EM COUPLING, ITS INTRINSIC VALUE, ITS REMOVAL AND THE CULTURAL COUPLING PROBLEM

Geophysics ◽  
1975 ◽  
Vol 40 (5) ◽  
pp. 831-850 ◽  
Author(s):  
Jeffrey C. Wynn ◽  
Kenneth L. Zonge
Keyword(s):  
Electromagnetic Induction ◽  
Electromagnetic Coupling ◽  
Intrinsic Value ◽  
Low Frequency ◽  
Induced Polarization ◽  
Electrode Polarization ◽  
Electrically Conductive ◽  
Coupling Problem ◽  
Complex Resistivity ◽  
Deep Sounding

The induced polarization method of geophysical prospecting has been in use for more than 25 years with varying degrees of success. Until recently, its two principle drawbacks were (1) the inability to distinguish between anomalous rock responses and, (2) inability to distinguish between these rock responses and inductive coupling. The first problem was solved by K. L. Zonge in 1972. Solutions to the coupling problem go back to 1932, and have been expanded and elaborated upon by successive authors since then. In most of these papers, electromagnetic coupling was separated into two functions, here designated as P, a purely inductive term, and Q, a grounding or purely resistive term. This paper extends this work into a study of the reflective coupling contribution and the effects of anisotropy. Two immediate results are: (a) the development of an ultra‐low‐frequency deep sounding technique for highly conductive overburden environments, and (b) a successful iterative technique for the removal of coupling from complex resistivity field data. A study was made of the effect of electrically conductive pipelines on induced polarization and complex resistivity data. It appears that the so‐called “pipeline effect” is a composite of several effects, including current focusing nonlinearities, electromagnetic induction, and complex electrode polarization. The pipeline effect is generally predictable, while the effect of a fence or an irregular conductive inhomogeneity is not as simple.

RECENT ADVANCES AND APPLICATIONS IN COMPLEX RESISTIVITY MEASUREMENTS

Geophysics ◽  
1975 ◽  
Vol 40 (5) ◽  
pp. 851-864 ◽  
Author(s):  
Kenneth L. Zonge ◽  
Jeffrey C. Wynn
Keyword(s):  
Host Rock ◽  
Electromagnetic Coupling ◽  
Field Measurements ◽  
Complete Removal ◽  
Induced Polarization ◽  
Laboratory Measurements ◽  
Spectral Measurements ◽  
Complex Resistivity ◽  
Geophysical Interpretation ◽  
Rock Alteration

Several years of accumulating complex resistivity spectral measurements have indicated that there are still many unexplored areas in induced polarization surveying that need to be investigated for a more complete understanding of the polarization process. In addition to providing mineral discrimination capabilities, complex resistivity spectra can be used to differentiate between various barren host rock responses, to facilitate the complete removal of electromagnetic coupling, and to identify pipeline, fence, and various other cultural coupling effects. Results of field measurements are presented in an effort to demonstrate the utility of and necessity for making complete spectral measurements for serious geophysical interpretation. Correlation of field measurements with laboratory measurements on core samples from the same area demonstrates that strong electromagnetic coupling can be accurately removed from complete spectra without removing the important rock response. Recent field and laboratory measurements indicate that most, if not all, induced polarization responses attributed to magnetite are not really due to this mineral but can be traced to a host rock alteration response. Also, characteristic host rock signatures for sulfide environments appear to vary according to locality and type of deposits making it impossible to provide a universal set of signatures for sulfide deposits.

scholarly journals Fracture Diagnostics Using Low Frequency Electromagnetic Induction and Electrically Conductive Proppants

2018 ◽  
Author(s):  
Mukul Sharma ◽  
Javid Shiriyev ◽  
Peng Zhang ◽  
Yaniv Brick ◽  
Dave Glowka ◽  
...  
Keyword(s):  
Electromagnetic Induction ◽  
Low Frequency ◽  
Electrically Conductive

Complex conductivity measurements and fractal nature of porosity

Geophysics ◽  
1991 ◽  
Vol 56 (6) ◽  
pp. 758-768 ◽  
Author(s):  
C. Ruffet ◽  
Y. Gueguen ◽  
M. Darot
Keyword(s):  
Fractal Dimension ◽  
Surface Area ◽  
Low Frequency ◽  
Internal Surface ◽  
Electrode Polarization ◽  
Electrical Measurements ◽  
Internal Surface Area ◽  
Complex Resistivity ◽  
Fontainebleau Sandstone ◽  
Temperature And Pressure

Complex resistivity measurements were performed on 22 saturated samples (sandstones, slate, shale, and granites) at room temperature and pressure over a frequency range from 1 Hz to 5 MHz, using a two‐terminal sample holder. Although low‐frequency measurements (from 1 Hz to 1–10 kHz) are perturbed by electrode polarization phenomena, we observed classical behavior for 20 samples, i.e., behavior that can be fitted to a Cole and Cole response function, and different behavior for the other two (two slates). These two last samples exhibit an almost constant imaginary part of the complex resistivity. Since the frequency dependence is caused by interfacial effects, it is possible to characterize the internal surface area from electrical measurements. We use models developed by Le Méhauté and Crépy (1983) and Po Zen Wong (1987) to calculate the fractal dimension d of the internal surface area from experimental data. An independent measurement confirms that the specific surface area correlates with d. The two models contradict each other, however, and we suggest that Le Méhauté and Cré py’s model is appropriate to describe the observed behavior. Fractal dimension varies between 2.02 (Fontainebleau sandstone) and 2.94 (shale).

On: “EM Coupling, Its Intrinsic Value, Its Removal, and the Cultural Coupling Problem”, by Jeffrey C. Wynn and Kenneth L. Zonge (GEOPHYSICS, October 1975, p. 831–850)

Geophysics ◽  
1976 ◽  
Vol 41 (3) ◽  
pp. 543-543 ◽  
Author(s):  
Charles M. Swift ◽  
Gerald W. Hohmann
Keyword(s):  
Intrinsic Value ◽  
Induced Polarization ◽  
Inductive Coupling ◽  
Polarization Data ◽  
Coupling Problem ◽  
Proper Interpretation

We agree with the authors that an understanding of inductive coupling is important in the proper interpretation of induced polarization data. We also agree that “the ultimate value and purpose of studying coupling is to effect its removal from induced polarization data and thereby contribute to the value and usefulness of these data.”

scholarly journals Estimation of permeability and saturation based on imaginary component of complex resistivity spectra: A laboratory study

2020 ◽  
Vol 12 (1) ◽  
pp. 299-306
Author(s):  
Jiang Jia ◽  
Shizhen Ke ◽  
Junjian Li ◽  
Zhengming Kang ◽  
Xuerui Ma ◽  
...  
Keyword(s):  
Water Saturation ◽  
Pore Space ◽  
Evaluation Model ◽  
Low Frequency ◽  
Petroleum Exploration ◽  
Western China ◽  
Imaginary Component ◽  
Estimation Model ◽  
Complex Resistivity ◽  
Linear Relationships

AbstractLow-frequency resistivity logging plays an important role in the field of petroleum exploration, but the complex resistivity spectrum of rock also contains a large amount of information about reservoir parameters. The complex resistivity spectra of 15 natural sandstone cores from western China, with different water saturations, were measured with an impedance analyzer. The pore space of each core was saturated with NaCl solution, and measurements were collected at a frequency range of 40–15 MHz. The results showed a linear relationship between the real resistivity at 1 kHz and the maximum values of imaginary resistivity for each core with different water saturations. The slopes of the linear best-fit lines had good linear relationships with the porosity and the permeability of cores. Based on this, a permeability estimation model was proposed and tested. In addition, the maxima of imaginary resistivity had power exponential relationships with the porosity and the water saturation of the cores. A saturation evaluation model based on the maxima of imaginary resistivity was established by imitating Archie’s formula. The new models were found to be feasible for determining the permeability and saturation of sandstone based on complex resistivity spectrum measurements. These models advance the application of complex resistivity spectrum in petrophysics.

Mineral interfacial processes in the method of induced polarization

Geophysics ◽  
1984 ◽  
Vol 49 (7) ◽  
pp. 1105-1114 ◽  
Author(s):  
James D. Klein ◽  
Tom Biegler ◽  
M.D. Horne
Keyword(s):  
Frequency Domain ◽  
Diffusion Layer ◽  
Electrode Potential ◽  
Rotation Speed ◽  
Low Frequency ◽  
Rotating Disk ◽  
Active Species ◽  
Hydrodynamic Theory ◽  
Electrode Polarization ◽  
Disk Electrodes

A phenomenological laboratory investigation has been conducted of the IP response of pyrite, chalcopyrite, and chalcocite. The technique that was used is standard in electrochemistry and employs rotating disk electrodes. The effect of rotation is to stir the electrolyte and thus to restrict the maximum distance available for diffusion of electroactive aqueous species. For high rotation speed and low excitation frequencies, the mean diffusion length exceeds the thickness of the diffusion layer. The net effect is to reduce the electrode impedance at low frequency. The thickness of the diffusion layer and thus the impedance at low frequency can be controlled by the rotation speed. Measurements using rotating disk electrodes have been conducted in both the time domain and the frequency domain. For both pyrite and chalcopyrite, the results were the same: no dependence on rotation was observed. For frequency domain measurements with chalcocite, a strong dependence on rotation was observed. The interpreted diffusion layer thickness was found to depend on rotation speed to the [Formula: see text] power, in agreement with results predicted by hydrodynamic theory. The results of this study imply that there are two physical processes responsible for electrode polarization in the IP method. For chalcocite and perhaps other related copper sulfide minerals, the probable mechanism is diffusion of copper ions in the groundwater. In case, the phenomenon is correctly described by the Warburg impedance. Chalcocite’s distinctive response is thought to be related to its forming a reversible oxidation‐reduction couple with cupric ions in solution. No other common sulfide mineral forms a reversible couple with its cations in solution. For the other minerals of this study, the lack of dependence on rotation implies that diffusion of active species in the electrolyte is not the controlling process. Possible alternate mechanisms include surface controlled processes such as surface diffusion or adsorption phenomena. Ancillary data obtained during this study indicate the interface impedance of chalcopyrite is proportional to the electrode potential which in turn can be controlled by rotation speed, electrolyte composition, or application of an external dc current or voltage. This implies that the surface concentration of active species is dependent on electrode potential.

Study of the significance of the ph of the substrate of the biogas installation during treating it with a low-frequency electromagnetic field

2021 ◽  
pp. 106-114
Author(s):  
M.M. Zablodsky ◽  
◽  
P.B. Klendiy ◽  
O. P. Dudar ◽  
◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Induction ◽  
Ph Value ◽  
Low Frequency ◽  
Decisive Role ◽  
Methane Fermentation ◽  
Different Types ◽  
Substrate Ph ◽  
Fermentation Substrate ◽  
Industrial Frequency

The article considers the issue of studying the value of pH, substrate in the process of methane fermentation in the mesophilic regime and the influence of the electromagnetic field of industrial frequency. The aim is to investigate the influence of electromagnetic fields on the pH value of the substrate during fermentation. Different types of microorganisms are involved in the process of methanogenesis, and the decisive role in it is played by methane-forming archaea, which are most sensitive to pH and should be in the range of 6.5 - 8. Therefore, it is necessary to check the effect of low frequency electromagnetic field on substrate pH. The study was performed for 25 days on two substrates, one of which was exposed to a low-frequency electromagnetic field with an electromagnetic induction of 3.5 mT. The research results show that the pH value of the substrate exposed to the electromagnetic field during the methane fermentation process was within acceptable limits, and the second substrate decreased, that is, it was acidified. Key words: methane fermentation, substrate, pH value, electromagnetic field

On: “Recent Advances and Applications in Complex Resistivity Measurements,” by K. L. Zonge and J. C. Wynn (GEOPHYSICS, Oct. 1975, p. 851–864)

Geophysics ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 120-121 ◽  
Author(s):  
P. H. Nelson ◽  
G. D. Van Voorhis
Keyword(s):  
Spectral Data ◽  
Induced Polarization ◽  
Complex Resistivity ◽  
Resistivity Measurements ◽  
Recent Advances ◽  
Measuring Techniques

In presenting a variety of induced polarization spectral data, Zonge and Wynn refer to a paper published earlier by us (Van Voorhis et al., 1973) which deals with the same topic. We feel Zonge and Wynn have misrepresented our measuring techniques, data, and conclusions in their references to our paper. Our principal objections center on three statements by the authors.

scholarly journals Very Low Frequency Electromagnetic Induction Surveys in Hydrogeological Investigations; Case Study from Poland

2016 ◽  
Vol 64 (6) ◽  
pp. 2322-2336 ◽  
Author(s):  
Szymon Oryński ◽  
Marta Okoń ◽  
Wojciech Klityński
Keyword(s):  
Electromagnetic Induction ◽  
Low Frequency ◽  
Very Low Frequency
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