Abstract: A method of installing a mechanical barrier in a wellhead includes receiving a false bowl within a bowl of a casing head housing of the wellhead, generating a first sealed interface between the false bowl and the bowl with one or more first seals arranged about an exterior of the false bowl, receiving a plug within the false bowl, generating a second sealed interface between the plug and the false bowl with one or more second seals arranged about an exterior of the plug, and receiving a back-pressure valve within the plug.

Abstract: A subsea tree assembly with a flow monitoring and measuring apparatus includes a production wing valve block coupled to a production wing branch, the production wing valve block including a wing block connector, and a fluid processing module including a frame, a module connector including an inlet and an outlet, and a fluid flow loop coupled between the inlet and the outlet, wherein the module connector is fluidicly coupled to the wing block connector. A production fluid flow goes from the production wing valve block and returns to the same block via the wing block connector, the module connector, and the fluid flow loop. A flow monitoring and measuring apparatus for a subsea tree assembly includes a module frame, a module connector connectable to a production wing valve block, the module connector including an inlet and an outlet, and a fluid flow conduit forming a loop from the outlet of the module connector back to the inlet of the module connector.

Abstract: Embodiments of the present disclosure include a system for coupling objects in a wellbore includes a unidirectional valve having a body. The body includes two or more body lugs extending radially outward, each body lug of the two or more body lugs extending at least a portion of a circumferential distance of the body. The system also includes a tubing hanger having a bore that receives the unidirectional valve. The bore includes an axial restraint system that receives the two or more body lugs and blocks axial movement of the unidirectional valve in a first position and enables axial movement of the unidirectional valve in a section position, the unidirectional valve being non-threadingly coupled to the tubing hanger.

Abstract: A valve assembly is installed within a wellhead such as a conventional tubing hanger or casing hanger used to suspend pipe or other tubular goods in a well. A seal bushing assembly is installed in a tubing head assembly or other wellhead component. A hanger valve assembly is stung into the seal bushing assembly and includes a valve that can be selectively opened or closed. In the open position, the valve does not restrict a central flow path diameter through the hanger and wellhead. In the closed position, the valve contains pressure and/or fluid flow and fully seals against wellbore pressure acting on the valve. A wellhead adapter covers the hanger valve assembly and provides an attachment point for a conventional Christmas tree or other wellhead equipment.

Abstract: A dual barrier lock screw for a wellhead assembly is provided that includes a first seal disposed at a first axial location along the body of the screw and a second seal disposed at a second axial location along the body of the screw, wherein the first and second axial locations are different from one another. The screw may also include a passage extending axially through the body of the screw and coupled to a port at the end of the screw. The port is configured to receive external pressure and allow testing of the dual barrier seals of the lock screws. A system that includes the lock screw and methods of operating and testing the lock screw are also provided.

Abstract: A method for testing an insert packer assembly positioned within a diverter assembly includes inserting a test tool through an opening of the insert packer assembly and into a bore of the diverter assembly. The method includes driving multiple annular flexible components of the insert packer assembly radially inward to contact an outer annular surface of the test tool to form a sealed space between the multiple annular flexible components and the outer annular surface of the test tool. The method also includes applying a fluid to the sealed space to increase a pressure within the sealed space and monitoring the pressure within the sealed space over a period of time to determine a condition of the insert packer assembly.

Abstract: A backspin reducing device for reducing an amount or a rate of backspin of a rod string when lifting the rotor apart from the stator of an oil or gas downhole progressive cavity pump. The backspin reducing device includes a substantially cylindrical housing having one or more threaded pin receptacles holding respective threaded pins in threaded engagement around a polished rod portion of the rod string of the progressive cavity pump. Turning threaded pins in their respective threaded pin receptacles causes the interior ends of the threaded pins to move towards or away from the polished rod in the center of the housing. Attached to the interior end of each threaded pin is a friction roller.

Abstract: The present invention relates to a device and to a method for blocking the outflow of a pressurized fluid from an underwater well, in particular, for blocking the outflow of crude oil and/or of natural gas, for carrying out an operation of closure of the well. In particular, the invention relates to a device and to a method for quickly stopping the flow and closing the well in case of incident and/or in case of fault of emergency shut-off devices of the underwater well, such as “blowout preventer” (“BOP”) systems, in order to reduce harm to the environment and economic losses due to fluid outflow from the well.

Abstract: A wellhead plug and a method for using a wellhead plug are presented. The ahead plug includes a plug body having at least a locking module, multiple sealing members, and a threaded connection tool. The wellhead plug according to the present disclosure offers multiple advantages over existing technologies. For example, the device may serve duplex roles as a wellhead pressure plug and/or a connection test tool. The device may, for example, serve as a blowout preventer (BOP) connection test tool, as well as an emergency drill pipe hang off tool (EDPHOT). This Abstracts submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A system, in certain embodiments, includes a horizontal fracturing tree. The horizontal fracturing tree includes a first hydraulic fracturing bore configured to flow a first fluid, wherein the first hydraulic fracturing bore extends along a first horizontal axis, and the first horizontal axis is generally perpendicular to a vertical axis of a wellhead.

Abstract: The present disclosure relates to providing a hub coupled into a production tree, manifold, or other equipment, and a base module that is attachable to and retrievable from the hub. The base module may be reconfigurable. The base module may be configured to receive other modules that are reconfigurable, wherein the other modules are retrievable from the base module. The hub provides a dedicated space or support at or near the production tree or equipment for using the base module. An interface is provided between the base module and the production tree. A fluid conduit provides a fluid path across or through the interface. The hub may be part of the interface such that the module can fluidly couple to the fluid conduit and the production tree across the interface via the hub.

Abstract: A hydraulic connector (14) attaches a valve chamber (16) to a flow pipe (P) using a hydraulic clamp (20) to grab the pipe (P) or a flange (F). The valve chamber (16) contains a primary hydraulic ram (26) to telescopically extend a primary seal (28) on the ram (26) to close or open the outlet ports (22) by moving the primary seal (28) to permit flow through valve up flow tubes (34) to a riser (R). Outlet ports (22) in the cap valve (12), or an intermittent pipe (18), permit unrestricted flow while the connector (14) is being installed.

Abstract: A deepwater blow out throttling apparatus and method. The apparatus is sized to reach an equilibrium between the force of the oil flow against the equipment that constitute the apparatus during its assembly and the forces available from the ROV and the drill ship and connexion pipe to hold the pieces in position for assembly. This solution is applicable to all wells and requires sizing the diffusion transition spool and the throttling valves such that the forces of the flow of the free discharging oil can be overcome by the forces available from the ROV and drill ship. Downward loading from the drill ship during the throttling is applied as throttling generates forces and vibration that can exceed the physical strength of the riser piping and connections. Slow closing of the throttling device must be assured to avoid shocking (or water hammering) the oil well installation.

Abstract: A system in some embodiments includes a back pressure valve. The back pressure valve includes a body, a plunger disposed internal to the body, and a friction member disposed about the exterior of the body. The friction member is configured to expand radially to contact an internal surface of a bore. In some embodiments, a method includes disposing a back pressure valve into a straight bore and expanding a friction member of the back pressure valve radially into contact with an internal surface of the straight bore.

Abstract: Systems and methods for performing operations on a well include first and second flow control devices positioned between upper and lower sections of a conduit. An upper connector assembly engaged with the upper section includes connectors adapted for connection to a chemical stimulation device, a blowout preventer, or other well intervention apparatuses. A lower connector assembly engaged with the lower section includes connectors adapted for connection to a chemical stimulation device, a running tool, wellbore conduits, or other well intervention apparatuses. The two connector assemblies, above and below the flow control devices, enable sequential or simultaneous operations to be performed, and can enable operations to be performed independent of the state of the flow control devices.

Abstract: Internal tree cap (201) (ITC) adapted to be installed in the bore of a subsea well unit (301) or to an internal tubular element (303) of the same, comprising a locking element (209) for releasably locking the internal tree cap (201) to said subsea well unit (301) or internal tubular element (303). The ITC further comprises a fluid channel (215) extending through a fluid barrier between the lower and upper part of the internal tree cap (201), which fluid channel (215) is blocked by a burst element (217) adapted to break and open for fluid flow through the fluid channel (215) when exposed to a predetermined pressure difference over the burst element (217). The invention also relates to an ITC running tool (101) and a locking mechanism (117) for supporting the ITC in the tool.

Abstract: A seal assembly for use in a valve that maintains a seal during operational excursions of high temperature, such as during a fire. The seal assembly includes a eutectic material that retains an energizing element in place during normal conditions, which in turn keeps a secondary seal spaced axially away from a sealing position. During high temperature excursions, the eutectic material degrades and releases the energizing element. When released, the energizing element energizes a secondary seal that is in an annular space between a valve stem and valve housing.

Abstract: A retrievable bridge is provided which mounts to the top of a subsea tree to provide fluid communication between the production line of the subsea tree and a production flowline. The retrievable bridge mounts to the top of the subsea tree and preferably connects to a vertically oriented pipe of the production flowline. The retrievable bridge can be utilized to carry wear items such as chokes, subsea control modules, and flow meters which may require maintenance more often than other components of the subsea tree. By mounting these items along the flow passageway in the retrievable bridge the components are securely mounted and still available for maintenance/replacement without the need to remove the entire tree. In one embodiment, Intervention into the well is available without removing the retrievable bridge.

Abstract: A system useful for monitoring or controlling the back pressure of fluid in a wellbore is disclosed. The system may include: a choke assembly including: a housing having an inlet, an outlet, and a bore; a choke member disposed in the bore for controlling a flow of a fluid from the inlet to the outlet, and a rod coupled to the choke member and extending through the housing; a cylinder including: a housing having an axial bore; a piston, directly or indirectly coupled to the rod, disposed in the axial bore and separating the axial bore into a first chamber and a second chamber; a position indicating device fluidly coupled to the second chamber, wherein a change in volume of fluid in the second chamber causes a corresponding change in volume of fluid in the position indicating device, thereby indicating a change in the position of the choke member.

Abstract: A method for determining a position of a fluid discharge in an underwater environment, the method including: collecting data relating to an underwater area through at least two acoustic sensors; filtering and processing the data collected to identify the presence of the discharged fluid and the underwater area involved; forming a single stereoscopic image by combining the plurality of single three-dimensional images; and estimating the position of the fluid discharge on the basis of the stereoscopic image thus obtained.

Abstract: A system includes a back pressure valve. The back pressure valve includes a body, a plunger disposed internal to the body, and a friction member disposed about the exterior of the body. The friction member is configured to expand radially to contact an internal surface of a bore. A method includes disposing a back pressure valve into a straight bore and expanding a friction member of the back pressure valve radially into contact with an internal surface of the straight bore.

Abstract: A reinforced wellhead member for use during fracing operations. The wellhead member is preloaded at a flange section by creating compressive stresses via a ring that interacts with a tightening nut on a bolt. The bolt is rigidly attached to an adapter which may also be modified to create stresses on the flange of the wellhead member. The induced stresses counter the tensile stresses experienced by the flange during fracing operations, allowing a standard wellhead member to be utilized.

Abstract: A valve assembly for use in regulating a fracturing fluid that includes an actuating stem for actuating a gate, a balancing stem, and a backseat on the stem that defines a backseat seal when urged against a profile in the valve assembly. The backseat seal is energized by applying a force to an end of the balancing stem. An end of the balancing stem is enclosed within a plenum, so that the force on an end of the balancing stem can be applied by pressurizing the plenum. The assembly can be on an opposite side of the valve body/bonnet to create a backseat seal on a balancing stem/bonnet to allow changing the stem packing on the balance stem side while maintaining pressure integrity.

Abstract: The present invention provides a check valve comprising a valve housing (1,2), a substantially circular flapper (3), a valve seat (16) for the flapper (3), an expandable chamber (11) in fluid contact with a connecting port (8) for hydraulics fluid, and a piston (4) having a first and a second end, the flapper comprises a first (19) and a second (18) connection point and is pivotably connected at the first connection point (19), said flapper is capable of pivoting between a closed position in close contact with the valve seat (16) and an open position which allows fluid to flow through the valve, the piston (4) is in contact with the expandable chamber (11) and a pre-stressed compressible device (15), said piston (4) pivotably connected at the first end to the flapper (3) via the second connection point (18), wherein the compressible device (15) can move the piston (4) in a direction towards the valve seat (16), and that hydraulics fluid can move the piston (4) in a direction away from the valve seat when suff

Abstract: A blowout containment system is permanently positioned on the wellhead. The blowout containment system is relatively inexpensive, is always available and in place, it does not interfere with normal drilling operations, will capture all of the oil and gas emitted by the blowout, does not require special or unique sea surface or underwater apparatus or vessels, does not have any operational requirements that are different than those which drilling crews normally use and are already familiar, and is activated the using actions are similar to those used by drilling crews for well drilling and completion.

Abstract: A sealing mechanism is provided. In one embodiment, a system includes a connector configured to couple one or more flow-control valves to equipment installed at a well and an isolation sleeve configured to be retained by the connector. The isolation sleeve may include a seal and a hydraulically actuated piston disposed adjacent one another about a body of the isolation sleeve such that actuation of the piston engages the seal. Additional systems, devices, and methods are also disclosed.

Abstract: Sealing mechanisms are provided. In one embodiment, a system includes a connector configured to couple one or more flow-control valves to equipment installed at a well and an isolation sleeve configured to be retained by the connector. The isolation sleeve may include a seal and a hydraulically actuated piston disposed adjacent one another about a body of the isolation sleeve such that actuation of the piston engages the seal. The isolation sleeve may also include a mechanically driven actuator ring, where the actuator ring energizes a seal against the bore of a tubing hanger. Additional systems, devices, and methods are also disclosed.

Abstract: A method of, and system for, collecting and controlling hydrocarbons leaking from offshore sea bottom environments entail providing a concrete containment barrier and catenary gasket around the leak source, pumping concrete onto the catenary gasket, opening ports and valves in a containment vessel while it is positioned over the leak source, at least partially embedding the containment vessel in the pumped concrete, closing the ports and valves to capture leaking fluids, and communicating the fluids to the surface for further processing. The modular containment barrier may be placed around an existing or potential well site, or an operating well, abandoned well or sea bottom fissure to facilitate implementation of the method in the event of a leak.

Abstract: Methods and apparatus for diverting fluids either into or from a well are described. Some embodiments include a diverter conduit that is located in a bore of a tree. The invention relates especially but not exclusively to a diverter assembly connected to a wing branch of a tree. Some embodiments allow diversion of fluids out of a tree to a subsea processing apparatus followed by the return of at least some of these fluids to the tree for recovery. Alternative embodiments provide only one flowpath and do not include the return of any fluids to the tree. Some embodiments can be retro-fitted to existing trees, which can allow the performance of a new function without having to replacing the tree. Multiple diverter assembly embodiments are also described.

Abstract: An angled or inline choke for flowing drilling fluid to a choke and kill manifold, wherein the choke has a body with a bore, a connection can be sealed to the body and can have a connection bore in communication with the bore. A locking plate can index the connection to the body. The choke can have a cavity with a piston. A port can be in communication with the cavity to provide a hydraulic fluid to the piston. A choke bean in the bore can flow drilling fluid to the choke and kill manifold. A tip can connect to the choke bean with a rod. When the hydraulic fluid passes into the port, the piston can move within the bore and compress a choke element around the tip to cause restriction of the drilling fluid, enabling for control of a pressure of the drilling fluid.

Abstract: A pressure relief device is used to relieve pressure in a void within a wellhead housing. In one embodiment, the pressure relief device includes a plunger having a stepped plug, wherein the plug can be fully open to allow flow from the void, restricted to allow a predetermined flow to relieve pressure, or closed to prevent flow from the void. In another embodiment, the pressure relief device includes a vacuum puller that creates negative pressure in a vessel. As fluid in the void expands, it is able to enter the space formerly occupied by the plunger. In yet another embodiment, a rupture disc is used to prevent fluid from flowing from the void, through a passage, to the wellbore. If pressure in the void exceeds a predetermined value, the rupture disc yields and allows the trapped fluid to flow to the wellbore.

Abstract: An apparatus and method for containing oil from a deep water (greater than 1,000 meters) oil well is disclosed herein. The apparatus has an anchor section, a plurality of riser sections, an upper section and a flow tube. A pressure within the apparatus is equal to a pressure outside of the apparatus to prevent collapse of the apparatus, and to prevent crystallization. Oil is suctioned from the interior of the apparatus through the flow tube to a surface of the ocean.

Abstract: An apparatus and method for containing oil from a deep water (greater than 1,000 meters) oil well is disclosed herein. The apparatus has an anchor section, a plurality of riser sections, an upper section and a flow tube. A pressure within the apparatus is equal to a pressure outside of the apparatus to prevent collapse of the apparatus, and to prevent crystallization. Oil is suctioned from the interior of the apparatus through the flow tube to a surface of the ocean.

Abstract: A wellhead assembly for an injection tubing string is provided which allows a master valve to be closed without damaging the injection tubing string while still allowing for the use of a back pressure valve to isolate the tree. Wellhead assemblies and related methods of the present invention include a flange adapted to be connected between a wellhead and a Christmas tree. The assembly also includes a mandrel adapted to being inserted into the longitudinal bore of the flange, the mandrel having a port for communicating with an injection port which extends radially through the flange. The assembly further includes a hanger adapted to connect to the upper end of the injection string, wherein the hanger is further adapted to land in the longitudinal bore of the mandrel. The hanger includes a communication passageway for facilitating fluid communication between the port of the mandrel and the injection tubing string.

Abstract: A subsea wellhead assembly has a tubing hanger landed in a wellhead housing. A spool lands on the wellhead housing and has a bore with a laterally extending production flow outlet. A tree cap having an axially extending flow passage and a laterally extending production flow outlet lands within the bore of the spool. Upper and lower seals on the tree cap seal between the tree cap and the bore of the spool above and below the production flow outlet of the spool. An isolation tube on a lower end of the tree cap sealingly engages the production flow passage of the tubing hanger. The tree cap may be ran with the spool as an assembly and retrieved from the spool for workover operations.

Abstract: The invention describes a system for capping an abandoned well having production casing and surface casing. The system enables the effective sealing of the production casing volume from the surface casing volume such that any gases leaking from either volume can be independently released from independent valves. The system is particularly effective in improving the safety of re-entering an abandoned well.

Abstract: A wellhead assembly includes a tree cap having a production mandrel extending down into a production passage of a Christmas tree to form a seal. The tree has an annulus bore and an annular cavity at the upper end of the tree surrounding the upper ends of the production and annulus bore. A communication gallery leads between the annulus bore and the cavity. The tree cap also includes an annular sealing member that enters the cavity for sealing a communication gallery.

Abstract: Multiple ball launch assemblies comprise a plurality of ball launch pods disposed around an outer wall surface of a housing. The ball launch pods are operatively associated with a flow tube disposed within the housing. An actuator assembly rotates the flow tube to align a first opening in the flow tube with a first ball launch pod so that a first ball is launched into the wellbore. Further rotation of the flow tube aligns subsequent openings in the flow tube with subsequent corresponding ball launch pods so that subsequent balls are launched into the wellbore.

Abstract: The invention includes methods of collecting crude oil and apparatus which collect crude oil. In one implementation, a crude oil collection header apparatus comprises a collection reservoir. A plurality of fluid conduits is connected to feed crude oil to the collection reservoir. The fluid conduits respectively comprise a collection reservoir feed valve, a bypass valve, and a crude oil feed inlet received between the collection reservoir feed and bypass valves. A flow meter conduit is connected with multiple of the plurality of fluid conduits downstream of the respective bypass valves. A flow meter is operably connected with the flow meter conduit. A crude oil outlet is associated with the collection reservoir. Other aspects and implementations are disclosed.

Abstract: The invention includes methods of collecting crude oil and apparatus which collect crude oil. In one implementation, a crude oil collection header apparatus includes a collection reservoir and a plurality of fluid conduits connected to feed crude oil to the collection reservoir. The fluid conduits respectively include a collection reservoir feed valve, a bypass valve, and a crude oil feed inlet received between the collection reservoir feed and bypass valves. A bypass conduit to which the fluid conduits connect is received downstream of the respective bypass valves. The bypass conduit includes a gas separator device. A flow meter conduit is connected with the bypass conduit downstream of the gas separator device. A flow meter is operably connected with the flow meter conduit. A crude oil outlet is associated with the collection reservoir. Other aspects and implementations are disclosed.

Abstract: A wellhead assembly for an injection tubing string is provided which allows a master valve to be closed without damaging the injection tubing string while still allowing for the use of a back pressure valve to isolate the tree. Wellhead assemblies and related methods of the present invention include a flange adapted to be connected between a wellhead and a Christmas tree. The assembly also includes a mandrel adapted to being inserted into the longitudinal bore of the flange, the mandrel having a port for communicating with an injection port which extends radially through the flange. The assembly further includes a hanger adapted to connect to the upper end of the injection string, wherein the hanger is further adapted to land in the longitudinal bore of the mandrel. The hanger includes a communication passageway for facilitating fluid communication between the port of the mandrel and the injection tubing string.

Abstract: A safety valve system for removing down-hole tools from a coal-bed methane well. The system includes first and second horizontally opposed stuffer-blocks, a stuffer-box housing for housing the stuffer-blocks, a means for attaching said stuffer-box housing to a coal-bed methane wellhead, and a means for delivering fluid to move the stuffer-blocks between an open position and a closed position. In one embodiment, the safety valve system further includes a controller, at least one methane sensor, a stuffer-box position sensor, and a stuffer-block activation system. A control algorithm is stored on or in communication with the controller enabling the controller to control the position of the stuffer-blocks, moving the stuffer-blocks between an open and closed configuration, wherein the stuffer-blocks are maintained in an open configuration if the methane level is below a predetermined threshold level. The valve system may further comprise a free-rotating stripper-diverter atop of the valve system.

Abstract: A casing vent security device includes an in-line section in communication with a casing vent, the in-line section having an ambient air passageway for selectively allowing ambient air to pass through the in-line section and into the vent. The device further includes a plurality of sensors disposed within the in-line section for monitoring the ambient air passing through the in-line section. The device still further includes at least one mechanism for selectively occluding the passage of ambient air into the vent upon receiving a signal from the sensors. The device provides information on the plurality of sensors and the vent.

Abstract: A coupling switches control fluid from a tubing hanger to a downhole completion of a subsea well. The coupling, located between a tubing hanging running tool and a downhole completion, includes a coupling body and a tubing hanger. A hydraulic poppet switches control fluid flow from a first and second flow path. The hydraulic poppet includes an isolation sleeve for opening and closing a first and second inlet port. At least two perimeter seals provide fluid isolation for the first flow path. A retainer seal seals the coupling body against the second inlet port. A retaining sleeve holds the coupling body against the tubing hanger. A first and second circumferential seal are located on opposite ends between the coupling body and tubing hanger. The hydraulic poppet is adapted to move perimeter seals and the retainer seal to open and close the first and second inlet ports.

Abstract: A subsea production system is disclosed. The subsea production system may comprise a well head, a tubing spool, a tubing hanger, an annulus, a production tree, and a bypass flow path.

Abstract: A wellhead assembly is provided including a casing and a tubular member mounted over the casing. A flange extends from the tubular member. A generally elongated annular member is provided in the tubular member. The generally elongated annular member has a first end portion above the tubular member and second end portion below the first end portion. A seal is formed between the second end portion and the tubular member. A hanger may be suspended within the tubular member. In such case, a seal may be formed between the elongate annular member and the hanger.

Abstract: A method and assembly for recovering fluids from, or injecting fluids into, a well having a christmas tree; the fluids typically flow between first and second flowpaths in a continuous path. The assembly may be located within the main bore, or a side passage of the christmas tree. Embodiments of the invention allow the fluids to be fed to a processing apparatus, (e.g. a pump or chemical injection apparatus) for treatment, before being returned to the christmas tree. Optionally, the assembly may include a pump located inside the christmas tree body.

Abstract: A pressurized sealing arrangement suited for providing a seal between a valve stem and a valve body is provided. The sealing arrangement includes a piston that is restrained in and statically sealed to the valve body and which surrounds the valve stem. Contained within the piston is an annular seal packing that includes two sealing elements spaced apart by a spacer element. The piston includes a face acted upon by a process fluid flowing through the valve body in such a manner that the piston exerts pressure upon a lubricant cavity. The lubricant cavity is in fluid communication with the seal packing such that lubricant contained therein forms a lubricant ring around the stem. Lubricant is also thereby supplied to sealing elements of the packing seal. To prevent contamination of the seal packing, a removable cover is provided that encloses the piston and seal packing.

Abstract: A plug-dropping container used for releasing plugs or other objects into a wellbore during fluid circulation procedures. In one aspect, the plug-dropping container is used as part of a cementing head. The plug-dropping container comprises an elongated housing, and a canister disposed co-axially within the housing. The canister is configured to receive the plug, such as a drill pipe dart. A valve is disposed below the canister. The valve is movable from a plug-retained position where the plug is blocked, to a plug-released position where the plug may be released into the wellbore there below. In the plug-retained position, fluid is permitted to flow through the canister-housing annulus and around the valve.

Abstract: A cap for covering an open upper end of a subsea structure includes a base and a body. The base has a size, after shrinkage, at least slightly larger than the exterior of the open upper end of the subsea structure. The body is connected to the base and projects downward from the base. The body has an open bottom. The cap is positioned over the open upper end of the subsea structure with the base of the cap resting on the open upper end of the subsea structure and the body of the cap forms a wall around the exterior of the open upper end of the subsea structure for inhibiting the cap from slipping off the open upper end of the subsea structure.