In this paper, a finite-difference based method is presented to simulate the electromagnetic field generated by arbitrarily-oriented coil antennas in three-dimensional (3-D) complex underground media. The media have multiple layers in both the vertical and horizontal direction and can be fully anisotropic. The developed finite-difference method uses a staggered grid to approximate a vector equation in terms of the scattered electric field. The resultant linear sparse matrix is solved iteratively using a generalized minimal residual (GMRES) algorithm and an incomplete LU precondition technique is applied to improve the convergence behavior of the linear equation, thus accelerate the solution. The developed algorithm is validated by numerical examples and then applied to the simulation and study of the popular triaxial induction tools in electrical well logging engineering for anisotropy detection.
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