磁场相关性在远参考大地电磁数据处理中的应用

Application of magnetic field correlation in remote reference magnetotelluric data processing

首先分析了基站存在不同噪声强度时,远参考大地电磁对测深曲线的影响,发现在低信噪比条件下,常规远参考大地电磁数据对测深曲线质量的提升有限,不能满足后续资料处理的要求;然后对攀西地区实测磁场资料进行统计分析,结果认为最远相隔40km的长周期大地电磁测深点的各个磁道数据具有很好的相关性。因此提出利用基于参考站与基站之间磁场相关的远参考大地电磁法来筛选功率谱,避免了常规远参考大地电磁法仅关注噪声与信号之间、或者基站噪声与参考站噪声之间的非相关性,却未考虑基站与参考站磁场信号之间的相关性这一局限,以达到去除磁场噪声的目的。实验数据及实测数据处理结果表明,基于磁场相关的远参考大地电磁法效果优于常规远参考大地电磁法,证明了该方法的有效性和正确性。

We discuss in this paper applications of magnetic field correlation in remote reference magnetotelluric processing.We first analyze the influences of remote reference magnetotelluric on sounding curves with different noise level at the base station.The following phenomena are found:a.The sounding curve quality with a low signal-noise ratio cannot be improved by conventional remote reference magnetotelluric methods;b.Based on statistics of some magnetic survey data,there is a strong correlation among magnetic signals at sounding points with the maximum distance of 40 km in Panxi Area.On this basis,a magnetic field correlation method between base stations and the reference stations using remote reference magnetotelluric data is proposed in order to screen out power spectra and eliminate the noise.Test results on experimental data and measured data prove the effec tiveness and correctness of the proposed method,and show better effects than conventional remote reference magnetotelluric methods.