Systems and processes for subsea marine managed pressure operations. One system includes a modified riser joint configured to fluidly connect inline with one or more riser joints. The modified riser joint and the one or more riser joints are connected to form a riser connecting a floating vessel with a wellhead. The system further includes a subsea pressure management sub-system configured to be operatively and fluidly connected to the modified riser joint at a subsea location.

A sub-plate mounted valve for installation in a sub-plate or manifold for controlling hydraulic systems, such as subsea blowout preventers. A spool (123) disposed within the valve is movable between an open position in which fluid flow is permitted from a supply port (108) of the manifold to a function port (106) of the manifold, and a closed position in which fluid flow is permitted between a return port (110) of the manifold and the function port (106). The spool (123) is moved between the open and the closed position by supplying pressurized fluid to a piston (126) disposed on the outside surface of the spool. One or more springs (130) may also act on the piston to bias the spool into the open or the closed position. To facilitate proper alignment of the valve within the manifold, the valve may be rotated within the manifold to align indicators (450, 452) corresponding to particular features of the manifold and the valve.

A sub-plate mounted valve for installation in a sub-plate or manifold for controlling hydraulic systems, such as subsea blowout preventers. A spool (123) disposed within the valve is movable between an open position in which fluid flow is permitted from a supply port (108) of the manifold to a function port (106) of the manifold, and a closed position in which fluid flow is permitted between a return port (110) of the manifold and the function port (106). The spool (123) is moved between the open and the closed position by supplying pressurized fluid to a piston (126) disposed on the outside surface of the spool. One or more springs (130) may also act on the piston to bias the spool into the open or the closed position. To facilitate proper alignment of the valve within the manifold, the valve may be rotated within the manifold to align indicators (450, 452) corresponding to particular features of the manifold and the valve.

A ball valve is provided. The ball valve includes a housing, a ball seat arranged in the housing, a ball member mounted within the housing and being rotatable relative to the ball seat between open and closed positions, the ball seat and ball member defining respective through bores, the ball member including a sealing surface, a bore surface and a leading edge surface extending between the sealing surface and the bore surface, the leading edge surface being configured to cut a body extending at least partially through the valve upon closure of the ball member, wherein said leading edge surface is truncated. The ball member may include a relief region proximate the leading edge surface.

A ball valve is provided. The ball valve includes a housing, a ball seat arranged in the housing, a ball member mounted within the housing and being rotatable relative to the ball seat between open and closed positions, the ball seat and ball member defining respective through bores, the ball member including a sealing surface, a bore surface and a leading edge surface extending between the sealing surface and the bore surface, the leading edge surface being configured to cut a body extending at least partially through the valve upon closure of the ball member, wherein said leading edge surface is truncated. The ball member may include a relief region proximate the leading edge surface.

A technique facilitates failsafe closure of a valve used in, for example, a subsea test tree. The technique utilizes a valve combined with a cutter oriented to sever well equipment passing through an interior passage of the valve. The valve is operatively coupled with an actuation system having an actuator piston which controls cutting and valve closure. The failsafe valve and the cutter are shifted to an open position by applying pressure in a control fluid chamber to shift the actuator piston. However, the actuator piston, and thus the valve and cutter, are biased toward a closed position via pressure applied in a pressure chamber and a gas precharge chamber. The combined pressure ensures adequate force for shearing of the well equipment and closure of the valve when hydraulic control pressure is lost. In some applications, additional closing force may be selectively provided to the actuator piston.

A technique facilitates failsafe closure of a valve used in, for example, a subsea test tree. The technique utilizes a valve combined with a cutter oriented to sever well equipment passing through an interior passage of the valve. The valve is operatively coupled with an actuation system having an actuator piston which controls cutting and valve closure. The failsafe valve and the cutter are shifted to an open position by applying pressure in a control fluid chamber to shift the actuator piston. However, the actuator piston, and thus the valve and cutter, are biased toward a closed position via pressure applied in a pressure chamber and a gas precharge chamber. The combined pressure ensures adequate force for shearing of the well equipment and closure of the valve when hydraulic control pressure is lost. In some applications, additional closing force may be selectively provided to the actuator piston.

This disclosure includes methods for testing hydraulically-actuated devices and related systems. Some hydraulically-actuated devices have a housing defining an interior volume and a piston disposed within the interior volume and dividing the interior volume into a first chamber and a second chamber, where the piston is movable relative to the housing between a maximum first position and a maximum second position in response to pressure differentials between the first and second chambers. Some methods include: (1) moving the piston to the first position by varying pressure within at least one of the first and second chambers such that pressure within the second chamber is higher than pressure within the first chamber; and (2) while the piston remains in the first position: (a) reducing pressure within the second chamber and/or increasing pressure within the first chamber; and (b) increasing pressure within the second chamber and/or decreasing pressure within the first chamber.

A subsea support system comprises: at least one component (501) which is configured to be fixedly connected to a pressure conductor (101) in a seabed; and a subsea support (601) which is configured to compliantly support the at least one component (501); wherein, when the at least one component (501) is fixedly connected to the pressure conductor (101), substantially all of a mechanical load (T) which is applied to the subsea support (601) is transmitted by the subsea support (601) to the seabed while the at least one component (501) is substantially free of the mechanical load and remains fixed relative to the pressure conductor (101).

A protection system for a drilling riser. The drilling riser includes a main drilling riser bore and a drilling riser annulus and extends from a floating installation to a location on a seafloor and is fluidly connected to a subsea BOP. The system includes a fluid conduit which extends from the floating installation to a lower region of the drilling riser. The fluid conduit is fluidly connected with the drilling riser annulus in the drilling riser. The fluid conduit provides at least one of a rapid pressure relief and a fluid bypass for the main drilling riser bore to prevent the drilling riser from an uncontrolled pressure build-up due to an inadvertent plugging or a restriction resulting in a maximum allowable working pressure (MAWP) of the drilling riser being exceeded, if a restriction, a plug or a blockage exists in the drilling riser annulus or in riser outlets.