高瓦斯煤层群顶板定向长钻孔抽采技术研究

为了解决近距离煤层群瓦斯易超限问题，提出采用顶板定向长钻孔抽采技术。以万峰煤矿1201工作面为工程背景，采用数值模拟和理论计算方法，研究煤层开采后对邻近煤层的影响及合理的钻孔布置位置。受煤层开采影响，上下邻近煤层会发生卸压，导致瓦斯解吸，为了保障抽采效果，顶板定向长钻孔应布置在靠近回风巷的断裂带，在水平方向上要避开重新压实区。现场应用结果表明，瓦斯抽采过程可分为增长阶段、稳定阶段和衰减阶段，在稳定阶段抽采瓦斯浓度达60%～70%、瓦斯纯流量达5～6 m³/min、上隅角瓦斯浓度维持在0.3%～0.4%,抽采效果较好；增长阶段和衰减阶段抽采效果有所降低，分析认为这是由于断裂带范围未发展到顶板定向长钻孔位置和钻孔高度降低后钻孔完整性遭到破坏所致，可采取辅助措施对这两个阶段的邻近层和采空区瓦斯进行加强抽采。

Study on directional long borehole extraction technology in roof of coal seam group with high gas content

In order to solve the problem that the gas in contiguous seams is easy to exceed the limit, the directional long borehole extraction technology in roof is proposed. Taking 1201 working face of Wanfeng Coal Mine as an example, the influence of coal seam mining on adjacent coal seams and reasonable borehole layout position are studied by numerical simulation method and theoretical calculation method. Under the influence of coal seam mining, the upper and lower adjacent coal seams will be depressurized, resulting in gas desorption. In order to ensure the extraction effect, directional long boreholes in roof should be arranged in the fractured zone close to the return airway, and the re-compaction area should be avoided in the horizontal direction. The field application results show that the gas drainage process can be divided into growth stage, stable stage and attenuation stage. In the stable stage, the gas concentration reaches 60% to 70%, the pure gas flow reaches 5 m3/min、上隅角瓦斯浓度维持在0.3%～0.4%,抽采效果较好；增长阶段和衰减阶段抽采效果有所降低，分析认为这是由于断裂带范围未发展到顶板定向长钻孔位置和钻孔高度降低后钻孔完整性遭到破坏所致，可采取辅助措施对这两个阶段的邻近层和采空区瓦斯进行加强抽采。In order to solve the problem that the gas in contiguous seams is easy to exceed the limit, the directional long borehole extraction technology in roof is proposed. Taking 1201 working face of Wanfeng Coal Mine as an example, the influence of coal seam mining on adjacent coal seams and reasonable borehole layout position are studied by numerical simulation method and theoretical calculation method. Under the influence of coal seam mining, the upper and lower adjacent coal seams will be depressurized, resulting in gas desorption. In order to ensure the extraction effect, directional long boreholes in roof should be arranged in the fractured zone close to the return airway, and the re-compaction area should be avoided in the horizontal direction. The field application results show that the gas drainage process can be divided into growth stage, stable stage and attenuation stage. In the stable stage, the gas concentration reaches 60% to 70%, the pure gas flow reaches 5 m³/min to 6 m3/min to 6 m³/min, and the gas concentration in the upper corner is maintained at 0.3% to 0.4%, the extraction effect is good; the extraction effect decreases in the growth stage and attenuation stage, which is believed to be caused by the failure of the fractured zone to develop to the position of directional long borehole in roof and the destruction of the integrity of the borehole after the borehole height decreases, auxiliary measures can be taken to strengthen extraction in the adjacent coal seam and goaf in these two stages.