Abstract: Master valve and cable hanger system for deploying and making electrical connection to an electric submersible pump. A landing for the cable hanger (50) is in the through bore below the valve closure element. The landing has a seal area and a bore transverse to the through bore penetrating into the seal area for allowing electric connection to the pump. The cable hanger has a seal section having longitudinally spaced apart seals engageable with an interior of the seal area, electrical contacts disposed between the seals, and a lockdown profile. Flow ports are arranged to bypass seal area and seal section. A blanking plug (58) is disposed in the transverse bore to seal the seal area prior to insertion of the cable hanger.

Abstract: A snubbing plug containing a body and a piston is configured to be secured within a component of a mineral extraction system by an internal locking mechanism. A fluid passage extends at least partially through the piston of the snubbing plug. The snubbing plug is configured to selectively open the fluid passage during installation or removal of the snubbing plug.

Abstract: A circulation unit and an arrangement are arranged to continuously circulate drilling fluid during drilling. A housing is provided with a center bore arranged to accommodate a portion of a pipe. The center bore includes upper and lower sealing elements. The sealing elements are provided with center openings which, by the expansion of said sealing elements, are closable or fit tightly against the pipe by the abutment of an inner sealing surface against the pipe. Each of the sealing elements is connected in a fluid-tight manner to a packing pipe which is located in the housing and which is rotatable around the center axis of the center bore. The packing pipe is surrounded by a packing assembly fitting tightly between the periphery of the packing pipe and the housing.

Abstract: A circulation unit is for an arrangement arranged to continuously circulate drilling fluid during drilling. A housing is provided with a center bore which is defined by upper and lower annular sealing elements which are rotatably supported in the housing. The sealing elements are provided with a center opening which, by the expansion of said sealing elements, is closable or fits tightly against a pipe. A gate valve in a closed state forms a fluid-tight partition between upper and lower chambers in the housing. Each of the sealing elements is connected in a fluid-tight manner to a rotatable packer pipe surrounded by a packer assembly that fits tightly against the circumference of the packer pipe and against the housing. An arrangement is for the continuous circulation of drilling fluid during drilling, including as circulation unit arranged between upper and lower rotary units.

Abstract: An apparatus, method, and system for inserting and securing a high pressure transition tube of a fluid transfer tool assembly into a positive position whereby the seal element is packed off in the wellhead set point. Once attached the transition tube is pushed to contact the bit guide, secondary seal or bore machine prep. A lower nose compression seal is seated against transition tube and compressed using an energizer seal to isolate and protect lower pressure wellhead and well control equipment from the higher rated frack pressures or pushing the transition tube and lower nose isolation compression seal to contact the bit guide, secondary seal or bore prep. Pressure is applied to push a seal against the lower and upper compression ring locking them in place preventing movement to form a compression seal and isolating the high pressure passing through the transition tube protecting the wellhead assembly and well control equipment.

Abstract: A system in some embodiments includes a back pressure valve configured to mount in a mineral extraction system. The back pressure valve comprises a cylindrical body comprising a venting port coaxial with a longitudinal axis of the cylindrical body and a plunger disposed in the venting port, wherein the plunger comprises a stem that extends from the venting port into an adjacent cavity of the cylindrical body. In some embodiments, a method of operating a valve, includes biasing a plunger to an open position, biasing a valve locking mechanism to a locked position in relation to a bore of a mineral extraction system, and biasing a plunger to a closed position.

Abstract: A wellhead system includes a bypass sleeve for temporarily isolating portions of a wellhead assembly from pressurized fracing fluid. The bypass sleeve may include a generally tubular body having a tool interface, a lock ring disposed at least partially around the body, and an anti-rotation device coupled to the body. The anti-rotation device includes a resilient member disposed in a cavity in the body, and an anti-rotation member biased away from the body by the resilient member. The anti-rotation member extends radially outward from the body.

Abstract: Method and subsea sensors display system configured to display data about a blowout preventer (BOP) stack. The subsea sensors display system includes a display panel having plural universal subsea displays, each universal subsea display being configured to display a value measured by a sensor attached to the BOP stack; and a J-box electrically connected to the display panel and configured to provide electrical power to the display panel and to receive data from the display panel. The electrical power is provided from a pod provided on the BOP stack or from a battery when the pod is not available or from a remote operated vehicle (ROV) when connected to the display panel.

Abstract: An embodiment of a pressure control assembly for a wireline cable disposed in a wellbore comprises a housing frame, at least a pair of sealing devices disposed in the housing, the sealing devices defining an aperture for a cable to pass therethrough and a chamber therebetween, and a lubricant recirculation system for injecting and recirculating a lubricant into the chamber, the assembly operable to lubricate the cable and seal the cable, and maintain a predetermined pressure within the housing frame while the cable is disposed therein.

Abstract: A setting tool for hanging a tubular string includes: a tubular mandrel having an actuation port formed through a wall thereof; a debris barrier for engaging an upper end of the tubular string; and a piston having an upper face in fluid communication with the actuation port. The setting tool further includes: an actuator sleeve extending along the mandrel and connected to the piston; a latch releasably connecting the debris barrier to the actuator sleeve and for releasably connecting the debris barrier to the tubular string; a packoff connected to the mandrel below the piston and operable to seal against an inner surface of the tubular string, thereby forming a buffer chamber between the debris barrier and the packoff; and a passage. The passage: is in fluid communication with a lower face of the piston, is formed in a wall of and along the mandrel, and bypasses the packoff.

Abstract: A system for sealing a wellhead. The system includes a setting frame, a driver cylinder selectively applying an axial motion, an adaptor attached to the wellhead, and a power mandrel operatively attached to the driver cylinder. The system may also include a setting sleeve attached to the power mandrel, with the setting sleeve having a packer element, wherein the setting sleeve is responsive to a pressure applicator and retractor device so that the packer element is expanded within the master valve. A method of isolating a wellbore is also disclosed.

Abstract: An integral diverter system for diverting drilling fluid returns into flowlines connected to outlets for return to the drilling fluid reservoirs or other desirable locations is disclosed. The diverter assembly includes a lower tubular body that is coupled to a conductor and an upper tubular body having one or more diverter flow outlets, and one or more additional outlets. A connecting means secures the lower tubular body to the upper tubular body. One or more additional packer elements are disposed within the upper tubular body and locking means are provided for securing the one or more additional packer elements in position within the upper tubular body.

Abstract: A back pressure valve for sealing a wellbore. The back pressure valve has a cylindrical body with threads designed to engage threads in the opening of a tubing hanger within the wellbore. The back pressure valve also has a metal sealing surface. When the threads of the back pressure valve engage the threads in the opening of the tubing hanger, the metal sealing surface of the valve seals against the metal of the tubing hanger, forming a metal to metal seal.

Abstract: A well apparatus system that includes a wellhead, a tree, a tubing hanger, a tubing spool that is located between the wellhead and the tree, and a production isolator surrounded by the tree and the tubing spool. The tree component of this system can include a vertical or horizontal tree. More importantly, this system can be constructed in a number of different sequences. In addition, this well apparatus system allows for installation, retrieval, and/or work-over the tubing hanger and associated completion system without disturbance of the tree. The presented system also allows for installation and retrieval of the tree independent of the tubing hanger and associated completion system. Some embodiments can include valve-type mechanisms to serve as production environmental barriers. These mechanisms are integral to the production isolator.

Abstract: Wellhead-based systems, apparatus, and methods for controlling a well are provided. During a failure of an emergency system such as a blowout provider, a wellhead based emergency control apparatus according to an embodiment of the invention can be employed to control the well. A casing strings compression assembly can radially compress each of the casing strings and/or drilling pipe extending through the wellhead housing to restrict or stop well fluid passage. A casing strings penetrator of an emergency well fluid diversion assembly can also or alternatively be employed to form an aperture in the casing strings. A diverter, integral with or connected to the penetrator, is extended through an aperture in a side of the wellhead housing and one or more of the apertures cut by the penetrator to divert well fluid from within the wellhead housing through a passageway in the diverter and to an external conduit.

Abstract: A system includes a back pressure valve configured to mount in a mineral extraction system. The back pressure valve comprises a cylindrical body comprising a venting port coaxial with a longitudinal axis of the cylindrical body and a plunger disposed in the venting port, wherein the plunger comprises a stem that extends from the venting port into an adjacent cavity of the cylindrical body. A method of operating a valve, includes biasing a plunger to an open position, biasing a valve locking mechanism to a locked position in relation to a bore of a mineral extraction system, and biasing a plunger to a closed position.

Abstract: A wellhead system, in an embodiment, includes a first wellhead component with an internal bore, and a second wellhead component with a lower end disposed within the first wellhead component internal bore and an upper end disposed outside of the first wellhead component internal bore. The upper end of the second wellhead component has a groove disposed on an outer surface thereof. The wellhead system also includes a retaining member with a plurality of sections, wherein a portion of the retaining member is at least partially disposed in the groove on the second wellhead component, the retaining member is coupled to the first wellhead component, and an anti-rotation mechanism engages both the retaining member and the second wellhead component.

Abstract: An annulus isolation valve comprises a valve actuation bore and a flow passage capable of providing fluid communication between an upper annulus and a lower annulus. The flow passage comprises a first flow path and a portion of the valve actuation bore. Further, the first flow path has a second longitudinal axis that is different from a first longitudinal axis. The annulus isolation valve further includes a plug gate positioned in the valve actuation bore. The plug gate is configured so that in the open position it allows fluid communication between the upper annulus and the lower annulus. The annulus isolation valve further includes a biasing mechanism positioned in the valve actuation bore. The biasing mechanism is capable of forcing the plug gate into the closed position when the actuation force is not applied.

Abstract: A wellhead protection tool for simultaneously fitting within a lower portion of a tubing head and extending into a gate valve can have four portions with different diameters. A plurality of sealing grooves with seals can provide for sealing of the wellhead protection tool. A locking ring can engage the tubing head and injection portions thereof, allowing for continuous monitoring of seals between the tubing head and the gate valve using a client device at a remote location.

Abstract: A locking assembly for seals within inner and outer members. The locking assembly includes a segmented tube with an inner surface that is segmented into a plurality of pieces cut in radial or reversed angles to allow assembling segments in a circumferential groove machined in the internal diameter of a housing. The housing has an internal diameter that is smaller than the outside diameter of the segmented tube. The segments that make up the segmented tubing are locked into place within the housing via a bushing or locking ring that match a profile on the inner surface of the segmented tube to lockingly engage. The bushing and segmented tube retain a lower inner seal in place and support an upper inner seal. The segmented design of the segmented tube allows for smaller diameter members to be used and minimizes leak paths.

Abstract: A system and method are provided for direct connecting downhole control hydraulics through an oil field hanger, where the hanger is coupled to a wellhead, to hydraulic lines extending outside the wellhead. Further, the direct connection allows hydraulic system integrity with reduced contamination and leakage. Hydraulic tool ports, formed on the hanger, are coupled with hydraulic lines extending downward to a hydraulic tool. Side ports, formed in the hanger, are fluidicly coupled to the hydraulic tool ports. Hydraulic lines extending outside the wellhead are directly coupled with the side ports by accessing the side ports through access openings in the wellhead when the ports are aligned with the access openings. The system can still maintain pressure within internal spaces of the wellhead after the connection by sealing the access openings with flanges, where the hydraulic lines extend through openings in the flanges that are also sealed around the lines.

Abstract: A master ball valve with an integrated main hanger below the valve which may be used to hang jointed tubing, coil tubing, or electrified coil tubing for connection with an electric submersible pump.

Abstract: A system and method are provided for direct connecting downhole control hydraulics through an oil field hanger, where the hanger is coupled to a wellhead, to hydraulic lines extending outside the wellhead. Further, the direct connection allows hydraulic system integrity with reduced contamination and leakage. Hydraulic tool ports, formed on the hanger, are coupled with hydraulic lines extending downward to a hydraulic tool. Side ports, formed in the hanger, are fluidicly coupled to the hydraulic tool ports. Hydraulic lines extending outside the wellhead are directly coupled with the side ports by accessing the side ports through access openings in the wellhead when the ports are aligned with the access openings. The system can still maintain pressure within internal spaces of the wellhead after the connection by sealing the access openings with flanges, where the hydraulic lines extend through openings in the flanges that are also sealed around the lines.

Abstract: A method of completing a well having a casing hanger set in a subsea wellhead housing includes attaching a running tool to a tubular bridging hanger. A metal-to-metal inner seal is attached to a lower exterior portion of the bridging hanger and a metal-to-metal outer seal is located on an upper exterior portion of the bridging hanger. The assembly is lowered into the well and the lower exterior portion of the bridging hanger is inserted into the casing hanger. The inner seal is wedged between the casing hanger and the bridging hanger in response to weight of the running string. The running tool is actuated to set the outer seal between the upper exterior portion of the bridging hanger and the wellhead housing. Then, a tubing hanger is landed and sealed in the interior of the bridging hanger.

Abstract: A retrievable frac mandrel and a well control adapter are used to efficiently accomplish well completion, re-completion or workover. The retrievable frac mandrel is inserted in a tubing head spool of a well to be completed, re-completed or re-worked. The well control adapter is mounted to a top of the tubing head spool and seals off against a top of the retrievable frac mandrel. After well completion, re-completion or workover is completed, the frac mandrel can be retrieved from the tubing head spool without killing or plugging the well.

Abstract: An isolation sleeve and plug assembly that may be used to protect a wellhead assembly from being damaged by high-pressure wellbore fracturing operations. Both the isolation sleeve and plug may be installed by the same running tool, and may be installed by lowering the running tool through an isolation valve on the wellbore.

Abstract: A well system comprising a tubular housing, a hanger assembly, and a load member disposed in a recess within the central bore of the housing to support the hanger assembly from the housing. The recess and the load member are configured so that a greater portion of the area of the load member extends into the central bore of the housing as the load member is moved axially in a first direction within the recess.

Abstract: An RCD is used to provide a system and method for sealing a marine riser having a rotatable tubular. A bypass internal channel or external line may be used to allow fluid to bypass the RCD seal. An RCD seal assembly seal could be a mechanically extrudable seal or a hydraulically expanded seal to seal the RCD with the riser.

Abstract: A wellhead system comprising a seal with a restraining member adapted to cooperate with a housing to restrict axial movement of the seal. The seal is adapted to form a seal between the housing, such as a wellhead, and a tubular member, such as a casing hanger. The seal has a latch ring that is expanded outward as the seal is installed within the wellhead. Axial movement of the seal is restricted by engagement between the expanded latch ring and the inner profile of the housing. The seal and housing may be adapted so that a portion of the seal is received by a recess in the inner profile of the housing.

Abstract: The invention concerns a dual-type plug to be used in a wellhead. The plug has a separate retrievable inner plug (50). Retrieving only the inner plug allows the use of lighter workover equipment than if the whole plug (10) must be pulled.

Abstract: A master ball valve with an integrated main hanger below the valve which may be used to hang jointed tubing, coil tubing, or electrified coil tubing for connection with an electric submersible pump.

Abstract: An apparatus and a method of substantially sealing a throughbore of a tubular with a line running therethrough. The method comprises the steps of: (a) substantially enclosing the line and sealing a portion of the throughbore around the line using an enclosing means; (b) injecting a fluid that contains solid particles in the region of the line; and (c) substantially sealing a remaining portion of the throughbore using the solid particles such that the sealed throughbore is capable of withstanding a pressure differential. The method can include settling out the solid particles from the fluid in response to a drop in pressure of the fluid during step (b). The method can include injecting a first fluid in the region of the line prior to step (b). The first fluid can be a heavy hydrocarbon such as a grease and the fluid containing solid particles can be a drilling fluid.

Abstract: A wellhead assembly to seal and suspend an in-casing hydraulic drive unit for a downhole pump, including pressure-containing wellhead body members with a vertical bore and a production bore at its uppermost portion. A hydraulic pump hanger is retained and sealed in the vertical bore. The hydraulic pump hanger suspends and seals the hydraulic cylinder, includes a bore extending vertically therethrough, forms at least one hydraulic line to communicate with hydraulic fluid supply lines, forms a hydraulic inlet port to each hydraulic line, and provides a check valve sealed in each hydraulic inlet port. The wellhead body member(s) includes a stem port aligned with each hydraulic inlet port, with a valve actuating stem sealed in each stem port to actuate each check valve between a normally closed and open position. The wellhead body member(s) also includes hydraulic injection port(s) formed to supply hydraulic fluid to each hydraulic inlet port.

Abstract: An apparatus operatively coupled to a well having a production casing positioned therein, the apparatus including a first device having and internal bore, a second device having an internal bore, and a fracture isolation sleeve disposed at least partially within the internal bores of the first and second devices, wherein the fracture isolation sleeve has an internal diameter that is greater than or equal to an internal diameter of the production casing.

Abstract: A wellhead completion assembly has a head connected to surface casing. A rotatable flange or the like can be used to connect various components to a threaded end of the head. A casing hanger installs in the head, and the hanger's upper end extends beyond the head's top edge. This exposed end has an external threaded connection to connect to various wellhead components using a rotatable flange or the like. For example, a locking ring can threadably connect to the head's threaded end to support the hanger in the head. Then, a rotatable flange can threadably connect to the hanger's exposed end so that another component, such as a completion spool or gate valve, can nippled up directly to the hanger. When the hanger is fluted, a pack-off assembly can allow testing off inner and outer sealing integrity via a test port accessible through an opening in the locking ring.

Abstract: Disclosed herein is an apparatus for preventing pollution of a groundwater borehole, which increase water-tightness. The apparatus for preventing pollution of a groundwater borehole has a structure that both sides of an underwater motor pump supported by a first intake pipe having a groundwater borehole for discharging groundwater to the outside are all supported inside a second intake pipe connected with the first intake pipe. The apparatus always maintains balance of the motor pump inside the intake pipes, thereby preventing displacement occurring by supporting only a side of the motor pump like the prior arts, and preventing water leakage and providing watertight efficiency by maintaining the close contact efficiency of an induction pipe connector mounted inside the second intake pipe.

Abstract: A tubing hanger lands in a tubular outer wellhead member and supports a string of production tubing. The tubing hanger has a production passage for communicating with the interior of the production tubing and an annulus passage for communicating with a tubing annulus on the exterior of the production tubing. An access port leads from the annulus passage to an exterior portion of the body for communicating the tubing annulus with the annulus passage. A valve stem is movable along an axis of the annulus passage between a closed position, blocking the access port, and an open position, exposing the annulus port. A pressure equalizing passage extends from the annulus passage above the valve stem to the annulus passage below the valve stem.

Abstract: The invention provides a wellhead assembly including a wellhead housing supporting a tubing hanger within its central bore and forming a housing stem port through its outer wall to the central bore. The tubing hanger has a side stem port formed through its body intermediate its upper and lower ends providing access to the central bore of the hanger and being aligned with the housing stem port. The tubing hanger includes a ball valve member having a spherical exterior surface sealed and seated from above and below within the central bore of the hanger. The ball valve member forms a through port extending therethrough aligned with the production bore, and is rotatable in its seated position between open and closed positions with the through port being aligned with the production bore when in the open position. A slot in the exterior surface of the ball valve member if formed proximate the stem port.

Abstract: An externally testable redundant connection for a subsea well includes a tube, a connector assembly, and collar. The connector assembly includes a jam nut over the tube; a ferrule over the tube adjacent the jam nut; and a double jam nut disposed over the tube adjacent to the ferrule. The double jam nut includes a test port adapted to receive a test fluid through the test port for determining if the primary seal and the secondary seal are providing a leak proof sealing engagement. The collar engage the tube and transfers an axial force from the double jam nut and compresses the tube into a female profile forming a primary seal. A secondary seal is formed from a compression of the ferrule into the double jam nut using the jam nut.

Abstract: A subsea wellhead assembly has a tree that connects internally to the bore of wellhead housing. The tree has a lower end that has a lock member that is moved radially outward into engagement with a profile in the bore of the wellhead housing. The tree is a monobore, having a production passage but no tubing annulus passage extending through it. The tubing hanger has a tubing annulus passage and a production passage. A valve is mounted in the tubing hanger for controlling flow through the tubing annulus passage.

Abstract: The horizontal spool tree assembly 10 controls fluid flow through a production tubing string 18 within a well. The horizontal spool tree assembly is adapted for use with a workover string for fluid communication with the tree assembly. The spool body 12 has a central bore 14 for receiving a tubing hanger 22 therein, with a production passageway extending laterally through the spool body to a production line 36. The spool body also includes an annulus passageway extending laterally through the spool body for fluid communication between the tubing annulus 16 and the annulus line 52. The spool tree assembly has improved porting for the production line and the annulus line, and also for both workover and crossover operations.

Abstract: A lockdown flange for use with an independent screwed wellhead includes an annular body having a center passageway with an internal diameter at least as large as a passageway through the wellhead. The lock down flange may be used to construct a multi-lock adapter for connecting a high pressure valve, a blowout preventer or a well stimulation tool to the independent screwed wellhead. The lockdown flange ensures that stress on connection points to the screwed independent wellhead due to elevated fluid pressures used for well stimulation procedures does not exceed engineered s.

Abstract: A frac head comprising a main body with plural side entries oriented around the main body such that flow from each of the side entries meets flow from an opposing side entry in the internal bore. A replaceable abrasion resistant wear sleeve is secured in the internal bore of the main body downstream of the side entries and positioned to intercept flow from the side entries and prevent the flow from impacting directly on material of the main body. The side entries terminate at the internal bore equidistantly from the lower end of the main body, and are symmetrically arranged around the main body. The side entries are oriented at about 450 to the downstream direction. The replaceable abrasion resistant wear sleeve is held against movement downstream by abutment of a shoulder on the replaceable abrasion resistant wear sleeve against a shoulder on the frac body, and has a tapered internal bore.

Abstract: A christmas tree to control the production from a subsea oil or gas well is disclosed. The christmas tree design including a tree body having a first flow port and a tree cap; a tubing hanger landed within the tree body; an actuation mandrel landed within the tree body, the actuation mandrel having a flow port; and a flow diverter disposed within the tree cap to divert flow through the flow port. The christmas tree arrangement allows for dual barriers within the tree cap without placing or retrieving any plugs from within the tubing hanger, thereby reducing the number of downhole trips required to complete and/or service the subsea well.

Abstract: The invention provides a casing adapter tool which connects and seals to a casing pipe at its lower end and to production or service equipment at its upper end, and is used with well servicing equipment, such as is involved in fracturing. The casing adapter tool includes a generally tubular casing adapter body having an upper end and a lower end, and is formed with a central bore extending therethrough. The central bore provides a profile which forms a casing seal chamber at the lower end, and a barrier seal chamber located thereabove. The barrier seal chamber is formed with a profile to accommodate and seal to a first removable pressure barrier on removal of any well servicing equipment. Most preferably, the barrier seal chamber has a profile sized to provide full bore access to the casing pipe and to accommodate and seal to the first removable pressure barrier which is of a threaded, latched or snap ring type check valve or plug.

Abstract: In a subsea wellhead assembly, a tubing hanger in communication with the subsea well has a hanger port extending through its side. A diverter surrounds the tubing hanger and diverts well fluid transmitted from the hanger port around a portion of the tubing hanger. The diverter transmits the well fluid to the inner surface of a wellhead member. A production port extending through a side of the wellhead member transmits the well fluid from the tubing hanger and diverter to an exterior of the wellhead member.

Abstract: A pressure reducing apparatus for controlling the pressure of oil is provided. The apparatus has ceramic components that resist wear caused by sand and debris in the oil. In one embodiment of the invention, the apparatus has a hollow body having an upstream channel, a downstream channel, and a pressure reducing chamber between the upstream channel and the downstream channel. The pressure reducing chamber has a longitudinal axis and contains a disk that is rotatable on the longitudinal axis of the pressure reducing chamber. The disk has a sidewall that abuts the upstream channel and a bottom end that abuts the downstream channel. The sidewall has a height that varies along the circumference of the disk. The disk is rotatable within the pressure reducing chamber so that the height of the sidewall facing the upstream channel can be varied to throttle the flow of oil from the upstream channel.

Abstract: The horizontal spool tree assembly 10 controls fluid flow through a production tubing string 18 within a well. The horizontal spool tree assembly is adapted for use with a workover string for fluid communication with the tree assembly. The spool body 12 has a central bore 14 for receiving a tubing hanger 22 therein, with a production passageway extending laterally through the spool body to a production line 36. The spool body also includes an annulus passageway extending laterally through the spool body for fluid communication between the tubing annulus 16 and the annulus line 52. The spool tree assembly has improved porting for the production line and the annulus line, and also for both workover and crossover operations.

Abstract: A subsea wellhead assembly has a tubing hanger with a tubing annulus passage and a production passage. A metal-sealing shuttle valve is mounted in the tubing hanger for blocking upward flow through the tubing annulus passage. The shuttle valve has a retention mechanism that prevents the shuttle from moving to the open position when fluid pressure is applied from above. The retention mechanism is released by the running tool after testing has been completed, causing the shuttle to close. The tree has an engaging member that can be stroked downward into the tubing hanger annulus passage to move the shuttle valve to the open position for communicating with the annulus.

Abstract: A retaining apparatus, in particular an internal tree cap, for use in a wellhead having a central bore and first and second retaining means, such as a shoulder and a groove, within the bore of the wellhead. The retaining apparatus has a housing for location within the bore of the wellhead. A first engagement assembly is provided for engaging with the first retaining means in the bore of the wellhead to thereby retain the housing within the bore of the wellhead. A second engagement assembly for engaging with the second retaining means in the bore of the wellhead is also provided. The apparatus further comprises a preload assembly operable when the housing is located within the bore of the wellhead to apply a preload to the housing between the first and second retaining means. A method for retaining an assembly within a wellhead bore, in which a preload is applied between the first and second retaining means, is also disclosed.