Simulation of the desorption process of methane adsorbed in a coal rock, taking into account intermolecular sorption interactions in the system “methane-coal”

Prusova, Alla; Minieiev, Oleksandr; Ryzhova, Svitlana

doi:10.1051/e3sconf/201910900073

Cited by 3 publications

(1 citation statement)

References 8 publications

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“…The complexity of the mechanism for the occurrence of such gas-dynamic phenomena hampers the development of effective antioutburst measures. Modern numerical methods allow to solve complex systems of coupled equations that describe the physical processes occurring during the outburst of coal and gas: the deformation of the coal and rocks, filtration and desorption of gas [3]. They allow you to take into account the properties of the rocks and the geometry of the workings.…”

Section: Introductionmentioning

confidence: 99%

Outburst cavity formation in the working face driven along the outburst-prone coal seam

2020

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In Donbas coal mines, coal and gas outbursts present a major risk for the mining operation safety. Rapidly released energy can cause serious damage to the mine’s personnel and production equipment. Modern numerical methods allow modeling complex physical processes occurred during the coal and gas outbursts. The mathematical model was developed for the coupled processes of the rock massif deformation and gas filtration in the mine face near the tectonic dislocation. When solving the problem, the finite element method was used. The calculation results of the stresses, inelastic deformation zones, pressures of methane and configuration of cavity of the coal and gas outburst are represented in the paper. It is shown that an outburst cavity is formed inside the coal seam and is bounded from above and from below by the host rocks. The calculated geometry of the fracture cavity at the gas-dynamic phenomena in the mine working face coincides with actual data obtained in the mines of Donbas and, therefore, confirms the adequacy of the developed mathematical model.

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Section: Introductionmentioning

confidence: 99%

Outburst cavity formation in the working face driven along the outburst-prone coal seam

2020

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Calculation of the changing cofficient of the folmerov diffusion of methane desorped from coal in the face area of the coal layer at great depths

Minieiev¹,

Prusova²,

Yanzhula³

et al. 2021

Geoteh. meh.

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An algorithm for calculating the Volmer diffusion coefficient of methane adsorbed in coal in the bottomhole zone of the formation to the maximum reference pressure is developed with taking into account the change in the Folmer porosity and the size of the space of this zone. The algorithm is based on the using of the exponential law of compression, which describes the structural changes in the reference pressure of the coal seam. This allowed us to determine the diameter of the Folmer pores in the study area depending on its stress state. Based on these data and the calculation of the exponential nature of the change in porosity, the regularity of the Folmer diffusion in the bottomhole region at its fixed length and initial porosity of coal is established. By using a method of step-by-step approximating the solution of this problem for different parameters, the research results are generalized to the existing ranges of change in the Folmer porosity of coal and the size of the bottomhole region of reference pressure in mining conditions at great depths. The functional approximation dependence is established, which allows to perform calculations of the Volmer diffusion coefficient of methane desorbed from the coal layer, with simultaneous change of two parameters - initial porosity of coal and distance between the bottom to the maximum reference pressure zone. Calculations showed that when reference pressure approached its maximum at a distance of up to 10 m from the face the coefficient of Folmer diffusion of methane in coal decreased slightly. In this case, there is a strong dependence of the Volmer diffusion coefficient on the diameter of the Folmer pores in the virgin coal layer. For example, when this diameter increases twofold - from 8 А to 16 А at the distance of 20 m from the face to a maximum reference pressure, the coefficient of Folmer diffusion increases by 1.5 times. That is, Folmer's diffusion is the most intensive in the disturbed zones of the coal layer. This can be the area of maximum reference pressure, if there is a zone of disintegration, or in that part of the face zone, which is characterized by the developed system of fractures. Key words: adsorbed methane, coal layer, face zone, Folmer pores, Folmer diffusion coefficient.

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Regularity of change in the volmer diffusion coefficient of methane adsorbed in the microsorption structure of the elastic zone of the coal seam bearing pressure

2023

Geoteh. meh.

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The Volmer diffusion coefficient of methane adsorbed in the micropores of coal in the elastic zone of the coal seam bearing pressure, which normally is under conditions of significant compressive stress, was calculated with taking into account the energy of the methane sorption connection with coal, the energy of Volmer diffusion activation in the porous space of coal, and the stressed state of the elastic zone with its influence on the change of Volmer porosity. During the calculations, such parameters as the diameter of Volmer micropores and the length of the descending branch of the bearing pressure diagram were varied. As a result of the approximation of these calculations, both pairwise dependences of the Volmer diffusion coefficient on the listed parameters and its multifactorial relationship with them were established. Therefore, it is concluded that the process of methane diffusion in the elastic zone of bearing pressure is not blocked by the rock pressure, as previously thought, but is actively developing. The diffusion of free methane will be determined by the established regularity of changes in the Volmer diffusion coefficient in the elastic zone of the coal seam bearing pressure. The calculations show that as the distance from the maximum of the bearing pressure increases, the Volmer diffusion coefficient of methane in the coal seam increases, which is due to a decrease in the pressure of rocks in the descending branch of the bearing pressure diagram. However, this growth is not great due to the weak compressibility of pores. Therefore, for pores of the same diameter, the Volmer diffusion coefficient in the elastic zone of the coal seam bearing pressure for the given mining geological conditions can be considered a constant. For depths of, for example, 1000 m and pore diameters of 10 Å, the value of the Volmer diffusion coefficient will be approximately 3.77·10-8 m2/s. This confirms that methane gas release is caused not only by filtration of free gas, but also by Volmer diffusion of adsorbed methane. In turn, the reserves of the latter are known to be the main reserves of methane in coal. Therefore, the established regularity makes it possible to more accurately calculate the volumes of methane, which will be released from the coal massif during mining operations, in order to assess safety of conditions for coal deposits mining and to develop technologies for coal mine methane production.

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Simulation of the desorption process of methane adsorbed in a coal rock, taking into account intermolecular sorption interactions in the system “methane-coal”

Cited by 3 publications

References 8 publications

Outburst cavity formation in the working face driven along the outburst-prone coal seam

Outburst cavity formation in the working face driven along the outburst-prone coal seam

Calculation of the changing cofficient of the folmerov diffusion of methane desorped from coal in the face area of the coal layer at great depths

Regularity of change in the volmer diffusion coefficient of methane adsorbed in the microsorption structure of the elastic zone of the coal seam bearing pressure

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