scholarly journals Modeling Peculiarities of Reinforced Crack of Hydraulic Fracture of Coal Seams for Estimation of Their Permeability

2014 ◽  
Author(s):  
Mihail Alekseevich Baev
Keyword(s):  
Hydraulic Fracture ◽  
Coal Seams

scholarly journals Fully Coupled Multi-Scale Model for Gas Extraction from Coal Seam Stimulated by Directional Hydraulic Fracturing

2019 ◽  
Vol 9 (21) ◽  
pp. 4720 ◽  
Author(s):  
Ge ◽  
Zhang ◽  
Sun ◽  
Hu
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Scale Model ◽  
Gas Extraction ◽  
Coal Seams ◽  
Directional Hydraulic Fracturing ◽  
Coal Mine Methane ◽  
Multi Scale ◽  
Fully Coupled

Although numerous studies have tried to explain the mechanism of directional hydraulic fracturing in a coal seam, few of them have been conducted on gas migration stimulated by directional hydraulic fracturing during coal mine methane extraction. In this study, a fully coupled multi-scale model to stimulate gas extraction from a coal seam stimulated by directional hydraulic fracturing was developed and calculated by a finite element approach. The model considers gas flow and heat transfer within the hydraulic fractures, the coal matrix, and cleat system, and it accounts for coal deformation. The model was verified using gas amount data from the NO.8 coal seam at Fengchun mine, Chongqing, Southwest China. Model simulation results show that slots and hydraulic fracture can expand the area of gas pressure drop and decrease the time needed to complete the extraction. The evolution of hydraulic fracture apertures and permeability in coal seams is greatly influenced by the effective stress and coal matrix deformation. A series of sensitivity analyses were performed to investigate the impacts of key factors on gas extraction time of completion. The study shows that hydraulic fracture aperture and the cleat permeability of coal seams play crucial roles in gas extraction from a coal seam stimulated by directional hydraulic fracturing. In addition, the reasonable arrangement of directional boreholes could improve the gas extraction efficiency. A large coal seam dip angle and high temperature help to enhance coal mine methane extraction from the coal seam.

scholarly journals The impact of cleats on hydraulic fracture initiation and propagation in coal seams

2014 ◽  
Vol 11 (4) ◽  
pp. 532-539 ◽  
Author(s):  
Tiegang Fan ◽  
Guangqing Zhang ◽  
Jinbang Cui
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Initiation ◽  
Coal Seams ◽  
Initiation And Propagation ◽  
The Impact

scholarly journals Numerical Simulation of Hydraulic Fracture Propagation in Coal Seams with Discontinuous Natural Fracture Networks

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 113 ◽  
Author(s):  
Shen Wang ◽  
Huamin Li ◽  
Dongyin Li
Keyword(s):  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Fracture Network ◽  
Natural Fracture ◽  
Cohesive Element ◽  
Natural Fractures ◽  
Fracture Networks ◽  
Coal Seams ◽  
Hydraulic Fracture Network ◽  
Hydraulic Fracture Propagation

To investigate the mechanism of hydraulic fracture propagation in coal seams with discontinuous natural fractures, an innovative finite element meshing scheme for modeling hydraulic fracturing was proposed. Hydraulic fracture propagation and interaction with discontinuous natural fracture networks in coal seams were modeled based on the cohesive element method. The hydraulic fracture network characteristics, the growth process of the secondary hydraulic fractures, the pore pressure distribution and the variation of bottomhole pressure were analyzed. The improved cohesive element method, which considers the leak-off and seepage behaviors of fracturing liquid, is capable of modeling hydraulic fracturing in naturally fractured formations. The results indicate that under high stress difference conditions, the hydraulic fracture network is spindle-shaped, and shows a multi-level branch structure. The ratio of secondary fracture total length to main fracture total length was 2.11~3.62, suggesting that the secondary fractures are an important part of the hydraulic fracture network in coal seams. In deep coal seams, the break pressure of discontinuous natural fractures mainly depends on the in-situ stress field and the direction of natural fractures. The mechanism of hydraulic fracture propagation in deep coal seams is significantly different from that in hard and tight rock layers.

Natural fractures in soft coal seams and their effect on hydraulic fracture propagation: A field study

2020 ◽  
Vol 192 ◽  
pp. 107255 ◽  
Author(s):  
Shuaifeng Lyu ◽  
Shengwei Wang ◽  
Xiaojun Chen ◽  
Suifeng Wang ◽  
Tao Wang ◽  
...  
Keyword(s):  
Field Study ◽  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Natural Fractures ◽  
Coal Seams ◽  
Soft Coal ◽  
Hydraulic Fracture Propagation

Resource-saving technologies during mining of thin and very thin coal seams

2014 ◽  
Vol 8 (1) ◽  
pp. 55-60
Author(s):  
V Buzylo ◽  
◽  
O Koshka ◽  
S Poimanov ◽  
D Malashkevych ◽  
...  
Keyword(s):  
Coal Seams ◽  
Resource Saving
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