Research on Sealing Premium Connections in Corrosive CO2 Environments

To investigate corrosion and resulting changes in the sealing performance of premium connections in corrosive CO2 environments, we carried out a simulation analysis of their secondary current distribution and structural mechanics based on multi-physics field coupling. A finite element calculation model of Ф88.9 mm × 6.45 mm taper–taper premium connections (steel grade P110) was established using COMSOL6.0 general software. By analyzing corrosion laws under different environmental parameters, five internal pressures and tensile displacements were set. We simulated premium connections under different operating conditions using a secondary current distribution module. To investigate the distribution of the corrosion current density in premium connections under different operating conditions, the sealing performance before and after corrosion was quantitatively evaluated using a seal strength index. The results show that the current density is higher at the torque shoulder of the premium connections, which is more susceptible to damage. As the internal pressure increases, the current density in the inner wall of the column increases, and on the threads, the current density is highest at the rounded corners of the root of the thread, which is also more likely to be damaged. Under different internal pressures, although the sealing strength of the premium connections meets the sealing criterion, the corroded ones show a significant reduction in sealing performance. The results of this study provide a reliable theoretical basis for research on sealing premium connections in corrosive environments.