重复压裂总应力场计算模型

Computation model of total stress field while multiple fracturing

定量描述垂直裂缝井重复压裂前各种因素产生的诱导应力场分布状况计算模型的研究还不完整,为此系统地研究了引起垂直裂缝井重复压裂前原地应力场变化的主要因素,建立了重复压裂时的总应力场计算模型;综合应用渗流力学、岩石力学和热力学理论,建立了热—流—固三场耦合应力场计算模型。该模型对耦合渗流方程、耦合温度场方程采用有限差分法求解,对岩土变形方程则采用有限元法求解,并采用显示交替求解方式将其结合起来整体求解,可以得到热流固三场耦合作用下油/水井生产/注入引起的应力场变化,实现了对垂直裂缝井重复压裂前由于长期生产/注入活动产生的诱导应力场的定量分析和模拟,为现场实施压裂改造提供了指导。

Refracturing is a key way for enhancing productivity and recovery for the maturing oil field. Based on the stress change disciplinarian nearby the wellbore and the initial fracture, the mechanism of new fracture creation for refracturing is systematically studied and a total stress field mathematical model is abstractly presented in this paper. Integrating percolating mechanics and thermody- namics with rock mechanics, given the reservoir is elastic-plastic a thermal-hydrological-mechanical mathematical model is abstractly presented.; as solving, adopting the method of finite difference for percolating model thermal model, the finite element method （FEM） for rock-deformation model, the stress field resulted from change of pore pressure and temperature by oil production or injection is obtained. Quantitative analysis and simulation are also done for this induced stress field. Then a relevant example was given.