顺层钻孔瓦斯抽采合理封孔深度

The Reasonable Sealing Depth of Horizontal Drilling Gas Extraction

为确定顺层钻孔瓦斯抽采合理封孔深度,基于实际地质条件,运用理论分析、数值模拟和现场试验相结合的方法,对薛湖煤矿2306运输巷侧帮卸压带范围及合理顺层钻孔瓦斯抽采封孔深度进行研究.研究结果表明:钻孔初始瓦斯流量与地应力、钻孔直径、钻进深度、钻进时间、煤体的物理性质以及瓦斯压力梯度密切相关,且当钻进方式和煤层确定时,影响钻孔初始瓦斯流量的主要因素为瓦斯压力梯度;当瓦斯压力梯度确定时,随着钻进深度的增加,钻孔初始瓦斯流量也逐渐增加,且钻孔初始瓦斯流量与瓦斯压力梯度之间存在明显的线性关系;数据显示封孔深度为10 m时可实现瓦斯的持续性抽采,而连续流量法测得的卸压带宽度为0~10 m,验证了连续流量法所测得的卸压带宽度的准确性.

In order to determine the reasonable sealing depth of the horizontal drilling gas extraction,based on the actual geological conditions,the reasonable sealing depth of the horizontal drilling gas extraction on the side of the transport lane 2306 in Xuehu Coal Mine is studied by using the method of field test,theoretical calculation and numerical simulation.Results show that the initial gas flow rate of borehole is closely related to ground stress,diameter of borehole,drilling depth,drilling time,physical properties of coal body and gas pressure gradient,and the main factor affecting the initial gas flow rate of borehole is gas pressure gradient when drilling mode and coal seam are determined.When the gas pressure gradient is determined,the initial gas flow rate of borehole increases with the increase of drilling depth,and there is an obvious linear relationship between the initial gas flow rate of borehole and gas pressure gradient.The accuracy of the pressure relief width measured by the continuous flow method is verified by the realization of continuous linear gas extraction when the width of the relief band measured by the continuous flow method is 0~10 m and the hole sealing depth is 10 m.