页岩气水平井分段压裂簇间形态干扰规律分析

Analysis of the interference between the morphology of fracturing clusters during multi-cluster staged fracturing of horizontal wells in shale reservoirs

针对页岩气储层水平井分段多簇水力压裂过程中单压裂段内的多个压裂簇之间存在的相互干扰规律不清晰的问题,基于弹塑性力学理论,利用Abaqus有限元模拟软件建立了平面应变有限元数值模型,并以缝长和缝宽为研究对象对3个压裂簇同时扩展的工况进行了分析。研究结果表明:簇间距是影响缝间干扰的最主要因素,随着压裂簇间距的增大,簇间应力干扰会逐渐减小,且各裂缝的扩展变得趋于均匀;地层弹性模量的增大会促进各射孔簇裂缝的纵向延伸,但却会阻碍裂缝的横向张开;另外,压裂过程中适当增大压裂液排量对于得到长宽缝较为有利。模拟结果较为全面的说明了簇间干扰的存在及其对裂缝形态的影响,可以在一定程度上为多段分簇压裂设计优化提供参考。

In order to understand the inter-cluster interference between different hydraulic fractured clusters within the single fracturing section of the shale horizontal wells during multi-cluster fracturing,a plane strain model is established by using ABAQUS finite element simulation software.The length and width of fracturing are used to analyze the case of simultaneous expansion of three fracturing clusters.The simulation results show that the interference between the fracturing clusters decreases with the increase of the distance between adjacent clusters,and the propagation of different fracturing becomes uniform.Moreover,increasing the elastic modulus of the shale formation promotes the propagation of the fractures longitudinally,but it hinders the crack opening of the fracture laterally.In addition,properly increasing the injection rate of fluid during fracturing is more advantageous for obtaining long and wide fractures,whereas the increase of fracturing fluid viscosity makes it easier to get short and wide fractures.The existence of inter-cluster interference will influence the morphology of fracturing clusters comprehensively,which can provide a reference for the design and optimization of multi-segment cluster fracturing to some extent.