海上废弃井套管磨料射流切割监测系统

Monitoring System for Cutting Abandoned Casing Pipe in AWJ at Sea

针对海上废弃井套管切割的实际需求,提出了磨料射流切割状态实时监测系统。根据磨料射流切割理论,采用了高精度压电换能器拾取磨料撞击套管后产生的振动信号。在此基础上,通过对振动信号进行短时傅里叶变换(short-time Fourier transform,STFT),并利用Savitzky-Golay(S-G)方法完成信号功率谱时域滤波,最后通过频谱特性分析判断每层套管是否切断。试验表明,在水泥浇筑的3层管柱模拟井中,该监测系统可以准确判断每一层套管的切割状态,实现磨料射流切割的实时监测,有效提高作业效率。

Based on the practical requirements on cutting abandoned casing pipe at sea,a real-time monitoring system of the abrasive waterjet (AWJ)cutting was proposed to detect cutting signal.According to the theory of AWJ cutting,a high precision piezoelectric transducer was used to pick up the vibration signal produced by abrasive particles impingement on the walls of casing pipe.On this basis,Short-time Fourier transform (STFT)was used to analyze vibration signal spectrum in time-frequency domain.Then Savitzky-Golay(S-G)filter was selected to smooth the power spectrum.Finally, spectrum characteristic analysis was used to judge whether each layer casing pipe was completely cut or not.The experimental results show that the system can realize accurate judgement of the cutting status of abandoned casing within the 3 layer casing string simulated well pouring by cement,and achieve the monitoring of AWJ cutting in real-time and improve the efficiency of working.