The Study On Reservoir Architecture And Remaining Oil Of 3^rd-4^th Sand Group Of Guantao Formation In The East Of Gudao Oilfield

Gudao Oilfield is a large integrated oil and gas field in Jiyang depression of Bohai bay basin.After decades of development and production adjustment,Gudao Oilfield has entered the high water cut period.Due to the relatively low recovery factor of the Gudao Oilfield,commonly about 30 %,a considerable amount of the remaining oil is still stored underground,which is characterized by overall dispersion and local enrichment.Therefore,the fine hierarchical reservoir architecture characterization of the research area was conducted to determine the stacked patterns of the architecture elements and analyze the distribution law of the remaining oil under the stacked patterns of the architecture elements,which has important guiding significance for the further exploration of the remaining oil in the research area.Based on the core,well logging and production performance data in the study area,the high-resolution sequence stratigraphy and the architecture model of the sedimentary prototype area were taken as the guide,and the method of "model fitting and hierarchical analysis" was adopted to carry out this research.We first conducted the hierarchical architecture characterization of the reservoir in the upper section of Guantao formation in the eastern part of Gudao Oilfield so as to determine the distribution laws of different hierarchical architecture elements.On the basis of architecture characterization,using the analysis of tracer well group and numerical simulation of conceptual model,the law of remaining oil distribution under reservoir architecture control was expounded.Studies have shown that:(1)Three distribution patterns are developed on the sandbody plane of meandering river channel in the study area,which are "continuous sheet ","cross ribbon" and "single ribbon".The plane distribution pattern of channel sandbody changes from "continuous sheet" to "single ribbon" vertically;(2)The point bar sandbody is widely developed in the main layer of the study area,and its size varies greatly,with a general span of 800 m ? 1100 m.The abandoned channel is used as the boundary to limit the span range of the point bar.The width of the abandoned channel is150 m ? 250m;(3)The multi-stage lateral accretion sandbodies and shale drapes take the imbricate lateral stack as the point bar sandbody.The thickness of the single lateral accretion sandbody is 2m ? 5m.The thickness of the single shale drape is 0.1m ? 0.6m.The direction of river abandonment is the downdip direction of shale drape,and the dip angle is about 7°;(4)The remaining oil in the study area is mainly controlled by architecture stacked patterns.The remaining oil controlled by the architecture elements of channel sandbodies is mainly concentrated on the edge and top of channel sandbodies.Due to the shielding effect of the shale drape,the remaining oil inside the point bar is mainly concentrated in the middle of the adjacent shale drape and the edge of point bar sandbodies.