Abstract: In the reservoir of mud-bearing glutenite,because the effect of lithology and argillaceous rock on electric property is larger than that of oil-bearing character,that is,the re- sponses of resistivity curve to the characteristics of oil hori- zon and water layer are insensitive,it is difficult to identify oil and water horizons using regular discrimination plates. On the basis of calculating the effect of shale content on oil - bearing character,the oil horizon and water layer in 13304 block are identified by selecting well logging data of interval transit time to calibrate the shale content,using the archies formula to calculate the water saturation of reservoir,and distinguishing the water layer and oil horizon in terms of wa- ter saturation and justifying the results by production test.