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

The EM?coupling is one of the basic interference in the spectral?induced polarization, especially when the working area is covered with lower?resistivity 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 EM?coupling are centered on the multi?frequency amplitude and the multi?frequency phase. These methods are based on the amplitude and the phase difference between the IP effect and the EM?coupling, which do not work well at strong EM?coupling. The authors'work is based on the IP model, and fits the IP effects with exponential function. Then the EM?coupling effects are removed from the time domain data. The phase and the relative phase after removing EM?coupling are confirmed more effectively based on the application in field data.