多道瞬变电磁法(MTEM)虚拟波场提取技术

多道瞬变电磁法(MTEM)是近年来发展起来的一种新的地球物理勘查技术,其数据采集方式与地震法类似,因此,采用瞬变电磁拟地震解释方法对MTEM数据进行处理解释具有一定的优越性.研究MTEM虚拟波场有效提取方法具有重要意义.在以往奇异值分解法、预条件正则化共轭梯度法两种不同的常规提取方法研究基础上,本文提出采用相关叠加法提取MTEM虚拟波场信息.首先采用预条件正则化共轭梯度法对全时段MTEM数据进行虚拟波场提取,然后采用同种方法对划分的各时间段数据进行虚拟波场提取,最后对全时段提取结果与各个时间段提取结果进行相关性叠加,叠加结果作为最终的提取结果.实测MTEM数据虚拟波场提取结果表明,采用相关叠加法可以得到稳定、光滑的虚拟波场波形曲线,且抗干扰能力强.

Pseudo wavefield extraction in the multi-channel transient electromagnetic (MTEM) method

The multi-channel transient electromagnetic (MTEM) is a new exploration method developed in recent years. The data acquisition mode of MTEM is similar to that of seismic methods so that pseudo-seismic interpretation technology is suitable for MTEM data. It is significant to research pseudo-seismic wavefield extracting technology for MTEM data. Based on the singular value decomposition (SVD) method and preconditioned regularized conjugate gradient method, we propose a correlation stacking method to extract pseudo-seismic wavefield of MTEM data. We firstly extract the pseudo-seismic wavefield from whole-time-domain MTEM data with the preconditioned regularized conjugate gradient method, then extract the pseudo-seismic wavefield from the data of each time quantum determined with the same method. Finally, this method stacks the pseudo-seismic wavefield data according to their correlations, regarding the stacking result as the final extracting result. Comparison shows that the pseudo-seismic wavefield extracted from the measured MTEM data with the correlation stacking method is smoother than that of the SVD method or the preconditioned regularized conjugate gradient method. Besides, the anti-interference ability of this new method is stronger.