【摘要】 针对页岩气藏水平井分段压裂中应力阴影的表征方法及影响因素不明确的问题,基于水平井分段压裂理论,借鉴水力压裂裂缝诱导应力产生机理,从单一垂直裂缝入手,利用应力叠加原理得出了多条裂缝应力阴影效应的数学模型。应用该模型分析了应力阴影的影响因素,结果表明:①泊松比与水平主应力方向的应力阴影呈线性关系,当泊松比为0.2~0.4时,最小水平主应力方向的诱导应力为0.36~0.72 MPa;②裂缝数量越多间距越小,应力阴影效应作用越强;③裂缝数量增加的同时也增大了施工难度,5条裂缝比3条裂缝的净压力增加了41.46%;④当裂缝间距小于100 m时,裂缝容易转向形成缝网;⑤裂缝间距是缝高的1.5倍时,应力阴影效应非常小,超过2倍后可以忽略不计。上述结论对合理利用应力阴影效应进行水平井分段压裂优化设计具有指导意义。更多还原

【Abstract】 This paper aims to make a better understanding of the stress shadow in the staged fracturing horizontal shale gas wells based on the relevant theory in this field,and the induced stress mechanism of hydraulic fractures,in terms of a single vertical fracture,a stress shadow effect mathematical model for multiple fractures was built by using the stress superposition principle.Then the model was used to analyze the influencing factors of stress shadow,and the results show that:①the Poisson’s ratio has a linear relationship with the stress shadow in the direction of the horizontal principal stress.When the Poisson’s ratio was 0.2-0.4,the induced stress in the minimun horizontal principal stress direction was 0.36-0.72 MPa.②the more the fractures,and the smaller the fracture spacing,the stronger the stress shadow effect will be;with the increase of fracture number,the difficulty of fracturing operation rises.The net pressure of making five fractures was 41.46%higher than that of making three fractures;when fracture spacing is less than 100 m,fractures are likely to divert into a network.③when the fracture spacing is 1.5 times the fracture height,the shadow stress effect is very small,and when the fracture spacing is more than 2 times the fracture height,the stress shadow effect is negligible.These conclusions have very good guiding significance to the rational utilization of stress shadow effect in the design of the staged fracturing of horizontal wells.更多还原