油基钻井液条件下页岩气侧钻水平井固井技术

CEMENTING TECHNOLOGY FOR SHALE SIDETRACKING HORIZONTAL WELL UNDER CON⁃DITION OF OIL-BASED DRILLING FLUID

DYS4侧钻水平井完钻井深5587 m,垂深4186.34 m,水平位移1607.72 m,具有油基钻井液固相含量高、井壁和套管壁清洗困难、封固段长(5584.49 m)、顶底部温差大(110℃)、顶替效率难以保证等诸多固井难点。通过优化固井方案,优选了双凝双密度水泥浆体系和驱油型隔离液体系,且采用了油基泥饼固化剂,制定了配套防气窜、井眼清洁等固井技术措施。现场应用结果表明,该井固井一、二界面胶结质量优质,有效封固了页岩气水平段,达到了预期目的,为后续大型分段体积压裂奠定了良好的井筒基础,同时也可为油基钻井液条件下的水平井固井提供借鉴和参考。

The sidetracking horizontal well DYS4 has a well depth of 5584.00 m,a vertical depth of 4186.34 m and a horizon⁃tal displacement of 1607.72 m.It faces many complex problems in cementing,such as high solid content in oil-based drilling fluid,difficulties of cleaning the wellbore and casing wall,long cementing segment(5584.00m),large temperature difference between the top and the bottom(110℃),unsure displacement efficiency and so on.By optimizing the cementing scheme,sepa⁃rable setting and dual density cement slurry system and type of oil displacement spacer fluid system have been adopted,and oil-based mud cake solidifying agent has been used.Multifarious cementing technology measures also have been developed to meet the qualification of gas migration prevention,wellbore cleaning,etc.Field application result shows that the cementation quality of the casing-cement interface and the cement-formation interface is high,and the horizontal section of shale gas is ef⁃fectively sealed,which achieved the expected goals.It not only lays the wellbore foundation for the subsequent large-scale segmented volumetric fracturing,but also provides reference for horizontal well cementing under the condition of oil-based drilling fluid.