顺层钻孔瓦斯抽采半径确定研究

Study on determining radius of gas drainage in drill holes along seam

为了准确确定顺层钻孔瓦斯抽采半径,以提高煤层的瓦斯抽采率,采用数值模拟和现场验证相结合的方法,建立了抽放孔内瓦斯流动模型以及瓦斯抽放数值模型,研究了瓦斯压力与其距孔壁距离以及时间的关系、钻孔周围围岩应力分布、瓦斯比流量分布,抽放影响下测试钻孔压力变化等。研究结果表明:模拟结果得出顺层钻孔瓦斯抽放有效半径为1.4~1.5 m,现场验证了顺层钻孔瓦斯抽放有效半径在1.5 m左右。数值模拟结果与现场验证结果相近,表明了数值模拟的可靠性,为其他类似顺层钻孔瓦斯抽放提供了借鉴。

In order to accurately determine the radius of the borehole drilling gas extraction and improve the gas extraction rate of coal seam. The numerical simulation and field verification method were used to establish the gas flow model and the gas drainage model. The relationship between gas pressure and its distance from the hole wall and the time,the stress distribution around the surrounding rock,the distribution of the gas flow rate and the change of the drilling pressure under the influence of the drainage were studied. The results show that the simulated drilling effective radius of the drainage is 1. 4 ~ 1. 5 m,the effective radius of the gas drainage is about 1. 5 m according to the field. The numerical simulation results are similar to the results of field verification,and the reliability of numerical simulation is shown,which provides reference for other similar borehole gas drainage.