Case Studies of Comprehensive Gas Control Method during Fully Mechanized Caving of Low-Permeability Ultrathick Coal Seams
Case Studies of Comprehensive Gas Control Method during Fully Mechanized Caving of Low-Permeability Ultrathick Coal Seams
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DOI：
10.1155/2021/5558678
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发表时间：
2021-07-22
期刊：
影响因子：
1.7
通讯作者：
Zhang, Jihua
中科院分区：
文献类型：
--
作者：
Jiang, Bangyou;Gu, Shitan;Zhang, Jihua
切片综放开采是特厚煤层标准高效开采方法。但瓦斯治理的成效加大了低渗透特厚煤层综放开采的难度。本研究主要针对中国新疆省刘皇沟煤矿 9-15 号煤的开采。为此，结合理论分析和现场试验结果，探索低渗透特厚煤层综放瓦斯综合治理方法。 (9-15)06号面板是9-15号煤的顶切面板，采高9m。瓦斯分析结果显示，(9-15)06 工作区瓦斯排放主要来源于煤壁、放顶煤、采空区及邻近煤层。提出了基于气源分离的综合瓦斯治理方法。该方法采用沿煤层预抽瓦斯、顶部高位钻孔、采空区预埋管道和平衡压力通风相结合的方法。低渗透煤层通过水力压裂提高渗透率和瓦斯预抽性能。根据煤层特征和地应力分布，设计了钻孔布置和后向分段压裂技术。从现场结果来看，煤层在水力压裂作用下呈现出明显的预压裂效果。此外，与水力压裂前相比，钻孔平均气体预排量提高了四倍。最后，采用所提出的基于气源的综合控制方法，在(9-15)06号面板进行了现场试验。测量结果表明，回风气体浓度波动范围为0.05%~0.35%。所提出的瓦斯治理方法可为其他类似工程提供有益的参考。
Slicing fully mechanized caving mining is a standard high-efficiency mining method for ultrathick coal seams. However, the effectiveness of gas control has accentuated the difficulty in fully mechanized top coal caving of low-permeability ultrathick coal seams. This study focused on mining the No. 9-15 coal in Liuhuanggou Coal Mine, Xinjiang Province, China. To this aim, the results of theoretical analyses and field tests were combined to explore a comprehensive gas control method for fully mechanized caving of low-permeability ultrathick coal seams. The No. (9-15)06 panel was a top-slicing panel of the No. 9-15 coal with a mining height of 9 m. Gas analysis results revealed that gas emissions in the No. (9-15)06 panel are mainly sourced from the coal wall, caving top coal, goaf, and neighboring coal seams. Based on gas source separation, a comprehensive gas control method was proposed. The proposed method was based on the combination of gas predrainage alongside the coal seam, high-position drilling on the top, preburial of pipes in the goaf, and pressure-balancing ventilation. The permeability and gas predrainage were enhanced by hydraulic fracturing in low-permeability coal seams. According to the characterizations of coal seam and crustal stress distribution, the arrangement of the boreholes and backward-segmented fracturing technology were designed. From the field results, the coal seam presented a remarkable prefracturing under hydraulic fracturing. Besides, the mean gas predrainage from the boreholes was enhanced by four times compared to the prehydraulic fracturing state. Finally, using the proposed comprehensive control method based on the gas sources, field tests were performed in the No. (9-15)06 panel. The measured results demonstrated that gas concentration in the return airflow is fluctuated within a range of 0.05% to 0.35%. The proposed gas control method can provide an insightful reference for other similar projects.