Stefanovych L.I., Feldman E.P., Mazur O.Yu. Influence of gas-filled fracturеs on the electrical conductivity of coal at direct current

Details

Parent Category: Geo-Technical Mechanics, 2022

Category: Geo-Technical Mechanics, 2022, Issue 162

Geoteh. meh. 2022, 162, 126-134

https://doi.org/10.15407/geotm2022.162.126

 

INFLUENCE OF GAS-FILLED FRACTURЕS ON THE ELECTRICAL CONDUCTIVITY OF COAL AT DIRECT CURRENT

Stefanovych L.I., Feldman E.P., Mazur O.Yu.

Branch for Physics of Mining Processes of the Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine

UDC 622.831: 622.537.87

Language: English

Abstract. The article is devoted to the theoretical study of the influence of fractures on the static electrical conductivity of coal in order to develop and justify the non-destructive method for determining the fracturing of coal and other rocks that conduct electric current. The inability of the effective medium model to describe the behavior of fractures in rocks on a macroscopic scale and the complexity of experimental observations due to the low electrical conductivity of coal necessitates an additional theoretical study.
In this paper, an approach is proposed that uses a hydrodynamic analogy between an electric current flowing around fractures and the motion of an ideal incompressible fluid in a potential flow around solids proposed earlier in our previous studies. The problem is reduced to solving a boundary value problem by the Cauchy-type integral method using the Sokhotsky-Plemel formulas. Integral dependences of the relative additional electrical resistance on the fracturing coefficient of the coal sample for an arbitrary ratio between the dimensions of coal sample and dimensions of fractures are found. The dependences of the additional electrical resistance on the fracturing coefficient of the coal sample were numerical calculated. Based on these calculations, the influence of the shape of cracks and the dimensions of a coal sample on the additional electrical resistance caused by fractures was analyzed. The nonlinear behavior of the dependence of the relative change in the additional electrical resistance of coal on the coefficient of fracturing and the thickness of the sample was established. It is shown that with an increase in the fracture coefficient, the growth of the electrical resistance of the sample occurs according to the root law, and further - according to the power law. An inverse relationship was established between the gaping of fractures and the electrical resistance of a coal sample.
The results obtained can be used as a noninvasive method for determining the fracturing coefficient not only for coal, but also for other rocks that conduct electric current.
Keywords: electrical resistance, coal sample, gas-filled cracks, hydrodynamic analogy, fracturing coefficient.

REFERENCES

1. Shvidler, M.I. (1985), Statistical Hydrodynamics of Porous Media [in Russian], Nedra, Moscow, Russia.

2. Sizin, P.E. and Shkuratnik, V.L. (2015), “Theoretical assessment of the influence of microfracturing of rocks on their conductivity in the Maxwell approximation”, Mining Information and Analytical Bulletin, no. 3, pp. 212–218. (in Russian).

3. Feldman, E.P., Granovsky, Ya.I., Kalugina, N.A. and Vinnik, E.A. (2010), “Influence of porosity and pore size on the electrical resistance of coal”, Physical and technical problems of mining, no. 13, pp. 39–41.

4. Salganik, R.L. (1974), “Transfer processes in bodies with a large number of cracks Conductivity of a body with a large number of cracks”, Engineering Physics Journal, no. 27, pp. 1069–1075. https://doi.org/10.1007/BF00863006

5. Salganik, R.L. (1980), “On the effective characteristics of a material with a large number of cracks. Possibility of geophysical determination of reservoir fracture parameters in connection with the task of ensuring outburst safety”, Preprint, Moscow Institute Problems of Mechanics AN USSR, no. 154, 25 p. (in Russian).

6. Feldman, E.P., Vinnik, E.A., Granovsky, Ya.I. and Kalugina, N.A. (2011), “Electrical resistance of a conductive material containing cracks”, Physical and technical problems of mining, no. 14, pp. 54–58.

7. Stefanovich, L.I., Feldman, E.P. and Chesnokova, O.V. (2019), “Influence of fracturing on the static conductivity of coals”, Physical and technical problems of mining, no. 21, pp. 43–53.

8. Landau, l.D. and Lifshitz, E.M. (1987), Fluid Mechanics. Theoretical Physics, Pergamon Press, Oxford, UK.

9. Gakhov, F.D. (1958), Boundary tasks, State publishing house of physical and mathematical literature, Moscow, Russia.

About authors:

Stefanovych Leonid Illich, Doctor of Physical and Mathematical Sciences (D.Sc.), Senior Researcher in Department of Physics of Coal and Rocks, Deputy Director of the Research Department, Branch for Physics of Mining Processes of the Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Feldman Eduard Petrovych, Doctor of Physical and Mathematical Sciences (D.Sc.), Chief Researcher, Department of Physics of Coal and Rocks, Branch for Physics of Mining Processes of the Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Mazur Olha Yuriivna, Candidate of Physical and Mathematical Sciences (Ph.D.), Researcher, Department of Physics of Coal and Rocks, Branch for Physics of Mining Processes of the Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

• < Prev
• Next >