A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine

Large numbers of gobs are produced as a result of underground longwall mining, and a large amount of these gobs is known to contain methane gas reserves. The efficient drainage of these methane resources is directly dependent on accurately determining the methane enrichment zone (MEZ) in longwall mi...

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Main Authors: Guorui Feng, Ao Zhang, Shengyong Hu, Xiangqian Guo, Chao Li, Guocai Hao, Zhen Li
Format: Article
Language:English
Published: Hindawi-Wiley 2019-01-01
Series:Geofluids
Online Access:http://dx.doi.org/10.1155/2019/2438075
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spelling doaj-f2ea200f04584ec382da534b949a3b0e2020-11-25T02:22:57ZengHindawi-WileyGeofluids1468-81151468-81232019-01-01201910.1155/2019/24380752438075A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal MineGuorui Feng0Ao Zhang1Shengyong Hu2Xiangqian Guo3Chao Li4Guocai Hao5Zhen Li6College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaCollege of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaCollege of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaShanxi Jincheng Anthracite Mining Group Co. Ltd., Jincheng 048000, ChinaShanxi Jincheng Anthracite Mining Group Co. Ltd., Jincheng 048000, ChinaCollege of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaCollege of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan 030024, ChinaLarge numbers of gobs are produced as a result of underground longwall mining, and a large amount of these gobs is known to contain methane gas reserves. The efficient drainage of these methane resources is directly dependent on accurately determining the methane enrichment zone (MEZ) in longwall mining gobs. In this study, a method for accurately determining the MEZ within the zone of interconnected fractures, which utilized a surface directional borehole (SDB) technique, was proposed. The SDB was designed and implemented in a longwall gob located in the Sihe Coal Mine in China’s Shanxi Province. The trajectory of the SDB constantly varied in the different overlying stratum layers and locations above the gob. The methane flow rate and concentration from the SDB, along with the methane concentration in the upper corner of the longwall face, were monitored and obtained as the longwall face advanced. Then, by analyzing the acquired data of the different horizontal and vertical positions of the SDB, the accurate locations of the MEZ within the zone of interconnected fractures were determined. There were the methane decrease zone (MDZ) and methane shortage zone (MSZ) below and above the MEZ, respectively. The results showed that in the MEZ, both the methane flow rate and concentration displayed slight decreasing trends and maintained high levels as the distance from the roof of the coal seam increased. In the MDZ, a sharp decline was observed in the methane flow rate. However, a relatively high methane concentration had still been maintained. In the MSZ, both the methane flow rate and concentration displayed dramatic fluctuation and relatively low levels. The average methane flow rates in the MEZ were determined to be 1.3 and 1.6 times higher than those in the MDZ and MSZ, respectively.http://dx.doi.org/10.1155/2019/2438075
collection DOAJ
language English
format Article
sources DOAJ
author Guorui Feng
Ao Zhang
Shengyong Hu
Xiangqian Guo
Chao Li
Guocai Hao
Zhen Li
spellingShingle Guorui Feng
Ao Zhang
Shengyong Hu
Xiangqian Guo
Chao Li
Guocai Hao
Zhen Li
A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine
Geofluids
author_facet Guorui Feng
Ao Zhang
Shengyong Hu
Xiangqian Guo
Chao Li
Guocai Hao
Zhen Li
author_sort Guorui Feng
title A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine
title_short A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine
title_full A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine
title_fullStr A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine
title_full_unstemmed A Method to Accurately Determine the Methane Enrichment Zone of a Longwall Coal Mine
title_sort method to accurately determine the methane enrichment zone of a longwall coal mine
publisher Hindawi-Wiley
series Geofluids
issn 1468-8115
1468-8123
publishDate 2019-01-01
description Large numbers of gobs are produced as a result of underground longwall mining, and a large amount of these gobs is known to contain methane gas reserves. The efficient drainage of these methane resources is directly dependent on accurately determining the methane enrichment zone (MEZ) in longwall mining gobs. In this study, a method for accurately determining the MEZ within the zone of interconnected fractures, which utilized a surface directional borehole (SDB) technique, was proposed. The SDB was designed and implemented in a longwall gob located in the Sihe Coal Mine in China’s Shanxi Province. The trajectory of the SDB constantly varied in the different overlying stratum layers and locations above the gob. The methane flow rate and concentration from the SDB, along with the methane concentration in the upper corner of the longwall face, were monitored and obtained as the longwall face advanced. Then, by analyzing the acquired data of the different horizontal and vertical positions of the SDB, the accurate locations of the MEZ within the zone of interconnected fractures were determined. There were the methane decrease zone (MDZ) and methane shortage zone (MSZ) below and above the MEZ, respectively. The results showed that in the MEZ, both the methane flow rate and concentration displayed slight decreasing trends and maintained high levels as the distance from the roof of the coal seam increased. In the MDZ, a sharp decline was observed in the methane flow rate. However, a relatively high methane concentration had still been maintained. In the MSZ, both the methane flow rate and concentration displayed dramatic fluctuation and relatively low levels. The average methane flow rates in the MEZ were determined to be 1.3 and 1.6 times higher than those in the MDZ and MSZ, respectively.
url http://dx.doi.org/10.1155/2019/2438075
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