煤层顶板岩层水平井分段压裂技术是碎软低渗煤层发育区开发煤层气的一种新方法。 为 探究水平井空间位置对压裂裂缝扩展的影响规律，采用弹性力学和断裂力学理论建立考虑地层倾 角、井眼轨迹的裂缝扩展应力分析模型，理论分析裂缝扩展过程和影响因素，推导裂缝起裂、转向和 穿层扩展的临界水压，采用扩展有限元方法，揭示水平井井眼空间位置对压裂裂缝扩展的影响规 律。 结果表明:1 水平井筒和煤层空间相对位置影响着压裂裂缝的起裂、扩展和形态，主要影响因 素包括:垂直应力、顶板岩层水平应力、煤层水平应力、射孔角度、射孔深度、地层倾角、井筒距煤距 离、煤岩界面性质、煤和顶板岩石力学性质等因素。 2 射孔孔眼与地层夹角越小，压裂裂缝转向角 和转向距离就越大，压裂起裂压力就越高，裂缝高度不易控制，裂缝向顶板上部延伸长度大;井筒距 离煤层越近越有利于裂缝穿层扩展，裂缝起裂压力就越低，距离越远裂缝延伸压力越大;射孔孔眼 长度越大，裂缝起裂压力越低;煤层倾角增大至 45°时，裂缝主要在煤层顶板内扩展，裂缝延伸压力 高、波动大。 3 研究结果对一口水平井的射孔位置进行了优化，现场应用效果表明水平井眼空间 位置对压裂裂缝扩展影响的分析有助于煤层顶板岩层水平井分段压裂煤层气抽采模式的推广和 应用。

The staged fracturing technology of horizontal wells in the coal roof is a new method for the development of coalbed methane in the development area of soft，low⁃permeability coal seams. In order to explore the influence law of horizontal well spatial position on fractured fracture propagation，based on the related theories of elasticity and frac⁃ ture mechanics，a fracture propagation stress analysis model considering formation dip angle and wellbore trajectory is established. The crack propagation process and influencing factors were theoretically analyzed. The critical water pres⁃ sure for crack initiation，diversion and interlayer propagation is deduced. The numerical simulation is used to reveal the influence law of horizontal wellbore spatial position on fracture propagation. Results show that:1 the relative position of horizontal wellbore and coal seam space affects the expansion and shape of fractured fractures. It is mainly affected by factors such as vertical stress，horizontal stress of roof rock layer，horizontal stress of coal seam，perforation angle， perforation depth，formation dip angle，distance between wellbore and coal，coal⁃rock interface properties，roof rock and coal⁃rock mechanical properties. 2 The smaller the angle between the perforation hole and the formation，the lar⁃ ger the fracture turning angle and turning distance，the higher the fracture initiation pressure. Also，the crack height is not easy to control，the length of the crack extending to the upper part of the roof is large. The closer the wellbore is to the coal seam，the more favorable it is for the fracture to propagate through the layer，and the farther the distance is，the higher the fracture propagation pressure. The longer the perforation hole length，the lower the fracture initiation pressure. The longer the perforation hole length， the lower the fracture initiation pressure. When the dip angle of the coal seam increases to 45°，the fractures mainly expand in the roof of the coal seam，and the fracture extension pressure fluctuates greatly and the extension pressure is high. 3 The perforation position of a horizontal well is opti⁃ mized through the research results. The field application results show that the research results are useful to the pro⁃ motion and application of the staged fracturing coalbed methane drainage mode of coal roof horizontal well.