高瓦斯低透气性煤层水力压裂数值模拟研究

Numerical simulation on hydraulic fracturing procedure of coal seam with high gas and low air permeability

针对高瓦斯低透气性煤层,采用RFPA2D-Flow软件,对水力压裂进行了数值模拟研究,再现了水力压裂过程中压裂孔周围裂纹的生成和扩展、渗透性和应力的变化。模拟结果表明:压裂过程中,裂纹规模和剪应力随着注水压力的不断增加而增大,并且剪应力的增加随着钻孔周围裂纹的扩展不断远离压裂孔,压裂孔周围的渗透性有了很大程度的提高,最大主应力和最小主应力随着注水压力的增加而减小。水力压裂的模拟结果对煤矿高瓦斯低透气性煤层的瓦斯抽采工作具有很重要的指导意义。

In view of the coal seam with high gas and low air permeability, by using numerical simulation software RFPA2D-Flow, the hydraulic fracturing procedure was numerically simulated, the generation and extensions of sur- rounding cracks in fracturing hole, and the change of permeability and stress in the hydraulic fracturing process were recreated The simulation results showed that： During the fracturing process, crack scale and shear stress in- creases rapidly with the increase of water injection pressure. The shear stress increases with the crack surrounding a borehole expand, and stay away from the pressure hiatus. The permeability around the fracturing hole has been greatly improved. The maximum principal stress and the minimum main stress decrease with the increase of injec- tion pressure. The simulation results of hydraulic fracturing have a very important guiding significance for gas drain- age in coal mine with high gas and low air nermeabilitv.