Test tool for subsea blowout preventer stack

Abstract

A test tool adapted for use during pressure testing of a subsea blowout preventer stack is disclosed. The tool has an upper and a lower body connected in a first connection by left hand threads. A check valve landed in the bore of the tool prevents downward fluid flow from the interior of the tool, but allows upward flow through the tool and the attached drill pipe for the detection of leakage of the wellhead sealing tool about the wellhead during pressure testing of a blowout preventer in the stack. During testing of a shear ram blowout preventer, the upper body is disconnected from the lower body by turning the drill pipe to the right. Raising the drill pipe then causes the upper body to shift a second set of right hand threads into position and moves the upper body and the drill pipe from the bore of the shear ram allowing it to be closed for pressure testing. The lower body and a connected wellhead sealing tool may be retrieved without tripping the drill string by lowering the upper body for reconnection to the lower body by the right hand threads of the upper body engaging a second set of right hand threads on the lower body. After reconnection, drain ports are open in the tool allowing the drill pipe to be raised while draining drilling fluid from its interior.