首页|Experimental study on permeability evolution of deep high-stressed coal under major horizontal stress unloading paths

Experimental study on permeability evolution of deep high-stressed coal under major horizontal stress unloading paths

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Both bulk stress (σⅱ) and stress path (SP) significantly affect the transportation characteristics of deep gas during reservoir pressure depletion.Therefore,the experimental study of horizontal stress unloading on seepage behavior of gas-bearing coal under constantσⅱ-constraints is performed.The results show that coal permeability is affected by horizontal stress anisotropy (σH≠σh),and the contribution of minor hor-izontal stress to permeability is related to the differential response of horizontal strain.The slippage phe-nomenon is prominent in deep high-stress regime,especially in low reservoir pressure.σⅱ and SP jointly determine the manifestation of slippage effect and the strength of stress sensitivity (γ) of permeability.Deep reservoir implies an incremental percentage of slip-based permeability,and SP weakens the slip-page effect by changing the elastic-plastic state of coal.However,γis negatively correlated with slippage effect.From the Walsh model,narrow (low aspect-ratio) fractures within the coal under unloading SP became the main channel for gas seepage,and bring the effective stress coefficient of permeability (x) less than 1 for both low-stress elastic and high-stress damaged coal.With the raise of the effective stress,the effect of pore-lined clay particles on permeability was enhanced,inducing an increase in x for high-stress elastic coal.

True triaxial stress pathConstant bulk stressHorizontal stressEffective stress coefficient of permeabilitySlippage effect

Chao Liu、Jiahao Zhang、Songwei Wu、Jinghua Qi、Beichen Yu、Liang Wang

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School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China

State Key Laboratory of Mining Disaster Prevention and Control,Ministry of Education,Shandong University of Science and Technology,Qingdao 266590,China

School of Safety Engineering,China University of Mining and Technology,Xuzhou 221116,China

State Key Laboratory of Coal Mine Disaster Prevention and Control,China University of Mining and Technology,Xuzhou 221116,China

Key Laboratory of Theory and Technology on Coal and Rock Dynamic Disaster Prevention and Control,National Mine Safety Administration,China University of Mining and Technology,Xuzhou 221116,China

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2024

矿业科学技术学报(英文版)
中国矿业大学

矿业科学技术学报(英文版)

CSTPCDEI
影响因子:1.222
ISSN:2095-2686
年,卷(期):2024.34(11)