大通径管柱冷冻暂堵技术

Freeze temporary blocking technology of large bore size string

目前冷冻暂堵技术主要用于封堵各层套管环空、油套环空及油管内通道,最大封堵管内直径仅为88.9 mm。由于向?88.9 mm以上大通径管柱内注入暂堵剂时,暂堵剂不易黏附于管壁形成桥塞,因而对于空井(井内无油管)泄漏井口装置的控制,只能采用压井的方式。但压井作业周期长,施工成本高,会对储层造成不可逆的伤害,严重影响油气井产量。为了实现空井泄漏井口装置的安全控制,通过改变暂堵剂配方与注入方式,研究出一种大通径管柱冷冻暂堵方法。室内实验分析表明:新型暂堵剂在?180.0 mm管柱内可顺利形成冷冻桥塞,桥塞承压能力达到70 MPa。应用研究成果完成了×井冷冻暂堵?139.7 mm套管施工。该方法对于提升带压治理泄漏井口装置能力,避免储层伤害和保障油气井安全生产具有重要指导意义。

At present,the freeze temporary blocking technology is mainly used to plug multilayer casing annulus,tubing casing annulus and tubing.The largest size of freeze temporary blocking is onlyФ88.9 mm.When the temporary blocking agent is filled into large bore size string which is aboveФ88.9 mm,it is not easy to stick on pipe wall to form bridge plug.So,well killing is the only way to reconstruction the leakage wellhead for wells without tubing.But this way has these shortcomings:the operation cycle is long and construction cost is very high;it is very harmful to the reservoir and seriously affects the output of oil or gas wells.In order to reconstruct the leakage wellhead for wells without tubing in a safe way,a freeze temporary blocking method of large bore size string is developed by changing the formula and the injection way of temporary blocking agent.The laboratory experiment shows that the new method can ensure to form frozen bridge plug inФ180.0 mm string,and the pressurization capacity is 70 MPa.The research result has been successfully applied to guide theФ139.7 mm casing freeze temporary blocking operation of Well X.It is of great significance for improving the capacity of old well reconstruction with pressure,protecting reservoir and ensuring the production safety of oil and gas wells.