注水井井筒完整性设计方法

A design method for the well integrity of water injector well

注水井服役工况复杂,管柱腐蚀、疲劳断裂、密封失效等情况时有发生,给井筒完整性管理带来巨大挑战。现行的井筒完整性标准并未对生产井与注水井严格区分,注水井的井筒屏障划分方法尚有诸多缺陷。参考挪威NORSOK D-010标准,结合注水开发现状分析了注水井井筒工作状态的特殊性,探讨了井筒屏障失效原因,明确了应重点关注的井屏障部件。建立了注水井的井筒屏障系统,将井下安全阀从第一级屏障划出,将井口至井下安全阀之间的油管柱及部件、采油树二号主阀纳入第一级屏障范畴。讨论了关键部件的验收标准,从井屏障设置、腐蚀控制、寿命预测、作业参数控制及井资料记录五个方面探讨了注水井井筒完整性设计内容。最终形成了注水井井筒完整性设计流程,对各油田维持注水开发的安全稳定、经济高效具有重要指导意义。

In water injectors,service conditions are complicated,and string corrosion,fatigue failure and seal failure happen from time to time,which brings great challenges to well integrity management.Current well integrity standard cannot distinguish producers and water injectors strictly,and the well barrier classification method of water injector has many defects.Referring to NORSOK D-010 standard,combining with the status of water flooding development,this paper analyzed the working state particularities of the well in a water injector,discussed the reasons for the failure of well barrier and determined key well barrier components.The well barrier system of water injector was established,in which the downhole safety valve is removed out of the primary well barrier and the tubing pipeline and components between well and downhole safety valve and the No.2 main valve of christmas tree are included in the category of primary well barrier.The acceptance standard of key components were discussed,and the design contents of the well integrity of water injector were discussed from five aspects,i.e.,well barrier setting,corrosion control,service life prediction,operation parameter control and well data record.In this way,the design process on the well integrity of water injector was finally developed,which is of great significance to guiding the safe,stable,efficient and cost-effective water flooding development of each oilfield.