THEORETICAL INVESTIGATION OF THE ELECTROMAGNETIC WAVE PROPAGATION TOOL.

Abstract

A theoretical investigation of the electromagnetic wave propagation (EPT) is presented. An asymptotic analysis, using contour integration, was utilized to derive approximations for the waves at the receivers of the EPT tool. The waves at the receivers are decomposed into a guided and a lateral wave. When the mudcake layer is thin, the lateral wave nearly satisfies the guidance condition of the mudcake layer, and its algebraic decay is diminished from the negative one-half power with distance. In this case, the guided and lateral waves propagate with a wave number close to the wave number of the invaded zone. Plots of the directional dependence of the transmitted wave n the invaded zone demonstrate that more power is directd along the planar boundary in the invaded zone when the mudcake layer is thin. Plots of the total magnetic field and the magnetic field from the guided wave at the receiver locations are presented as a function of mudcake thickness. Travel times are computed, using asymptotic approximations and a plane-wave assumption. These results are compared with the results of R. Freedman and J. P. Vogiatzis.