利用指数函数拟合去除扩频激电信号中的电磁耦合感应

A new method for removing EM-coupling in spread spectrum induced polarization based on exponential function fitting

电磁耦合感应是频谱激电法中一种很强的干扰因素,尤其在低阻区和大极距测量时,影响了探测深度和探测效果。国内目前主要的去除电磁耦合的方法有多频振幅去耦和多频相位去耦,这些方法去耦的原理是基于激电效应和电磁耦合效应在频域内振幅和相位的差异,但去耦效果在电磁耦合感应强烈时并不理想。此次研究从激电效应的模型出发,采取指数函数拟合激电效应的方法,从时域内去除耦合感应,并通过计算去耦后的相位和相对相位与直接进行相对相位校正的结果进行对比,发现进行指数函数拟合后计算得到的相位受电磁感应的影响更小,去耦效果更佳。

The EMcoupling is one of the basic interference in the spectralinduced polarization, especially when the working area is covered with lowerresistivity layer or the current electrode spacing is large. It has great impact on the depth of the exploration and the effect of exploration. Recently, most methods to remove the EMcoupling are centered on the multifrequency amplitude and the multifrequency phase. These methods are based on the amplitude and the phase difference between the IP effect and the EMcoupling, which do not work well at strong EMcoupling. The authors＇work is based on the IP model, and fits the IP effects with exponential function. Then the EMcoupling effects are removed from the time domain data. The phase and the relative phase after removing EMcoupling are confirmed more effectively based on the application in field data.