致密油层多簇裂缝扩展缝内注入压力与缝间应力场耦合响应研究

Research on the coupling response between fractures injection pressure and stress field during multi-fractures propagation in tight reservoir

针对致密油层体积压裂过程中缝内注入压力与缝间应力场耦合响应问题,建立了多簇裂缝扩展流-固耦合模型,采用裂缝扩展单元表征岩层破裂与渐进扩展,协同计算多个求解域、模拟多裂缝同步延伸,研究多簇裂缝扩展过程中缝内注入压力与缝间应力场的动态变化,定量评价射孔簇间距对流-固耦合响应的影响规律。研究结果表明:多簇裂缝扩展缝间应力场干扰导致裂缝延伸压力上升,而缝内高压流体诱导缝间应力场转向;减小射孔簇间距有利于增大缝间应力干扰,但导致多裂缝延伸压力差异显著;应优化射孔方案调控流-固耦合影响,促进多裂缝均衡扩展。本文研究成果可为水平井多簇裂缝均衡扩展调控提供理论依据。

Aiming at the coupling response between multi-fractures injection pressure and stress field during volume fracturing in tight reservoir,a fluid-solid coupling model of multi-fractures propagation is established.Fracture propagation element is used to characterize rock fracturing and progressive propagation,to collaboratively calculate multiple solution domains,and to simulate the synchronous extension of multi-fractures,so as to study the dynamic changes of injection pressure and stress field during the propagation of multi-fractures,and to quantitatively evaluate the influence of perforation cluster spacing on fluid-solid coupling response.The results indicated that stress field interference between multi-fractures leads to fracture extension pressure increase,while high pressure fluid induces the local stress field re-orientation in correspond.Decreasing the perforation cluster spacing is beneficial to increase stress interference effect,but results in significant difference between multi-fractures extension pressures.Optimized perforation scheme should be applied to control the fluid-solid coupling effect and promote the uniform propagation of multi-fractures.The research results provide a theoretical basis for the control of uniform propagation of multi-fractures in horizontal wells.