Abstract: For an oil reservoir in the middle-late development stages, a fine study about sedimentary condition, sedimentary microfacies and their features are very important in modeling a proper reservoir, getting a proper knowledge of remaining oil distribution and improving oil recovery rate. Based on core, well logging, mud log and related test data from Wenliu ore field, the sedimentary microfacies of Wusha Formation from middle section of the third member in Wen72 block were studied. This district belongs to meandering river delta deposit. Five microfacies can be classified as submerge distributary channel, mouth bar, distal bar, interdistributary and prodelta mud. The submerge distributary channel deposit and mouth bar deposit are major reservoir sands. The evolution and distribution of the microfacies in every number have also been studied. The discussion on the relationship between microfacies and oil-bearing indicates that the accumulation of oil and gas is controlled by microfacies. The oilbearing ability of submerge distributary channel is the highest, that of mouth bar secondly, and that of distal bar the lowest. The conclusions can provide a geological foundation for the development scheme adjustment and dynamic analysis of the Wenliu oil reservoir.

Key words: sedimentary microfacies, meandering river delta, reservoir, Wen72 block