Common Misconceptions About Capacitively-Coupled Resistivity (CCR) What It Is And How It Works

Capacitively-coupled resistivity imaging systems have been available as commercial geophysical instruments for over eight years and have seen increased acceptance in near-surface engineering applications (Ball 2006), (Garman et. al. 2004). In order for a geophysicist to determine whether a capacitively-coupled resistivity meter would be appropriate for a particular application requires a fundamental understanding of the technique and its relative capabilities and limitations in relation to other near-surface imaging tools. The underlying principles of the technique are outlined in the existing literature (Kuras et. al. 2006), (Timofeev et. al. 1994). This paper is intended to point out and discuss some of the most common misconceptions about capacitively-coupled resistivity (CCR) and to review practical considerations in basic survey fundaments compared to other resistivity measuring techniques. The Geometrics OhmMapper TRN is a commonly used CCR instrument, using a dipole-dipole configuration, and will be the base of reference for this paper (Figure 1).