With the oil and gas exploration and development shifting toward deep and ultra-deep formations，the temperature and pressure conditions of the wellbore are becoming more and more complicated，and the problem of seal failure of packer rubber cylinders attracts increasing attention. Based on the principle of thermal-mechanical coupling，a numerical calculation model of the rubber cylinder of packers in ultra-deep wells was established according to the temperature distribution characteristics of the wellbore of ultra-deep wells，which revealed the influence of the wellbore temperature in ultra-deep wells on the sealing ability and safety of the rubber cylinder. It is shown that with the increasing wellbore temperature，the axial compressive deformation and radial expansion deformation of the cylinder both grow，and the sealing performance of the cylinder climbs up. However，the safety of the cylinder after setting is degraded. Based on the dynamic load distribution characteristics of the wellbore during perforation completion of an ultra-deep well in Sichuan Basin，the limit distance between the packer and the perforation section is calculated to be 220 m. Therefore，it is recommended that the packer be designed to be set at a position 90 m further down from 6 810 m toward the well bottom to improve the sealing performance of the rubber cylinder after setting. The research provides technical references for the optimization of packer setting positions in ultra-deep well completion.

As oil and gas wells are gradually extended to deep and ultra-deep layers，the safety of completion strings during perforation has attracted more attention. Based on the principles of computational fluid dynamics，a perforated interval-packer detonation wave propagation model was established，revealing the detonation wave propagation and reflection rules in the wellbore completion fluid and clarifying the characteristics of the influence of completion fluid on detonation wave propagation. Research shows that the detonation wave propagation process demonstrates extremely strong non-periodicity and irregularity. When the detonation wave propagates to the packer position，the amplitude of the detonation wave pressure is reduced by up to 75.65%. The detonation reflected waves show better periodicity，and the amplitude of the detonation pressure waves is reduced by 23.4% when it propagates to the perforated interval. The density of the completion fluid not only has a great influence on the amplitude of the detonation waves during propagation，but also has a great interference on the waveform characteristics of the detonation waves. The viscosity of the completion fluid has almost no impact on the waveform characteristics of the detonation waves during propagation，and has a small impact on the amplitude of the detonation waves. With the impact of detonation waves on the completion string considered only，priority should be given to selecting a completion fluid system with low density and high viscosity to reduce the impact of detonation waves on the downhole completion string. The research results of this article provide a reference for the design of on-site completion fluid parameters for oil and gas wells.