基于磁-声结合的特殊螺纹油管密封检测方法研究

Method for Detecting Sealing of Premium Connection Tubing Based on Magnetic-Acoustic

针对特殊螺纹油管下井后仍存在密封失效的问题,提出采用金属磁记忆和超声相结合的检测技术应用于特殊螺纹油管密封性能的检测。搭建金属磁记忆检测系统,采集上扣前后接头的磁记忆信号,提取并分析特征参数磁记忆信号梯度值。结果表明:磁信号梯度值可以表征螺纹形貌;上扣后啮合螺纹应力分布不均,起始端磁信号梯度值大,应力集中程度高。搭建超声检测系统,采集上扣前后油管密封面回波信号,计算声强反射系数,并利用声强反射系数与接触应力的关系得到密封面接触应力分布。结果表明,上扣后密封面环形带上保持了较高的接触应力,具有一定密封能力。磁-声结合的检测方法实现了对接头螺纹连接部位应力集中情况和密封面接触应力分布的检测,进而可评估密封性能,为保障油管下井服役提供了更安全更有效的密封检测手段。

With view to the sealing failure of premium connection tubing still exists after the downhole,the combined detection technology of metal magnetic memory(MMM)and ultrasound was proposed to detect the sealing performance of the joints.A MMM detection system was built to collect the magnetic memory signal of the joints before and after make-up,and the characteristic parameter magnetic memory signal gradient value was extracted and analyzed.The results show that the magnetic signal gradient value can characterize the thread shape,and the stress distribution of the engaging thread is uneven after make-up,and the magnetic signal gradient value is large at the beginning of the thread,so the stress concentration is high.The ultrasonic testing system was set up to collect the echo signal of the sealing surface before and after make-up,the acoustic intensity reflection coefficient was calculated,and the contact stress distribution of the sealing surface was obtained based on the relationship between the reflection coefficient of sound intensity and the contact stress.The results show that the high contact stress is maintained on the annular belt of the sealing surface after make-up,which has certain sealing ability.The magnetic-acoustic detection method realizes the detection of the stress concentration of the threaded and the contact stress distribution on the sealing surface,and then the sealing performance can be evaluated.It provide a safer and more effective detection method to ensure the service of tubing down the well.