Fractal and pore dispositions of coal seams with significance to coalbed methane plays of East Bokaro, Jharkhand, India

Mendhe, Vinod Atmaram; Bannerjee, Mollika; Varma, Atul Kumar; Kamble, Alka Damodhar; Mishra, Subhashree; Singh, Bhagwan D.

doi:10.1016/j.jngse.2016.12.020

Cited by 88 publications

(73 citation statements)

References 94 publications

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“…In the mercury intrusion curves, five coal samples have a hysteresis loop, and the hysteresis loops of the lignite coal samples are obvious, which indicates that there are many closed pores in lignite; gas that is adsorbed in closed pores is not easily excreted 45 . www.nature.com/scientificreports www.nature.com/scientificreports/ As shown in Table 3, the pore volume of coal powder decreases with coal development.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study on the Physisorption Characteristics of O2 in Coal Powder are Effected by Coal Nanopore Structure

Tan¹,

Cheng²,

Zhu³

et al. 2020

Sci Rep

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Bo tan , Gang cheng ✉ , Xiaoman Zhu & Xianbing Yang coal is a porous medium. oxygen molecules in the air penetrate through the pores of coal and are adsorbed on the coal surface. Low-temperature oxidation of coal then occurs, by which coal spontaneous combustion is promoted. Given this process, the authors analysed the physisorption characteristics of o 2 in pulverized coal from the perspective of nanopore structure. In this study, five different kinds of coal samples (two lignites, one bituminous coal, and two anthracites) were selected, and the surface morphology, pore structure parameters and oxygen physisorption capacity of the pulverized coals were determined by scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and oxygen adsorption with chromatography (OAC), respectively. The experimental results of SEM and MIP show that with the development of coal, the surface folds increase, and the pores increase in number and shrink, which leads to the nanopores of anthracite and bituminous coal being smaller and more complex than those of lignite. The experimental results of OAC show that adsorbed oxygen is physisorbed by pulverized coal in the order lignite > bituminous coal > anthracite. Analysis of the oxygen desorption curves shows that the oxygen desorption rates of the anthracites and bituminous coal are slower than those of the lignites. The results show that the amount of oxygen physisorbed by pulverized coal is proportional to the fractal dimension of the coal pores, proportional to the pore volume of the nanoscale pores, and inversely proportional to the number of closed pores in the coal. Based on the results of the analyses mentioned above, it is important to analyse the process of coal-oxygen chemisorption and the mechanism for low-temperature oxidation of coal to prevent coal spontaneous combustion. The confirmed worldwide reserves of coal stood at approximately 1,055 billion tons in 2018. The United States, Russia, Australia and China together accounted for 66.1% of the world's coal reserves 1. During mining, storage and transportation, coal can undergo spontaneous combustion, resulting in a huge waste of resources and economic losses in the United States and China per annum. The initial stage of coal spontaneous combustion involves coal low-temperature oxidation, in which oxygen permeates into the coal through pores, then physisorbs and chemisorbs with the functional groups on the coal surface, and adsorption heat is generated and accumulated 2,3 , as shown in Fig. 1. Coal is a porous medium, and the pore structure of coal varies with coal development 4 ; therefore, oxygen diffusion in coal pores and adsorption on coal surfaces are also different 5. The significance of the coal low-temperature oxidation mechanism in the physisorption, chemisorption and diffusion of oxygen in coal nanopores has been studied. In this paper, all oxygen adsorption involved physisorption. Scholars from various countries have performed much work on the influencing factors of coal low-temperature oxidati...

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Section: Resultsmentioning

confidence: 99%

Experimental Study on the Physisorption Characteristics of O2 in Coal Powder are Effected by Coal Nanopore Structure

Tan¹,

Cheng²,

Zhu³

et al. 2020

Sci Rep

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show abstract

“…The complex geological structure, high ground stress, high gas pressure and content, and low permeability in deep coal seams greatly increase the risk of coal and gas outburst 2–5 . Furthermore, coalbed methane (CBM) can not only cause gas disasters during the coal mining process 6–8 but is also a greenhouse gas, 9–13 and a kind of efficient clean energy 14–19 . There are particularly rich CBM resources in China.…”

Section: Introductionmentioning

confidence: 99%

Coal permeability evolution characteristics: Analysis under different loading conditions

et al. 2020

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The drainage and utilization of coalbed methane (CBM) resources can not only ensure the safe production of coal mines but also can reduce greenhouse gas emissions and protect the environment. 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. The results indicate that the coal permeability evolution laws measured by different gases are completely different under constant hydrostatic pressure conditions due to the influence of effective stress and the coal matrix sorption-induced deformation. Under constant effective stress conditions, the helium permeability of coals is almost unchanged if the effects of the Biot's coefficient of coals are ignored, but the methane permeability of coals decreases with increasing gas pressure. In the complete stress-strain process, the variation of coal permeability as the axial strain increases at different stages is almost completely different and the coal permeability in the residual plastic flow stage increases by 2.4-71 times, 1.5-39 times, and 2.8-116 times that of the initial state under the different boundary conditions. Furthermore, it is also found that the coal permeability evolution laws are determined by the effective stress, the sorption-induced deformation of coal matrices, and the malconformation of gas adsorption in coals. This study can help us better understand the seepage characteristics of gas in coals and guide the CBM development. C

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“…Coal is plant remains subjected to a prolonged and complicated process of biological, chemical, and tectonic factors under high temperatures and pressures, which is an anisotropic rock with a sophisticated pore structure 7–9 . Under different stress and strain environments, the interaction of primary pore and secondary pore induced by inelastic deformation produces great changes in porosity, permeability, adsorption, and desorption properties of coal 10 .…”

Section: Introductionmentioning

confidence: 99%

Investigation on the pore characteristics of coal specimens with bursting proneness

Jiang

Zhang

et al. 2019

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To achieve further insight into the pore characteristics, the coal specimens with different bursting proneness before and after uniaxial compression failure are tested and compared in this paper. The data of mercury intrusion test is corrected by that of low-temperature nitrogen adsorption and desorption test (LTNAD). The pore size distribution and pore volume of specimens are obtained. The pore compressibility coefficient is determined based on the fractal dimension of pore. Scanning electron microscope (SEM) and computed tomography (CT) are combined to evaluated the pore connectivity. The value of pore compressibility coefficient of specimens with high bursting proneness is larger than that of medium bursting proneness. It means more compressibility and abrupt failure under stress. The researches of both SEM and CT indicate that the pore connectivity of specimens with medium bursting proneness is better. The results show that great differences exist in the pore characteristics of specimens with high and medium bursting proneness, and uniaxial compression failure exacerbates the complexity of pore characteristics.

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Fractal and pore dispositions of coal seams with significance to coalbed methane plays of East Bokaro, Jharkhand, India

Cited by 88 publications

References 94 publications

Experimental Study on the Physisorption Characteristics of O2 in Coal Powder are Effected by Coal Nanopore Structure

Experimental Study on the Physisorption Characteristics of O2 in Coal Powder are Effected by Coal Nanopore Structure

Coal permeability evolution characteristics: Analysis under different loading conditions

Investigation on the pore characteristics of coal specimens with bursting proneness

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