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Effects of Bedding on Hydraulic Fracturing in Coalbed Methane Reservoirs


Affiliations
1 Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
 

Bedding is a special structure of coal, which has notable effects on the mechanical parameters of coal and on the hydraulic fracture propagating in coal bed methane reservoirs. To study the effects of bedding onanisotropic characteristics of coal fracture toughness,three-point bending tests have been carried out on raw coal specimens. The results indicate that fracture toughness and failure modes of the specimens both have strong anisotropy due to bedding. A geological geomechanical model of a coal bed methane (CBM)reservoir is built taking into account the effect of bedding to study the hydraulic fracture propagation and the influence of bedding on the fracture network. The hydraulic fracture initiates at the end of the perforation and tends to bifurcate and swerve at the bedding to produce induced fractures. Ultimately, these fractures form a complicated fracture network. The fracture toughness of bedding has great influence on hydraulic fracture geometry. The fracture is likely to bifurcate and swerve at the bedding to form multiple secondary fractures with larger bedding fracture toughness.

Keywords

Coalbed Methane, Coal Seam, Fracture Toughness, Hydraulic Fracturing, Numerical Simulation, Three Point Bending Test.
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  • Effects of Bedding on Hydraulic Fracturing in Coalbed Methane Reservoirs

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Authors

Tingting Jiang
Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
Jianhua Zhang
Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
Gang Huang
Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
Shaoxian Song
Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China
Hao Wu
Hubei Province Key Laboratory of Processing of Mineral Resources and Environment, School of Resource and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China

Abstract


Bedding is a special structure of coal, which has notable effects on the mechanical parameters of coal and on the hydraulic fracture propagating in coal bed methane reservoirs. To study the effects of bedding onanisotropic characteristics of coal fracture toughness,three-point bending tests have been carried out on raw coal specimens. The results indicate that fracture toughness and failure modes of the specimens both have strong anisotropy due to bedding. A geological geomechanical model of a coal bed methane (CBM)reservoir is built taking into account the effect of bedding to study the hydraulic fracture propagation and the influence of bedding on the fracture network. The hydraulic fracture initiates at the end of the perforation and tends to bifurcate and swerve at the bedding to produce induced fractures. Ultimately, these fractures form a complicated fracture network. The fracture toughness of bedding has great influence on hydraulic fracture geometry. The fracture is likely to bifurcate and swerve at the bedding to form multiple secondary fractures with larger bedding fracture toughness.

Keywords


Coalbed Methane, Coal Seam, Fracture Toughness, Hydraulic Fracturing, Numerical Simulation, Three Point Bending Test.

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DOI: https://doi.org/10.18520/cs%2Fv113%2Fi06%2F1153-1159