南海高温高压气田尾管回接管柱改进及入井质量控制

南海西部海域高温高压条件苛刻,气井开发将准177.8 mm尾管回接至井口并全井段封固作为井筒完整性保障的技术措施之一。由于常规回接工具插入回接筒困难、密封能力有限,不能满足高温高压气井的要求,同时回接尾管材质软,采用特殊螺纹设计,入井质量要求高,因此优化改进了尾管回接工具及管柱结构,包括节流带孔碰压浮箍、4道密封件以及顶部封隔器+防上顶卡瓦的设计;开展了特殊螺纹上扣准确度控制技术研究,基于螺纹密封脂的摩擦因数修正了套管上扣扭矩计算公式,总结了上扣曲线可接受度的关键判断方法,提出了上卸扣速度精细化调整建议。上述工具和技术在6口高温高压开发井进行了应用,尾管回接作业提效20%,并有效提高了套管入井质量和井筒完整性。

Running quality control and structure improvement of liner tie-back string of HTHP gasfield in South China Sea

The 177.8 mm production liner was tied back to the wellhead and cemented in the whole section as one of the security measures to ensure whole life-cycle wellbore integrity of developed gas well under the severe high temperature and high pressure condition in western South China Sea.However,it was difficult to insert into the tie back cylinder for conventional liner tie back equipment,and its sealing ability of was limited.The running quality of tie-back liner with soft chromium and premium threaded connection had the high requirement.Therefore,tieback liner equipment and structure of the string were optimized,including the design of orifice float collar,the tieback stinger with four sealing components,the top packer and anti-retraction slip.The study on accuracy control of premium threaded connection makeup torque was conducted.The correction calculation formula of makeup torque based on friction coefficient of thread sealing grease was established.The key judgment method of acceptability of makeup torque curve and suggestions for make-and-break speed were summarized.The research results have been applied to 6 development wells of high temperature and high pressure gas field,which enhanced the liner tieback operation by 20%and improved the wellbore integrity and the running casing quality.