Wang Xinfeng, Hao Fuxu, Xu Haofu, Zhu Chuanqi, Jiang Tian, Jiang Yunhui
College of Environment and Resources, Xiangtan University, Xiangtan, 411105, Hunan, China.
State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mine, Anhui University of Science and Technology, Huainan, 232001, Anhui, China.
Sci Rep. 2024 Oct 23;14(1):25046. doi: 10.1038/s41598-024-76071-z.
Extraction of gas from low-permeability thick coal seams poses challenges globally, attributed to low extraction efficiency, limited enrichment content, and extraction complexities. Investigating static fracturing in low-permeability thick coal seams holds substantial engineering significance and practical utility. This research delves into the current conditions in the Western region, characterized by low gas permeability and challenging extraction in thick coal seams. Through the utilization of FLAC and COMSOL, simulation schemes are devised to analyze the influence of borehole parameters on fracture efficacy, elucidating the mechanisms by which external loads and internal gas pressure impact coal seam permeability. Field monitoring tests are employed to evaluate and model gas extraction enhancement via borehole positioning. The results suggest that the application of a static fracturing agent inducing 40 MPa expansion stress, along with a 75 mm borehole diameter and 0.5 m spacing, effectively fractures low-permeability thick coal seams. The spacing between extraction and fracturing holes adversely affects gas extraction efficiency due to the limited range of static fracturing. Field experiments demonstrate that static fracturing significantly improves gas extraction from low-permeability thick coal seams, resulting in a twofold increase in average gas extraction purity post-fracturing. This study establishes a robust theoretical foundation for optimizing gas extraction and mining activities in challenging low-permeability thick coal seam environments.
从低渗透厚煤层中抽采瓦斯在全球范围内都面临挑战，原因在于抽采效率低、富集含量有限以及抽采复杂。研究低渗透厚煤层中的静态压裂具有重大的工程意义和实际应用价值。本研究深入探讨了西部地区的现状，该地区煤层透气性低，厚煤层抽采困难。通过利用FLAC和COMSOL软件，设计了模拟方案，以分析钻孔参数对压裂效果的影响，阐明外部载荷和内部气体压力影响煤层渗透率的机制。采用现场监测试验来评估并模拟通过钻孔定位提高瓦斯抽采量的情况。结果表明，施加40MPa膨胀应力的静态压裂剂，结合75mm的钻孔直径和0.5m的间距，能有效压裂低渗透厚煤层。由于静态压裂范围有限，抽采孔与压裂孔之间的间距对瓦斯抽采效率有不利影响。现场试验表明，静态压裂显著提高了低渗透厚煤层的瓦斯抽采量，压裂后平均瓦斯抽采纯度提高了两倍。本研究为在具有挑战性的低渗透厚煤层环境中优化瓦斯抽采和开采活动奠定了坚实的理论基础。
