Effects of particle size and adsorption pressure on methane gas desorption and diffusion in coal

Li, Xiangchun; Li, Zhongbei; Ren, Ting; Nie, Baisheng; Xie, Lei; Huang, Tao; Bai, Sheng; Jiang, Ying

doi:10.1007/s12517-019-4995-7

Cited by 20 publications

(16 citation statements)

References 47 publications

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“…The methane diffusivity was measured from the slope of the early time desorption rate curve (Figure ) at various isotherm pressures based on the USBM volumetric desorption approach. The diffusion coefficient increases with an increase in the shale particle size (Figure ), which agrees with the observation for coal samples . Shale particle diameter affects the dynamic gas production process, in which a larger particle diameter leads to a longer path of diffusion …”

Section: Discussion On Resultssupporting

confidence: 87%

Shale’s Pore Structure and Sorption-Diffusion Characteristics: Effect of Analyzing Methods and Particle Size

et al. 2022

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The delineation of pore size and surface area distribution and methane sorption-diffusion capacity in gas shale reservoirs is crucial for the estimation of storage capacity, anticipating flow characteristics, and field development. A systematic approach and guidelines are needed for the analysis of the pore size and surface area distribution of shale formations. The effect of shale sample size on the gas sorption and diffusion properties is not well understood either. The low-pressure nitrogen adsorption technique is a prevalent method for pore characterization of nanoporous shale formations. Although researchers adopted some corrections to the classical method for the analysis of pore size and surface area distribution, there is a significant mismatch between different approaches in depicting fine mesopore size and surface area (2–10 nm). In this study, the classical methods and density functional theory are employed to comparatively analyze the pore characteristics of some shale and clay samples for their applicability, efficacy, and consistency issues. Furthermore, the effect of shale particle size on the methane sorption capacity and diffusion is being investigated. It seems that confinement stress has less of a considerable effect on methane sorption (6% decrease). However, crushing shale rocks into smaller particles can significantly overestimate the methane adsorption capacity. The methane diffusion coefficient also increases with increasing the shale particle size by more than an order of magnitude.

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Section: Discussion On Resultssupporting

confidence: 87%

Shale’s Pore Structure and Sorption-Diffusion Characteristics: Effect of Analyzing Methods and Particle Size

et al. 2022

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“…The methane adsorption rate increases with increasing bedding plane angle, and the more effective paths for methane flow within the specimen, the faster the initial flow rate. Li et al (2019b) concluded from methane desorption and diffusion experiments that larger coal particle size in coal will result in a slower gas diffusion rate and longer desorption time. Zhou et al (2019) analyzed the potential energy change characteristics of methane near the pore throat based on Leonard-Jones potential function (Eq.…”

Section: Effect Of Pore Structures On Sorptionmentioning

confidence: 99%

Sorption characteristics in coal and shale: A review for enhanced methane recovery

2021

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The exploration and exploitation of hydrocarbon resources within coal and shale reservoirs is an engineering challenge. Well-developed internal micro-pore structures, complex sorption mechanism as well as numerous influencing factors affecting the gas flow are generally not well-accounted in the commercial life-cycle of shale gas and coalbed methane wells. Although large number of studies have been conducted to propose improved sorption models and study the influencing factors on adsorption and desorption characteristics of methane and CO 2 in coal and shale reservoirs, a systematic review of such studies for efficient understanding of the accumulated literature is missing, especially with a focus towards coal and shale reservoirs. In that context, this study presents a review of sorption characteristics of methane in coal and shale. Firstly, theoretical mechanisms for methane sorption are introduced, followed by description of sorption models. Further, three factors influencing the sorption of gas in coal and shale are described: total organic carbon and clays, pore structures, and reservoir conditions. Finally, the preferential sorption characteristics of hydrocarbons and carbon dioxide are described, and the methods to promote methane desorption for enhanced recovery are discussed, which include technologies such as gas injection, microwave heating, and hydraulic fracturing.

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“…e influence of particle size on gas loss is reflected in the influence of particle size on desorption speed. e larger the particle size of the coal sample, the smaller the initial kinetic diffusion parameter, and the smaller the amount of gas desorption at the same time [17,18]. On the other hand, the gas desorption behaviors of coal sample correlate with the surface area and depend significantly on porosity [19].…”

Section: Introductionmentioning

confidence: 99%

Study on Change Rules of Factors Affecting Gas Loss during Coalbed Air Reverse Circulation Sampling

Chen

Long

et al. 2021

Advances in Civil Engineering

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The gas loss in sampling is the root of coalbed gas content measurement error. The pressure and particle size have a significant impact on the gas loss. Using the self-developed coal particle pneumatic pipeline transportation experimental system, this study investigated the pressure and particle size changes in the sampling pipeline. It is found that the sampling process can be divided into four stages: no flow field stage, sample outburst stage, stable conveying stage, and tail purging stage. The extreme pressure in the sampling pipeline appears at the sample outburst stage; and the pressure in the pipeline has levelled off after sharp decrease in the stable conveying stage. It is also found that the extreme pressure increases first and then decreases with the increase of particle size. The duration of outburst stage is negatively correlated with particle size, and that of stable conveying stage is positively correlated with particle size. In addition, the results show that the loss rate of 1–3 mm particles is the smallest after the test but that particles less than 1 mm increase by about two times and particles greater than 3 mm decrease by more than three times. The study also shows that the particle size distribution of coal samples is a single peak with left skew distribution, and the gas reverse circulation sampling test does not change the location of the peak but makes it higher and sharper. The single size coal sample is more likely to collide than the mixture. This study can help to advance the understanding of impact factors on gas loss during reverse circulation sampling.

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Effects of particle size and adsorption pressure on methane gas desorption and diffusion in coal

Cited by 20 publications

References 47 publications

Shale’s Pore Structure and Sorption-Diffusion Characteristics: Effect of Analyzing Methods and Particle Size

Shale’s Pore Structure and Sorption-Diffusion Characteristics: Effect of Analyzing Methods and Particle Size

Sorption characteristics in coal and shale: A review for enhanced methane recovery

Study on Change Rules of Factors Affecting Gas Loss during Coalbed Air Reverse Circulation Sampling

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