fluid inside the reservoir and affect the overall development effect of the reservoir. Taking the fault block reservoir of Sha-2（S2） member of L11 fault block in Shinan oilfield as an example, the rock and layer type of intercalation in estuary bar sandstone body are analyzed by means of logging, core, analysis and dynamic production data, the spatial distribution law of intercalation is described, and the influence of intercalation on remaining oil distribution is expounded.The results show that the main oil layer of L11 fault block consists of mud, physical and calc interlayers, which account for 68%,21% and 11% respectively.The calc interlayers are concentrated in the distribution area of physical interlayers,and the development degree of physical interlayers is relatively high in the northeast near the provenance and the peak of the interlayer, while the development degree of mud interlayers is relatively high in the southwest far from the provenance. In the near-source direction, the fifth-order configuration interface is relatively thin, and in the far-source direction, the thickness is relatively thick, ranging from 0.60 m to 29.00 m. In the fourth-order interface, the drilling rate of interlayer is above 60%, the thickness is between 0.35 m and 4.10 m, and the inclination is less than 2.0°. The level 3 interfacial interlayer is spread no more than 3 well spacing, the thickness is less than 1.50 m, and the dip angle is 2.7° on average. Level 4 and 5 interfaces control the distribution of remaining oil,level 3 interface has little influence on the distribution of remaining oil, low injection and high production mode development effect is relatively good,high injection and low production mode development effect is relatively poor,through the injection and production mode can improve the well group oil displacement efficiency and development effect.The above results and understanding have important guiding significance for the efficient development of estuary bar sandstone reservoir.