中文摘要：

多级燃速爆燃气体驱动裂缝扩展过程中,裂缝形态与裂缝中的气体压力相互影响相互制约。分析了井下爆燃气体流动特性,建立了裂缝内爆燃气体流动模型,引入多级燃速爆燃气体压裂具体边界条件,在半解析法定性分析裂缝内气体压力分布的基础上,求出了爆燃气体在裂缝中流动过程的数值解。根据线弹性断裂力学,弹性力学理论,推导出油井不同载荷作用下裂缝尖端应力强度因子,作为裂缝起裂依据;利用裂缝尖端J积分得到的能量释放率确定起裂后裂缝扩展速度。将裂缝内气体流动方程和裂缝体对爆燃气体载荷响应方程联合求解,在井筒多级脉冲气体压力曲线设定的条件下,可以计算出裂缝起裂、止裂压力;对每一时步进行分析,可以确定该时步裂缝扩展量,从而确定该时刻对应的裂缝长度。实现了多级燃速爆燃气体压裂气体流动和裂缝扩展的耦合过程描述,对现场压裂施工优化设计具有重要的指导意义。

英文摘要：

During fracture extension driven by detonation gas of multi-pulse combustion rate, the frac ture displacement and gas pressure in the fracture affect each other. Based on the flow behavior of detonation gas in oil wells, a model of detonation gas flow in preliminary fracture was established. By introducing boundary condition, the numerical solution was obtained based on semi-analytical solution of gas pressure distribution in facture. Using linear elastic fracture mechanics and elasticity, the stress strength at the fracture tip was deduced, which is the basis for fracture initiation. Energy release rate obtained using J-integral at the fracture tip was used to determine fracture propagation speed. The fracture initialion and arrest pressure can be obtained as well as the total fracture length by solving the equation of gas flow in fracture and the equation of crack spread assuming knowing the wellbore multi-pulse gas pressure curve. The coupling between detonation gas flow and crack spread was realized which is very important to oil well fracturing work.