裂缝对大庆台肇地区低渗透砂岩储层注水的影响

Influence of fractures on injection for low-permeability sandstone reservoir in Taizhao area,Daqing Oilfield

在裂缝分布特征研究的基础上,对大庆台肇地区裂缝对注水的影响进行了分析。结果表明,该区葡萄花低渗透砂岩油层发育有近东西向、北西向、近南北向和北东向4组高角度构造裂缝,裂缝的储集能力较弱,主要起渗流通道作用。受现今地应力等因素的影响,上述4组裂缝在井口的开启压力分别为15.1,19.6,27.8和28.0 MPa,反映了不同方位裂缝在油田注水开发过程中的开启序列。目前,该区的注水压力基本超过了东西向裂缝的开启压力,因而东西向裂缝的注水反映特征十分明显。根据不同方向裂缝的渗流特点,采用线性注水、动态调配水、周期注水、层断间注及高含水井关井间抽等措施,进一步完善注采系统,可有效地提高注水开发效果。

Based on the investigation of fracture distribution characteristics, the influence of fractures on injection was analyzed in Taizhao area, Daqing Oilfield. The results show that four sets of structural fractures with high dip angle were developed in Putaohua low-permeability sandstone reservoir, whose orientations respectively were east-west, northwest-southeast, south-north and northeast-southwest. Fractures have little reservoir capacity but make main roles on seepage. Affected by foctols such as present stress fidd, the starting pressures of above fractures on the wellhead respectivdy are 15.1,19.6, 27.8 and 28.0 MPa, which show the different starting sequence of the fractures. Now, the injection pressures in the study area basically exceed the starting pressure of east-west fracture, and the reflection characteristics of injection are quite clear. According to seepage characteristics of different sets of fractures, it is available to improve developmaent effect by adopting linear injection well pattern, dynamic adjustment injection, cyclic injection, intermittent injection between layers and intermittent pumping after high water cut wells shut-in, and making further consummation injection-production system.