地面L型井抽采采空区瓦斯适应性及其水平段位置优选

Adaptability of goaf gas extraction with surface L-shaped boreholes and the location optimization of its horizontal section

地面L型井抽采采空区瓦斯不仅可减少工作面上隅角瓦斯积聚,而且可获取洁净能源,已在我国多个矿区进行了试验性应用,瓦斯治理效果和经济效益显著,但部分地面L型井抽采效果与预期目标仍有一定差距。为改进L型井瓦斯抽采效果,基于采场岩移“三带”理论及工作面瓦斯运移规律,全面分析了L型井抽采采空区瓦斯的影响因素,对其适应性和L型井水平段位置优选进行了研究。研究结果表明,地面L型井抽采采空区瓦斯技术适宜于采空区涌出量占比高、U型通风和仰采工作面、采空区瓦斯资源量多的高瓦斯工作面。L型井的水平段应靠近工作面回风巷侧布置,垂直方向上,其起始点至终孔点应呈一定的下向倾角,起始点和终孔点高度应分别位于裂隙带上部和下部;水平方向上应位于裂隙发育区内且尽量靠近回风侧边界,同时建立了L型井水平段起始点与煤层底板的垂直距离和距回风巷水平投影距离的计算方法。

Gas extraction in goaf with surface L-shaped boreholes can reduce gas accumulation in upper corner of working face, while obtaining clean energy. It has been experimentally applied in many mining areas in China, achieving remarkable gas control effect and economic benefits. However, in some areas, the gas extraction effect of surface L-shaped borehole did not come up to expectations. In order to improve the gas extraction effect of L-shaped boreholes, based on the “three zones” theory of stope strata movement and the gas migration law of working face, the influencing factors of L-shaped boreholes gas extraction is analyzed, and the adaptability of L-type borehole and position optimization of its horizontal section is studied. The results show that the technology is suitable for high gas working faces with high proportion of goaf emission, U-shaped ventilation and upward mining face, and gas-rich goaf. The horizontal section of the L-shaped borehole should be arranged close to the side of the air return way of the working face. In the vertical direction, the starting point to the final hole point should have a certain downward dip angle, and the starting point and the final hole point should be above and under the fracture zone, respectively. In the horizontal direction, the horizontal section of the L-shaped borehole should be located in the fracture development area and as close as possible to the boundary of the air return side. At the same time, the calculation methods are given respectively, for the vertical distance to the coal seam floor and the horizontal projection distance to the the air return way from the starting point of the horizontal section of the L-shaped borehole.