A review of recent research and development of the effect of hydraulic fracturing on gas adsorption and desorption in coal seams

Lu, Weiyong; Huang, Bingxiang; Zhao, Xinglong

doi:10.1177/0263617419857400

Cited by 51 publications

(28 citation statements)

References 62 publications

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“…Since the initial fracture has appeared, a repeated fracturing model controlled by the multihole hydraulic fracturing does not need to overcome the tensile strength T of the rock between the boreholes, i.e., T = 0. By substituting T = 0 into equation (11), the secondary fracture pressure P b2 can be obtained:…”

Section: Geofluidsmentioning

confidence: 99%

“…At present, directional hydraulic fracturing technology has made a significant difference in the control of coal seam hard top roof [1][2][3][4], the weakening and falling of hard top coal [5,6], the control of rock burst [7][8][9], gob retaining roadway, and the increased permeability of methane-bearing coal seam and shale oil and gas layer [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation on the Basic Rules of Multihole Linear Codirectional Hydraulic Fracturing

Wang

Zhang

2020

Geofluids

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Directional rupture is one of the most important and common problems in rock breaking engineering. The purpose of directional rock breaking can be effectively realized by using multihole linear codirectional hydraulic fracturing. In this paper, realistic failure process analysis (RFPA) software is used to verify the experimental results of multihole linear codirectional hydraulic fracturing and investigate its basic law. The following results are demonstrated: (1) RFPA software can be very helpful to study the basic law of multihole linear codirectional hydraulic fracturing; (2) the process of multihole linear codirectional hydraulic fracturing can be divided into four stages: water injection boost, fracture initiation, stable fracture propagation, and fracture connection; and (3) multihole linear codirectional hydraulic fractures propagate along the direction of borehole distribution. Multihole codirectional hydraulic fracturing is influenced by the angle between the direction of the hole distribution and maximum principal stress, the difference of the principal stress, and the spacing of the boreholes. The smaller the angle, the difference value of the principal stress, and the hole spacing, the better the multihole codirectional hydraulic fracturing effect.

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Section: Geofluidsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation on the Basic Rules of Multihole Linear Codirectional Hydraulic Fracturing

Wang

Zhang

2020

Geofluids

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“…Previous studies have mainly focused on fracture expansion direction, formation stress, influencing factors and numerical method modeling [6]. In addition, researches were also focused on the gas flow behavior in the gas extraction process [1,[7][8][9][10], from the early single-phase gas flow model to the later two-phase water-gas flow model [11]. Furthermore, the effects of initial permeability, Young's modulus, water saturation, and other factors on the fluid flow were studied [12].…”

Section: Model Conceptmentioning

confidence: 99%

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

et al. 2020

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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.

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“…On the one hand, it can provide new ideas and technology for the exploitation of coalbed methane and the hydraulic measures used to eliminate methane outbursts. On the other hand, it can increase the methane concentration of the air flow in the roadway in addition to the methane content and methane pressure of the local region in the coal seam, which is detrimental to the prevention of coal and methane outbursts and methane explosions (Lu et al., 2019; Ma et al., 2016; Huang et al, 2018). When the water-displacing-methane (W-D-M) effect is considered, its advantages should be enhanced and its disadvantages should be avoided.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of the functional mechanism of methane displacement by water in the coal

Huang

Chen

et al. 2020

Adsorption Science & Technology

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During hydraulic fracturing in a high-methane coal seam, there is a water-displacing-methane effect. A pseudo triaxle experimental system, which is opposite to the name of true triaxial system, for the water-displacing-methane effect was created. First, cylindrical coal samples in a methane adsorption equilibrium state, spontaneously desorbed. And then water was injected into the coal samples. The following was shown: (1) The displacement methane volume gradually rises with an increase of injected water, while the displacement methane rate tends to rise at first before declining later. Simultaneously, the water-displacing-methane process is characterised by a time effect. The methane displacement lags behind water injection. (2) Competitive adsorption and displacement desorption between the water and methane will promote adsorption methane into free methane, while the pore pressure increase caused by water injection will turn free methane into adsorption methane. The net free methane of the combination action provides a methane source for the water-displacing-methane effect. (3) A pore pressure gradient, which provides a power source for the water-displacing-methane effect, is formed and reduces gradually at the front of the water seepage along the seepage direction. The increase in water pressure can rapidly improve the pore pressure gradient and boost the displacement methane volume as well as improve displacement methane efficiency. (4) A starting porosity pressure gradient and limit pore pressure exist in the process of water-displacing-methane. When the pore pressure gradient is less than the starting pore pressure gradient, there is free methane in the coal rock, but it cannot be displaced. When the pore pressure is between the starting pore pressure and the limit pore pressure, the free methane can be displaced. When the pore pressure is greater than the limit pore pressure, the methane is almost completely adsorption methane, and water cannot be used to displace the free methane.

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A review of recent research and development of the effect of hydraulic fracturing on gas adsorption and desorption in coal seams

Cited by 51 publications

References 62 publications

Numerical Simulation on the Basic Rules of Multihole Linear Codirectional Hydraulic Fracturing

Numerical Simulation on the Basic Rules of Multihole Linear Codirectional Hydraulic Fracturing

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

Experimental investigation of the functional mechanism of methane displacement by water in the coal

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