Research Of2D CSAMT Occam Inversion

CSAMT is widely used in engineering geology, mineral surveys, oil and otherfields, it is a frequency-domain sounding method, a method of detecting undergroundstructures by changing the transmission frequency to achieve, because of its highcollection efficiency,so it’s widely to be used.Controlled source is in the development stage, and magnetotelluric developedrapidly, and it is have a lot of mature theory has been generally uesd in thetwo-dimensional, three-dimensional inversion. Because source effect, the dataprocessing of CSAMT is very complex, only far field has features of the plane wave,so it is necessary to build a forward and inversion procedure.In this paper, it is cleverly avoid the impact of the source by use the secondaryfield. So by the method of calculation of the secondary field, the accuracy of thecalculation is improved. It is detailed derivated the formula of forward, and usedquadrilateral subdivision. it is necessary to use the compressed storage method, andfinally obtained by solving the equation for the secondary field, with the primary fieldis obtained by adding the total market, by the operator to take the results of the totalfield of the wave number domain, the inverse Fourier transform to get the results ofthe spatial domain.In the process of Jacobian, the adjont field source method that put forward byMcGillivray is used. The sensitivities of different components can be deduced fromdifferent auxiliary source,respectively. I choose two forms of auxiliary source in mypaper and deduce the sensitivities of Ex and Hy. The sensitivities of apparentresistivity and apparent phase are deduced from the sensitivity of Ex and Hyultimately., applied Occam inversion, it is have affection to inverse result in differentmesh, and Give some details of mesh to guide inversion. At last, I use the data ofapparent resistivity and apparent phase to invert different model and get good result.