Consider Complex Boundary Injection Fluid And Injection Section Pipe Column Flow-solid Coupling Analysis

The detonation shock wave pressure generated after the detonation of the perforating charge can reach the GPa level,so that the perforating fluid moves violently and continues to propagate in the complex boundary of the narrow and small space of the perforating string.The existing research usually only applies the pulsating pressure of the perforating fluid as an external load to the string,which fails to fully realize the fluid-solid coupling of the perforating string.Therefore,a three-dimensional numerical model of perforating bullet-perforating gunperforating fluid-casing-reservoir is established by using LS-DYNA software,combined with ALE algorithm and Lagrange algorithm.The influence of explosive type on metal jet performance,penetration effect and casing damage is analyzed.Considering the pressure pulsation of the perforating fluid and the complex boundary conditions of the bottom hole,the fluid-solid coupling between the perforating fluid and the perforating string is realized based on the transient power module of FLUENT software,and the dynamic response mechanism of the perforating string is clarified.Based on the improved maximum heat release principle and Kamlet empirical formula,the analysis method of detonation velocity and detonation heat of perforating charge is improved.According to the C-J detonation theory and adiabatic index,the analysis formula of the explosive capacity of the perforating charge is derived.According to the conservation of energy and the expansion characteristics of explosive detonation products,the analysis method of detonation pressure and detonation temperature of perforating charge is established.The influence of explosive type on metal jet performance and penetration depth was analyzed by LS-DYNA software.Considering the propagation law of detonation shock wave in the perforating fluid and rigid wall,the pressure pulsation equation of the shock wave propagating to the rigid wall in the perforating fluid is established,and the analysis method of the pressure pulsation of the perforating fluid is preliminarily established.By using FLUENT software,the fluid dynamics model of perforating fluid pressure pulsation is established,and the pressure change process and change law of the key nodes of perforating fluid pressure pulsation are quantitatively analyzed,and the basic change law of perforating fluid pressure pulsation is verified.Based on the Euler-Bernoulli beam model,the fluid-solid coupling mechanical analysis model of perforating fluid and perforating string is established.Through the force analysis of the perforating string micro-element and the perforating fluid micro-element,the perforating string vibration equation considering fluid-solid coupling is established.The results show that the calculation error of the established method for analyzing the detonation parameters of perforating charges is less than 5 %.The type of explosive has a great influence on the metal jet performance and penetration performance.The new high explosive perforating bullet has a good effect on the penetration of high confining pressure reservoir.Through the post-processing function of fluid dynamics software,the fluid-solid coupling analysis of perforating fluid and perforating string is realized,and the dynamic response mechanism of string under the action of perforating fluid pressure pulsation and backflow is found out.The research in this paper can provide reference for the optimal selection of perforating charge,and also provide new ideas for the fluid-solid coupling problem of oil well string in complex underground environment.