Research on the construction and verification of evaluation model for borehole collapse in gas extraction

Xiao, Peng; Huang, Xiaosheng; Zhang, Chao; Liu, Xiaoxiao; Li, Bingkun; Chen, Liping; Chen, Zixi; Cheng, Renhui; Zhao, Yajie

doi:10.1016/j.fuel.2023.130800

Cited by 3 publications

References 21 publications

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Characteristics of the gas diffusion in water-bearing coal with different damage degree and its influence mechanism

Han,

Shi,

Yue

et al. 2024

Physics of Fluids

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The moisture content and degree of damage in water-bearing coal affect the gas diffusion characteristics in coal, which limits the effect of gas extraction. The experiments were carried out on water-bearing coal with different damage degrees using a self-built coal and gas adsorption–desorption system to study the gas diffusion characteristics of water-bearing coal with varying degrees of damage. The results show that the pore volume of tectonic coal is positively correlated with the degree of damage. The increased moisture content in coal decreases gas desorption performance, embodied in the simultaneous reduction of desorption amount, desorption speed, and diffusion coefficient. Under the same water content condition, the gas desorption amount, gas desorption rate, and gas diffusion coefficient of coal with different damage degrees all show a downward trend, and the decline range is positively correlated with the water content. The relation between the amount of gas desorption, the time, and the moisture content of the water-bearing coal with different damage degrees has been set up. The study results provide a solid theoretical foundation for evaluating and predicting the gas extraction characteristics of coal seams with varying degrees of damage.

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Characteristics of the gas diffusion in water-bearing coal with different damage degree and its influence mechanism

Han,

Shi,

Yue

et al. 2024

Physics of Fluids

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Impact of closed pores on gas transport and its implication for optimizing drainage borehole design

Xu,

Liu,

Zhai

et al. 2024

Physics of Fluids

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Mining disturbances can rupture the closed pores, releasing the gas and potentially triggering gas accidents. The pre-drainage of gas via boreholes is the primary measure for preventing coal and gas outbursts. Nevertheless, the influence of closed pores on gas migration remains unclear, leading to suboptimal borehole spacing and radius. Therefore, a gas–solid coupled model incorporating closed pores was developed to investigate the influence of closed pores on gas migration during gas drainage (GD). Subsequently, response surface methodology was employed to investigate the input parameters and their interactions on residual gas content (RGC) and pre-drainage time (PDT). Finally, an optimization methodology for borehole spacing/radius was presented. The results show that both RGC and PDT exhibit a positive correlation with the ratio of closed porosity to total porosity (λ) and the ratio of closed pore diffusion coefficient to that of the open pore (Do/Dc). Initially, the total gas production is primarily extracted from fractures and open pores, followed by closed pores in the later stages. Single-factor analysis demonstrates that λ, permeability, and Do/Dc have a more significant impact on RGC and PDT compared to borehole spacing and borehole radius. Borehole spacing interacts more strongly with λ, permeability and Do/Dc than borehole radius. An optimization method for borehole spacing and borehole radius, constrained by PDT, RGC, and the number of boreholes, is proposed using response surface optimization maps. This method provides guidance for borehole construction to optimize GD efficiency and minimize RGC.

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Experiment-Based Development of Microfoam Drilling Fluid: Ratio Concentration Range and Coal Carrying Performance Numerical Simulation

Cheng,

Hou,

et al. 2024

Preprint

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Research on the construction and verification of evaluation model for borehole collapse in gas extraction

Cited by 3 publications

References 21 publications

Characteristics of the gas diffusion in water-bearing coal with different damage degree and its influence mechanism

Characteristics of the gas diffusion in water-bearing coal with different damage degree and its influence mechanism

Impact of closed pores on gas transport and its implication for optimizing drainage borehole design

Experiment-Based Development of Microfoam Drilling Fluid: Ratio Concentration Range and Coal Carrying Performance Numerical Simulation

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