Optimization design of structural parameters for the shear mechanism of the hydraulic blowout preventer ball valve in offshore completion operations

Abstract

The hydraulic-controlled blowout preventer ball valve shearing mechanism is a critical tool for cutting operation strings and sealing high-pressure underground oil and gas emissions during emergencies in offshore completion operations. This study aims to address the challenges faced by existing tools in shearing operation strings. First, a finite element numerical model of the ball valve shearing mechanism was established based on the Johnson-Cook model, and its accuracy was validated through shearing experiments. Next, a single-factor analysis was performed on key structural parameters of the ball valve shearing mechanism, including the blade edge rounding radius, valve seat angle, and shearing clearance. Finally, the response surface methodology was applied to determine the optimal structural parameters of the ball valve shearing mechanism. The results showed that the shearing torque of the ball valve shearing mechanism initially decreases and then increases with variations in the blade edge rounding radius, shearing clearance, and valve seat angle. The optimal structural parameters of the ball valve shearing mechanism were determined to be a blade edge rounding radius of 1.89 mm, a valve seat angle of 32.06°, and a shearing clearance of 1.91 mm. Under these conditions, the peak shearing torque obtained from the response surface analysis was 12.68 kN·m, while the peak shearing torque calculated from the finite element numerical model was 13.02 kN·m, with a relative error of 2.62%. Compared to the original design’s peak shearing torque of 16.92 kN·m, this optimization reduced the shearing torque by 22.34%, significantly enhancing the performance of the mechanism.