顺层钻孔有效抽采半径影响因素及布孔间距研究

Study on the influencing factors of effective extraction radius and hole spacing of bedding boreholes

为确定顺层钻孔瓦斯抽采半径影响因素及布孔间距,基于贵州土层矿M12煤层赋存条件,建立瓦斯运移的多物理耦合数值模型,通过改变单一因素数值分析其对抽采半径的影响效果,并对单一钻孔和多钻孔抽采半径进行模拟研究。结果发现,通过流量法确定,在抽采时间达150 d时,抽采半径计算为2.2 m;由模拟分析发现抽采半径随着时间的延长不断增大,随钻孔孔径的增大而增大,随煤层初始渗透率的增大而增大,且增大的幅度随着抽采时间的延长而增涨,而抽采负压对有效抽采半径几乎没有影响;数值模拟分析表明,在抽采时间达150 d时,抽采半径模拟结果为2.1 m,受相邻钻孔抽采叠加的影响,其多钻孔抽采半径相对单个钻孔有所增大,约为单钻孔抽采半径的1.76倍,研究结果为现场合理布置抽采钻孔提供一定的理论依据。

In order to determine the influencing factors of gas extraction radius of bedding boreholes and the spacing of boreholes,a multi-physical coupling numerical model of gas migration was established based on the occurrence conditions of M12 coal seam in a mine in Guizhou.The effect of single factor on the extraction radius was analyzed by changing the single factor value,and the extraction radius of single borehole and multi-borehole was simulated.The results show that when the extraction time reaches 150 d,the extraction radius is calculated to be 2.2 m by the flow method.Through simulation analysis,it is found that the extraction radius increases with the extension of time,increases with the increase of borehole diameter,increases with the increase of initial permeability of coal seam,and the increase amplitude increases with the extension of extraction time,while the negative pressure of extraction has little effect on the effective extraction radius.According to the numerical simulation analysis,when the extraction time reaches 150 d,the simulation result of the extraction radius is 2.1 m.Affected by the superposition of adjacent boreholes,the extraction radius of multiple boreholes is larger than that of a single borehole.It is about 1.76 times of the extraction radius of single borehole.The research results provide a theoretical basis for the reasonable arrangement of extraction boreholes on site.