L oilfield in Bohai Bay Basin has entered the stage of medium water cut, and tapping the potential of remaining oil is the key direction of sustainable and stable production in the future. Using logging, drilling and core data, the macro heterogeneity characteristics of the reservoir are analyzed, which are mainly reflected in three aspects: plane heterogeneity, interlayer heterogeneity and intralayer heterogeneity, combined with the dynamic data, it is found that the reservoir heterogeneity has an obvious control effect on the remaining oil, and three enrichment modes of remaining oil in L oilfield are summarized: plane difference type, interlayer interference type and interlayer enrichment type, the interlayer enrichment type can be divided into single-stage in channel enrichment mode and multi-stage in channel enrichment mode. The plane difference is mainly controlled by the injection production orientation and the plane distribution of underwater distributary channel in Braided River Delta. The main stream of the river has obvious characteristics of water flooding, and the remaining oil is enriched at the edge of the river; the interlayer interference type is mainly caused by the vertical difference of reservoirs in II and III oil formation and the combined production of large sections, the remaining oil is mainly enriched in II oil formation; the intra layer enrichment type is controlled by the internal configuration interface of single-stage channel or multi-stage channel superposition interface, it is easy to form bottom water flooding and top residual oil enrichment in the single-stage channel. Under the cutting and superposition of two-stage channels, the injected water will break through the interface of two-stage channels, water flooding in the early channel and residual oil enrichment in the late channel. According to different remaining oil enrichment modes, corresponding potential tapping and treatment strategies are adopted, which provides a research direction for improving oil recovery.