scholarly journals Meshless method simulation and experimental investigation of crack propagation of CBM hydraulic fracturing

2018 ◽  
Vol 73 ◽  
pp. 72 ◽  
Author(s):  
Guojun Wen ◽  
Haojie Liu ◽  
Hongbo Huang ◽  
Yudan Wang ◽  
Xinyu Shi
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Mathematical Models ◽  
Meshless Method ◽  
Coalbed Methane ◽  
Physical Simulation ◽  
Rock Sample ◽  
Crack Opening ◽  
Hydraulic Pressure ◽  
Coal Rock

For simulating CoalBed Methane (CBM) hydraulic fracturing using 3-D meshless method, this paper analyzed the hydraulic fracturing mechanism and cracking form for coal rock and established the geometric and mathematical models of hydraulic fracturing propagation in coal rock in terms of the Hillerborg model on crack opening displacement theory. With the theoretical basis of hydromechanics, the formulas for calculating hydraulic pressure inside the fracture by numerical simulation were deduced from the analysis on this fluid-structure interaction problem. The geometric and mathematical models established above were described by 3-D meshless Galerkin (EFG, Element-Free Galerkin) method and compiled into the numerical simulation program using VB and FORTRAN programming language to simulate the fracture propagation for an actual coal rock sample with a drilling hole as an example. Then the physical simulation experiment of hydraulic fracturing propagation of coal seam was conducted on the same coal rock sample. Through the direct observation with naked eyes and detection by advanced instruments of ESEM and Micro-CT, the shape and parameters of cracks on the surface of and inside the coal rock sample were achieved, which indicated that experimental results are reasonably consistent with numerical simulation results.

scholarly journals The Influence of the Injected Water on the Underground Coalbed Methane Extraction

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1151
Author(s):  
Yanbao Liu ◽  
Zhigang Zhang ◽  
Wei Xiong ◽  
Kai Shen ◽  
Quanbin Ba
Keyword(s):  
Hydraulic Fracturing ◽  
Coalbed Methane ◽  
Gas Flow ◽  
Critical Time ◽  
Shanxi Province ◽  
Coal Bed ◽  
Hydraulic Pressure ◽  
Intrinsic Permeability ◽  
Permeability Evolution ◽  
Two Phase

The increasing demand on coal production has led to the gradually increase of mining depth and more high methane mines, which bring difficulties in terms of coalbed methane (CBM) extraction. Hydraulic fracturing is widely applied to improve the production of CBM, control mine gas, and prevent gas outbursts. It improves coal bed permeability and accelerate desorption and migration of CBM. Even though the impacts of hydraulic fracturing treatment on the coal reservoirs are rare, negative effects could not be totally ignored. To defend this defect, the presented work aims to study the influence of water filtration on coal body deformation and permeability evolution. For this purpose, a simulation based finite element method was developed to build a solid-fluid coupled two-phase flow model using commercial software (COMSOL Multiphysics 5.4). The model was verified using production data from a long strike borehole from Wangpo coal mine in Shanxi Province, China. Several simulation scenarios were designed to investigate the adverse impacts of hydraulic fracturing on gas flow behaviors. The mechanisms of both relative and intrinsic permeability evolutions were analyzed, and simulation results were presented. Results show that the intrinsic permeability of the fracture system increases in the water injection process. The impacts of water imitation were addressed that a critical time was observed beyond which water cannot go further and also a critical pressure exists above which the hydraulic pressure would impair the gas flow. Sensitivity analysis also showed that a suitable time and pressure combination could be observed to maximize gas extraction. This work provides an efficient approach to guide the coal bed methane exploitation and other unconventional gas reservoirs.

scholarly journals Experimental and Numerical Simulation Study of Hydraulic Fracture Propagation during Coalbed Methane Development

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qingshan Ren ◽  
Yaodong Jiang ◽  
Pengpeng Wang ◽  
Guangjie Wu ◽  
Nima Noraei Danesh
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Coalbed Methane ◽  
Fracture Propagation ◽  
Fractured Reservoir ◽  
Natural Fractures ◽  
Fracture Length ◽  
Coalbed Methane Reservoir ◽  
Hydraulic Fracture Propagation

The extraction of low-permeability coalbed methane (CBM) has the dual significance of energy utilization and safe mining. Understanding hydraulic fracturing mechanism is vital to successful development of CBM. Therefore, it is important to improve the law of hydraulic fracture propagation in coal and rigorously study the influencing factors. In this paper, laboratory experiments and numerical simulation methods were used to investigate the hydraulic fracture propagation law of coal in coalbed methane reservoir with natural fractures. The results show that the maximum and minimum horizontal in situ stress and the difference in stress significantly affect the direction of crack propagation. The elastic modulus of coal, the mechanical properties of natural fractures, and the injection rate can affect the fracture length, fracture width, and the amount of fracturing fluid injected. To ensure the effectiveness of hydraulic fracturing, a reservoir environment with a certain horizontal stress difference under specific reservoir conditions can ensure the increase of fractured reservoir and the controllability of fracture expansion direction. In order to increase the volume of fractured reservoir and fracture length, the pumping speed of fracturing fluid should not be too high. The existence of stress shadow effect causes the hydraulic fracture to propagate along the main fracture track, where the branch fracture cannot extend too far. Complex fractures are the main hydraulic fracture typology in coalbed methane reservoir with natural fractures. The results can provide a benchmark for optimal design of hydraulic fracturing in coalbed methane reservoirs.

scholarly journals Numerical Simulation Research on Hydraulic Fracturing Promoting Coalbed Methane Extraction

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fan Yongpeng ◽  
Shu Longyong ◽  
Huo Zhonggang ◽  
Hao Jinwei ◽  
Yang Li
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Production Rate ◽  
Coalbed Methane ◽  
Coupled Model ◽  
Research Process ◽  
Extraction Process ◽  
Methane Pressure ◽  
Two Phase ◽  
Fracture Length

Although hydraulic fracturing technology has been comprehensively investigated, few scholars have studied the influence of hydraulic fracturing on the effect of coalbed methane (CBM) extraction, and few considered the interaction between water and CBM in the research process, which is not conducive to guiding the engineering design of hydraulic fracturing wells. In this work, a hydraulic-mechanical-thermal coupled model for CBM extraction in hydraulic fracturing well is established; it combines gas-liquid two-phase infiltration, where nonisothermal adsorption is also considered. The COMSOL Multiphysics software is used to carry out the numerical simulation study of the CBM extraction process in hydraulic fracturing well and analyze the influence of coalbed permeability, initial methane pressure, and fracture length on CBM extraction in hydraulic fracturing well, and the results show that the hydraulic-mechanical-thermal coupled model for CBM extraction can be used for CBM extraction research in hydraulic fracturing well. The initial coalbed permeability, initial gas pressure, and fracture length all affect the migration speed of CBM to surface well in different ways and have a greater impact on the CBM production rate of hydraulic fracturing well. The greater the initial coalbed permeability and methane pressure are, the longer the fracture length is and the greater the CMB production rate of hydraulic fracturing well is. The change trend of coalbed permeability during the extraction process of surface fracturing well is directly related to the state of the reservoir. The factors of stress, temperature, and CBM desorption jointly determine the increase or decrease of coal seam permeability.

The Calculation Method of Accurate Shaping Curve of Inside Right-Angle Step in Cross Wedge Rolling

2010 ◽  
Vol 37-38 ◽  
pp. 1416-1420 ◽  
Author(s):  
Ran Zhao ◽  
Kang Sheng Zhang ◽  
Zheng Huan Hu
Keyword(s):  
Numerical Simulation ◽  
Mathematical Models ◽  
Contact Zone ◽  
Calculation Method ◽  
Cross Wedge Rolling ◽  
Forming Process

Deep study on Inside Right-angle Step (IRS) forming process was conducted to improve the precision of its (IRS) forming. According to its actual forming process, the zone, or the undeformed zone, was looked as semi-spiral declined cone and excluded the contact zone. A new algorithm was developed for calculating the size of the undeformed zone. More simple mathematical models and expressions weredeveloped for solving the shaping curve. The model was verified in terms of its simplicity and correctness based on the numerical simulation.

Physical simulation of hydrodynamic conditions in high rank coalbed methane reservoir formation

2009 ◽  
Vol 19 (4) ◽  
pp. 435-440 ◽  
Author(s):  
Bo WANG ◽  
Bo JIANG ◽  
Lei LIU ◽  
Gui-qiang ZHENG ◽  
Yong QIN ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Physical Simulation ◽  
High Rank ◽  
Hydrodynamic Conditions ◽  
Coalbed Methane Reservoir
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