Failure Analysis of Ram Body and Sealing Performance of Semi-Sealed Blowout Preventer

To study the working mechanism and failure causes of semi-sealed ram blowout preventer, the full-size simulation model of semi-sealed ram is established in this paper. The failure analysis and strength evaluation of semi-sealing ram are carried out. The simulation of the blowout preventer ram in the process of well sealing under different well pressure impacts is studied, and the stress and strain distribution law is found out, and the causes of rubber core seal failure are analyzed. The analysis results show that the groove root of the ram body just enters the yield deformation when the oil cylinder pressure exceeds a certain value, and the maximum von Mises stress occurs at the groove root of the ram body, and the stress concentration and fluid impact pressure lead to the premature fracture failure of the ram. It is also found that the stress concentration in the contact area between the rubber core and the upper end of the ram is the most obvious, indicating that the upper part of the rubber core is severely deformed due to extrusion because of well pressure, which will cause fatigue damage to the rubber core over time. Finally, the extrusion behavior of the contact part between the ram and the drill pipe is highly consistent with the shape of the high-stress zone in the simulation analysis, which proves that the simulation result is reliable.