基于时域信号重构的广域电磁法高频有效数据提取方法

Extracting useful high-frequency information from wide-field electromagnetic data using time-domain signal reconstruction

广域电磁法已经在油气、矿产及地质灾害勘探中得到了广泛应用,尤其在强干扰地区体现了很强的抗干扰能力,但在实际应用过程中,其高频成分,尤其是2048 Hz以上频率,对应广域视电阻率经常出现上翘现象,为地球物理反演和解释带来了诸多困难。本文研究发现,信号发送和采集对应的晶振时钟误差是造成该问题的主要原因。基于此,本文提出了一种基于时域信号重构的高频有效信息提取方法,其主要特点为记录完整发射电流时间序列和接收信号时间序列,并通过电流时间序列估计晶振误差,基于此误差对接收信号时间序列进行校正与重构,以获得校正后时域信号,进而提取数据中的高频有效信息。通过将该方法应用于实际数据,处理后的广域电磁归一化电场的高频部分不再上翘,获得了信号中准确的高频成分,表明该方法是提取广域电磁法高频信号有效方法。

The wide-field electromagnetic method is widely used in hydrocarbon exploration,mineral deposit detection,and geological disaster prediction.However,apparent resistivity and normalized field amplitude exceeding 2048 Hz often exhibit upward warping in data,making geophysical inversion and interpretation challenging.The cumulative error of the crystal oscillator in signal transmission and acquisition contributes to an upturned apparent resistivity curve.To address this,a high-frequency information extraction method is proposed based on time-domain signal reconstruction,which helps to record a complete current data sequence;moreover,it helps estimate the crystal oscillator error for the transmitted signal.Considering the recorded error,a received signal was corrected using a set of reconstruction algorithms.After processing,the high-frequency component of the wide-field electromagnetic data was not upturned,while accurate high-frequency information was extracted from the signal.Therefore,the proposed method helped effectively extract high-frequency components of all wide-field electromagnetic data.