小波包变换在井眼防碰振动信号处理中的应用

Application of Wavelet Packet Transform for Wellbore Anti-collision Signal Monitoring

随着海上油气田加密井调整开发技术应用越来越普遍,钻井过程中井眼碰撞的风险也成了一个不容忽视的问题。在采用钻头振动波方法进行丛式井防碰监测时,将小波分析应用于复杂环境下钻头振动信号的特征提取。采用小波包对信号的各频带进行分解,将信号分解成不同尺度域,得到信号在不同频带内的能量分布特性,通过能量大小对比分析,得出了振动特征显著的4个尺度。对特征尺度进行功率谱分析发现,其信号幅值和能量集中在200～300 Hz范围内;当钻头趋近邻井套管时,信号特征分量发生显著变化,为防碰信号处理提供了新的思路。

With the development of the offshore oil infill development drilling, more and more wells are drilled in dense well spac- ing, increasing the risk of wellbore collision. A new method of vibration signal analysis of drill bit based on wavelet transform has been developed for anti-collision of the offshore cluster well. To extract useful information contained in response signals under com- plicated environment, wavelet packet transform is used to decompose the original vibration signal of drill bit. By analyzing energy spectrum of the components after wavelet packet transform, the first four components are found that contain the feature of the drill bit. The specific frequency interval 200 - 300 Hz of the drill bit is found after analyzing power spectrum. When the bit is near to the casing of the close well, the analyzing result agrees well with the conclusion, which provides a new method for processing anti- collision si crnal~.