Massive Hydraulic Fracturing to Control Gas Outbursts in Soft Coal Seams

2022 ◽  
Author(s):  
Shuaifeng Lyu ◽  
Shengwei Wang ◽  
Junyang Li ◽  
Xiaojun Chen ◽  
Lichao Chen ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Coal Seams ◽  
Soft Coal

scholarly journals An Elastoplastic Softening Damage Model for Hydraulic Fracturing in Soft Coal Seams

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yang Hao ◽  
Yu Wu ◽  
Xianbiao Mao ◽  
Pan Li ◽  
Liqiang Zhang ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Damage Model ◽  
Water Injection ◽  
Injection Rate ◽  
The Novel ◽  
Coal Seams ◽  
Soft Coal ◽  
Pore Compressibility ◽  
Good Consistency ◽  
Novel Model

In order to improve the permeability of soft coal seams with low intensity and permeability by hydraulic fracturing, an elastoplastic softening damage model of soft coal seams has been established, which takes into consideration the lower elastic modulus and tensile strength and higher pore compressibility and plastic deformation. The model then was implemented to FLAC3D finite difference software to be verified with the on-site results of the Number 2709 coalface in Datong coal mine, China. The modelling results of fracture-influenced radius show good consistency with on-site results. Then the parameters of water injection rate and time on fracture-influenced radius were studied. The results indicate that the fracture-influenced radius increases rapidly with an increased injection rate initially. After reaching the maximum value, fracture-influenced radius decreases slowly with further increase of the injection rate. Finally, it remains constant. The fracture-influenced radius rapidly increases initially at a certain time and then slowly increases with the injection time. The novel model and numerical method could be used to predict the radius of hydraulic fracture-influenced area and choose the suitable injection parameters to help the on-site work more efficiently.

Paсker Sealing–Wellbore Interaction in Hydraulic Fracturing in Coal Seams

2020 ◽  
Vol 56 (4) ◽  
pp. 547-556 ◽  
Author(s):  
S. V. Klishin ◽  
V. I. Klishin
Keyword(s):  
Hydraulic Fracturing ◽  
Coal Seams

scholarly journals Coupling numerical model of hydraulic fracturing seepage in soft coal based on elastoplastic damage

2020 ◽  
Vol 198 ◽  
pp. 01038
Author(s):  
LI Liangwei
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Hydraulic Fracturing ◽  
Yield Criterion ◽  
Calculation Model ◽  
Field Application ◽  
Soft Coal ◽  
Plastic Shear Strain ◽  
Strain Relationship ◽  
Relationship Equation

In order to guide the field application of hydraulic fracturing of soft coal in coal mine, based on the elastic-plastic damage theory, the coupling numerical model of soft coal hydraulic fracturing seepage was studied. The porosity strain relationship equation, permeability strain relationship equation, the relationship between permeability and volume plastic tensile strain and volume plastic shear strain of coal and rock mass are derived, and the plastic correction equation and softening parameters are defined. The stress coupling equation and yield criterion are programmed and embedded into the finite difference software FLAC3D for numerical solution. The numerical simulation shows that the numerical calculation model of soft coal hydraulic fracturing conforms to the actual law, and the field fracturing radius investigation experiment is consistent with the numerical simulation results.

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.

Sign in / Sign up

Export Citation Format

Share Document