Aftereffects in the transient electropmagnetic method

2020 ◽  
Author(s):  
Nikolay O. Kozhevnikov ◽  
◽  
Evgeniy Yu. Antonov ◽  
Keyword(s):  
Spatial Distribution ◽  
Transient Response ◽  
Eddy Currents ◽  
Electric Polarization ◽  
Induced Polarization ◽  
Viscosity Effect ◽  
Magnetic Viscosity

We discuss the effect of induced electric polarization and magnetic viscosity on induction transient response. Since eddy currents evolution depends on induced polarization properties, one can, by measuring the induction transient response, find the distribution these properties in the ground. However, the magnetic viscosity effect is decoupled from that produced by eddy currents. Therefore, induction transient response does not contain information about the spatial distribution of magnetic viscosity.

Aftereffects in the Transient Electromagnetic Method: Inductively Induced Polarization

2021 ◽  
Vol 62 (12) ◽  
pp. 1440-1448
Author(s):  
N.O. Kozhevnikov ◽  
E.Yu. Antonov
Keyword(s):  
Transient Response ◽  
Electric Polarization ◽  
Induced Polarization ◽  
Point Of View ◽  
Electromagnetic Method ◽  
Time Range ◽  
General Point ◽  
Transient Electromagnetic Method ◽  
Transient Electromagnetic ◽  
Tem Method

Abstract —Inductively induced electric polarization (IIP) is one of the aftereffects inherent in the geologic materials and affecting results of the transient electromagnetic method. Its effect on the inductive transient response manifests itself as a nonmonotonic EMF decay, including the polarity reversal. The dependence of IIP on many conditions makes it difficult to study the basic regularities in its manifestation. One of the ways to address this problem is to present the simulation results as a normalized transient response. From the most general point of view, the intensity and time range of the IIP manifestation are controlled by the competition between induction and induced polarization phenomena. Induced polarization manifests itself differently, depending on the transmitter used for the excitation of the ground response. Therefore, when studying polarizable ground, the results of the conventional IP method and those of the TEM method do not always correlate.

On modeling a well casing for resistivity and induced polarization

Geophysics ◽  
1984 ◽  
Vol 49 (11) ◽  
pp. 2061-2063 ◽  
Author(s):  
James R. Wait
Keyword(s):  
Electrical Properties ◽  
Electric Dipole ◽  
Free Space ◽  
Eddy Currents ◽  
Interfacial Polarization ◽  
Induced Polarization ◽  
Mutual Impedance ◽  
The Earth ◽  
Horizontal Electric Dipole ◽  
Displacement Currents

In a previous communication I proposed an analytical model to simulate the electromagnetic (EM) and induced polarization (IP) response of a metal well casing (Wait, 1983). To facilitate the analysis, the earth was idealized as a homogeneous conducting half‐space of electrical properties (σ, ε, μ). The well casing was represented as a filamental vertical conductor of semiinfinite length that was characterized by a series axial impedance to account for eddy currents and interfacial polarization. A further basic simplification was to neglect displacement currents in the air; this was justified when all significant distances were small compared with the free‐space wavelength. Initially, the source was taken to be a horizontal electric dipole or current element I ds on the air‐earth interface. By integration of the results, the mutual impedance between two grounded circuits could be ascertained. In the absence of the vertical conductor (i.e., the well casing) the results reduced to those given by Sunde (1968) and Ward (1967).

A special circumstance of airborne induced‐polarization measurements

Geophysics ◽  
1996 ◽  
Vol 61 (1) ◽  
pp. 66-73 ◽  
Author(s):  
Richard S. Smith ◽  
Jan Klein
Keyword(s):  
Time Domain ◽  
Eddy Currents ◽  
High Arctic ◽  
Induced Polarization ◽  
Laboratory Measurements ◽  
Dielectric Polarization ◽  
Special Circumstance ◽  
Polarization Measurements ◽  
Airborne Electromagnetic

Airborne induced‐polarization (IP) measurements can be obtained with standard time‐domain airborne electromagnetic (EM) equipment, but only in the limited circumstances when the ground is sufficiently resistive that the normal EM response is small and when the polarizability of the ground is sufficiently large that the IP response can dominate the EM response. Further, the dispersion in conductivity must be within the bandwidth of the EM system. One example of what is hypothesized to be IP effects are the negative transients observed on a GEOTEM® survey in the high arctic of Canada. The dispersion in conductivity required to explain the data is very large, but is not inconsistent with some laboratory measurements. Whether the dispersion is caused by an electrolytic or dielectric polarization is not clear from the limited ground follow‐up, but in either case the polarization can be considered to be induced by eddy currents associated with the EM response of the ground. If IP effects are the cause of the negative transients in the GEOTEM data, then the data can be used to estimate the polarizabilities in the area.

scholarly journals Magnetic Viscosity Effect on Grounded-Wire TEM Responses and Its Physical Mechanism

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 6140-6152
Author(s):  
Linbo Zhang ◽  
Hai Li ◽  
Guoqiang Xue ◽  
Wen Chen ◽  
Yiming He
Keyword(s):  
Physical Mechanism ◽  
Viscosity Effect ◽  
Magnetic Viscosity

Transient electromagnetic response of a polarizable ground

Geophysics ◽  
1981 ◽  
Vol 46 (7) ◽  
pp. 1037-1041 ◽  
Author(s):  
T. Lee
Keyword(s):  
Time Constant ◽  
Transient Response ◽  
Induced Polarization ◽  
Electromagnetic Response ◽  
Relaxation Model ◽  
Reverse Polarity ◽  
Transient Electromagnetic ◽  
Show Evidence ◽  
Positive Time

When a uniform ground has a conductivity which may be described by a Cole‐Cole relaxation model with a positive time constant, then the transient response of such a ground will show evidence of induced polarization (IP) effects. The IP effects cause the transient initially to decay quite rapidly and to reverse polarity. After this reversal the transient decays much more slowly, the decay at this stage being about the same rate as a nonpolarizable ground.

scholarly journals Application of electric polarization to contaminant detection in soils

1989 ◽  
Vol 26 (4) ◽  
pp. 536-550 ◽  
Author(s):  
Raymond N. Yong ◽  
Edward J. Hoppe
Keyword(s):  
Contaminant Transport ◽  
Time Domain ◽  
Mineral Exploration ◽  
Electric Polarization ◽  
Induced Polarization ◽  
Time Domain Reflectometry ◽  
Dielectric Measurements ◽  
Polarization Method ◽  
Contaminant Detection ◽  
Nonpolar Liquids

Preliminary experiments indicate the feasibility of constructing for field use a contaminant-detection instrumentation based on dielectric measurements. This study applies the technique of time-domain reflectometry to assess characteristic "signatures" of some selected contaminants and soil–contaminant mixtures. The results imply that a proper differentiation between various signatures can be attained, allowing an assessment in regard to soil–contaminant status. The proposed technique is similar in principle to the induced-polarization method applied in mineral exploration. Key words: electric polarization, contaminant transport, dielectrics, induced polarization, nonpolar liquids, time-domain reflectometry, relaxation, contaminant–soil interaction.

A Diffusional Magnetic Viscosity Effect in Iron-Carbon Martensite

1968 ◽  
Vol 29 (1) ◽  
pp. K39-K41
Author(s):  
J. Kinel ◽  
J. W. Moroń ◽  
J. Przybyła
Keyword(s):  
Viscosity Effect ◽  
Magnetic Viscosity ◽  
Carbon Martensite
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