A valve assembly (100) is disclosed, for controlling fluid communication along a well tubular (10). The valve assembly comprises: a hydraulically operated valve (40, 42) comprising a valve member (41, 43) which is movable between open and closed positions, and a hydraulic actuator (148) associated with the valve member for moving the valve member between these positions; a control system (146) for selectively controlling the flow of hydraulic fluid to and from the actuator, to operate the valve; a vent chamber (84) operatively connectable to the actuator, for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position; and a vent conduit (172) operatively connectable to the actuator, for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position, the vent conduit being exposed to fluid external to the valve assembly at the prevailing external pressure. The control system has a first valve closing state in which the vent chamber is isolated from the actuator and fluid exhausted from the actuator during movement of the valve member to its closed position is vented to an exterior of the valve assembly through the vent conduit. The control system has a second valve closing state in which fluid exhausted from the actuator during movement of the valve member to its closed position is vented into the vent chamber. The control system is configurable in a selected one of the first and second valve closing states according to an operating requirement of the valve. A control assembly for a valve, and a method of operating the valve assembly, are also disclosed.

A valve assembly (100) is disclosed, for controlling fluid communication along a well tubular (10). The valve assembly comprises: a hydraulically operated valve (40, 42) comprising a valve member (41, 43) which is movable between open and closed positions, and a hydraulic actuator (148) associated with the valve member for moving the valve member between these positions; a control system (146) for selectively controlling the flow of hydraulic fluid to and from the actuator, to operate the valve; a vent chamber (84) operatively connectable to the actuator, for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position; and a vent conduit (172) operatively connectable to the actuator, for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position, the vent conduit being exposed to fluid external to the valve assembly at the prevailing external pressure. The control system has a first valve closing state in which the vent chamber is isolated from the actuator and fluid exhausted from the actuator during movement of the valve member to its closed position is vented to an exterior of the valve assembly through the vent conduit. The control system has a second valve closing state in which fluid exhausted from the actuator during movement of the valve member to its closed position is vented into the vent chamber. The control system is configurable in a selected one of the first and second valve closing states according to an operating requirement of the valve. A control assembly for a valve, and a method of operating the valve assembly, are also disclosed.

An assembly includes an inlet hub (112) coupled to a first flow passage (124) located within a flow control module, the first flow passage having a first flow bore, a flow meter (144) associated with the first flow bore and positioned for top-down fluid flow, a choke (109) disposed in a second flow passage (136) having a second flow bore, and an outlet hub (119) coupled to a distal end of the second flow passage. A system includes a flow control module assembly (902) having an inlet (912) and at least two outlets (914, 916), a main line (920) in fluid communication with the inlet, a first branch line (922) coupled to the main line and to a first outlet (916) of the at least two outlets, and a second branch line (924) coupled to the main line and to a second outlet (914) of the at least two outlets, and a tie-in connector (918) coupled to the inlet of the flow control module assembly.

An assembly includes an inlet hub (112) coupled to a first flow passage (124) located within a flow control module, the first flow passage having a first flow bore, a flow meter (144) associated with the first flow bore and positioned for top-down fluid flow, a choke (109) disposed in a second flow passage (136) having a second flow bore, and an outlet hub (119) coupled to a distal end of the second flow passage. A system includes a flow control module assembly (902) having an inlet (912) and at least two outlets (914, 916), a main line (920) in fluid communication with the inlet, a first branch line (922) coupled to the main line and to a first outlet (916) of the at least two outlets, and a second branch line (924) coupled to the main line and to a second outlet (914) of the at least two outlets, and a tie-in connector (918) coupled to the inlet of the flow control module assembly.

The method of providing blowout preventer ram actuator which will move a blowout preventer shear ram into the bore of the blowout preventer and retract the blowout preventer shear ram from the bore of the blowout preventer, comprising providing a first and second piston, pressuring the second cylinder extension area to move the blowout preventer shear ram into contact with the pipe to be sheared while venting the second cylinder, sensing that the blowout preventer shear ram has contacted the pipe to be sheared, pressuring the first and the second cylinder to shear the pipe and pressuring the first cylinder to retract the shear ram.

The method of providing blowout preventer ram actuator which will move a blowout preventer shear ram into the bore of the blowout preventer and retract the blowout preventer shear ram from the bore of the blowout preventer, comprising providing a first and second piston, pressuring the second cylinder extension area to move the blowout preventer shear ram into contact with the pipe to be sheared while venting the second cylinder, sensing that the blowout preventer shear ram has contacted the pipe to be sheared, pressuring the first and the second cylinder to shear the pipe and pressuring the first cylinder to retract the shear ram.

In a subsea blowout preventer stack system with valves in the choke and kill lines with the need for failsafe operation or automatic movement of a safe position when the operating control signal is lost, a method of providing failsafe operation to the safe position comprising providing a hydraulic cylinder having a piston with a piston rod connected to the valve closure member, providing a first hydraulic supply at a first pressure to a first side of the piston to move the valve closure member to an actuated position, providing a second hydraulic supply at a second pressure lower than the first pressure to a second side of the piston to move the valve closure member to the safe position when the first hydraulic supply is removed.

In a subsea blowout preventer stack system with valves in the choke and kill lines with the need for failsafe operation or automatic movement of a safe position when the operating control signal is lost, a method of providing failsafe operation to the safe position comprising providing a hydraulic cylinder having a piston with a piston rod connected to the valve closure member, providing a first hydraulic supply at a first pressure to a first side of the piston to move the valve closure member to an actuated position, providing a second hydraulic supply at a second pressure lower than the first pressure to a second side of the piston to move the valve closure member to the safe position when the first hydraulic supply is removed.

In a blowout preventer body having a central bore a method of reducing the size and weight of the blowout preventer body while maintaining an acceptable stress level at working pressure comprising machining a portion of the blowout preventer body to proximate the final dimensions, pressuring the blowout preventer body to a higher pressure than the working pressure of the blowout preventer body to yield high stress areas of the blowout preventer body, and relieving the higher pressure from the blowout preventer body such that when the blowout preventer body returns to the non-pressured state the high stress areas will retain compressive stresses and when the blowout preventer body is then pressurized to the working pressure of the blowout preventer body the stresses will be at an acceptable stress level.

A system for determining a fault in a subsea blowout preventer (BOP) stack includes a first sensor and a second sensor adapted to measure one or more properties of a subsea operation. The system further includes a first power supply adapted to provide operational power to the first sensor and a second power supply adapted to provide operational power to the second sensor. The system also includes a first power failure indicator and isolator (PFII) associated with the first sensor and the first power supply, the first PFII measuring a first pair of waveforms to identify a first fault and a second PFII associated with the second sensor and the second power supply, the second PFII measuring a second pair of waveforms to identify a second fault.