1. Xi’an Branch,China Coal Technology and Engineering Group Corp. Ltd. ,Xi’ an　 710077,China; 2. Shenzhen Branch of CNOOC Ltd. ,Shenzhen　518067,China

槽波记录的信噪比通常较低,常规去噪方法难以适用于具有频散特性的槽波数据。利用槽波信号与干扰波在偏振方向和偏振度上的不同,将频率域极化滤波用于槽波记录的噪声压制,并改进频率域的极化滤波权函数;利用多窗谱分析求取频率域槽波与干扰波的偏振系数,设计极化滤波器,在频率域实现噪声的压制;改进极化滤波权函数,减小噪声与有效信号之间的系数过渡,增强极化滤波对背景噪声的压制。同时,根据初至前的背景噪声求取噪声的谱密度矩阵,在偏振系数求取前消除噪声对有效信号的影响,从而提高有效信号偏振系数的准确性。实际三分量槽波数据处理结果表明:该方法对信噪比较低的槽波记录具有较为明显的去噪效果。

In-seam wave recording typically has a lower signal-to-noise ratio,and a dispersive characteristic that makes the conventional denoising methods difficult to be applied to in-seam wave data. Therefore,the polarization filtering in frequency domain is used to suppress the noise of in-seam wave recording based on the difference between in-seam wave and interference wave in polarization direction and polarization degree. Furthermore,the authors improve the po- larization filtering weight function in frequency domain. The polarization filtering uses multi-tapers spectral estimation to obtain the polarization coefficients of the in-seam wave and the interference wave,and designs polarization filter to suppress the noise in frequency domain. By improving the weight function of the polarization filtering,the transition of coefficient between the noise and the effective signal is reduced. Accordingly,the signal-to-noise ratio of in-seam wave data with strong background noise has been greatly improved by the polarization filtering. In addition,the authors elim- inate the influence of noise on the effective signal before the polarization coefficient is obtained. It is achieved by cal- culating the spectral density matrix of noise according to the background noise before first arrival,so that the polariza- tion coefficient of the effective signal is more accurate. The actual three component in-seam wave data processing re- sults show that this method has obvious denoising effect on the channel record with low signal-to-noise ratio.

JIN Dan,WANG Baoli,DOU Xuqian,et al. Application of polarization filtering in frequency domain to in-seam wave processing[J]. Jour- nal of China Coal Society,2018,43(5):1416-1422.