Theoretical fundaments to obtain Complex permittivity and Resistivity in CR method

ALBERTO LUCUY; M.V. BONGIOVANNI; GRUNHUT DUENYAS VIVIAN; ANA OSELLA

Conference Proceedings, 25th European Meeting of Environmental and Engineering Geophysics

EAGE

Año: 2019; p. 1 - 5

The resistive capacitive contact (CR) method is a non-intrusive geophysical technique that allows to characterize the subsoil, by means of electrical images. It is based on the capacitive coupling between the sensors (dielectric plates) and the ground, and is applied in environments where galvanic contact cannot be achieved or where high contact impedances result in poor data quality (soil contamination and aquifers, mining investigations, archaeological surveys, etc.) Two of the most important properties of the terrain are the resistivity and dielectric permittivity. There are several models that interpret how the electromagnetic signal propagates in terms of the conductivity and polarization of the charges under the action of an electric field. In general, most of the works focus on the phenomenon of polarization (either electronic, ionic, dipolar or by migration of accumulated particles along a separation interface (Bourdi and Rhazi, 2008)). When a time-varying electric field is applied on a surface with a sufficiently high frequency for there to be a considerable relaxation time, not only a complex susceptibility but also a complex conductivity are generated and therefore, a complex resistivity.The purpose of this work is to analyze the behavior of the electromagnetic signal on a soil, with relatively high frequencies, and to link the complex conductivity and resistivity through the tangent of losses, as a function of a scale factor and a phase shift between the emitted and received signal. Through an adequate description of the physical principles involved, a theoretical formulation will be developed.