顺层钻孔水力压裂有效影响半径确定与抽采效果分析

为了增加煤层透气性，提高煤层瓦斯抽采效果，以某矿501工作面煤层地质条件为工程背景，采用理论分析、数值模拟、现场试验等方法，对某矿煤层起裂压力、单次压裂时间、压裂流量、影响半径、压裂钻孔抽采效果等参数展开研究。结果表明，模拟压裂孔注水1 h后，煤层压力由压裂孔向周围迅速降低，最终呈现出以压裂孔为圆心的圆形区域的致裂范围，最大压裂半径达到8.315 m;当对压裂泵主动升压至38 MPa时，煤层瞬间破裂，压力回降，流量瞬间增大，且达到压裂泵额定流量值，此时，煤体破裂效果完美；4号压裂孔首次压裂已经接近压穿煤体，进行第二次压裂时，流量曲线增加比较平稳，说明该孔在之前已贯通大部分裂隙，压裂半径可达22 m;对水力压裂孔和普通钻孔进行抽采比较发现，压裂3号钻孔的瓦斯浓度平均达到17.68%效果最为显著，与普通钻孔相比其平均浓度为1号普通钻孔的4.77倍、2号普通钻孔的3.12倍。

Determination of effective influence radius of hydraulic fracturing in bedding drilling and analysis of drainage effect

In order to increase the permeability of the coal seam and improve the effect of coal seam gas drainage，this paper takes the geological conditions of the coal seam in the 501 working face as the engineering background and research goal.Based on the geological conditions of the coal seam in the 501 working face of a certain mine as the engineering background，this paper uses the methods of theoretical analysis，numerical simulation and field test to study the parameters of the coal seam fracturing pressure，single fracturing time，fracturing flow，influence radius，fracturing drilling and pumping effect of a certain mine.The results show that after one hour of water injection into the simulated fracturing hole，the coal seam pressure decreases rapidly from the fracturing hole to the surrounding area，and finally presents the fracturing range of the circular area with the fracturing hole as the center，and the maximum fracturing radius reaches 8.315 m.When the fracturing pump is actively boosted to 38 MPa，the coal seam ruptures instantly，the pressure drops back，the flow increases instantaneously，and reaches the rated flow of the fracturing pump.At this time，the coal fracturing effect is perfec.The 4# fracturing hole is close to penetrating the coal body for the first fracturing，and the flow curve increases relatively smoothly during the second fracturing，indicating that this hole has penetrated most of the fractures before，and the fracturing radius can reach 22 m.The comparison between hydraulic fracturing holes and ordinary drilling holes shows that the average gas concentration of fracturing 3# drilling holes reaches 17.68%，and the average gas concentration is 4.77 times higher than that of ordinary drilling holes，3.12 times of 2# ordinary drilling.