Research On 3D Forward Modeling Of Complex Resistivity Method Considering Both IP And Electromagnetic Effect

The resistivity and induced polarization of geologic body generally show the characteristics of complex resistivity. Some scholars have expressed the complex resistivity by some mathematical models, for example the Cole-Cole model. It has been proved that the electrical anomaly of geologic body can be quantitative estimatedby Cole-Cole model parameters. It is important to study the methods to obtain the complex parameters of geologic body.Field observational data by the method of frequency spectrum induced polarization always includes electromagnetic coupling of varying degrees. Therefore, it is very significant to study the apparent complex resistivity method of SIP and electromagnetic couplingFirstly, the paper analyzed some complex resistivity mathematical models and equivalent circuit models , then discussed the frequency spectrum characters of Cole-Cole model .Secondly, on the basis of analysis about the complex resistivity mathematical models , the Cole-Cole model is introduced into the 3D electromagnetic modeling. The complex resistivity 3D electromagnetic forward calculation is on basis of included surface electric dipole source. In the forward modeling , the staggered-grid finite difference method is used to simulate the three dimensional electromagnetic responses, it is shown that the staggered grid finite difference method combined with the Bi-cojugate gradient iterative solver processed with divergence correction and in-complete Cholesky decomposition procedures can efficiently improve the three dimensional electromagnetic calculation with high accuracy and stability.