浅层砂岩垂直井分段压裂起裂压力研究

浅层砂岩垂直井分段压裂,初次裂缝压裂的产生会对后续缝的起裂压力产生影响.在综合考虑了原始井筒周围地应力场的基础上,结合叠加原理和弹性力学理论,建立了浅层砂岩诱导应力场中井筒周围应力场应力分布模型和起裂压力的计算模型.研究结果表明:诱导应力场的分布受裂缝缝长、裂缝间距和原始地应力场的影响.在初次裂缝缝长一定的前提下,裂缝间距越小对诱导应力的影响越大.在裂缝间距一定的前提下,裂缝缝长越长对诱导应力场的影响越大.

Study on Initiation Pressure of Staged Fracturing for Shallow Sandstone Vertical Wells

Based on the superposition theorem and elasticity theory,considering systematically influencing factors such as wellbore pressure,in-situ stress distribution,and induced stress produced by hydraulic fracture,a theoretical model for calculating initiation pressure of staged fracturing for shallow sandstone vertical wells was established.The law of initial and subsequent fractures initiation was studied.The results show that induced stress field distribution is influenced by fracture length,fracture spacing and initial geostress field;When the initial fracture length is constant,the smaller the fracture spacing,the bigger the influence for the induced stress;When fracture spacing is constant,the longer the fracture length,the bigger the influence for the induced stress.