注水压力对低透气性煤层水力压裂增透效果影响研究

Research on water injection pressure of hydraulic fracturing on the low permeability effect of coal seam

对于低透气性煤层瓦斯瓦斯抽采难度加大问题,采用了水力压裂对煤层进行增透,与此同时,水力压裂中注水压力是一个控制压裂效果的关键参数之一。采用数值模拟方研究平煤十二矿己15-31040工作面煤巷条带区域注水压力煤层水力压裂效果的影响。从模拟结果可以看出,随着注水压力的增加,压裂影响半径亦随之增大。当注水压力增大到一定范围,注水压力的增大对压裂增透效果的影响意义不大。将数值模拟结果应用于现场实际工程中,在压裂施工中,未发生压裂事故,而且巷道顶板保持完好。压裂后本煤层瓦斯衰减系数原始区域减小了13.3倍,透气性系数比原始区域增大了21.2倍,而且与之同时,煤层进行水力压裂后,瓦斯抽采浓度和纯量大幅度提升,单孔抽采浓度和纯量为未压裂区域的2.94倍及13.5倍,压裂增透效果明显。

For the problem of increasing difficulty of gas extraction in low-permeability coal seam,hydraulic fracturing is used to improve the permeability of coal seam.Meanwhile,water injection pressure in hydraulic fracturing is one of the key parameters to control the fracturing effect.Numerical simulation was used to simulate and study the effect of hydraulic fracturing of coal seam with water injection pressure in the zone of coal roadway with Ji 15-31040 working face in Pingmei 12 mine.It can be seen from the simulation results that the influence radius of fracturing increases with the increase of water injection pressure.When the water injection pressure increases to a certain range,the increase of water injection pressure has little effect on the permeability improvement of fracturing.The numerical simulation results were applied to the actual field engineering,during the fracturing operation,no fracturing accidents occurred,and the roadway roof remained intact.Fracturing after the coal seam gas and attenuation coefficient of the original area reduced 13.3 times,coefficient of permeability is increased 21.2 times than the original area,and at the same time,with the coal seam after hydraulic fracturing,the concentration of the gas extraction and scalar greatly enhance,puckering extraction concentration and the scalar is not fracturing area of 2.94 times and 13.5 times of fracturing anti-reflection effect is obvious.