scholarly journals Gas-solid coupling laws for deep high-gas coal seams

2017 ◽  
Vol 27 (4) ◽  
pp. 675-679 ◽  
Author(s):  
Aitao Zhou ◽  
Kai Wang ◽  
Lingpeng Fan ◽  
T.A. Kiryaeva
Keyword(s):  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Anying Yuan ◽  
Hao Hu ◽  
Qiupeng Yuan

At the present time, it is considered to be of major significance to study the gas emission law and stability controls of coal bodies in deeply buried high-gas coal seams. For this reason, in view of the specific problems of gas emissions caused by unstable rib spalling in coal mine walls, comprehensive research methods were adopted in this study, in order to conduct an in-depth examination of micropore structure parameters, gas desorption, diffusion laws, and coal stability levels. The results showed that the development degree of the pores above the micropores, as well as the small pores in soft coal seams, was better than those observed in hard coal seams. In addition, the gas outburst phenomenon was found to have more easily formed in the soft coal seams. The coal body of the No. 6 coal seam in the Xieqiao Coal Mine not only provided the conditions for gas adsorption but also provided dominant channels for gas diffusion and migration. The abnormal gas emissions of the No. 6 coal seam were jointly caused by the relatively developed pores above the small holes in the coal body, rib spalling of coal mine walls, and so on. The research results also revealed the evolution law of mechanical characteristics of the No. 6 coal seam under different water content conditions. It was found that the strength levels of the No. 6 coal seam first increased and then decreased with the increase in water content, and the water content level at the maximum strength of the coal seam was determined to be 7.09%. This study put forward a method which combined the water injection technology of long-term static pressure water injections in deep coal mining holes and real-time dynamic pressure water injections in shallower holes. Field experiments were successfully carried out.


2021 ◽  
Vol 24 (4) ◽  
pp. 499-506
Author(s):  
Xiaoping Xie ◽  
Xinqiu Fang ◽  
Minfu Liang ◽  
Dechun Ai

Under the influence of geological structure, the surrounding rock of semi-coal seam is easy to be loose and fractured, and the repairing rate is high. Therefore, it is of great theoretical and practical significance to study semi-coal seam mining's mechanism and control technology. In this paper, the geological evolution principle of the semi-coal seam is analyzed theoretically. The mechanic's relationship between the mining height of the semi-coal face and the lower coal seam's pressure relief is interpreted. The mechanism of eliminating bad blind areas in non-pillar mining of upper protective seam is analyzed. Through numerical simulation analysis, it is concluded that the expansion deformation rate of a protective layer increases linearly with the increase of mining thickness of the protective layer, and the width of undesirable blind zone of coal seam increases linearly with the rise of protective layer thickness. This paper puts forward the technology of non-pillar mining in the protective seam's semi-coal and rock face. Field industrial test results show that the technology achieves the overall pressure relief and reflection reduction of low permeability and high gas coal seams. The underlying 3 + 4 protective layer achieves the general pressure relief and reflection reduction of low permeability and high gas coal seams. Coalbed methane can be pre-drained up to 18 m3/min with a concentration of 90%.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Dan Zhao ◽  
Mingyu Wang ◽  
Xinhao Gao

To reduce gas disasters in low permeability and high-gas coal seams and improve gas predrainage efficiency, conventional deep-hole presplitting blasting permeability increasing technology was refined and perfected. The numerical calculation model of presplitting blasting was established by using ANSYS/LS-DYNA numerical simulation software. The damage degree of coal and rock blasting was quantitatively evaluated by using the value range of the damage variable D. According to the actual field test parameters of coal seam #3 in the Sanyuan coal mine, Dlim = 0.81–1.0 was the coal rock crushing area, Dlim = 0.19–0.81 was the coal rock crack area, and Dlim = 0–0.19 was the coal rock disturbance area. By comparing and analysing the damage distribution nephogram of coal and rock mass under the influence of different millisecond blasting time interval and the blasting effect of simulation model, the optimal layout parameters of multilayer through cracks were obtained theoretically. And, the determined parameters were tested on the working face of the 1312 transportation roadway in coal seam #3 of the Sanyuan coal mine. The permeability effect was compared and analysed through the analysis of the gas concentration, gas purity, and mixing volume before and after the implementation of deep-hole presplitting blasting antireflection technology, as well as the change of gas pressure, attenuation coefficient, permeability coefficient, and other parameters between blasting coal seams. The positive role of millisecond blasting in reducing pressure and increasing permeability in low permeability and high-gas coal seam were determined.


2021 ◽  
pp. 53-69
Author(s):  
I.O. Kostyk ◽  
I.V. Buchynska ◽  
A.V. Poberezhsky

A geological-statistic analysis of commercial resources and the predictive coal-bearing potential of the fields of the South-Western coal region, the principal promising part of the Lviv-Volyn Coal Basin, has been carried out. Based on the detailed analysis and systematization of data from prospecting and exploratory-assessment works regarding the depth of occurrence and the thickness of coal seams, ash content, sulphur content and grade composition of coal, resources of the Tyagliv and Lyubelya fields has been re-evaluated. These characteristics have been studied by discrete intervals. Re-evaluation of resources and their classification were carried out for every coal seam, the mine field, the field, and the coal-bearing region on the whole. In total, the analysis was performed for 24 coal seams. By the depth of occurrence of coal seams the majority of coal reserves at the Tyagliv and Lyubelya fields belong to the group of 600-900 m. The majority of predictive resources of coal within the Lyubelya field (6.6%) falls to the group of 900-1200 m. According to the thickness of coal seams, the most of the balance and overbalance reserves at the Tyagliv field is attributed to the groups of 0.61-0.80; 0.81-1.00 m, and at the Lyubelya field to the groups of 0.81-1.00; 1.01-1.20; 1,21-1.50 and over 1.5 m. Within the Lyubelya field, the predictive resources of coal are contained in the group of 0.81-1.00 m. According to the value of ash content, 50 % of balance and overbalance reserves of coal at the Tyagliv field are related to the groups of the medium-ash and ash coal. At the Lyubelya field, the most of coal reserves (66.4%) also corresponds to the group of medium-ash coal, and predictive resources — to the groups of medium-ash (43.1%) and ash (53.1%) coal. According to the content of the mass fraction of sulphur, at the Tyagliv field the balance and overbalance reserves of high-sulphur coal prevail, with the amount of sulphur, low-sulphur and medium-sulphur coal being at the equal ratios. At the Lyubelya field, high-sulphur and low-sulphur coal prevail almost at the equal ratios. Regarding predictive resources, the group of high-sulphur coal prevails within the field. The coal seams within the Tyagliv and Lyubelya fields differ from analogous ones in the industrial part of the basin by the higher thickness and the area of distribution. The depth of occurrence of the seams increases for 15-300 m. Coal in the fields of the South-Western coal region has higher quality and the least ash content. According to brand composition of coal, the technologic groups of gas coal, gas-fat coal and fat coal (according to the Ukrainian classification) prevail at the Tyagliv field. It is proved that gas coal is suitable for coking. At the Lyubelya field, fat, coke-fat and coke coal prevail. Сoke coal comprises almost a half of the reserves. In the region, reserves and resources of coal are estimated to be over two billion tons, which exceeds in two times the residual reserves of the commercial part of the basin. The analysis of the raw material base of the Tyagliv and Lyubelya fields, estimation of reserves and evaluation of coal resources have a great importance for developing and working-out of the feasibility study for their commercial development.


Ugol ◽  
2019 ◽  
pp. 46-50
Author(s):  
E.S. Melekhin ◽  
◽  
E.S. Kuzina ◽  
Keyword(s):  
Gas Coal ◽  

2014 ◽  
Vol 8 (1) ◽  
pp. 55-60
Author(s):  
V Buzylo ◽  
◽  
O Koshka ◽  
S Poimanov ◽  
D Malashkevych ◽  
...  
Keyword(s):  

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