Characterization of pore-fracture networks and their evolution at various measurement scales in coal samples using X-ray μCT and a fractal method

Zhou, Hongwei; Zhong, J.C.; Ren, W.G.; Wang, X.Y.; Yi, Hongxia

doi:10.1016/j.coal.2018.02.007

Cited by 119 publications

(53 citation statements)

References 54 publications

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“…When the rock damage is intensified, both occur simultaneously when the internal fracture occurs. Before the rock failure, some scholars have established a model of the relationship between permeability and porosity (Cai et al 2014;Palmer and Mansoori 1998;Pan and Connell 2012;Reiss 1980;Shi and Durucan 2004;Zhou et al 2018):…”

Section: The Relationship Between Compression Parameter C and Permeabmentioning

confidence: 99%

Study on the relation between damage and permeability of sandstone at depth under cyclic loading

Zhao

Zhou

Zhong

et al. 2019

Int J Coal Sci Technol

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The damage and permeability evolution of rock under stress is of great significance to engineering safety. In this paper, the evolution law of rock damage and permeability is studied by means of acoustic emission (AE) seepage experiment on deep roof sandstone with cyclic loading. Characterization of damage uses the changes in acoustic emission fractal characteristics and compression parameter which based on elastic modulus. The experimental results show that the AE events has fractal characteristic, in which the AE b-value and correlation dimension can represent the damage of rock. When the fractal characteristic value of AE increases, it indicates that the rock is in the compaction stage and the damage is not obvious. When the fractal characteristic value of AE drops, it indicates that the rock was damaged, and the permeability increase. Under the cyclic load increasing step by step, the elastic modulus first increases and then decrease. Introducing compression parameter C to characterize the state of compaction and damage, it is obtained that the rock damage state and hydrostatic permeability show a power law function relationship with porosity and have the same monotonicity. When compression parameter is less than zero, the evolution law of permeability and damage can be described by functional relationship between hydrostatic permeability K and compression parameter C.

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Section: The Relationship Between Compression Parameter C and Permeabmentioning

confidence: 99%

Study on the relation between damage and permeability of sandstone at depth under cyclic loading

Zhao

Zhou

Zhong

et al. 2019

Int J Coal Sci Technol

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“…Commonly, a smaller hysteresis loop indicates a better connectivity of the pore (Liu et al., 2010; Maex et al., 2006; Suuberg et al., 1995). If the pores of the coal have fractal features (Lee et al., 2006; Niu et al., 2017, 2019; Song et al., 2017; Yao et al., 2008; Zhao et al., 2018), then the pore fractal dimension can also be used to quantitative evaluate the heterogeneity of the pores (Wang et al., 2019), and the Frenkel–Halsey–Hill (FHH) model is frequently used (Yao et al., 2008; Zhou et al., 2018). A multi-fractal is an expansion of the fractal and can represent the pore structure more finely (Li et al., 2015; Song et al., 2018; Sun et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

Isothermal characteristics of methane adsorption and changes in the pore structure before and after methane adsorption with high-rank coal

Wang

2020

Energy Exploration & Exploitation

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The pore structure is an essential factor that influences the isothermal characteristics of methane adsorption of coal, and the pore structure is altered after methane adsorption. In this study, a high-rank coal sample was investigated via methane adsorption isothermal measurement, and changes in the pore structure were studied using low-pressure N2 adsorption and low-pressure CO2 adsorption before and after the methane adsorption. The excess adsorption capacity exhibits a rapid increase at low pressure, reaching a maximum when the test pressure is approximately 8 MPa. Following that, the excess adsorption capacity of the high-rank coal tends to decrease. After the methane adsorption, the pore volume and specific surface area of the micro-, meso-, and macropores increase as compared to those before the methane adsorption, especially for micropores with apertures greater than 0.8 nm and mesopores with apertures below 10 nm. This is mainly caused by high pressure in the methane adsorption, indicating a pressure effect on the pore structure after the methane adsorption. After the methane adsorption, the ratio of pores with various sizes in the high-rank coal is enhanced, but the connectivity for meso- and macropores presents a slight decrease.

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“…Fractures are the main channel for fluid migration and output and are the key factor for coal permeability (Yao et al 2010a;Liu et al 2016). Fractures can be divided into macroscopic fractures and microscopic fractures (Chen et al 2015;Lai et al 2017;Zhang et al 2017;Zhou et al 2018). Microscopic fractures can be further divided into endogenous fractures and exogenous fractures (Chen et al 2015;Zhang et al 2017;Zhou et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of high-rank coal structure parallel and perpendicular to the bedding plane via NMR and X-ray CT

Liu

Sang

et al. 2020

Pet. Sci.

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Pores and fractures and their connectivity play a significant role in coalbed methane production. To investigate the growth characteristics and connectivity of pores and fractures in coal parallel and perpendicular to the bedding plane, the pores and fractures of high-rank coal samples collected from the southern Qinshui Basin were measured by low-field nuclear magnetic resonance, X-ray-computed tomography and field emission scanning electron microscopy. Then, the determinants of their connectivity were further discussed. The results show that the high-rank coal samples have similar pore size distributions both parallel and perpendicular to the bedding plane. They primarily contain mesopores (2-50 nm in width), followed by macrospores (> 50 nm in width). The research indicated that the high-rank coal connectivity parallel to the bedding plane is significantly better than that perpendicular to the bedding plane. The connectivity of high-rank coal is mainly determined by throats, and the orientation of the pores and fractures. The two connectivity modes in high-rank coal are "pore connectivity," in which the throats are mainly pores with a low coordination number, and "microfissure connectivity", in which the throats are mainly microfissures with a high coordination number.

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Characterization of pore-fracture networks and their evolution at various measurement scales in coal samples using X-ray μCT and a fractal method

Cited by 119 publications

References 54 publications

Study on the relation between damage and permeability of sandstone at depth under cyclic loading

Study on the relation between damage and permeability of sandstone at depth under cyclic loading

Isothermal characteristics of methane adsorption and changes in the pore structure before and after methane adsorption with high-rank coal

Characteristics of high-rank coal structure parallel and perpendicular to the bedding plane via NMR and X-ray CT

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