An adsorption model for cylindrical pore and its method to calculate pore size distribution of coal by combining NMR

Wang, Chaolin; Zhang, Xiaoying; Zhao, Yu; Bi, Jing; Ning, Lin; Zhang, Kun

doi:10.1016/j.cej.2022.138415

Cited by 23 publications

(7 citation statements)

References 52 publications

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“…Considering that the methane adsorption amount measured by nuclear magnetic resonance (NMR) represents the true methane adsorption of coal without the need to convert excess adsorption to absolute values, ,,,, methane adsorption amount measured by the NMR method can be used to verify the M–F-F model. Liu et al conducted methane isothermal adsorption experiments on a low-rank coal sample in southern Junggar Basin, China, by the volume method and NMR method, respectively .…”

Section: Discussionmentioning

confidence: 99%

“…Methane, as the primary component of CBM, primarily adsorbs on the surfaces of pores and fissures within coal. − The adsorption behavior of methane in coal can be well described by an adsorption isotherm. The commonly used adsorption isotherm testing methods are the volume method and weight method. − Due to the significantly higher temperature and pressure in deep reservoirs compared to the critical temperature (190.56 K) and critical pressure (4.64 MPa) of methane, methane typically exists in a supercritical state .…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Adsorption Isotherm for Deep Coalbed Methane: A Monolayer-Filling Model Based on Pore Fractal Dimension

Feng,

Li,

Tang

et al. 2024

Energy Fuels

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Understanding the state of adsorbed methane in coal under high temperatures and pressures is crucial for the exploration and production of deep coalbed methane (CBM). However, the commonly used isothermal adsorption models are inadequate in describing the complex adsorption behavior of methane with multiple occurrence states. Moreover, these models have limited applicability under high-temperature and highpressure conditions, restricting our understanding of the absorptivity and occurrence mechanism of deep CBM. To address this gap, low-temperature nitrogen adsorption and methane isothermal adsorption experiments under high-temperature and high-pressure conditions were carried out on four high-rank coal samples from the deep CBM block of Daning-Jixian in China's Ordos Basin. Based on the experimental results, a novel methane isothermal adsorption model combining the pore fractal dimension of coal was constructed, and the model exhibits good applicability in studying the adsorption behavior of methane in high-rank coal samples from a deep CBM reservoir. As the pressure increases, the monolayer adsorption amount of methane continues to rise slowly after reaching a certain value, while the adsorption amount in micropores decreases gradually after the pressure exceeds about 12 MPa. This phenomenon can be attributed to the transfer of methane molecules from the micropore filling area to the monolayer adsorption area at high pressures. Furthermore, it is found that the coal in the study area exhibits significant adsorption heterogeneity, with variations in adsorption capacity due to differences in coal composition and pore structure as well as varying degrees of coalification. The adsorption process of methane during the pressure rise can be categorized into three stages: a rapid increase in adsorption amount, conversion of micropore filling to monolayer adsorption, and final stabilization stage.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimation of Adsorption Isotherm for Deep Coalbed Methane: A Monolayer-Filling Model Based on Pore Fractal Dimension

Feng,

Li,

Tang

et al. 2024

Energy Fuels

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“…[1][2][3][4][5] The anisotropy induced by the parallel bedded plane can affect the magnitude of strength and the direction of seepage, ultimately governing the stability of rock engineering and the efficiency of oil/gas extraction. [6][7][8][9][10][11] As the dominant factors of macroscopic failure for rocks, the initiation, propagation, and connection of fractures/cracks and the microfracture modes (e.g., tension and shear) can be characterized by the AE (acoustic emission), CT (X-ray computed tomography), and NMR (nuclear magnetic resonance) techniques. Especially, the AE technique has been extensively popularized and applied by engineers and scholars in experiment investigation, hydraulic fracturing, tunnel excavation, and rockburst prediction.…”

Section: Introductionmentioning

confidence: 99%

“…Sedimentary rocks, commonly featuring foliations or stratified structures and pronounced anisotropy, are widely distributed on the Earth's surface 1–5 . The anisotropy induced by the parallel bedded plane can affect the magnitude of strength and the direction of seepage, ultimately governing the stability of rock engineering and the efficiency of oil/gas extraction 6–11 . As the dominant factors of macroscopic failure for rocks, the initiation, propagation, and connection of fractures/cracks and the microfracture modes (e.g., tension and shear) can be characterized by the AE (acoustic emission), CT (X‐ray computed tomography), and NMR (nuclear magnetic resonance) techniques.…”

Section: Introductionmentioning

confidence: 99%

Assessment on anisotropy degree and fracture modes for weakly anisotropic sandstone using the acoustic emission technique

Zheng

Wang

Zhao

et al. 2023

Fatigue Fract Eng Mat Struct

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Comprehensive understanding of anisotropy characteristics and fracture modes for weakly anisotropic rocks is required for engineering safety and energy exploitation. To investigate the fracture mechanisms, the uniaxial compression testing with AE (acoustic emission) technique is implemented on the weakly anisotropic sandstone because of its capability to provide the essential and frequently-used mechanical parameters. This research first adopts the longitudinal wave velocity and T 2 spectrum to validate the weak anisotropy of the bedded sandstone. The results experimentally indicate that both uniaxial compressive strength and Young's modulus have a negligible dependence on different bedding orientation angles, but both permeability and macroscopic failure patterns are considerably controlled by the bedding direction. The conventional AE index analysis indicates that the tension-dependent failure occurs in the bedded sandstone under the uniaxial compression. Interestingly, the developed k-means clustering method is consistent with both the latest crack classification concept and macroscopic failure patterns. K E Y W O R D S acoustic emission, fracture modes, k-means clustering, macroscopic failure patterns, weakly anisotropic sandstone Highlights • The weak anisotropy of the sandstone specimens is validated by the wave velocity and T 2 spectrum. • The anisotropy properties and fracture mechanisms are analyzed using the acoustic emission (AE) monitoring technique. • The k-means clustering method is developed by this work to compare the conventional AE parameter (RA and AF) analysis.

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“…The technology of microwave-assisted rock breaking is a promising method for rock breaking, because of its high efficiency, sustainability, and less pollution. Theoretical and experimental research shows that the technology of microwave-induced fracturing can improve efficiency and reduce energy consumption in practical engineering [1][2][3][4][5] .…”

mentioning

confidence: 99%

Acoustic emission characteristics and damage evolution of basalt by microwave irradiation

Yang

Wang

Zhao

et al. 2023

Sci Rep

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The microwave-assisted rock breaking technology has been proven to be feasible, and has received considerable attention in the field of civil and mining engineering. A copper foil was used to wrap basalt to simulate rock excavation of practical application scenario in this paper. To this end, a multi-mode cavity with an operating frequency of 2.45 GHz was used to conduct microwave irradiation experiments on basalts with different irradiation times and different power. The thermal properties, AE characteristics, and damage evolution process of basalt were studied. The results show that the high heat generated by microwave leads to the development of cracks in the upper part of basalt. The higher the power level, the higher the degree of crack propagation in the sample, the lower the basalt strength, and the more active the AE activity. The fluctuation rule of the b value indicates that the basalt is dominated by small-scale microfractures before failure. High power levels or long irradiation time lead to more microwave-induced cracks participating in the failure process during loading. Compared with unheated basalt, microwave-heating basalt detects the characteristics of the precursor of failure in advance. The AE source location and the nephogram of the maximum principal stress of microwave-treated basalt reflected that the fracture path begins in the upper part of the rock. In addition, the combination of high power level and short irradiation time can achieve the purpose of energy saving.

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An adsorption model for cylindrical pore and its method to calculate pore size distribution of coal by combining NMR

Cited by 23 publications

References 52 publications

Estimation of Adsorption Isotherm for Deep Coalbed Methane: A Monolayer-Filling Model Based on Pore Fractal Dimension

Estimation of Adsorption Isotherm for Deep Coalbed Methane: A Monolayer-Filling Model Based on Pore Fractal Dimension

Assessment on anisotropy degree and fracture modes for weakly anisotropic sandstone using the acoustic emission technique

Acoustic emission characteristics and damage evolution of basalt by microwave irradiation

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