scholarly journals Micropore Structure and Fractal Characteristics of Low-Permeability Coal Seams

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Guang-zhe Deng ◽  
Rui Zheng
Keyword(s):  
Fractal Dimension ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Coal Seam ◽  
Linear Relationship ◽  
Surface Area ◽  
Pore Volume ◽  
Low Permeability ◽  
Coal Seams ◽  
Scanning Electron

With the raw coal from a typical low-permeability coal seam in the coalfield of South Junger Basin in Xinjiang as the research object, this paper examined six kinds of coal samples with different permeabilities using a scanning electron microscope and a low-temperature nitrogen adsorption test that employed a JSM-6460LV high-resolution scanning electron microscope and an ASAP2020 automatic specific surface area micropore analyzer to measure all characteristic micropore structural parameters. According to fractal geometry theory, four fractal dimension calculation models of coal and rock were established, after which the pore structure characteristic parameters were used to calculate the fractal dimensions of the different coal seams. The results show that (1) the low-permeability coal seam in the coalfield of South Junger Basin in Xinjiang belongs to mesoporous medium, with a certain number of large pores and no micropores. The varying adsorption capacities of the different coal seams were positively correlated with pore volume, surface area, and the mesoporous surface area proportions, from which it was concluded that mesopores were the main contributors to pore adsorption in low-permeability coal seams. (2) The raw coal pore fractal dimension had a negative linear relationship to average pore size, a positive linear relationship with total pore volume, total surface area, and adsorption capacity, and a positive correlation with the mesoporous surface area proportion; that is, the higher the fractal dimension, the larger the pore volume and surface area of the raw coal. (3) The permeability of the low-permeability coal seam had a phase correlation with the micropore development degree; that is, the permeability had a phase negative correlation with the pore distribution fractal dimension, and there was a positive correlation between permeability and porosity. These results are of theoretical significance for the clean exploitation of low-permeability coal seam resources.

Research on the Ultra-Fine Titanium Dioxide Suspension Stability and Fractal

2011 ◽  
Vol 361-363 ◽  
pp. 288-295
Author(s):  
De Wei Chen ◽  
Xiao Ling Ge ◽  
Quen Tin Shi ◽  
Jiu Wang Tian
Keyword(s):  
Titanium Dioxide ◽  
Fractal Dimension ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Sediments ◽  
Suspension Stability ◽  
Matlab Program ◽  
Different Types ◽  
Scanning Electron ◽  
Dioxide Suspension

Using scanning electron microscope, the microscopic pictures of the surface on sediment have been obtained from the sub-micron titanium dioxide suspensions without dispersant or adding different types of dispersants. Deposits of titanium dioxide suspension have been observed and the mechanism of the dispersant has been analyzed. Meanwhile, deposits of titanium dioxide gray distribution figure have been gained by self-compiled Matlab program, which proved that the surface sediments is fractal, and the fractal dimension has been calculated under different conditions. The rules between suspension stability and fractal dimension have been achieved.

scholarly journals Effect of peat mire evolution on pore structure characteristics in thick coal seam: Examples from Xishanyao Formation (Middle Jurassic), Yili Basin, China

2020 ◽  
Vol 38 (5) ◽  
pp. 1484-1514 ◽  
Author(s):  
Rongfang Qin ◽  
Anmin Wang ◽  
Daiyong Cao ◽  
Yingchun Wei ◽  
Liqi Ding ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Coal Seam ◽  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Thick Coal Seam ◽  
Structure Characteristics ◽  
Cyclic Changes

The physical properties of thick coal seams show strong vertical heterogeneity; thus, an accurate characterization of their pore structure is essential for coalbed methane (CBM) exploration and production. A total of 18 coal samples, collected from a thick coal seam in the Yili Basin of NW China, were tested by a series of laboratory experiments to investigate the peat mire evolution and pore structure characteristics. The results show that the No. 4 coal seam has undergone multiple stages of evolution in the peatification stage, and was divided into four water-transgression/water-regression cycles according to the regular cyclic changes of the vitrinite/inertinite ratio, structure preservation index, gelification index, vegetation index, trace element ratios, and stable carbon isotopes of organic matter. The changes of pore structure characteristics with the changes of coal deposition cycles are also analyzed. It is concluded that pore structure characteristics of the four cycles are quite different. In each water-transgression cycle, the vitrinite gradually increased and the inertinite gradually decreased, resulting in a decrease of the porosity, pore volume, specific surface area, and fractal dimension. While in each water-regression cycle, the vitrinite gradually decreased and the inertinite gradually increased, leading to an increase of the porosity, pore volume, specific surface area, and fractal dimension. A strong relationship exists between the porosity, pore volume, specific surface area, fractal dimension, and submacerals, with fusinite and semifusinite which contained more pores having a positive correlation, desmocollinite and corpovitrinite which contained few pores having a negative correlation.

scholarly journals Synthesis ofMnO2Microfiber with Secondary Nanostructure by Cotton Template

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Huan-qin Wang ◽  
Ming-bo Zheng ◽  
Jin-hua Chen ◽  
Guang-bin Ji ◽  
Jie-ming Cao
Keyword(s):  
Crystal Structure ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Single Crystal ◽  
Surface Area ◽  
Single Crystal Structure ◽  
Bet Surface Area ◽  
Low Concentration ◽  
Adsorption Desorption ◽  
Scanning Electron

HierarchicalMnO2microfibers were prepared by using cotton as the template andKMnO4as the precursor via an ultrasonic assistance route. The results of scanning electron microscope characterization showed that the concentration ofKMnO4had a significant effect on the morphology ofMnO2microfiber. At low concentration ofKMnO4, the microfiber was composed ofMnO2nanorods with single crystal structure. With increasing the concentration ofKMnO4, the secondary nanostructure ofMnO2microfibers had a transformation from nanorod to nanoparticle. The results ofN2adsorption-desorption analysis indicated thatMnO2microfibers had BET surface area of about 25 m2/g. This synthesis provides a new way to control the secondary nanostructure ofMnO2microfiber by adjusting the concentration of precursor. Furthermore, the mechanism for the replication was proposed and discussed.

scholarly journals The Effect of Fly Ash on Some Surface Characteristics and Microstructure of β-C2S

1997 ◽  
Vol 15 (6) ◽  
pp. 407-417
Author(s):  
Kh.A. Khalil ◽  
A.A. Amer
Keyword(s):  
Electron Microscope ◽  
Fly Ash ◽  
Scanning Electron Microscope ◽  
Specific Surface ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Surface Characteristics ◽  
Ash Content ◽  
Sem Investigation ◽  
Scanning Electron

The effect of the addition of fly ash (0–15 wt. %) on the surface characteristics of β-C2S and its microstructure was investigated using nitrogen adsorption at −196°C together with scanning electron microscope (SEM) techniques. The results obtained revealed that the addition of fly ash up to 5 wt. % increased the specific surface area by 32% followed by a decrease of 34% when the fly ash content was increased up to 15 wt. %. SEM investigation showed that the hydrates produced form an outer shell which coats the fly ash particles.

scholarly journals Fractal Dimension of Fracture Surface in Rock Material after High Temperature

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Z. Z. Zhang
Keyword(s):  
Fractal Dimension ◽  
Electron Microscope ◽  
High Temperature ◽  
Fracture Surface ◽  
Scanning Electron Microscope ◽  
Fractal Dimensions ◽  
Threshold Value ◽  
Fracture Surfaces ◽  
Increasing Temperature ◽  
Scanning Electron

Experiments on granite specimens after different high temperature under uniaxial compression were conducted and the fracture surfaces were observed by scanning electron microscope (SEM). The fractal dimensions of the fracture surfaces with increasing temperature were calculated, respectively. The fractal dimension of fracture surface is between 1.44 and 1.63. Its value approximately goes up exponentially with the increase of temperature. There is a quadratic polynomial relationship between the rockburst tendency and fractal dimension of fracture surface; namely, a fractal dimension threshold can be obtained. Below the threshold value, a positive correlativity shows between rockburst tendency and fractal dimension; when the fractal dimension is greater than the threshold value, it shows an inverse correlativity.

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