Simulation and structural optimization of the sealing mechanical performance of a three-element rubber packer

The three-element rubber packer is designed for high-risk sealing in complex wells. The upper element endures the most stress and deformation, leading to fatigue. Despite design improvements, issues like uneven casing contact and excessive pressure differentials between elements persist. To improve sealing performance, the packer’s structure was optimized. Uniaxial tensile and compression tests were conducted on three rubber materials with varying hardness to characterize their mechanical properties. Using a third-order Ogden constitutive model, a 3D multi-body contact nonlinear finite element method was employed to analyze the impact of key design parameters. Results showed that friction and axial compression cause the upper element to experience the highest contact stress, while the middle and lower elements fail to achieve an ideal seal. Numerical simulations of deformation matched experimental results with errors of approximately 15.3%, 17.3%, and 12.2% for the upper, middle, and lower elements, respectively. Optimal parameters under specific conditions were identified: total thickness of 22 mm, sub-thickness of 18 mm, element heights of 85 mm (upper), 70 mm (middle), and 85 mm (lower), and hardness levels of 90 IRHD (upper), 80 IRHD (middle), and 70 IRHD (lower). The numerical method accurately predicts rubber deformation, and all elements remained within a good elastic range without significant extrusion.