The Terrain Correction In IP Sounding

In the establishment of a stable DC electric field or AC electric field, the observation of the underground electrical properties is carried out by gradually increasing the distance between the feeding electrodes. Using the symmetrical quadruple device, the apparent resistivity and the apparent polarizability in the different depths below the same observation point can be obtained. The underground mineral resources are surveyed according to the characteristics of apparent resistivity and apparent polarization rate measured at different supply poles at different points of the surface, and the distribution range is determined and the corresponding geological problems are solved.The terrain has a great influence on the apparent resistivity in the IP sounding. Therefore,in practical applications, the apparent resistivity data obtained under the undulating terrain need to be corrected,and the apparent resistivity is caused by the suppression of the terrain.In order to correct the influence of the terrain on the apparent resistivity,this paper uses the boundary element method with small dimensionality and higher computational efficiency to carry out the apparent resistivity under original terrain and the undulating terrain. The orthogonal design method is used to restore the true position of the depth range of the supply electrode distance.The terrain correction method has the characteristics of fast calculation,high applicability and stability.In order to test the effect of the terrain correction, In this paper, a number of two-dimensional models within inhomogeneous media are established.After the terrain correction, the terrain correction effectively remove the false anomalies, highlighting the anomalies caused by underground ore bodies.Finally, the method of joint terrain correction is applied to the copper-nickel mining in western Hunan province. The copper and nickel ore will produce high gravity, high magnetic,low apparent resistivity and high apparent polarization anomalies. The apparent resistivity of the high power excitation data collected in the mining area is corrected by terrain. The amplitude and shape of the non-homogeneous polarized medium observed on the surface are affected by the terrain. The amplitude and shape of the non-uniform polarized medium will change, but the variation range is small. In the copper-nickel mining area, comparing the apparent resistivity obtained by the terrain correction with the apparent polarizability in the mining area, The mining area has high gravity anomoly,high magnetic susceptibility anomoly,low apparent resistivity and high apparent polarization rate anomalies.Combined with geological data, this provides a strong surpport for position of drilling.