塔里木盆地顺南区块高温高压气井井筒完整性失效机理分析

Failure mechanism of wellbore integrity for HTHP gas wells, Shunnan block,Tarim Basin

塔里木盆地塔中北坡顺南区块奥陶系中统鹰山组有超深、超高温、超高压、中含CO_2、低含硫气藏,气井完钻和生产运行期间陆续出现环空带压、井口装置抬升、油管断裂、套管变形失效等异常情况,对该区块其他气井的安全生产构成了严重的威胁。因此,在调研国内外油气井井筒完整性研究现状的基础上,应用顺南区块12口已完钻井的井史资料及典型气井的现场测试结果,分析了鹰山组气井环空带压机理、套管变形失效机理及井口抬升机理,找出了顺南超高温超高压气井井筒完整性存在的问题,明确了影响塔中北坡气井井筒完整性的主控因素,提出了改善超高温超高压气井井筒完整性设计的建议,为后期塔中北坡顺南区块超高温、超高压气井井筒完整性控制及安全管理提供了重要参考。

Most gas reservoirs of Middle Ordovician Yingshan Formation, Shunnan block of Tazhong North slope, Tarim Basin, are characterized by ultra-deep burial depth, super high temperature and pressure, and moderate CO2 and low sulfur content. Several abnormalities occur one after another during completion, such as sustained casing pressure, wellhead uplifting, tubing fracture, and casing deformation or failure, which bring about serious threat to production safety for other gas wells in this block. So, both domestic and foreign research status on wellbore integrity were investigated. Then, the mechanisms of sustained casing pressure, casing deformation or failure, and wellhead uplifting were analyzed based on historical data on 12 wells in Shunnan block and on-site testing results of some typical gas wells. And accordingly, many wellbore-integrity problems appear in those gas wells with super high temperature and pressure in this block were identified, and the dominant factors affecting wellbore integrity in Tazhong North slope were also determined. Finally, the corresponding improvement measures were made. Research results provide important reference for the following wellbore-integrity control and management safety of gas wells with super high temperature and pressure in Shunnan block, Tazhong North slope.