Chapter 12 - Direct Current and Induced Polarization Methods

Abstract

This Chapter examines in detail the first class of electrical geophysical methods – the DC methods. While both electromagnetic and DC methods first came into use in the early part of the 20th century, the DC methods gained early acceptance because of less demanding theoretical and instrumentation considerations. DC methods have become the most widely used geoelectric method. We discuss three important groups of DC electric techniques including those known as vertical electric sounding (VES), horizontal profiling, and the electrical mapping methods. A highly important time-varying electrical method called Induced Polarization (IP) method is presented as well. In this method, it is recognized that the current flow in the earth represents a very complex EM phenomenon characterized by charge polarization and accumulation in the rocks. Mathematically, the IP phenomena can be analyzed based on models with frequency-dependent complex conductivity distribution, e.g., a Cole-Cole model. We also consider a generalized effective-medium theory of induced polarization (GEMTIP) which was introduced recently in order to provide a link between the petrophysical properties of the rocks and their complex conductivity spectra