Numerical analysis of permeability rebound and recovery during coalbed methane extraction: Implications for CO2 injection methods

Su, Erlei; Zou, Quanle; Xu, Minghan; Sasmito, Agus P.

doi:10.1016/j.psep.2020.10.037

Cited by 29 publications

(36 citation statements)

References 55 publications

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“…en, the gas in the fissure flows to the borehole under the action of the pressure gradient, and this process conforms to Darcy's law [16]. Su et al [17] described a dual pore model that paralleled coal seam gas migration. e diffusion and seepage of gas in gas drainage are simulated, and the influence of diffusion coefficient on gas pressure evolution and permeability in fractures is analyzed.…”

Section: Introductionmentioning

confidence: 90%

“…(a) Coal seam is a homogeneous, isotropic, doubleporosity elastic medium (b) e influence of water on gas migration in coal seams is ignored (c) e coal seam is an isothermal system, and gas is an ideal gas (d) e strain of the coal skeleton is infinitesimal [14,16,17] 2.2. Effective Stress Principle.…”

Section: Model Assumptionsmentioning

confidence: 99%

“…e simulation uses the PDE module and the solid mechanics module in COMSOL to calculate the model. e parameters used in the numerical simulation are shown in Table 1 [17].…”

Section: Geometric Model and Definite Solution Conditionsmentioning

confidence: 99%

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Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas‐Bearing Coal

Feng

2021

Advances in Civil Engineering

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Gas drainage through long seam boreholes is an effective method to prevent gas disasters in coal mines. In this paper, a multifield coupling model of gas migration in gas-bearing coal was first established. Then, a quantitative characterization method of gas drainage effect was put forward. Finally, the extraction effect of long boreholes was obtained under different layouts and drilling lengths. The research results show that, under the arrangement of long boreholes along the seam, the gas pressure around the borehole decreases significantly with the extraction time. There is no extraction blank in the middle of the working face. However, it is easy to cause uneven gas drainage in the combined arrangement of the long boreholes along the seam and the penetrating boreholes. Furthermore, it is found that the drainage volume of the long boreholes along the seam is similar to that of the joint layout under the same drainage time. As the length of the borehole increases, the influencing range of gas drainage increases. When the borehole lengths are 150 m and 240 m, the drainage volumes are about 1.31 and 2.50 times that of the 90 m boreholes, respectively. The research achievements could provide a specific reference for the layout of long boreholes along the bedding and the determination of reasonable parameters for gas drainage on site.

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Section: Introductionmentioning

confidence: 90%

Section: Model Assumptionsmentioning

confidence: 99%

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Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas‐Bearing Coal

Feng

2021

Advances in Civil Engineering

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“…e specific surface area of pores in coal mass is an important parameter for describing the pore characteristics. It is an important factor influencing the adsorption and desorption properties of gas in coal mass [5,35,36]. Figure 7 shows the distribution of the specific surface area of pores with the unit diameter under different loading frequencies, that is, the change in the relationship between the distribution density function ds(d) for the specific surface area and the diameter d. e development trend of curves shown in Figure 8 illustrates that the distribution densities of the specific surface area of all samples in the test were generally increased at first.…”

Section: Specific Surface Areas Of Poresmentioning

confidence: 99%

“…Efficient extraction of coalbed methane (CBM) is important for the safe production of coal in many underground coal mines [1,2]. Additionally, the extracted CBM can be used as energy, and the combustion of CBM can be part of the environmental protection plan of coal mine enterprises, because it can avoid the release of the greenhouse gas (CH 4 ) into the atmosphere [3][4][5]. However, the permeability of coal seams in China is generally low, which is unfavorable for the production and utilization of CBM [6,7].…”

Section: Introductionmentioning

confidence: 99%

Effects of Cyclic Loading on the Pore Structure of Anthracite Coal

Wang

Cheng

2021

Advances in Civil Engineering

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In the process of improving coalbed permeability through pulse hydraulic fracturing, the cyclic loading effect influences the characteristics of micropores in coal matrix, thus affecting the process of gas migration. Therefore, it is essential to investigate the effect of cyclic loading on the pore structure of coal. Seven groups of loading tests at different frequencies and amplitudes were conducted on anthracite coal obtained from Shanxi Province, China, using a fatigue-testing machine. Subsequently, using a PoreMaster GT-60 Mercury-intrusion apparatus, the influence of the frequency and amplitude on the structural characteristics (including mercury-injection and mercury-ejection curves, pore size distribution, porosity, and specific surface area) of pores in coal samples was analyzed. Finally, the law and mechanism of action of the loading frequency and amplitude on pores in coal samples were comprehensively analyzed. The test results showed that, in the case of maintaining the sine-wave amplitude unchanged during loading while altering the loading frequency, the overall porosity and pore volume rise at different degrees. The growth of the loading frequency presents a more significant promotive effect on the initiation and development of pores and fractures. Moreover, it drives the transformation of micropores and transition pores into mesopores and macropores, thus increasing the proportion of seepage pores. Under the condition of large sine-wave amplitude during loading, macropores and mesopores are subjected to the repeated action of the external force, thereby reducing the overall porosity. In addition, the volume of the seepage pores declines, and the number of the coalesced pores decreases. Finally, in light of these results, the implications of frequency and amplitude selection in the process of pulse hydraulic fracturing are discussed. Therefore, the results of this research will provide an important theoretical basis for the field application of pulse hydraulic fracturing technology in coal mines.

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Effect of liquid CO₂ phase change on pores and fractures in coal: An experimental study

Jiang,

Gao,

Liu

et al. 2024

Energy Science & Engineering

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The evolution characteristics of pores and fractures in coal after liquid carbon dioxide (CO2) phase change are important factors that determine the permeability increase effect. Therefore, it is critical to correctly understand the influences of liquid CO2 phase change on pores and fractures in coal. The changes of adsorption and desorption isotherm, pore size, pore volume, and specific surface area of fractured coal and fractured coal were compared by low temperature liquid nitrogen adsorption experiment. In addition, a scanning electron microscope was adopted to observe fracture characteristics of fractured and unfractured coal samples and analyze changes in the connectivity and fracture development. Experimental results show that the fractured coal samples exhibit better hysteresis loops and a larger proportion of gas desorption than the unfractured ones. Fractured coal samples contain more developed pores and fractures compared with unfractured ones, and their fragmentation degree, pore diameter, fracture width, and connectivity of pores and fractures are also better. Besides, the closer the samples from the fracturing boreholes are, the better the fracturing effect. This indicates that liquid CO2 phase change can effectively enhance the gas transport capacity in pores and fractures in coal. The research results provide a solid basis for the better application of liquid CO2 phase‐change fracturing to the prevention of coal and gas outburst disasters and the realization of efficient gas extraction in deep coal seams.

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Numerical analysis of permeability rebound and recovery during coalbed methane extraction: Implications for CO2 injection methods

Cited by 29 publications

References 55 publications

Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas‐Bearing Coal

Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas‐Bearing Coal

Effects of Cyclic Loading on the Pore Structure of Anthracite Coal

Effect of liquid CO₂ phase change on pores and fractures in coal: An experimental study

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Numerical analysis of permeability rebound and recovery during coalbed methane extraction: Implications for CO2 injection methods

Cited by 29 publications

References 55 publications

Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas‐Bearing Coal

Influence of Long Boreholes Layout and Drilling Length on Gas Drainage Based on Multifield Coupling Model of Gas‐Bearing Coal

Effects of Cyclic Loading on the Pore Structure of Anthracite Coal

Effect of liquid CO2 phase change on pores and fractures in coal: An experimental study

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Product

Resources

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Effect of liquid CO₂ phase change on pores and fractures in coal: An experimental study