基于阻抗张量旋转的大地电磁数据处理效果分析

Analysis of Magnetotelluric Data Processing Effect Based on Impedance Tensor Rotation

大地电磁法是以天然电磁场为场源的一种频率域电磁法。由于天然电磁场信号弱,频段范围宽,所以在强电磁干扰环境下,野外采集的原始数据不可避免地会受到电磁干扰噪声的影响,相关噪声会造成阻抗数据的严重畸变,从而引起错误的反演及解释。常规Robust阻抗估计无法去除相关噪声的影响。该文基于阻抗张量旋转的办法探讨数据处理效果,首先在大量实测数据分析基础上,总结相关噪声对阻抗估计的影响规律,根据受噪数据类型,采用阻抗张量旋转进行数据处理。结果表明,在相关噪声极化方向单一或干扰强度一般的条件下,通过阻抗旋转可以有效改善测量磁场平行于极化方向的数据质量。

The magnetotelluric method is a frequency domain electromagnetic method with natural electromagnetic field as the field source.Because the natural electromagnetic field signal is weak,and the frequency range is wide,so,in the strong electromagnetic interference environment,the raw data collected in the field will inevitably be effect by electromagnetic interference noise.The correlated noise will cause serious distortion of impedance data,which will lead to incorrect inversion and interpretation.The conventional Robust impedance estimation can not eliminate the influence of correlated noise.This paper discusses the effect of data processing based on impedance tensor rotation.Firstly,on the basis of a large number of measured data analysis,the influence rule of correlated noise on impedance estimation is summarized.According to the type of noised data,the impedance tensor rotation is used for data processing.The results show that the data quality of magnetic field parallel to polarization direction can be effectively improved by impedance rotation under the condition of single polarization direction of correlated noise or general interference intensity.