Inductively Induced Polarization and Its Overall Assessment Using a Normalized Transient Response

Abstract

Abstract —The paper considers the basic regularities of inductively induced polarization (IIP) manifestation in the transient electromagnetic method. When calculating inductive transient responses of a polarizable ground, we assumed that the electrical conductivity of geologic materials is described by the Cole-Cole model. To present and analyze the results of computer-based simulation of the IIP phenomenon, we used a normalized transient response. It is defined as the ratio of the transient electromotive force (EMF) response of a polarizable ground to the EMF response of a ground that differs from the polarizable one only in that it has zero chargeability. The coordinates of the minimum of the normalized transient response are useful for an overall assessment of IIP manifestation. We show, by the example of a homogeneous polarizable half-space, how the inductive transient response is affected by the Cole-Cole model parameters and the size of transmitter and receiver loops. For a two-layer ground, IIP manifestation depends also on whether the base or upper layer is polarizable, as well as on the layer thickness. Inductively induced polarization is most pronounced when a conductive polarizable layer overlies a resistive nonpolarizable base. In this case, at a certain thickness of the layer, the IIP effect far exceeds that observed in the presence of a thick polarizable layer and even of a homogeneous polarizable half-space.