Authors:
Xijian Li
1
;
Kegang Ling
2
and
Peng Pei
3
Affiliations:
1
School of Mining, Guizhou University, Huaxi, Guiyang and Guizhou, China
;
2
Department of Petroleum Engineering, University of North Dakota, 243 Centennial Dr., Upson II Room 366, Grand Forks and ND
;
3
School of Mining, Guizhou University, Huaxi, Guiyang, Guizhou, Institute for Energy Studies, University of North Dakota, 243 Centennial Dr., Upson II Room 366, Grand Forks and ND, China
Keyword(s):
Soft and hard coals of stratified structure, coal gas outburst, coal gas mining, coal gas desorption characteristic
Abstract:
Based on the importance of coal gas desorption characteristics to coal bed methane mining, extraction, and prevention and control of coal and gas outburst, the coal samples from the soft and hard layer of stratified structure in the northwest of Guizhou were selected as research subjects, and a High Capacity Adsorption(HCA) device using high pressure capacity method was utilized to perform research on adsorption characteristics of the soft and hard layer coal under different temperatures and pressures. Seventy-two experiment groups have been carried out. The characteristics and rules of gas desorption of the soft and hard layer coal were analyzed comprehensively. The results showed that the gas desorption rate of the soft and hard layer coals was highest within the first minute after coal body was exposed or gas pressure was relieved, and gas desorption volumes increase almost linearly, then leveled off. The gas desorption of the soft and hard layer coals took place in the first 30 m
inutes after coal body was exposed or gas pressure was relieved, and the first minute gas desorption volumes accounted for 62.67-86.06% of the first two- hour gas desorption volumes. The initial gas desorption rate, the cumulative volume, and the desorption proportion of different time periods were affected by temperature and pressure, and increased slightly with the increase of temperature and pressure. Under the conditions of same temperature and pressure, the initial gas desorption rates of the soft layer coal were 1.282-1.892 times of the hard. The cumulative gas desorption of the hard layer coal would exceed that of the soft at the end of desorption. The shortest desorption process can happen in 10 minutes. The results provide a reference and guideline to coal gas mining and gas outburst control in the northwest of Guizhou.
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