Fractal analysis of pore characteristics and their impacts on methane adsorption of coals from Northern China

Li, Ziwen; Lin, Baiquan; Gao, Yabin; Cao, Zhaodan; Cheng, Yanying; Yu, Jingjie

doi:10.1504/ijogct.2015.071507

Cited by 19 publications

(25 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Following gas drainage, the sampling borehole GFH-0.5~8 was constructed. All the coal samples were carefully packed and laboratory tests were conducted immediately (Li et al, 2013). Six laboratory tests were arranged, including proximate analysis, determination of coalbed gas content, determination of initial gas desorption velocity, determination of coal hardiness coefficient, mercury injection capillary pressure (MICP) and nitrogen gas adsorption (N 2 GA).…”

Section: Methodsmentioning

confidence: 99%

Variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage: insight into pore characteristics

Zou

Lin

Liu

et al. 2017

IJOGCT

View full text Add to dashboard Cite

In this paper, the variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage were investigated by testing seven coal samples obtained from the coal seam #10 of Yangliu Coal Mine. The MICP and N 2 GA were combined to characterise the pore-size distribution. It is revealed that the residual coalbed gas content decreases substantially with the decrease in boreholes distances. Nevertheless, the variations in initial gas desorption velocity and coal hardiness coefficient represent an opposite tendency. In the microscopic aspect, the variation in pore-size distribution is notable. With the decrease in the boreholes distances, the adsorption pore proportion decreases and the seepage pore proportion increases. The drilling-slotting integration technique and gas drainage affect the aforementioned three macroscopic indices by changing the pore characteristics and moisture content. Besides, the guiding significance for field application of this technique is elaborated.

show abstract

Section: Methodsmentioning

confidence: 99%

Variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage: insight into pore characteristics

Zou

Lin

Liu

et al. 2017

IJOGCT

View full text Add to dashboard Cite

show abstract

“…According to ISO 15901∼1 : 2005 (PSD and porosity of sturdy materials by mercury porosimeter and method adsorption, Part 1: mercury porosimeter) [48,49], the MicroAutoPore IV 9500 mercury intrusion instrument (test aperture range d > 3 nm, mercury injection pressure 0.1∼413.05 MPa) was used to carry out the MIP test on the coal samples with frequencies of 0 Hz (S 0 ), 25 Hz (S 25 ), 50 Hz (S 50 ), 75 Hz (S 75 ), and 100 Hz (S 100 ), respectively, to obtain TPV, SSA, and PSD data on the pore-fissures. e fractal dimension D 1 of pores in coal is calculated by formula (1) based on mercury injection data and using the Menger model and thermodynamic method [20,37,47]:…”

Section: Mipmentioning

confidence: 99%

“…e density functional theory (DFT) was applied to quantify the adsorption-desorption isotherms, in which the TPV, SSA, and PSD of minipores and micropores were analyzed. At present, the FHH fractal model is widely applied to calculate the adsorption data of LPNA and obtain the pore fractal dimension [20,37,42]:…”

Section: Mipmentioning

confidence: 99%

“…Often, coal and gas outbursts occur in areas that have been disturbed by tectonism, and the coal bodies in those areas are then characterized as crumpled and cracked [15]. e vibration caused by a "small disturbance" may lead to a change in the pore structure of the coal, which has an important influence on its permeability, coal strength, elastic modulus, gas adsorption, and diffusion [16][17][18][19][20]. erefore, it is of great significance to study how vibration affects the evolution of pores and fissures in the coal to reveal the microscopic mechanism of "small disturbances" that affect the instability of coal rock and the gas adsorption and diffusion characteristics of the coal seam.…”

Section: Introductionmentioning

confidence: 99%

“…Fractal geometry is a powerful tool for quantitatively characterizing the morphology of pores and fractures in coal samples [20,42,45]. e fractal characteristics of coal are also one of the important factors affecting the adsorption, desorption, and diffusion of gas in the coal matrix [13,37,46].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Mechanical Vibration with Different Frequencies on Pore Structure and Fractal Characteristics in Lean Coal

Shen

Chen

2021

Shock and Vibration

View full text Add to dashboard Cite

The mechanical vibrations caused by underground operations can easily lead to coal and gas outbursts in coal mines. Using the MVGAD-I experimental platform that we designed, the raw coal (0 Hz) was treated with vibration frequencies of 25, 50, 75, and 100 Hz, and the coal samples with different frequency vibrations were obtained. The total pore volume (TPV), specific surface area (SSA), pore size distribution, and the pore fractal dimension (PFD) of five coal samples were analyzed by mercury intrusion porosimetry and low-pressure nitrogen adsorption data. We found that the TPV, SSA, and PFD of the coal samples fluctuate with the increase of vibration frequency. The changes of the TPV and SSA of coal samples treated with 25 and 75 Hz vibrations were significantly greater than those subjected to vibrations of 50 and 100 Hz. Compared with the raw coal (0 Hz), the TPV and SSA of macropores, mesopores, and micropores increased the most in 75 Hz vibration coal sample. Therefore, the 75 Hz vibration excitation can improve the permeability of a body of coal mass and is conducive to the diffusion and seepage of coalbed methane and its production.. The influence of 25 Hz vibration on the TPV and SSA of macropores and mesopores is not obvious, but the TPV and SSA of minipores and micropores decrease significantly, which is not conducive to gas diffusion and adsorption. In addition, 25 and 75 Hz vibrations obviously damaged the fractal characteristics of both mesopores and micropores, resulting in the change of gas adsorption and diffusion ability. The rational use of a 75 Hz vibration is beneficial to both the production of gas and the prevention of outbursts, while a 25 Hz vibration should be avoided. The results are expected to reveal the microscopic mechanism of a vibration-induced outburst and provide theoretical guidance for employing the appropriate frequency of vibration to improve the rate of gas drainage and reduce the risk of outbursts.

show abstract

Experimental investigation on microstructure fractal characteristics of low-temperature oxidation of gas-bearing coal

Tian,

Li,

et al. 2024

Environ Earth Sci

View full text Add to dashboard Cite

In order to study the multi-field coupling mechanism of gas and coal spontaneous combustion, low-temperature nitrogen adsorption and SEM were applied to carry out microstructure testing experiments on oxidation of gas-bearing coal in this paper. And a pore fractal calculation model incorporating pore size distribution was established. The effects of low-temperature oxidation and gas ad/de-sorption on the change of coal pore structure were investigated. The results showed that the pore volume of coal oxidized and gas-bearing coal oxidized were decreased by 1.805 and 2.232×10 -3 cm 3 •g -1 in all pore size distributions, where the micropores and macropores were converted to mesopores after oxidation of coal and macropores were formed by destruction of micropores and mesopores after oxidization of gas-bearing coal; coal oxidation and gas-bearing coal oxidation specific surface area decreased by 2.264 and 2.320 m 2 •g -1 , respectively, and the modifying effect of coal pore surface was stronger in the latter than in the former; the irregularity of the surface morphology increased after oxidation of the coal, and a large number of micropores were connected to form microcracks, while the surface morphology of the pores of the oxidized gas-bearing coal tended to be more regular compared with the oxidation of the non-gas-bearing coal; a pore fractal model based on the characteristics of the pore diameter distribution was established, and Dfb is 2.14-2.23, and the coupled action of gas desorption and oxidation on pore modification is stronger than the oxidation. The gas storage state of gas-bearing coal and the distribution of desorbead gas in goaf were affected by change of pore structure, so that the oxidation of gas-bearing coal can be weakened and the risk of spontaneous combustion of gas-bearing coal can be declined, which can provide a theoretical basis for the judgment of the risk of spontaneous combustion of gas-bearing coal in goaf.Keywords： Gas-bearing coal； Low-temperature oxidation； Porosity； Micro-structure；Fractal characteristics

show abstract

Fractal analysis of pore characteristics and their impacts on methane adsorption of coals from Northern China

Cited by 19 publications

References 0 publications

Variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage: insight into pore characteristics

Variations in coalbed gas content, initial gas desorption property and coal strength after drilling-slotting integration technique and gas drainage: insight into pore characteristics

Effect of Mechanical Vibration with Different Frequencies on Pore Structure and Fractal Characteristics in Lean Coal

Experimental investigation on microstructure fractal characteristics of low-temperature oxidation of gas-bearing coal

Contact Info

Product

Resources

About