Study on dynamic response and failure mechanism of tubing string under pressure during the whole perforation process

To address the engineering problem of tubing-string and downhole-tool failures induced by transient pressure fluctuations during perforating operations in ultra-deep wells, this study moves beyond the limitation of analyses based on a single peak load. On the basis of transient pressure evolution simulation throughout the entire perforation process, a dynamic model of the perforating string is established by coupling the full-cycle effects of detonation pressure and dynamic underbalance pressure. Field test data from Well X1 in the Junggar Basin are used to validate the model accuracy. The relative error between the calculated and measured acceleration peaks is 8.62%, indicating that the model can effectively capture the acceleration peak and main oscillation characteristics during the early strong-impact stage of perforation. Taking an ultra-deep well in the Sichuan Basin as an example, the propagation and evolution characteristics of stress waves in the perforating string, the acceleration response behavior, and their sensitivity to key operating parameters are systematically analyzed. The results show that the detonation pressure peak directly governs the axial compressive stress level of the string, whereas the dynamic underbalance pressure trough plays a decisive role in axial tensile stress. Strong reflection and superposition of stress waves occur at the fixed packer end, making the packer and adjacent connection regions high-risk zones for tensile peak amplification, threaded-connection failure, and packer mandrel damage. This study establishes a relatively complete analytical framework from load evolution and dynamic response to failure-risk identification, providing a theoretical basis for tubing-string integrity evaluation throughout the entire perforation process.