New techniques for removing static shift from CSAMT data based on Fourier transform and Radon transform

摘要

This paper proposed two new techniques to reduce the static shift effect in Controlled Source Audio-frequency Magnetotelluric (CSAMT) method in terms of image and signal, by applying Radon transform and Fourier transform, respectively, for data processing. The first method compensates for the static effect in CSAMT data by repositioning the value around θ = 90° and θ = 270° in Radon domain. The second method corrects the CSAMT data by smoothening out the low-frequency components, in Fourier domain. We established 3D model to simulate the static shift that occurs when a low resistive body exists near the surface and corrects it with the two methods. We also applied the two methods to real CSAMT data. The study proved that the effects of small-scale scattering caused by inhomogeneity near the surface can be effectively removed by Radon transform method and Fourier transform method.