Collaborative optimization research on the formula and structure of CCUS well packer rubber cylinder

This article focuses on the degradation of sealing performance faced by the sealing cylinder of the carbon capture, utilization, and storage (CCUS) downhole packer under multi field coupling conditions of high temperature, high pressure, and CO 2 corrosive media. A systematic study was conducted on the collaborative optimization of material formulation and sealing structure. Four rubber formula samples were prepared based on different component ratios. Through accelerated corrosion experiments simulating actual working conditions, combined with corrosion behavior analysis and finite element numerical simulation, the evolution behavior of mechanical properties of each formula rubber in corrosive environments and its impact on sealing performance were systematically characterized. Based on experimental data and simulation results, select the No. 4 rubber formula with the best comprehensive performance. Further orthogonal experimental methods were used to optimize the key structural parameters of the rubber cylinder through multiple factors, revealing that the thickness of the rubber cylinder is the dominant influencing factor on the sealing performance. The optimized combination of structural parameters (height of 63 mm, thickness of 33 mm, shoulder width of 20 mm) significantly improved the stress distribution and contact state of the rubber cylinder. Compared with the unoptimized structure, the maximum equivalent stress decreased by 46.5%, the maximum contact stress increased by 155.95%, and the average contact stress and effective contact length increased by 62.3% and 13.1%, respectively. The results indicate that the optimization scheme significantly enhances the reliability and service life of the sealing system under harsh working conditions. This study provides theoretical support and technical path for the optimization design of packer rubber cylinder under extreme working conditions.