Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations

Gas flow in a coal seam is a complex process due to the complicated coal structure and the sorption characteristics of coal to adsorbable gas (such as carbon dioxide and methane). It is essential to understand the gas migration patterns for different fields of engineering, such as CBM exploitation,...

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Autores principales:	Haibo Liu, Zhihang Shu, Yinbin Shi, Xuebing Wang, Xucheng Xiao, Jia Lin
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	coal seam gas CBM permeability borehole size gas drainage CO<sub>2</sub> geo-sequestration Mineralogy QE351-399.2
Acceso en línea:	https://doaj.org/article/30907d48edae40dda701df7e5049d668
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spelling	oai:doaj.org-article:30907d48edae40dda701df7e5049d6682021-11-25T18:26:38ZGas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations10.3390/min111112542075-163Xhttps://doaj.org/article/30907d48edae40dda701df7e5049d6682021-11-01T00:00:00Zhttps://www.mdpi.com/2075-163X/11/11/1254https://doaj.org/toc/2075-163XGas flow in a coal seam is a complex process due to the complicated coal structure and the sorption characteristics of coal to adsorbable gas (such as carbon dioxide and methane). It is essential to understand the gas migration patterns for different fields of engineering, such as CBM exploitation, underground coal mine gas drainage, and CO<sub>2</sub> geo-sequestration. Many factors influence gas migration patterns. From the surface production wells, the in-seam patterns of gas content cannot be quantified, and it is difficult to predict the total gas production time. In order to understand the gas flow patterns during gas recovery and the gas content variations with respect to production time, a solid-fluid coupled gas migration model is proposed to illustrate the gas flow in a coal seam. Field data was collected and simulation parameters were obtained. Based on this model, different scenarios with different borehole sizes were simulated for both directional boreholes and normal parallel boreholes in coal seams. Specifically, the borehole sizes for the directional boreholes were 10 m, 15 m, and 20 m. The borehole sizes for the normal parallel boreholes were 2 m, 4 m, and 6 m. Under different gas drainage leading times, the total gas recovery and residual gas contents were quantified. In Longwall Panel 909 of the Wuhushan coal mine, one gas drainage borehole and five 4 m monitoring boreholes were drilled. After six months of monitoring, the residual gas content was obtained and compared with the simulation results. Of the total gas, 61.36% was drained out from the first 4 m borehole. In this field study, the effective drainage diameter of the drainage borehole was less than 8 m after six months of drainage. The gas drainage performance was tightly affected by the borehole size and the gas drainage time. It was determined that the field observations were in line with the simulation results. The findings of this study can provide field data for similar conditions.Haibo LiuZhihang ShuYinbin ShiXuebing WangXucheng XiaoJia LinMDPI AGarticlecoal seam gasCBMpermeabilityborehole sizegas drainageCO<sub>2</sub> geo-sequestrationMineralogyQE351-399.2ENMinerals, Vol 11, Iss 1254, p 1254 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	coal seam gas CBM permeability borehole size gas drainage CO<sub>2</sub> geo-sequestration Mineralogy QE351-399.2
spellingShingle	coal seam gas CBM permeability borehole size gas drainage CO<sub>2</sub> geo-sequestration Mineralogy QE351-399.2 Haibo Liu Zhihang Shu Yinbin Shi Xuebing Wang Xucheng Xiao Jia Lin Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
description	Gas flow in a coal seam is a complex process due to the complicated coal structure and the sorption characteristics of coal to adsorbable gas (such as carbon dioxide and methane). It is essential to understand the gas migration patterns for different fields of engineering, such as CBM exploitation, underground coal mine gas drainage, and CO<sub>2</sub> geo-sequestration. Many factors influence gas migration patterns. From the surface production wells, the in-seam patterns of gas content cannot be quantified, and it is difficult to predict the total gas production time. In order to understand the gas flow patterns during gas recovery and the gas content variations with respect to production time, a solid-fluid coupled gas migration model is proposed to illustrate the gas flow in a coal seam. Field data was collected and simulation parameters were obtained. Based on this model, different scenarios with different borehole sizes were simulated for both directional boreholes and normal parallel boreholes in coal seams. Specifically, the borehole sizes for the directional boreholes were 10 m, 15 m, and 20 m. The borehole sizes for the normal parallel boreholes were 2 m, 4 m, and 6 m. Under different gas drainage leading times, the total gas recovery and residual gas contents were quantified. In Longwall Panel 909 of the Wuhushan coal mine, one gas drainage borehole and five 4 m monitoring boreholes were drilled. After six months of monitoring, the residual gas content was obtained and compared with the simulation results. Of the total gas, 61.36% was drained out from the first 4 m borehole. In this field study, the effective drainage diameter of the drainage borehole was less than 8 m after six months of drainage. The gas drainage performance was tightly affected by the borehole size and the gas drainage time. It was determined that the field observations were in line with the simulation results. The findings of this study can provide field data for similar conditions.
format	article
author	Haibo Liu Zhihang Shu Yinbin Shi Xuebing Wang Xucheng Xiao Jia Lin
author_facet	Haibo Liu Zhihang Shu Yinbin Shi Xuebing Wang Xucheng Xiao Jia Lin
author_sort	Haibo Liu
title	Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
title_short	Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
title_full	Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
title_fullStr	Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
title_full_unstemmed	Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
title_sort	gas migration patterns with different borehole sizes in underground coal seams: numerical simulations and field observations
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/30907d48edae40dda701df7e5049d668
work_keys_str_mv	AT haiboliu gasmigrationpatternswithdifferentboreholesizesinundergroundcoalseamsnumericalsimulationsandfieldobservations AT zhihangshu gasmigrationpatternswithdifferentboreholesizesinundergroundcoalseamsnumericalsimulationsandfieldobservations AT yinbinshi gasmigrationpatternswithdifferentboreholesizesinundergroundcoalseamsnumericalsimulationsandfieldobservations AT xuebingwang gasmigrationpatternswithdifferentboreholesizesinundergroundcoalseamsnumericalsimulationsandfieldobservations AT xuchengxiao gasmigrationpatternswithdifferentboreholesizesinundergroundcoalseamsnumericalsimulationsandfieldobservations AT jialin gasmigrationpatternswithdifferentboreholesizesinundergroundcoalseamsnumericalsimulationsandfieldobservations
_version_	1718411125491499008

Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations

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