Research On Reservoir Architecture Of Delta-front Facies And Physical Simulation Of Remaining Oil

Prediction of remaining oil distribution is a common concern issue of oil producing countries in the world,and the delta reservoir is one of the main oil-bearing reservoir.The underground geological conditions can be predicted by researching on the reservoir architecture,and the heterogeneity of the reservoir and the distribution of remaining oil can be more deeply understood.Nowadays,Liang60 fault block has entered the stage of high water cut development.It has become an important research content of oil and gas development to finely depict the reservoir characteristics and find the distribution area of remaining oil.Therefore,it is of great significance to understand the internal structure of reservoir and predict the distribution of remaining oil by remaining oil physical simulation experiment according to reservoir architecture.The 7^thand 8^thsand groups of the second member of Shahejie Formation in Liang60fault block of Dongying sag,Jiyang depression,Bohai Bay basin is taken as an example in this paper.Combined with the regional sedimentary background,core and logging data,the sedimentary facies marks have been identified.By describing the distribution characteristics of reservoir and summarizing the laws of various microfacies,the sedimentary facies model of the study area has been established.By determining the correlation relationship between each level of reservoir architecture units and reservoir units,the reservoir architecture units and reservoir architecture interfaces of different levels are divided,and the reservoir architecture model of delta-front in the study area is established.Finally,the physical simulation experiments of remaining oil are carried out by designing the reservoir architecture models of the estuarine bar.The study shows that the 7^thand 8^thsand groups of the second member of Shahejie Formation in Liang60 fault block mainly are delta-front subfacies and the sediments come from northeast.The sand bodies are widely distributed in the study area.The 7^thand 8^thsand groups in vertical direction can be divided into 5 five-level architecture units and 19four-level architecture units.Three vertical stage marks of separation,shallow cutting and deep cutting among single sand bodies are identified and five lateral boundary marks of elevation difference,lithology mutation between sand bodies,thickness difference,logging curve shape difference and"thick-thin-thick"are identified.There are two filling modes of estuarine bar:vertical superimposition and lateral superimposition.According to the architecture results of the estuarine bar,three groups of physical simulation experiments of remaining oil were carried out,which were parallel to the provenance,vertical superimposition and lateral superimposition.It is found that the distribution of remaining oil in the estuarine bar is mainly controlled by the reservoir architecture interface.Parallel to the provenance direction,the interlayer at the top of the estuarine bar has the strongest ability to block the fluid,and the interlayer at the bottom has the least ability to block the fluid.The interface of vertical superimposed estuarine bar is arched,which blocks the vertical migration of fluid.The remaining oil is enriched at the top of single estuarine bar and accretion body.The reservoir architecture interface in the lateral superimposed estuarine bar can block the lateral migration of fluid and form a large amount of residual oil enrichment in the upper part of the estuarine bar.