A novel in-seam borehole hydraulic flushing gas extraction technology in the heading face: Enhanced permeability mechanism, gas flow characteristics, and application
A novel in-seam borehole hydraulic flushing gas extraction technology in the heading face: Enhanced permeability mechanism, gas flow characteristics, and application
复制标题
新型掘进工作面煤层钻孔水力冲刷瓦斯抽采技术：增透机理、瓦斯流动特性及应用
DOI：
10.1016/j.jngse.2017.08.022
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发表时间：
2017-10-01
影响因子：
--
通讯作者：
Wang, Wei
中科院分区：
文献类型：
--
作者：
Zhang, Hao;Cheng, Yuanping;Wang, Wei
松软低透气性煤层掘进工作面是我国煤与瓦斯突出事故多发的高危区域之一。为了防治这些灾害，煤层钻孔瓦斯抽采技术因其施工成本低而得到广泛应用。为此，提出了一种新的煤层钻孔水力冲洗瓦斯抽采技术，利用水力冲洗技术提高煤层钻孔瓦斯抽采效率。本文以新井煤矿为工程背景，对这一新技术进行了详细的研究。首先，我们使用有限元方法模拟了该技术的增渗机理和水力冲洗钻孔的气体流动特性。在此过程中，考虑了煤体的应变软化特性以及煤体破坏对渗透率演化的影响。其次，考虑掘进工作面钻孔的发散特性和多钻孔在瓦斯抽采过程中的相互影响，设计了合理的瓦斯抽采方案。最后，在S5进风巷实施了瓦斯抽采方案，验证了模拟结果，评价了该技术的有效性，现场试验结果与模拟结果一致，验证了模型的正确性。采用该技术后，掘进工作面瓦斯抽采钻孔数减少了50%。相反，基于瓦斯抽采的浓度和流量分别增加了10倍和6倍，这导致瓦斯抽采时间减少了65%，煤矿巷道的月开挖长度增加了100%。结果表明，该技术是实现松软低透气性煤层掘进工作面高效瓦斯抽采和快速掘进的一种有效方法。(C)2017爱思唯尔B.V.保留所有权利。
The heading face in soft and low-permeability coal seams is one of the most high-risk areas for Chinese coal and gas miners because of the number of outburst-related accidents. To prevent and control these disasters, the in-seam borehole gas extraction technology is widely used because of its low construction cost. Unfortunately, few studies consider its gas extraction efficiency.Thus, a new in-seam borehole hydraulic flushing (ISBHF) gas extraction technology is proposed in this paper, where the hydraulic flushing technology is used to enhance the gas extraction of in-seam bore holes. Based on the engineering background in the Xinjing coal mine, a detailed study of this new technology is conducted. First, we model the permeability-increasing mechanism of this technology and the gas flow characteristics of the hydraulic flushing boreholes using a finite-element method. During this process, the strain-softening behavior of the coal mass and the effect of the coal mass failure on the permeability evolution are considered. Second, a reasonable gas extraction scheme is designed, which considers the divergent characteristics of boreholes in the heading face and the interactions among multiple boreholes in the gas extraction process. Finally, the gas extraction scheme is implemented at the S5 intake airflow roadway to verify the simulation results and to evaluate the efficiency of this technology.The field test results are consistent with the simulation results, which validates our model. Moreover,.using this new technology, the number of gas extraction boreholes in the heading face decreased by 50%. Conversely, the gas extraction-based concentration and flow increased 10- and 6-fold, respectively, which results in.a 65% decrease in gas extraction time and a 100% increase in monthly excavation length of the coal mine roadway. These results indicate that this new technology is a promising method to achieve efficient gas extraction and rapid excavation in the heading face of soft and low-permeability coal seams. (C) 2017 Elsevier B.V. All rights reserved.