Calculation of the fall in gas pressure during degassing of thin coal seams by large-diameter boreholes

1972 ◽  
Vol 8 (3) ◽  
pp. 291-295 ◽  
Author(s):  
V. V. Khodot ◽  
R. N. Isaeva ◽  
V. G. Krupenya

1966 ◽  
Vol 2 (5) ◽  
pp. 465-471 ◽  
Author(s):  
S. V. Kuznetsov
Keyword(s):  




1993 ◽  
Vol 109 (5) ◽  
pp. 331-335
Author(s):  
Ken GOTOH ◽  
Tomohiro MURAKAMI ◽  
Hidefumi OHMUTA


1988 ◽  
Vol 24 (3) ◽  
pp. 181-199 ◽  
Author(s):  
S. A. Khristianovich ◽  
Yu. F. Kovalenko
Keyword(s):  


2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jiazhuo Li ◽  
Penghui Guo ◽  
Wenhao Xie ◽  
Jiaqi Chu ◽  
Zhiqiang Yin ◽  
...  

For the quantitative recognition and characterization of the flow characteristics of polymorphism coalbed gas in tectonic coal, experiments on pore morphology, pore diameter distribution, and methane adsorption law in outburst tectonic coal were carried out by field emission scanning electron microscopy and low-field nuclear magnetic resonance. The results revealed abundant round and dense “pyrolysis pores” in outburst tectonic coals, most of which were adsorption and seepage pores, with micropores accounting for 78.2%. Most pores were independent and formed the network pore space for gas enrichment and migration in outburst tectonic coal. The transverse relaxation time (T2) of methane adsorption in tectonic coal and crushed outburst tectonic coals presented three peaks, namely, adsorption, drifting, and free peaks. The isolation of nanopores and micropores revealed lower adsorption capacity of outburst tectonic coal than that of crushed outburst tectonic coal. The gas staged adsorption of raw coal with outburst tectonic low-permeability was observed. Under low gas pressure, the T2 spectral peak area of methane adsorption increased remarkably, whereas that of desorbed methane increased slightly. As gas pressure was increased to a certain numerical value, the increment of methane adsorption decreased and tended to reach equilibrium. This finding reflected that methane adsorption tended to be saturated after gas pressure reached a certain value, but desorbed methane in isolated micropores increased quickly. The quantitative recognition and characterization of pore structure and gas adsorption in tectonic low-permeability outburst coal seams based on low-field magnetic resonance imaging provide an experimental method for gas exploitation in coal seams and the study and control of coal and gas outburst mechanism.



1970 ◽  
Vol 39 (11) ◽  
pp. 1190-1196
Author(s):  
Yoshinori Ito ◽  
Akio Michishita




Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xiao Cui ◽  
Jiayong Zhang ◽  
Liwen Guo ◽  
Xuemin Gong

Coal seam gas pressure is one of the fundamental parameters used to assess coal seam gas occurrence and is an important index in assessing the risk of gas disaster. However, the geological characteristics of coal seams become increasingly complex with increasing mining degree, thus decreasing the accuracy and success rate of direct methods for measuring gas pressure. To address such issues, we have developed a new method for direct measurement of gas pressure in water-bearing coal seams. In particular, we developed a pressure measurement device based on theoretical analysis and quantified the basic parameters of the device based on well testing. Then, we verified the applicability of our method based on comparative analysis of the results of field experiments and indirect measurements. Our results demonstrate that this new method can resolve the effects of water pressure, coal slime, and other factors on the estimation of gas pressure. The performance of this new method is considerably better than that of traditional methods. In particular, field test results demonstrate that our method can accurately and efficiently measure gas pressure in water-bearing coal seams. These results will be of great significance in the prevention and control of coal seam gas disaster.



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