气井井下油管泄漏地面声波检测试验研究

Experimental study on ground detection of gas well down-hole tubing leak based on acoustic method

为探究井下油管泄漏声波法检测技术及方法,开展油管泄漏室内试验。在分析油管泄漏声波产生机制的基础上,提出油管泄漏声波地面检测技术及其实施方式。搭建室内全尺寸油管泄漏检测系统,并进行一系列模拟试验;在时频域内分析试验采集的声波信号,结果表明,油管泄漏声波信号时域绝对均值(AMV)及有效值(RMS)特征随着泄漏孔径及压差的增加而增大;该信号是宽频信号,其能量主要集中在1~130 Hz;检测信号的时域特征AMV和RMS、频域分布特征、自相关分析主峰值等,可作为判断泄漏发生的特征量;利用自相关分析能实现单探头对井下油管泄漏的检测与定位,具有较高精度。

In order to research the method of leak detection for down-hole tubing based on acoustic method,experiments were conducted after designing and setting up the full-size tubing leak system. On the basis of analyzing leak acoustic waves generating mechanism of tubing strings,a ground detection mechanism and an implementation way were presented. The signals measured in the experiments were analyzed in time and frequency domain. The results indicates that the time domain characteristics AMV and RMS of leaking acoustic wave signals are increasing with the increase in both orifice diameter and pressure difference,that the frequency domain distribution of leak acoustic waves is widely and mainly centralized in1-130 Hz,that the main peak value of auto-correlation coefficients as well as the ASL and RMS characteristics and the frequency domain distribution of detecting signals can be used to judge the occurrence of leakage,and that using auto-correlation analysis the detection and localization of down-hole tubing leakage can be achieved with a high accuracy.