F. M. Kamenetsky, G. M. Trigubovich, A. V. Chernyshev.
Three lectures on geological medium induced polarization.
Munich, Vela Verlag, 2014. - 56 p.
Nearly thirty years ago geophysicists started to consider induced polarization (IP) as an electromagnetic phenomenon, which was the reason to create a review work to generalize this experience. It has been done on the basis of general phenomenological theory of electromagnetic field in micro-heterogeneous (multi-component and/or multi-phase) geological medium.
The medium of the sort covers all the rocks including uniform ones considered on macro-level. This medium demonstrates an induced polarization, which tends to rock electric properties (conductivity and permittivity) dependence on frequency or transient time. The presence of disseminated magnetic nano-particles (of 10-50 nm in size) is the cause of magnetic polarization (magnetic viscosity or superparamagnetism - SPM), which tends to magnetic permeability dependence on frequency or transient time. The proposed theory is based on applying Maxwell’s equations to a polarizable-dispersive medium by considering them as written in their canonical form. We refer to the ability to generate an EM field by time changing of the electric and magnetic properties of the medium under investigation. In general, the equations describing material correlations must be presented in terms of convolution integrals. The authors are developing the ideas of S. M. Sheinmann and especially V. V. Kormiltsev, who was the first to introduce the polarizability into equations of electrodynamics. The further attention is paid to the additivity of induction and polarization responses at later transient stage, to the possibility of their separating and solving the inverse geophysical problem in this way.
The new opportunities for research into the IP and SPM effects provided by the separation of induction and polarization fields are confirmed by the results of the modeling and field experimental studies. The phenomenological approach is now the only one used to solve the practical problems of transient electromagnetic sounding (TEM). This is especially true regarding the development of 3D continuous TEM survey technologies and automatic data inversion.
The main objective of this publication is the urgent need to rebuild presentations of geophysicists regarding the geological medium polarization. Most of electromagnetic investigations are still based on the analysis of the so-called “pure substance” with constant properties in case of frequency or transient time change, and the IP influence is considered in rare special cases only. Development of the modern geoelectromagnetic theory shows the need to change the existing steady state over. The geological medium polarization is supposed to be a rule, and the absence of polarization is the rare exception.
Translated from Russian by N. N. Novitskaya.
Felix М. Кamenetsky 2014
Aero-geophysical Surveys Closed Corporation 2014
Vela Verlag, 2014. 56p.