A METHOD AND APPARATUS FOR THE DETECTION OF INDUCED POLARIZATION AND ELECTRICAL RESISTIVITY IN ROCKS AND SOILS FREE OF THE EFFECT OF THE ELECTROMAGNETIC COUPLING PHENOMENON

摘要

An improved apparatus and method for conducting Induced Polarization surveys for polarizeable material located in the subsurface. This apparatus and method provides results that are free of the influence of electromagnetic coupling. The apparatus consists of a direct current generator and electrodes that inject a steady direct current into the same volume of earth to which a standard Induced Polarization syste m is being applied. This direct current perturbs the electrochemical processes that are the cause of the Induced Polarization phenomenon and thereby causes a change of the output of the standard Induced Polarization system that can only be caused by a change in the Induced Polarization effects because a direct current can not cause any chan ge in the electromagnetic effects that are an inherent part of the data provided by an y Induced Polarization survey. In any survey which is performed with the invention the recorded dat is the change of the Induced Polarization and Resistivity readings when the biasing current is switched on. This perturbation of the Induced Polarization effect also leads to changes of the measured DC Resistivity of any survey site that contains polarizeable material. This change in the Resistivity permits the presence of polarizeabl e material to be recognized in Direct Current conditions.