三间房组油藏沉积微相及其对注水开发效果影响研究

Study on Sedimentary Microfacies in Sanjianfang Reservoir and Its Effect on the Water-flooding Development

三间房组油藏储层辫状河三角州平原和前缘亚相比较发育。其主要微相由辫状河分流河道、心滩、水下分流河道、分流间区等组成。受沉积微相控制，储层砂体在平面上的分布特征导致和影响了注水开发中的油水运动和产量变化。由于河道砂体物性好、连通性好、吸水强度大，且具有明显的方向性，故注入水沿河道砂体发育方向推进速度快，油井含水上升也快，从而造成沿主河道砂体方向上的高产井初期不含水，后期高含水的现状。剖面上受沉积旋回控制，动用程度较高的层段主要集中在每一砂层组中下部的第３ 、４ 小层。

The braided river delta plain and front are well developed in Sanjianfang Formation reservoir,in which the main microfacies include braided river distributary channel,channel bar,underwater distributary channel and zones between distributary channels.The sedimentary microfacies in Sanjianfang reservoir and its effect on waterflooding result are studied through determination of sedimentary,combination of dynamic and static information as well as observation of production test.Based on the analysis of lithological,electrical and corresponding physical characters,the relationship between lithology and electricity is firstly set up,then according to the depositional cycle developped by sedimentation of each distributary river from formation to development and abandonment,the layer correlation is made by each well in matrix profiles.On the basis of what mentioned above,the top and bottom are as well as distribution range of every unit, i.e.,sandstone group,sandstone layer and substratum are determined.Finally,Sanjianfang Formation is subdivided into five sandstone groups,eighteen sandstone layers and twenty four substrata. Controlled by the depositional microfacies,the movement of water—oil and the variation of production are primarily affected by the horizontal distribution of sandbodies.The relatively good physical properties,connection and high water intake capacity results in high velocity of injecting water in distributary channels and quick increase of water in production wells.For this reason the high yield wells produces no water at the beginning and much water at last. In vertical profiles,controlled by the sedimentary cycles,the highly produced layers are mainly the third and the forth substrata located in the middle low part of every sandstone group.On the whole,affected by the plane and vertical heterogeneity,the injected water tends to breakthough in one direction horizontally and one layer vertically which further increases contradivtion between intralayer and interlayer during waterflooding.