Research Of CSAMT Two Dimension Forward And Inversion

Currently, The data processing and inversion of CSAMT(Controlled Source audio frequency magnetotelluric method) is still mostly based on 1D horizontal layered model when carrying out the data processing and interpretation, while in this case, it can not reflect the lateral variation of the real underground medium. However, if take the earth model as the three-dimensional model directly, it would bring out large computer memory and decreasing the work efficiency of data processing and interpretation. Especially for some electrical structure such as plate veins, ore body and surrounding rock along the power lines unchanged basically, changes to occur only along the inclination and vertical, this can be used as a two-dimensional structure, there is no need to handle as three-dimensional model. Study on two dimensional problems of CSAMT can provide reference for solving practical problems, but also can be used as the basis of the three dimensional problems.This paper starting based on the Maxwell’s equations, firstly calculated the electromagnetic field excited horizontal electric dipole source while in homogeneous half space and layered geoelectric model, and analyzes the characteristic the horizontal electric field and magnetic field. In addition, analysis various apparent resistivity definitions through the electromagnetic field expressions in homogeneous half space, and also compared various definitions of apparent resistivity in layered model. Analyzed the mechanism of phase parameter sounding in frequency sounding, also discussed and compared the characteristics phase curve which transformed by apparent resistivity curve. Secondly in assuming that the dipole source along the formation toward the direction of the extending to infinity, build the equation which the line current source meet, through numerical simulation of two-dimensional model of two-dimensional field by using finite difference method, calculation and analysis infinite length source in two dimensional media of electromagnetic wave propagation characteristics, draw the pseudosection map of electric field, magnetic field, apparent resistivity and impedance phase while the measuring line vertical on electric dipole source. At last, take forward data as the foundation, try the 2D inversion by using the rapid relaxation inversion(RRI) method for the CSAMT 2D forward data. The inversion results of different low resistivity anomaly model (including single, multiple and fault) show that the inversion results is relativity well, which can reflect the geological structure of the underground geological bodies in whole...