套管低偏心度下的水泥浆顶替界面特性研究  

Cement Displacement Interface Characteristics under Low Casing Eccentricity in Horizontal Well

作　　者：张晋凯[1,2] 周仕明[1] 陶谦[1] 方春飞[1] 张林海[1] 高元[1] 

机构地区：[1]中国石化石油工程技术研究院 [2]中国石油大学(北京)

出　　处：《石油机械》2016年第7期1-6,共6页China Petroleum Machinery

基　　金：国家科技重大专项"复杂地层固井技术研究"(2011ZX05031-004-002)

摘　　要：水平段固井顶替水泥浆时,国内外学者对水平井顶替的机理与顶替界面的变化规律还没形成系统的理论认识。鉴于此,针对水平井偏心环空固井的动态顶替问题,建立了考虑流态耦合与质量扩散的水平井偏心环空两相流体数值试验模型,对低偏心度下正密度差的顶替界面形态变化进行了长距离的数值模拟,在此基础上进行深入分析,揭示了随着偏心度增大,界面长度先减小后增大,顶替效率先增大后减小,存在一个临界最优偏心度,在该偏心度下界面长度增长最慢。最后结合现场施工指出,在水泥浆顶替设计时应以达到临界最优偏心度为目标,同时兼顾下套管难度,合理选择套管扶正器的位置、类型与尺寸,最大限度地接近临界最优偏心度,其次要尽量增大浆体的正密度差,这样仍能较好缓解界面的指进趋势,减小界面长度和混浆体积,提高顶替效率。研究结果对提高水平井的固井质量具有重要的指导意义。For the horizontal section cement slurry displacement, scholars have not formed a systematic theo-retical understanding on the displacement mechanism and displacement interface varying pattern. In view of this, to address the issue of dynamic cementing displacement in the horizontal well eccentric annulus, a numerical simula-tion model of two-phase fluid displacement is established considering the flow states coupling and mass diffusion, based on which the displacement interface under low eccentricity and long horizontal displacing distance with posi-tive density difference is simulated. Then, in-depth analyses have been done. The simulation has revealed that the displacing interface length decreases but then increases with the increase of eccentricity. There is a critical optimal eccentricity under which displacing interface length has the slowest growth. Further analysis of the flow field is car-ried out. Combined with the field operation, critical optimal displacing eccentricity should be set as the goal in the displacement design, as well as considering the casing running operability. Optimizing the centralizer position, type and size, reaching the critical optimal eccentricity as close as possible and maximizing the positive density difference are the measures that could weaken the displacing interface fingering trend, decrease interface length and mix slurry volume and increase the displacing efficiency. The study could provide important guidance for impro-ving the cementing quality of horizontal wells.

关 键 词：水平井 固井 顶替 偏心环空 顶替界面 流场 

分 类 号：TE925[石油与天然气工程—石油机械设备]