Modeling Broadband Electromagnetic Induction Responses of 2-D Multilayered Structures

MARTINELLI, PATRICIA; OSELLA, ANA; LASCANO, EUGENIA

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Año: 2006 vol. 44 p. 2454 - 2460

0196-2892

Dual-coil electromagnetic induction systems are generally used as detectorsof buried metallic objects, but they are also frequently used forenvironmental purposes such as detection of contaminant plumes andarchaeological prospecting. Data is analyzed directly from its In-Phase andQuadrature components, and also by applying 1D and 2D forward and inversiontechniques based on finite difference and finite element approaches. In thispaper we present an alternative 2D forward modelling technique to study theresponse of electromagnetic induction systems based on a Rayleigh-Fourierexpansion for a multilayered earth. This technique enables us to study anunderground structure consisting of layers of nearly uniform conductivityseparated by irregular boundaries. We numerically simulate the response ofvarious soil models frequently found in environmental research. Weconsidered non metallic objects both conductive and resistive respect to thehost media for different orientations of the transmitter and receiver coils.We found that a good resolution can be obtained for detecting andcharacterizing resistive objects, though their response is much lower thanthe one obtained for conductive bodies. In all the cases, the bestconfiguration was the one in which the transmitter and receiver dipoles wereparallel to the ground surface and the instrument axis parallel to theburied body´s symmetry axis. Finally, we applied this technique to interpretfield data acquired in a zone were resistive anomalies corresponding tounderground contamination were detected. We used a dipole-dipolegeoelectrical profile obtained in that zone as our starting model. A goodcorrelation between data and synthetic response was achieved, proving boththe efficiency of our numerical technique and the capability ofelectromagnetic systems to successfully detect and characterize resistivebodies.