Study On Casing Strength Analysis And Protection Measures In Perforating Operation

The main function of oil and gas well perforation is to establish the oil and gas flow channel between well bore and reservoir,which is convenient for reservoir fluid to flow into wellbore and finally to the surface.During the perforating operation,the perforating bullet generates a huge jet velocity and a high temperature of tens of thousands of degrees at the moment of explosion,and the casing inevitably produces some damage.The damage forms include casing deformation and cracks,etc.The integrity failure of the casing seriously threatens the subsequent safety production.Aiming at this problem,this paper mainly studies the formation and casing force,casing strength and casing protection during perforating operation.Firstly,considering the elastic and plastic deformation of the formation and the fluid-solid coupling effect,the stress model of the formation-cement ring-perforated casing and the calculation method of casing strength are established.By means of finite element method,the calculation results of casing strength under different parameters such as casing size,perforation aperture,perforation density and perforation phase Angle are studied,and the influence law of different perforation parameters on casing strength is analyzed.Finally,the technical measures of protective casing in perforating operation are put forward,and a shaped perforating device is designed.The results show that the radial displacement of the casing increases with the increase of the perforation aperture,and the casing strength decreases with the increase of the perforation density.With the increase of the perforation phase Angle,the casing bearing capacity first increases and then decreases.The casing bearing capacity reaches its peak when the phase Angle is 45°,and the casing bearing capacity is minimum when the phase Angle is 0 ° or 180 °.The new perforating gun device and the perforating section casing detection device can timely measure the data of casing strength damage,so as to timely adjust the parameters in the perforating process or replace the casing,so as to ensure the safety of subsequent operations.