特厚煤层综放开采瓦斯运储区演化及定向钻孔抽采技术

Evolution of gas transportation storage area and directional borehole drainage technology in ultra-thick coal seam with fully mechanized caving mining

为解决特厚煤层综放开采工作面上隅角瓦斯超限的问题,采用物理相似模拟实验分析了典型高瓦斯特厚煤层的裂隙演化情况,同时,利用二维核密度估计方法研究了采场上方的瓦斯运储区分布规律,分析了钻孔抽采的最优层位,并进行现场工程应用。研究结果表明:采动覆岩的整体离层量呈开切眼侧高、工作面侧低的两峰分布,其中不规则垮落带高度为9.4 m,规则垮落带高度为38.0 m,裂隙带高度为158.0 m;瓦斯运储区呈动态的梯形分布,当推进至岩层发育稳定时,规则垮落带上部形成了明显的临时储集空间,该区域可作为瓦斯抽采优选层位,具体位置为距煤层顶板高10~40 m,距回风巷内5~40 m。试验周期内,上隅角瓦斯浓度出现了明显下降。

In order to solve the problem of gas overlimit in the upper corner of fully mechanized caving face in extra-thick coal seam,physical analog simulation experiment was used to analyze the fracture evolution of typical extra-thick gassy coal seam.At the same time,the two dimensional kernel density estimation method was used to study the distribution law of gas transportation storage area above the stope,the optimum stratum of drilling extraction was analyzed and applied in field engineering.The results show that the total bed-separated quantity of the overlying strata is a two-peak distribution of the high side of open-off cut and low side of working face,among them,the height of irregular caving zone is 9.4 m,the height of regular caving zone is 38.0 m,and the height of fissure zone is 158.0 m;the gas transportation storage presents a dynamic trapezoidal distribution,and when the rock formation develops steadily,an obvious temporary reservoir space is formed in the upper part of the regular caving zone,this can be used as the preferred layer for gas extraction,which is 10 m to 40 m away from the roof of coal seam and 5 m to 40 m away from the return airway.During the test period,the gas concentration in the upper corner decreases obviously.