倾斜煤层水力冲孔有效影响半径数值模拟研究

针对目前水力冲孔技术研究较少考虑倾斜煤层水力冲孔卸压范围随方向变化的特点及煤层倾角对水力冲孔卸压有效半径影响的问题,以某煤矿3号煤层为研究对象,利用多物理场耦合数值模拟软件COMSOL Multiphysics对倾斜煤层水力冲孔有效影响半径进行了数值模拟,研究了不同方向上的钻孔有效抽采半径。数值模拟结果表明:在冲孔作用下,抽采影响范围随抽采时间的增加而不断扩大,但扩展速度随时间下降;在冲孔卸压作用下,煤层渗透性大大增加,钻孔周边影响范围呈近似椭圆形分布;连续抽采90 d后,上部方向的影响半径为6 m左右,下部方向的影响半径为4 m左右,水平方向的影响半径为5 m左右;为了确保抽采达标,该煤层水力冲孔钻场横向钻孔布置间距设定为3.5 m左右,纵向钻孔布置间距为4.0 m左右。该研究结果对于优化水力冲孔工艺参数、指导抽采钻孔的准确布置、提升矿井的瓦斯治理效果具有重要的现实意义。

Numerical simulation research on effective influence radius of hydraulic punching in inclined coal seam

Current research on hydraulic punching technology seldom considers that pressure relief range of hydraulic punching in inclined coal seam varies with direction and influence of coal seam inclination on the effective radius of hydraulic punching pressure relief.In view of the above problem,taking the coal seam No.3 of a coal mine as research object,the effective influence radius for inclined coal seam under hydraulic punching was numerically simulated by using multi-physics coupling numerical simulation software COMSOL Multiphysics.The effective extraction radius of borehole in different directions was studied.The numerical simulation results show that under the action of punching,the range of extraction influences continues to increase with the increase of extraction time,but the expansion speed decreases with time.Due to the stress relief under punching,the permeability of coal seam is greatly increased,and the influence range around the borehole is approximately elliptic.After 90 days of continuous extraction,the influence radius is about 6 m in the upper direction,the influence radius is about 4 m in the lower direction and the influence radius is about 5 m in the horizontal direction.In order to reach the gas extraction standard,the horizontal drilling arrangement spacing of the hydraulic drilling tunnel of the coal seam is about 3.5 m,and the longitudinal drilling arrangement spacing is about 4.0 m.The research results have important practical significance for optimizing hydraulic punching process parameters,guiding the accurate layout of extraction boreholes,and enhancing the gas control effect of the mine.