水、ScCO2致裂煤体裂纹形态与形成机制研究#br#

doi:10.13722/j.cnki.jrme.2019.0562

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Abstract

In order to study the morphology and formation mechanism of fractures in coal induced by hydraulic fracturing under different conditions，water/ScCO2 fracturing tests were carried out on anthracite specimens under axial/confining pressures of 12/10，14/10 and 16/10 MPa，respectively. The micro-CT and three-dimensional shape scanning were used to characterize the internal fracture morphology and fracture surface roughness of fractured samples，and the fracture initiation and propagation mechanisms with different fracturing conditions were discussed. The results show that ScCO2 fracturing forms a larger number of fractures with more bifurcation，smaller opening and higher fracture tortuosity. The pore fracture rate obtained by micro-CT indicates that，compared with hydraulic fracturing，the transformation range of ScCO2 fracturing is larger and ScCO2 fracturing releases more energy，resulting in a fracture network tending to form once. Fracture initiation and propagation resulted from water/ScCO2 fracturing are affected by the geo-stress state and the bedding or weak surface. Only in the case that the vertical ground stress difference coefficient is greater than 0.6，vertical fracture can be produced，otherwise transverse fracture occurs. The maximum tensile stress theory can better predict the critical initiation pressure of longitudinal fractures，while the initiation criterion based on Mohr-Coulomb theory can better predict the critical initiation pressure of transverse fractures induced by water and ScCO2 fracturing with a relative error within 5%.

Key words： mining engineering hydraulic fracturing ScCO2 fracturing initiation pressure fracture morphology Mohr-Coulomb criterion

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	LI Chang1
	2
	LIANG Weiguo1
	2
	HOU Dongsheng1
	2
	YAO Hongbo1
	2
	SONG Xiaoxia1

Cite this article:

LI Chang1,2,LIANG Weiguo1, et al. Morphology and formation mechanism of fractures in coal using hydraulic/ScCO2 fracturing#br#[J]. , 2020, 39(4): 761-772.

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https://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2019.0562 OR https://rockmech.whrsm.ac.cn/EN/Y2020/V39/I4/761

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