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 for preventing hydraulic shock and water hammer in downstream equipment, the valve including a valve body with an internal oil dampening chamber, an orifice arranged within the oil dampening chamber, a flow dampener positioned between the valve inlet and the orifice, and a spring between the valve body and the orifice. The valve is pressure compensated based on the ambient fluid pressure.

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 modular hydraulic intensification system includes a housing configured to be deployed within a subsea landing string. The modular hydraulic intensification system also includes multiple hydraulic intensifiers positioned within the housing, wherein each hydraulic intensifier includes a first chamber configured to fluidly couple to a hydraulic fluid supply and a second chamber configured to fluidly couple to one or more landing string valves within a lower portion of the subsea landing string. The modular hydraulic intensification system further includes a shuttle valve fluidly coupled to the respective second chambers of the multiple hydraulic intensifiers, wherein the shuttle valve is configured to enable flow of an output fluid across the shuttle valve from the respective second chambers of the multiple hydraulic intensifiers and to block backflow of the output fluid across the shuttle valve toward the respective second chambers of the multiple of hydraulic intensifiers.

A valve assembly for controlling fluid communication along a well tubular that includes hydraulically operated valve that includes a valve member movable between open and closed positions, and a hydraulic actuator for moving the valve member; a control system for selectively controlling the flow of hydraulic fluid to and from the actuator; a vent chamber for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position; and a vent conduit for selectively receiving hydraulic fluid exhausted from the actuator when the valve member is moved to its closed position. The control system has a first valve closing state in which the vent chamber is isolated from the actuator. 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.

An apparatus 10 comprising a drilling tool 12 for locating in a wellhead 14. The drilling tool has fluid ports 16 therein. The apparatus further comprises a collar 18 which is mateable with the drilling tool, such that the fluid ports in the drilling tool are blocked by the collar when the collar is mated with the drilling tool. In embodiments, the drilling tool is a bit runnable drill string tool. In embodiments, the apparatus further comprises a bit runnable wear bushing 22. The apparatus can advantageously be used to perform a method of testing a blowout preventer (BOP) on the subsea wellhead.

Latch position indicator systems remotely determine whether a latch assembly is latched or unlatched. The latch assembly may be a single latch assembly or a dual latch assembly. An oilfield device may be positioned with the latch assembly. Non-contact (position), contact (on/off and/or position) and hydraulic (flowmeter), both direct and indirect, embodiments include fluid measurement systems, an electrical switch system, a mechanical valve system, and proximity sensor systems.

A valve seat for a valve is disclosed, the valve seat facilitating cutting of a body located within the seat. The valve seat includes a sealing surface for sealing with a valve member and an annular cutting component having a plurality of cutting teeth. The cutting teeth are circumferentially spaced and each defines an elongate crest. A valve is disclosed having a housing with a bore), a valve member and the valve seat. The valve seat is arranged within the housing in communication with the housing bore. The valve member is movable relative to the housing between an open position and a closed position.

A subsea test tree assembly is provided which includes at least one subsea test tree or SSTT, the SSTT including a valve having at least one of a cutting function and a sealing function, the valve being movable between an open position and a closed position via hydraulic fluid supplied to the valve through control lines; and a control system including a source of hydraulic fluid, the control system being arranged to supply hydraulic fluid from the source of hydraulic fluid to the valve of the at least one SSTT on detecting that the control lines have been sheared, to automatically move the valve to the closed position. A method of controlling a well using an SSTT assembly is also provided.