Dynamic Response Of Perforating String Under Perforation Condition

The technologies of high perforation charge and high density shots are used during perforating in unconventional and deep-water wells,which causes the string bend,fracture and the packer releasing,broken in such bad working conditions.In order to reduce the damage of the string under the blast impact load and reduce the occurrence of perforation safety accidents,it is necessary to study the dynamic response of the perforation string under perforation conditions.This paper applies the theory of detonation theory and the knowledge of pipe string mechanics to analyze the output of perforating blast load and the force characteristics of perforating pipe string,and forms the damage criteria of string and packer under perforation conditions.On the basis of reasonable simplification of perforating string,the ANSYS/LS-DYNA finite element software is used to consider the number of projectiles,the amount of charge,the length of the tubing,the pressure of the formation,the pressure of the wellbore and so on.The numerical simulation of the load characteristics at different positions of the pipe string is carried out,through which the weak and vulnerable links at the bottom and the top of the tubing are revealed,and the strength and deformation of the perforating string and the dynamic response of the packer under different perforation conditions are obtained.A large number of numerical simulations are carried out for 5 "and 7" perforating guns.The empirical formula of the peak pressure at the key position of the wellbore(the bottom of the perforating gun,the bottom of the tubing,the packer)under different perforation conditions is fitted,and its accuracy is verified by the field measured data.In order to evaluate the safety of pipe string and packer under different perforation conditions,the safety assessment software for perforated tube string is designed and developed by C# language.The research in this paper is of great significance for improving perforation safety and reducing perforation accidents in oil and gas wells.