Fine Anatomy And Remaining Oil Research Of The Reservoirs In Baiyushan Encryption Area

The reservoir of Baiyushan encryption area in Jingan oilfield belongs to ultra-low permeability reservoir.Since the advance water injection development in 2002,three encryption have been carried out.At present,due to the complex internal structure of reservoir and the lack of understanding of sand body connectivity,there are problems such as uneven water drive and unclear distribution of residual oil.Therefore,the research of anatomy and remaining oil in this reservoir is of great practical significance for improving the development effect of water flooding in this reservoir.The main reservoir is divided into 6 small layers by comprehensive utilization of various geological data.Based on the regional sedimentary background and log facies,it is analyzed that the study area belongs to delta front deposition,which mainly develops four kinds of sedimentary microfacies: subaqueous distributary channel,distributary channel flank,distributary bay and estuarine dam.The direction of the river is north East to South West.There are 4～5 channels in this area,the width of the channel is150～650 m,the swing is faster.The main oil layer is divided into 10 single sand bodies in the vertical direction,marked by the intersediment section.Five patterns and five sand body contact relationships identified by the sand body boundary are summarized,and the sand body connectivity is verified by dynamic method.The distribution law of sand body in plane and vertical direction is studied.It is considered that the sand body size changes greatly,the sand body continuity in the direction of the source is better,the sand body continuity in the direction of the vertical source is poor,and the sand body in the plane is controlled by the stable extension of the sedimentary phase along the river direction.A method for determining sand body connectivity and injection-production connectivity based on sand body contact relationship and dynamic data is proposed.Based on the anatomy of the reservoir,the characteristics of water flooding,the characteristics of oil well effect and the adaptability of well network are analyzed,and four models of oil well effect are summarized.Using numerical simulation and water-flooded layer analysis,it is found that the remaining oil in the plane is distributed in a strip between two rows of wells,and the water washing degree in the longitudinal oil layer is low,and the residual oil in the flank of the distributary channel is enriched.Based on the results of reservoir anatomy and dynamic data,the influence of single sand body configuration,interlayer,hyperosmotic passage,sedimentary rhythm and well net on the distribution of residual oil was analyzed.Six kinds of measures for tapping the potential of the remaining oil are put forward,which indicates the direction for the adjustment and tapping of the potential in the block.