海洋可控源电磁数据中海水扰动噪声的小波校正方法研究

A wavelet correction method for the seawater turbulence noise in marine controlled-source electectromagnetic data

海洋可控源电磁法(Marine controlled-source electectromagnetic method,MCSEM)采集的信号极易受多种噪声的干扰,其中由海浪、暗流运动引起的海水扰动噪声是影响信号质量与后期处理解释的主要噪声之一。针对海水扰动噪声,提出了一种基于小波多分辨率分析的校正方法:根据水平电偶极源发射波形与小波基特点,选取最优小波基并研究其最佳分解层数,利用最高分解层数所对应的近似序列估计出海水扰动噪声并从原始信号中去除,达到消除海水扰动噪声的目的。对比校正前、后MCSEM信号的振幅随偏移距变化(Magnitude versus offset,MVO)曲线,表明方法有效。

The signals acquired by marine controlled-source electromagnetic method （MCSEM） are seriously disturbed by various noises,and the interferences generated by the movement of waves and undercurrent are the main noise （i . e. seawater turbulence noise,） that affects the signal qual ity and the processing ＆ interpretation for MCSEM data. To suppress the seawater turbulence noise, we propose a correction method based on wavelet multi-resolution analysis. According to the charac-teristics of the waveform transmitted by horizontal electric dipole source and the wavelet basis, we selected the optimal wavelet basis and studied its optimum decomposition levels;by using the approximate arrays corresponding to the highest decomposition level, the seawater turbulence noise is estimated,and the seawater turbulence noise is suppressed by removing the estimated noise from the original signals. By comparing the magnitude versus offset （MVO） curve before and after correction, we verified the effectiveness of the method based on wavelet multi-resolution analysis.