基于预设随机裂隙的煤层注水数值模拟研究

Numerical Simulation of Coal Seam Water Injection Based on Precast Random Fractures

为研究煤体内大量不规则裂隙对煤层注水效果的影响,通过MATLAB编程实现裂隙的随机分布,结合COMSOL软件进行煤层注水过程中渗流压力场、速度场与水分增量的数值模拟。研究结果表明:与注水孔相交裂隙的附近区域内,水压可达3.03 MPa,此类裂隙可延伸压力场的作用范围;随煤体内水分运移范围的逐渐扩大,平均渗流速度降低,48h后约为6.59mm·s^(-1),整体渗流速度趋向均衡;未与注水孔相交的裂隙同样可提升注水效果,且毛细作用力对提升煤体润湿效果的影响高于水压对提升煤体润湿效果的影响。

In order to study the effect of a large number of irregular fractures on coal seam,the random distribution of fractures were precast by MATLAB programming.The numerical simulation of the flow field,velocity field and moisture increment in the process of coal seam water injection was carried out with the help of COMSOL.The results show that the water pressure can reach up to 3.03 MPa in position around the fractures intersecting with boreholes,which can extend the action range of pressure field.As the transport scope of coal body water expands gradually,the average seepage velocity decreases.It can decrease to 6.59mm·s^（-1） after 48 hours and the overall seepage velocity tends toward equilibrium then.Fractures which do not intersect with boreholes can also improve the effect of water injection,and the influence of the capillary force to improve the wetting effect of coal body was higher than that of water pressure.