Impact of goaf gas drainage from surface vertical boreholes on goaf explosive gas zones

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS
Yuehan Wang , Guangyao Si , Bharath Belle , David Webb , Liang Zhao , Joung Oh
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Abstract

Goaf gas drainage is extensively employed in Australian gassy underground coal mines to manage safety and productivity and to mitigate gas emissions. As mining operations reach greater depths and produce higher levels of gas emissions, narrower spacing between adjacent vertical goaf boreholes and higher suction pressure are increasingly being adopted. While this proactive goaf gas drainage design enhances gas extraction efficiency, there is a concern that an increased amount of ventilation air might be drawn back into the deep goaf, potentially resulting in the formation of an explosive gas zone (EGZ) composed of methane-air mixtures. Extensive goaf gas drainage data from various Australian coal mines have undergone detailed analysis in preceding back analysis studies (Wang et al., 2022a, 2023). These findings serve as crucial validation input for a CFD model of the goaf, providing ventilation engineers with visualization of an otherwise inaccessible environment. In this paper, the simulation outcomes of the CFD model were integrated with Coward's triangle to demarcate potential EGZ within the active goaf areas. It indicated that the EGZ was pushed far away from the longwall face under the impact of intensive goaf gas drainage compared to the EGZ without the active goaf boreholes, exhibiting a ‘U-shaped’ distribution. Furthermore, this study delves into the gas drainage factors influencing EGZs in the goaf, emphasising the impact of various gas drainage designs on gas explosion risks within the goaf. Factors such as the number of active boreholes and completion depth are assessed, with the size of EGZ serving as a quantitative evaluation criterion. Therefore, this paper plays a pivotal role in optimising goaf gas drainage efficiency, striving to minimise gas emissions into the atmosphere while upholding the priority of mining and worker safety.

地表垂直钻孔排出的煤层气对煤层爆炸性气体区的影响
澳大利亚多瓦斯地下煤矿广泛采用煤层瓦斯抽放技术来管理安全和生产,并减少瓦斯排放。随着开采深度的增加和瓦斯排放水平的提高,相邻垂直巷道钻孔之间的间距越来越小,抽吸压力也越来越高。虽然这种前瞻性的煤层瓦斯抽放设计提高了瓦斯抽放效率,但也有人担心,更多的通风空气可能会被抽回深部煤层,从而可能形成由甲烷-空气混合物组成的爆炸性气体区(EGZ)。澳大利亚多个煤矿的大量煤层瓦斯抽放数据已在之前的回采分析研究中进行了详细分析(Wang 等,2022a, 2023)。这些研究结果为煤层气 CFD 模型提供了重要的验证输入,为通风工程师提供了一个可视化的环境。本文将 CFD 模型的模拟结果与 Coward 三角形相结合,在活跃的果穗区内划分出潜在的 EGZ。结果表明,与没有活跃羊槽钻孔的 EGZ 相比,在密集羊槽瓦斯抽放的影响下,EGZ 被推向远离长壁工作面的位置,呈现出 "U "型分布。此外,本研究还深入探讨了影响巷道内 EGZ 的瓦斯抽放因素,强调了各种瓦斯抽放设计对巷道内瓦斯爆炸风险的影响。研究评估了活动井眼数量和完井深度等因素,并以 EGZ 的大小作为定量评估标准。因此,本文在优化煤矿瓦斯抽放效率方面发挥了关键作用,在坚持采矿和工人安全优先的同时,努力将排放到大气中的瓦斯降至最低。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
International Journal of Coal Geology
International Journal of Coal Geology 工程技术-地球科学综合
CiteScore
11.00
自引率
14.30%
发文量
145
审稿时长
38 days
期刊介绍: The International Journal of Coal Geology deals with fundamental and applied aspects of the geology and petrology of coal, oil/gas source rocks and shale gas resources. The journal aims to advance the exploration, exploitation and utilization of these resources, and to stimulate environmental awareness as well as advancement of engineering for effective resource management.
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