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Permeability Characteristics of Coal after Supercritical

CO 2 storage in coal seams has become one effective method to reduce CO 2 emission and help exploit coalbed methane (CBM). The permeability is a key parameter for CBM extraction. In deep coal seams (>800 m), CO 2 exists in the supercritical state. In the present work, permeability tests were performed on briquettes before and after supercritical CO<sub>2</sub> (SC-CO<sub>2</sub>) adsorption at

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Study on the permeability characteristics of coal

Jul 31, 2018· Likewise, the gas permeability of natural brown coal and reconstituted coal specimens has been tested in different effective stress and coal swelling. 22 In addition, a number of permeability models have been developed for coal seams with methane gas. 23-25 Due to the reversible deformation and irreversible extension of fractures in coal

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Damage‐induced permeability model of coal and its

May 16, 2019· Coal permeability explosively increases after the peak stress, so the peak stress point can be regarded as the extreme point of permeability. The equivalent plastic strain was used to describe the damage of coal. Then, on the basis of simplified permeability evolution law, a new damage‐induced permeability model, which considers the effect of

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Improving permeability of coal seams by freeze-fracturing

Nov 01, 2020· 4.3. Coal permeability changes under freeze-fracturing. Coal permeability is an important index for evaluating gas production in coal seams since it reflects the gas flow ability, and is closely related to the distribution and connectivity of cores. Porosity and pore size distribution curve of the T 2 spectrum can be used to calculate permeability.

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Evolution of Broken Coal Permeability Under the Condition

Jun 05, 2019· The permeability of broken coal is not only mainly controlled by coal structure, but also unavoidably influenced by variations of stress, particle size, moisture content, and temperature. In this paper, a self-designed experimental device was utilized to investigate the permeability evolution of seven coal samples with different particle size ratios during the loading processes under the

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Characteristics of Bituminous Coal Permeability Response

The coal permeability is known to be influenced by the pore pressure and effective stress in coal mines. In this study, the characteristics of the bituminous coal permeability response to the pore pressure and effective shear stress in the Xutuan coal mine in Huaibei Coalfield in China were investigated under different stress conditions. For this purpose, gas seepage tests with various stress

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Mechanical response characteristics and permeability

And coal reservoir is a typical double porosity medium.3,4 and also significant for enhancing gas extraction efficiency As a basic attribute of coal, the permeability determines coal and gas production, which is also sensitive to many factors, including swelling stress and shrinkage effect, coal

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Modelling Permeability for Coal Reservoirs: A Review of

body of research on coal permeability behaviour and model development. This article presents a review of coal permeability and the approaches to modeling its behaviour. As an important part of this, the field and laboratory data used to test the models are reviewed in detail. This article also aims to identify some potential areas for future work.

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Permeability dynamic variation under the action of stress

Sep 01, 2015· Prior to the start of the permeability test with N 2, nine coal cores with the size of about 2.5 cm in diameter, 2–5 cm in length were drilled along the direction parallel to the bedding plane (face cleat).In order to discuss the effects of the pore and fracture development anisotropy on the permeability damage/loss, six extra cores (two series: three parallel to the butt cleat and three

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(PDF) Effect of Permeability and Geomechanical Properties

The impacts of stress- strain on permeability of coal matrix are also discussed. The effect on permeability of coal matrix and its shrinkage/swelling during adsorption/desorption of gases has been

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Experimental Research on Dynamic Variation of Permeability

Accordingly, to reduce the damage of coal reservoir permeability, the pressure should steadily change either in the process of fracturing or drainage. 1. INTRODUCTION Coalbed methane (CBM) has become an important clean energy resource.1 Permeability in coal is more complicated than that in conventional gas reservoirs.2 The permeability of

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Coal permeability evolution characteristics: Analysis

Coal permeability is the key factor that affects the CBM drainage efficiency. To understand the coal permeability evolution characteristics, coal specimens reconstituted by coal powder with different particle sizes were prepared and their permeability under loading conditions was investigated.

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Study on the Permeability Evolution and Its Formation

Study on permeability evolution of an aquifer coal seam in Western China is of great significance for preventing water inrush disaster and realizing water-conserving coal mining. The permeability evolution of an aquifer coal seam is related to a loading path closely under plastic flow. In this work, permeability variations of the Xiaojihan water-bearing coal seam and Longde nonwater coal seam

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Study on the Permeability Evolution and Its Formation

Research Article Study on the Permeability Evolution and Its Formation Mechanism of Xiaojihan Aquifer Coal Seam under Plastic Flow Jingna Guo ,1,2 Jiangfeng Liu ,1,2 Qiang Li,1 and Zhanqing Chen 1 1State Key Laboratory for Geomechanics and Deep Underground Engineering, And School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China

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Evolution of Broken Coal Permeability Under the Condition

The permeability of broken coal is not only mainly controlled by coal structure, but also unavoidably influenced by variations of stress, particle size, moisture content, and temperature. In this paper, a self-designed experimental device was utilized to investigate the permeability evolution of seven coal samples with different particle size ratios during the loading processes under the

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Characteristics of Bituminous Coal Permeability Response

The coal permeability is known to be influenced by the pore pressure and effective stress in coal mines. In this study, the characteristics of the bituminous coal permeability response to the pore pressure and effective shear stress in the Xutuan coal mine in Huaibei Coalfield in China were investigated under different stress conditions. For this purpose, gas seepage tests with various stress

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Permeability dynamic variation of coal under various

Although an extensive literature has emerged on the use of low-field nuclear magnetic resonance (LFNMR) relaxation spectrometry for the determination of various petrophysical properties of conventional reservoir rocks, relative few papers have reported the use of LFNMR discovering coal characterizations, especially the permeability dynamic variation.

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Modelling Permeability for Coal Reservoirs: A Review of

body of research on coal permeability behaviour and model development. This article presents a review of coal permeability and the approaches to modeling its behaviour. As an important part of this, the field and laboratory data used to test the models are reviewed in detail. This article also aims to identify some potential areas for future work.

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The effect of CO on the geomechanical and permeability

of low-rank 4-mm coal cubes to crushing under two separate conditions containing different gas envi-ronments and pressures. They used a ram-loading device and dynamometer to determine the loads at which coal specimens failed in an air atmosphere at 0.1 MPa and in a CO 2 atmosphere at 2.0 MPa. In the case of the CO 2 sorbed tests, samples were

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Mechanical response characteristics and permeability

And coal reservoir is a typical double porosity medium.3,4 and also significant for enhancing gas extraction efficiency As a basic attribute of coal, the permeability determines coal and gas production, which is also sensitive to many factors, including swelling stress and shrinkage effect, coal

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A dual-permeability model for coal under tri-axial

Oct 01, 2020· 1. Introduction. Coal is typically considered a dual-porosity medium consisting of porous matrix blocks and fractures (Chen et al., 2013; Connell, 2009; Zhang et al., 2018).The matrix system is the main reservoir for gas (~98%) with low flow capacity, while the fracture system provides an essential and effective flow path for methane but has low storage capacity (Xia et al., 2016; Yan et al

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Intermediate coal pillar instability and permeability

May 11, 2019· Protective seam mining method is an effective way to eliminate the coal and gas outburst hazard. Auger mining (AM) is adopted to protective seam thinner than 1.0 m. The key of AM is to set intermediate coal pillar (ICP) because they have two functions: on the one hand, ICPs have to support the roof temporarily to avoid coal auger crushing; on the other hand, they have to be broken

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Effects of variogram characteristics of coal permeability

Coal seams in the Qinshui Basin have relatively low permeability, ranging from 0.1-10×10-15 m2 (0.1- 10 mD; Stevens et al., 1998; Keim et al., 2011). Our experimental data show that the coal seam permeability is low as 3 ×10-17 m2 (0.03 mD) and sensitive to effective stress. The strong heterogeneous coal permeability has strong effects on

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Modified permeability modeling of coal incorporating

The variation in the cleat permeability of coalbed methane (CBM) reservoirs is attributed primarily to two cardinal processes, with opposing effects. Increase in effective stresses with reduction in pore pressure tends to decrease the cleat permeability, whereas the sorption-induced coal matrix shrinkage actuates reduction in the effective stresses which increases the reservoir permeability.

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