Study on tubing string safety during perforation detonation in ultra-deep wells

To address the challenge of quantitatively predicting the wellbore pressure and the force of the tubing string below the packer during the perforation detonation, a prediction model for the wellbore pressure and the axial force of the tubing string is established. The evolution laws of the wellbore pressure and the axial force of the tubing are analyzed. The sensitivity analysis of four primary controlling factors is further studied. The obtained results indicate that the peak pressure of the wellbore at the bottom of the perforating gun is the cause of the tubing string failure. The relative error of the predicted peak pressure of the wellbore is 2.22%. The major sensitive parameters affecting the peak pressure of the wellbore at the bottom of the perforating gun and the peak axial force at the bottom of the tubing are ranked as follows: the initial wellbore pressure, the shot density, the explosive mass, and the perforating fluid density. The work presented can provide a theoretical foundation and technological basis for the quantification of the wellbore pressure and the force of the tubing string during the perforation detonation, which is critical for well completion design and wellbore safety evaluation.