1. China Aero Geophysical Survey & Remote Sensing Center for Natural Resources, Beijing 100083, China; 2. School of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing 100083, China
Lots of observational data have indicated that anisotropic physical properties are common in rocks in the depth. This requires the construction of anisotropic models to obtain a true reflection of the underground medium. The basis of the present study is a review of previous research results and an investigation of the electrical properties of a layered medium representing actual geological conditions. For a symmetrical anisotropic body, an anisotropy coefficient is proposed, together with an equation for the variation of the Earth's electromagnetic field regarded as two-dimensional. Finally, a finite element simulation of a symmetrical anisotropic body is described. The finite element calculation results are compared with finite difference results to verify the accuracy of the FE program. Three sets of model conditions are considered: (1) fixed anisotropy coefficient and different dip angles, showing the effect of dip angle on an anisotropic body; (2) fixed dip angle and different anisotropy coefficients, showing the effect of the anisotropy coefficient on an anisotropic body; (3) different dip angles and different anisotropy coefficients. Forward pseudo section maps clearly demonstrate the relationship between dip angle, anisotropy coefficient and their anisotropic effect.
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