Analysis Of Strength And Safety Of Packer Central Tube Under Perforating Impact Loading

In order to increase oil recovery and production of oil and gas wells,high-perforation,large-aperture perforations are continuously pursued,and the charge,charge density,and detonation energy of a single perforation charge are increased,often resulting in plastic bending and rupture of the perforated segment.And the packer center tube fracture accident.To understand the pressure pulsation of the perforation fluid,in order to clarify the dynamic response mechanism of the packer central tube under pulsating pressure,the strength and safety of the center tube of the packer were analyzed.Launched the "Strength Safety Analysis of Packer Center Tube under Perforating Impact Load".Applying the principle of unsteady flow in pressurized pipelines,a set of differential equations for damping pressure pulsation in perforating fluids is established.Using the theory of partial differential equations,a special solution equation for the pulsation law of perforating fluid pressure is obtained;based on the AUTODYN module,multi-substance flow solids are used.A numerical model for the detonation of a perforated projectile under borehole is established by the coupling method.The perforating fluid and the perforating projectile that produces the phase change are described by the Euler-Multimaterial model.The casing is described by the Lagrange model.Based on the natural connection between the theoretical basis of the two,the realization Fluid-solid coupling between the two.The key data of the numerical analysis results were extracted and the density,velocity and pressure pulsation of the perforating fluid were analyzed.Based on the AUTODYN module,a transient response model for the center tube of the packer was established,in which the perforating fluid and the perforating projectile with phase change were described by the Euler-Multimaterial model,and the casing and the perforated segment were described by the Lagrange model.The similar collaborative transformation of the ALE method realizes the fluid-structure coupling between the two.Really describes the detonation process of the perforating bomb,the violent movement of the perforating liquid in a confined space,and the dynamic response of the center tube of the packer.The key data were extracted to analyze the velocity and stress changes of the perforation segment string and the packer central tube.The control variable method was used to analyze the influence of the charge and charge density on the safety of the perforation segment string and the packer core tube.A numerical calculation model was established using a 7 "?12.65 mm TP140 bushing,27/8" ?7.82 mm P110 pipe,and 1 meter containing 16 perforations.After the initial reflection of the pressure wave,a maximum of 523 MPa is reached at the bottom end of the packer,which is greater than the maximum pressure before the injection.The maximum velocity 2m from the top of the perforation segment is 1.24 times that at 4m.The closer to the top of the perforation segment,the greater the axial velocity.The equivalent stress of the perforated section of the packer at the restraint end of 1669 mm is up to 940MPa;the closer to the restraint end,the faster the packer center tube reaches the stress peak,and the larger the peak value is,the maximum stress is 635 MPa.Maintaining the same amount of charge,the change in charge density has little effect on the power safety of the perforated segment string and packer center tube.Keeping the charge density constant,the maximum axial velocity of the perforated pipe string and packer central tube increases with the increase of the charge volume,and the closer the distance from the perforating bullet,the greater the velocity,reaching 53.8m/s;With the increase of the dose,the maximum stress of the packer's center tube increases to 902MPa;the closer to the restraint end of the packer,the greater the maximum stress value,the faster the increase,and the more obvious the stress concentration.This paper can provide a basis for the selection of high-temperature and high-pressure deep-hole perforating bullets and the strength and safety analysis of the column.