1D EM responses of borehole-surface method in frequency-domain

摘要

Borehole-surface electromagnetic (BSEM) method is an earth exploration method by means of measuring the EM response on the earth surface excited by a Vertical Linear Current Source with Finite Length (VLCSFL) in borehole to inferring the construction in subsurface. In this paper, the forward formula of BSEM in frequency-domain in a stratified medium of n, homogenous conducting layers is derived, and the electromagnetic fields are obtained by integrating the time-harmonic response of the vertical electric dipole (VED) whose analysis formula is derived using Hankel transformation and the coefficient recursion relations solved from a linear equations obtained from the tangential component continuity. Finally, the BSEM responses of a stratified medium for different frequency, different length and different buried depth of VLCSFL respectively, and the variation characters of the response curves are analyzed.