Bibliographic Details
| Title: |
低渗煤层顺层射流轴向平面切缝技术卸压机制及应用研究. |
| Alternate Title: |
Study on pressure relief mechanism and application of axial plane cutting technology of bedding jet in low permeability coal seam. |
| Authors: |
牛心刚1,2 xingangniu@163.com, 张志刚1,2, 张永将1,2, 石必明3 |
| Source: |
Coal Science & Technology (0253-2336). Feb2026, Vol. 54 Issue 2, p287-301. 15p. |
| Subject Terms: |
*Gas extraction, *Permeability measurement, *Hydraulic conductivity, *Coalbed methane |
| Abstract (English): |
Hydraulic permeability increase technology is currently one of the key techniques for gas prevention and control. However, existing methods still suffer from issues such as discontinuous decompression zones and complex construction processes. To further improve coal seam decompression and permeability increase, a novel method of axial plane slotting using in-seam jet cutting is proposed. First, a theoretical model for plane slotting was established. followed by an analysis of how surrounding rock pressure and jet slotting parameters influence the development morphology of pressure-relief fractures. This revealed the pressure-relief and permeability increase mechanism of the axial plane slotting technique along the coal seam, and optimized the axial plane slotting parameters. Field application tests were conducted for three technologies: pre-extraction through boreholes along the coal seam, annular slotting through boreholes to increase permeability, and axial plane slotting through jets to increase permeability. The advantages and disadvantages of the three technologies were compared. The research findings indicate: When the lateral pressure coefficient is 1 and the confining pressure increases from 18.75 MPa to 40 MPa, the fracture development height exhibits a linear upward trend. Below 18.75 MPa, non-through fracture zones exist, and the larger the lateral pressure coefficient approaches 1, the larger the de-pressurized fracture zone becomes. When the horizontal slot spacing is 1.25 m or less, the de-pressurized fracture zone achieves full connectivity. With vertical slot spacing below 5 m, fractures between two rows of slots can form a connected zone. However, when vertical spacing exceeds 5 m, fracture connectivity between slots becomes difficult. For coal seams thicker than approximately 4 m, two rows of slots can be constructed. Field tests indicate that compared to the following-strike drilling pre-extraction technique and longitudinal annular slotting for permeability increase, jet axial planar slotting increases gas extraction concentration by 0.27 and 0.5 times, boosts net gas extraction by 1.43 and 2.35 times, and reduces the time to achieve extraction targets to 48 days. This further validates the effectiveness of the jet axial planar slotting pressure relief and permeability increase technique. [ABSTRACT FROM AUTHOR] |
| Abstract (Chinese): |
水力化增透技术是当前瓦斯防治的重要技术之一, 但现有水力化增透技术依旧存在卸压区域 不连续, 施工工艺复杂等问题, 为进一步提高煤层卸压增透效果, 提出了顺层射流轴向平面切缝新方法, 首先构建了平面切缝理论模型, 随后分析了围岩压力与射流切缝参数对卸压裂隙发育形态的影响, 揭示了顺层射流轴向平面切缝卸压增渗机制, 并优化了轴向平面切缝参数, 开展了顺层钻孔预抽技术、钻孔环形割缝增透技术、射流轴向平面切缝增透技术的现场应用试验, 对比了 3 种技术的优劣。研究结果表明: 采用复变函数的方法构建的顺层射流平面切缝受力模型, 能够准确地描述煤体内各点的应力场、应变场变化; 侧压系数为 1, 围压从 18.75MPa 不断增大到 40MPa 时, 裂隙发育高度呈现线性上升趋势, 围压小于 18.75MPa 时, 存在裂隙发育非贯通区, 且侧压系数越靠近 1 卸压裂隙区越大; 水平缝槽间距为 1.25m 或更小时, 卸压裂隙区得到充分贯通, 垂直缝间距在 5m 以下时, 两排切缝之间的裂隙能够形成贯通区, 但垂直缝间距大于 5m 时, 切缝之间难以形成裂隙贯通区, 而煤层厚度大于 4m 左右时可施工两排切缝; 现场试验表明, 与顺层钻孔预抽技术、顺层钻孔环形割缝增透技术相比, 射流轴向平面切缝增透技术可将瓦斯抽采浓度提高 0.27 倍和 0.5 倍、 将瓦斯抽采纯量提高 1.43 倍和 2.35 倍, 将抽采达标预期时间缩短为 48d, 进一步验证了顺层射流轴向平面切缝卸压增渗技术的有效性。 [ABSTRACT FROM AUTHOR] |
| Database: |
Energy & Power Source |
