The depth location by induced polarization of a target equivalent to a simple induced dipole in a semi-infinite homogeneous medium

Abstract

An electric field set up in the earth by a dipole transmitter causes an isolated metallic body to exhibit induced polarization effects (the induced electric field). Assuming that the induced electric field is proportional to the applied field at any point, it is shown that in the simple case of a small spheroidal body in a uniform half-space, the position of a target body, for maximum response to be registered at the receiver, is at the intersection of two lines drawn at an angle of 59° 26′ of depression from the transmitter and the receiver. This angle is different from the 45° currently used, but agrees with the results of field experience, which shows that on drilling to small targets in uniform ground, the depths are greater than indicated by the induced polarization method.