川西长裸眼水平井下尾管循环解阻关键技术

为解决川西长裸眼水平井中尾管下入遇阻和不易下到设计位置的问题，从提高尾管固井工具可靠性和尾管固井管串组合通过性等方面入手，优化了尾管固井管串组合，并选用压力平衡式尾管悬挂器、整体式弹性扶正器和弹浮式浮箍等关键工具，制定了降低尾管下入遇阻概率和提高解阻成功率的技术措施，形成了适用于长裸眼水平井的下尾管中途大排量循环解阻技术。压力平衡式尾管悬挂器能消除循环憋堵或异常高压导致尾管悬挂器提前坐挂的风险；整体式弹性扶正器最小复位力约为常规单弓弹性扶正器的2倍，可提高套管居中度；弹浮式浮箍能解决常规弹簧式浮箍大排量长时间循环弹簧疲劳失效和回压阀冲蚀密封失效的问题。长裸眼水平井下尾管中途大排量循环解阻用技术在川西50口中浅层水平井进行了应用，解决了尾管下入遇阻和下不到设计位置的问题，尾管到位率达到了98%。研究结果表明，长裸眼水平井下尾管中途循环解阻技术可以解决川西长裸眼水平井尾管下入存在的问题。 

Key Techniques for Eliminating Resistance while Running Liner with Circulation in Long Horizontal Openhole Wells in the Western Sichuan

In order to solve the problems of resistance encountered while running liner and the fact that it is often hard to run liner through the full extent of long horizontal openhole wells in the Western Sichuan Area, cementing pipe string liner was optimized to improve the reliability of liner cementing tools and to enhance the mobility of the liner cementing pipe string. Key tools such as pressure-balanced liner hanger, integral elastic centralizer, and elastic/buoyant floating collar were adopted, and the technical measures that can reduce the resistance encountering probability of liner and increase the success rate of resistance removal were formulated, through which the mid-way resistance removal technology for running liner in long openhole horizontal wells was formed with large flowrate circulation. The pressure-balanced liner hanger can eliminate the risk of premature setting caused by the pressure build-up during circulation or abnormal high pressure. In this case, the minimum resetting force of integral elastic centralizer is about 2 times that of the conventional single-bow elastic centralizer, and that can improve the casing centering. In the meantime, the elastic/buoyant floating collar can solve the problems of spring fatigue failure due to large flowrate long-term circulation and the erosion failure of back pressure valve seal in conventional spring-type floating collar. The resistance removal technology by mid-way large flowrate circulation has been applied to 50 shallow horizontal wells for running liners in long openholes in the Western Sichuan Area, and it solved the problems of getting hung up and getting out of design position in running liner. Using the new technique, the liner succssfully arrived at the end of the hole at the rate of 98%. The research results showed that this technology could solve the problems of running liner in long horizontal openhole wells in the Western Sichuan Area.