Remaining oil distribution of sandy conglomerate reservoir heterogeneity:A Case Study from Karamay reservoir in Yidong Block

The voidage-injection imbalance,interlayer interference and complex remaining oil distribution are leaded by the reservoir heterogeneity in the later stage of production.Take the Karamay formation in the east of block as an example,on the basis of studying of core,logging and production data,the relationship between different sedimentary micro facies and lithofacies can be obtained by using single sand body description technique.There are five lithofacies types:braided streams conglomerate facies,braided streams conglomerate glutenite facies,floodplains sandy mudstone facies,distributary channel glutenite facies and distributary bay mudstone facies.Combining with the macroscopic and microscopic heterogeneity,the remaining oil can be divided into3 enriched types:I-type braided streams conglomerate glutenite facies,which has mesopore and fine throat texture;II-type floodplains sandy mudstone facies,which has small pore and small throat texture;III-type braided streams conglomerate facies,which has mesopore and small throat texture.I-type and II-type are currently focused of remaining oil potential.The remaining oil distributed in the upper and strong heterogeneity area of the reservoir,with netlike or porphyritic distribution.Due to the effect of III-type's physical properties,the high permeability channel form easily after mater flooding.And remaining oil distributed in the strong heterogeneity area of the reservoir,with zonal distribution.