萨北油田曲流型河道砂体建筑结构研究

Study on architecture of meander channel sandbody in Sabei Oilfield

于德水

Yu Deshui

大庆油田有限责任公司勘探开发研究院;

Research Institute of Exploration and Development, Daqing Oilfield Co. Ltd., PetroChina, Daqing 163712, China

面对高含水后期影响储层剩余油分布的砂体内部建筑结构等深层次的储层非均质性问题,特别对于曲流型河道砂体而言,其纵向上的非均质性及内部单砂体建筑结构是影响剩余油分布的主要因素。以现代沉积和野外露头理论模式为指导,应用Miall的层次界面和结构要素分析法,采用"层次分析、模式预测"研究思路,结合油田密井网资料,对萨北油田北二西区萨Ⅱ1+2b沉积单元曲流型河道砂体建筑结构进行分级精细解剖。应用"废弃河道定边,砂体厚度定位"方法综合识别点坝砂体分布;详细分析砂体内部侧积体和侧积夹层空间分布规律,并求得点坝内部定量判断侧积层倾角的经验公式;在此基础上,建立基于井点数据的砂体内部三级界面-侧积夹层三维地质模型,为高含水后期综合调整,剩余油挖潜提供地质依据。

Faced with the reservoir heterogeneity problem of inside sandbody architecture which affects the distribution of remaining oil at the late stage of high watercut, especially for the meander channel sandbody, the vertical heterogeneity and inside sandbody architecture are considered to be the major factors which affect the distribution of remaining oil. Based on the theoretical model of modern deposition and outcrop, using Miall′s graded interfacial and the analysis method of structural element, and with the scale analysis and mode fitting for the research ideal, the architecture of meander channel sandbody was scaled in the SⅡ1+2b sedimentary unit of the second western region of Sabei Oilfield combined with the information of dense well pattern. Using the method of abandoned channel boundary determining and sandbody thickness locating, the distribution of point-bar sandbody was distinguished, the spatial distribution law of lateral accretion bodies and lateral accretion interlayer in the sandbody were analyzed and the empirical equation of quantitative estimating the dip angle of lateral accretion interlayer inside the point par was derived. Based on this, the third boundary of inside sandbody based on well point data (3D geology model of lateral accretion interlayer) was established, which provided geologic basis for comprehensive adjustment and remaining oil potential tapping at the late stage of high watercut.