Experimental study of gas pressure and effective stress influencing on gas seepage characteristics of bituminous coal in both axial and radial directions

Deep coalbed methane (CBM) is widely distributed in China and is mainly commercially exploited in the Qinshui basin. The in situ stress and moisture content are key factors affecting the permeability of CH4-containing coal samples. Therefore, considering the coupled effects of compressing and infiltrating on the gas permeability of coal could be more accurate to reveal the CH4 gas seepage characteristics in CBM reservoirs. In this study, coal samples sourced from Tunlan coalmine were employed to conduct the triaxial loading and gas seepage tests. Several findings were concluded: (1) In this triaxial test, the effect of confining stress on the permeability of gas-containing coal samples is greater than that of axial stress. (2) The permeability versus gas pressure curve of coal presents a ‘V’ shape evolution trend, in which the minimum gas permeability was obtained at a gas pressure of 1.1MPa. (3) The gas permeability of coal samples decreased exponentially with increasing moisture content. Specifically, as the moisture content increasing from 0.18% to 3.15%, the gas permeability decreased by about 70%. These results are expected to provide a foundation for the efficient exploitation of CBM in Qinshui basin.

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Effects of acid-based fracturing fluids with variable hydrochloric acid contents on the microstructure of bituminous coal: An experimental study

Energy ◽

10.1016/j.energy.2021.122621 ◽

2021 ◽

pp. 122621

Author(s):

Wang Zepeng ◽

Ge Zhaolong ◽

Li Ruihui ◽

Liu Xianfeng ◽

Wang Haoming ◽

...

Keyword(s):

Experimental Study ◽

Hydrochloric Acid ◽

Bituminous Coal ◽

Fracturing Fluids

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Experimental study of the thermochemical treatment of the low-grade coal prior to boiler combustion at coal-fired power station

E3S Web of Conferences ◽

10.1051/e3sconf/201910900119 ◽

2019 ◽

Vol 109 ◽

pp. 00119

Author(s):

Volodymyr Yemelianenko ◽

Vitalii Pertsevyi ◽

Oleksandr Zhevzhyk ◽

Iryna Potapchuk ◽

Oleksandr Lutai

Keyword(s):

Experimental Study ◽

Power Plants ◽

Thermal Power ◽

Thermochemical Treatment ◽

Gas Pressure ◽

Pulverized Coal ◽

Time Range ◽

Low Grade ◽

Boiler Furnace ◽

Coal Fuel

Analysis of the perspectives of the coal fuel for thermal power plants is carried out. The necessity of the experimental study for temperature measurement in the boiler furnace. The results of the experimental study are presented: temperature change over time at the burner outlet for different constant pressure value of the backlighting gas, dependence of the temperature at the burner outlet from the backlighting gas pressure for constant concentration value of pulverized coal in coal-air mixture, dependence of the temperature at the burner outlet from the concentration of pulverized coal in coal-air mixture for constant value of the backlighting gas pressure, temperature measurements for constant backlighting gas pressure value, constant value of the concentration of pulverized coal in coal-air mixture when plasmatron is switched and operates for some time range. The results of the study could be applied to the solid fuel treatment for different thermal units.

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Collisional Relaxation of Fast Electrons Energy in Gas

EPJ Web of Conferences ◽

10.1051/epjconf/202124804002 ◽

2021 ◽

Vol 248 ◽

pp. 04002

Author(s):

Alexander Metel ◽

Enver Mustafaev ◽

Yury Melnik ◽

Khaled Hamdy

Keyword(s):

Experimental Study ◽

Glow Discharge ◽

Electron Energy ◽

Initial Energy ◽

Gas Pressure ◽

Collisional Relaxation ◽

Fast Electrons ◽

Electrostatic Confinement ◽

The Mean

We present results of theoretical and experimental study of collisional relaxation of fast electrons energy in gas. The dependence on the gas pressure p and electron energy ε of the mean pass Λ of fast electrons injected into a gas being sufficient to spend on ionization all their initial energy ε has been calculated. It was found that Λ is directly proportional to ε2 and inversely proportional to the gas pressure. To sustain glow discharge with electrostatic confinement of fast electrons, Λ should be less than the mean way to the anode of emitted by the cathode electrons.

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Thermos-Solid-Gas Coupling Dynamic Model and Numerical Simulation of Coal Containing Gas

Geofluids ◽

10.1155/2020/8837425 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9

Author(s):

Xiao Fukun ◽

Meng Xin ◽

Li Lianchong ◽

Liu Jianfeng ◽

Liu Gang ◽

...

Keyword(s):

Principal Stress ◽

Dynamic Model ◽

Gas Flow ◽

Flow Behavior ◽

Coupling Model ◽

Gas Pressure ◽

Permeability Model ◽

Gas Seepage ◽

Coupling Dynamic ◽

Coupling Dynamic Model

Based on gas seepage characteristics and the basic thermo-solid-gas coupling theory, the porosity model and the dynamic permeability model of coal body containing gas were derived. Based on the relationship between gas pressure, principal stress and temperature, and gas seepage, the thermo-solid-gas coupling dynamic model was established. Initial values and boundary conditions for the model were determined. Numerical simulations using this model were done to predict the gas flow behavior of a gassy coal sample. By using the thermo-solid-gas coupling model, the gas pressure, temperature, and principal stress influence, the change law of the pressure field, displacement field, stress field, temperature field, and permeability were numerically simulated. Research results show the following: (1) Gas pressure and displacement from the top to the end of the model gradually reduce, and stress from the top to the end gradually increases. The average permeability of the Y Z section of the model tends to decrease with the rise of the gas pressure, and the decrease amplitude slows down from the top of the model to the bottom. (2) When the principal stress and temperature are constant, the permeability decreases first and then flattens with the gas pressure. The permeability increases with the decrease of temperature while the gas pressure and principal stress remain unchanged.

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