时空效应下水力冲孔有效影响半径研究

Study on Effective Influence Radius of Hydraulic Punching under Spatio-Temporal Effect

为提高煤体渗透率和瓦斯抽采效率,合理确定布孔参数的问题,采用数值模拟、现场试验的方法对水力冲孔有效影响半径进行分析,考察冲煤量、冲煤时间对有效影响半径的影响。研究结果表明:冲煤量越多,渗透率明显提高,其有效影响半径也逐渐增加,冲煤量0.8 t/m时为最优冲煤量,由压力分布曲线可知,在半径2 m范围内,瓦斯压力变化幅度大,随着影响半径的增加,瓦斯压力逐渐增加并趋近于原始煤层瓦斯压力,抽采90 d后其有效影响半径达8 m,研究结果可为煤层瓦斯抽采钻孔布置提供重要参考。

In order to improve the coal permeability and gas extraction efficiency and to reasonably de-termine the problem of laying parameters,numerical simulation and field test were used to analyze the effective radius of influence of hydraulic flushing and to investigate the influence of flushing volume and flushing time on the effective radius of influence.The results show that the permeability increases obviously with the increase of coal flushing quantity,and the effective influence radius also increases gradually.The optimal flushing volume is 0.8 t/m.From the pressure distribution curve,it can be seen that the gas pressure varies widely within the radius of 2 m.As the radius of influence increases,the gas pressure gradually increases and converges to the original coal seam gas pressure,and the effective influence radius reaches 8 m after 90 d of extraction.The results of the study can provide an important reference for the arrangement of coal seam gas extraction boreholes.