Abstract: In the drilling of a well, a dedicated drilling wellhead (520) mounted at the top of the casing cluster whilst the well is being drilled. At the end of drilling, a seal ring or sleeve (534) which during the drilling phase has the function of an annular sleeve isolating the well bore pressure from the production annulus space (540), is manipulated into an alternative position in which it acts to block the annular space (540) thereby acting as a temporary abandonment seal. A further plug seal is fitted in the well bore. The well is now temporarily sealed and the drilling wellhead can then be removed and can be reused on another well during the drilling phase of that well. A production wellhead (550,556) which has a cantilever christmas tree fitted on its side over a production wellhead (557) which can accept a conventional christmas tree on top is then fitted on to the casing hanger cluster.

Abstract: A completion system for a subsea well includes a tree having a generally cylindrical wall forming an internal bore therethrough and a production port extending laterally through the wall in communication with the internal bore. The internal wall has a landing arranged to support a tubing hanger having seals for sealing the production port between the tubing hanger and the internal wall, the production port being arranged to communicate with a lateral production fluid outlet port in the tubing hanger. A workover port extends laterally from an opening in the internal wall below the production port and the production port seals and a tubing annulus seal sealing the workover port from the tubing annulus. A tubing annulus port extends from an opening in the tree below the tubing annulus seal and the tubing annulus port and workover port being arranged to be in fluid communication externally of the internal bore.

Abstract: The concentric tubing completion system of the present invention comprises a surface Christmas tree which is located on a surface structure, a tieback connector which is secured to a mudline wellhead that is installed at the upper end of a subsea well bore, a mudline tubing hanger which is supported in the tieback connector, and a pair of concentric tubing strings which are suspended from corresponding tubing hangers in the surface Christmas tree and connected to the mudline tubing hanger. The annulus between the concentric tubing strings communicates with a number of passages in the mudline tubing hanger which are connected to the tubing annulus below the mudline tubing hanger. Thus, lift gas or other fluids may be communicated between the surface christmas tree and the tubing annulus through this annulus between the concentric tubing strings.

Abstract: A subsea wellhead with a tension latching system for a casing hanger or a tubing hanger, a tension latching system for hangers, and a method for adjusting the tension on a casing hanger or tubing hanger for subsea wells.

Abstract: A wellhead has, instead of a conventional Christmas tree, a spool tree (34) in which a tubing hanger (54) is landed at a predetermined angular orientation. As the tubing string can be pulled without disturbing the tree, many advantages follow, including access to the production casing hanger (21) for monitoring production casing annulus pressure, and the introduction of larger tools into the well hole without breaching the integrity of the well.

Abstract: A tieback connector includes a passive lower locking system and an active upper locking system to exert a positive locking force on the connection between a production riser and a high pressure wellhead. The tieback connector is composed of an outer housing which carries lower locking dogs, upper locking dogs and a piston. The piston is located above the lower end of the production riser and controls the movement of the outer housing. As the piston is stroked the outer housing cams the lower dogs into grooved profile in the wellhead housing. As the piston is stroked further the upper dogs exert a force onto the production riser that locks the riser to the wellhead housing.

Abstract: A horizontal Christmas tree is adapted for ESP/HSP or downhole sensor deployment by a coiled tubing hanger 38 received in the tubing hanger 12. Coiled tubing 40 suspends downhole equipment such as ESP 60, and carries power/signal lines. These lines are connected to an external line 58 via a transition connector 46 in a tubing access plug 44 provided in an internal tree cap 32. A debris cap 50 is provided with a further connector 52. Self orientating wet mate connectors 48, 54, 56 are provided between the connectors 46, 52 and external line 58. The coiled tubing hanger and/or tubing hanger may be provided with flow by flutes or holes (78, 80 FIGS. 4 and 5) sealable by a separate adapter plug (88, FIG. 5) above the coiled tubing hanger. Flow test procedures are also disclosed.

Abstract: A connection between a riser and a receptacle of a floating platform may be preloaded to reduce fatigue. The platform has a receptacle with upper and lower grooved profiles. A hanger is connected to the upper end of the riser. The hanger has a latch that engages the lower grooved profile in the receptacle to resist downward pull of the riser. A tieback connection inserts from above into the receptacle. The tieback connection has an outer member that lands on the hanger. The outer member has a latch that engages the upper grooved profile. The tieback connection also has an inner member with a set of internal threads. Threads on the inner member engage threads on the latch, rotating the inner member relative to the outer member exerts an outward force on the tieback connection latch. As the latch is pushed into the tieback grooved profile, a downward preload force is created, which passes to the hanger latch.

Abstract: A horizontal spool tree wellhead system 10 utilizes a casing 18, 19 installed in a well bore and a wellhead housing 20 at the upper end of the casing. A spool 23 of the horizontal tree 22 is connected to the upper end of the wellhead housing, and includes at least one radially extending side port. The BOP 28 is also installed at the upper end of the housing with a bore aligned with the wellhead housing bore. After drilling the well, the casing string 19 carrying a casing hanger 42 may be lowered through the bores of the BOP, the spool tree, and the wellhead housing and into the well. An orientation/isolation sleeve 60 may be installed in a predetermined rotational orientation with the spool tree. A tubing hanger 70 having a side port is landed onto the orientation sleeve and is automatically oriented to align the tubing hanger side port with the spool side port.

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.

Abstract: An apparatus for securing a tubular member under tension is provided, the member secured to and extending between a first and second fixed assembly. The apparatus comprises a first tubular assembly connectable at a first region to the tubular member to be tensioned and a second tubular assembly having a first and a second engageable portion, the second tubular assembly being arranged concentrically with respect to the first tubular assembly and movable longitudinally with respect to the first tubular assembly. A first engagement assembly is provided for engaging the first engageable portion of the second tubular assembly with the first fixed assembly, such that movement of the second tubular assembly toward the tubular member to be tensioned is prevented.

Abstract: A running tool for a wellhead has an outer sleeve, a piston, an inner sleeve, each with respective hydraulic chambers, and a pair of collets for engaging a tubing hanger in a wellhead. Pressure is applied to the various chambers to actuate the collets and engage and/or release the tubing hanger. This process is gradual so that the tubing hanger is landed softly in a production bore of a tree or wellhead. The piston is forced downward to actuate a lower sleeve and move locking dogs into a bore profile to secure the tubing hanger. This process is reversed to release the collets and detach the running tool from the tubing hanger. The running tool is then brought back to the surface without the tubing hanger, which remains landed in the bore.

Abstract: There is disclosed wellhead apparatus which includes a spool for use in a horizontal tree and having a vertical bore therethrough, and a tubing hanger adapted to be lowered into and landed within the bore of the spool to suspend a tubing string on the lower end of the tubing hanger within the wellbore. The spool has a radial opening therethrough to receive a bellows which forms a fluid passageway removably mounted within the opening by means of a flange on the outer end of the bellows releasably connected to the outer side of the spool. The tubing hanger has an opening therethrough which includes a lateral portion connecting with its outer diameter and a vertical portion leading to a pressure responsive operator for a tubing safety valve. The passageways have seal surfaces on their opposing ends, and the end of the stem is engaged by the seal surface of the bellows to open the poppet as the hanger is lowered.

Abstract: A gate valve for a component which includes an elongated body and a flow passage extending generally longitudinally through the body, the flow passage including a generally lateral first branch connected to a generally longitudinal second branch. The gate valve comprises a gate which is moveable generally longitudinally across the first branch between an open position in which a hole in the gate is aligned with the first branch and a closed position in which the hole is offset from the first branch; a conduit which extends through the body from the gate; an actuating mechanism positioned in the conduit for moving the gate from a first position to a second position; and a return biasing mechanism for moving the gate from the second position to the first position; wherein one of the first and second positions corresponds to the open position of the gate and the other position corresponds to the closed position of the gate; and wherein the conduit extends generally longitudinally through the body.

Abstract: A flow completion system for controlling the flow of fluid from a well bore, the flow completion system comprising a tubing spool which includes a central bore that extends axially therethrough and a production outlet which communicates with the central bore; a tubing hanger which is supported in the central bore and which includes a production bore that extends axially therethrough and a production passageway that communicates between the production bore and the production outlet, the tubing hanger supporting a tubing string which extends into the well bore and defines a tubing annulus surrounding the tubing string; a first closure member which is positioned in the production bore above the production passageway; a first annular seal which is positioned between the tubing hanger and the central bore above the production passageway; wherein the first closure member and the first seal comprise a first pressure-containing barrier between the well bore and a surrounding environment; a second closure member which

Abstract: A controls bridge for a flow completion system which comprises a tubing spool having a production outlet, a tubing hanger having a production bore that communicates with the production outlet and at least one service and control conduit extending therethrough, and at least one external service and control line that terminates near the tubing spool, the controls bridge comprising a first body portion; a mechanism for securing the first body portion to the top of the tubing spool and/or the tubing hanger; at least one first coupling member which is adapted to engage a second coupling member that is mounted in the service and control conduit; at least one third coupling member which is adapted to engage a fourth coupling member that is connected to the external service and control line; a bridge line which is connected between the first coupling member and the third coupling member; a first actuator for moving the first coupling member into engagement with the second coupling member; and a second actuator for mo

Abstract: A flow completion system for controlling the flow of fluid from a well bore, the flow completion system comprising a tubing spool which includes a central bore that extends axially therethrough and a production outlet which communicates with the central bore; a tubing hanger which is supported in the central bore and which includes a production bore that extends axially therethrough and a production passageway that communicates between the production bore and the production outlet, the tubing hanger supporting a tubing string which extends into the well bore and defines a tubing annulus surrounding the tubing string; a first closure member which is positioned in the production bore above the production passageway; a first annular seal which is positioned between the tubing hanger and the central bore above the production passageway; wherein the first closure member and the first seal comprise a first pressure-containing barrier between the well bore and a surrounding environment; a second closure member which

Abstract: A gate valve for a component which includes an elongated body and a flow passage extending generally longitudinally through the body, the flow passage including a generally lateral first branch connected to a generally longitudinal second branch. The gate valve comprises a gate which is moveable generally longitudinally across the first branch between an open position in which a hole in the gate is aligned with the first branch and a closed position in which the hole is offset from the first branch; a conduit which extends through the body from the gate; an actuating mechanism positioned in the conduit for moving the gate from a first position to a second position; and a return biasing mechanism for moving the gate from the second position to the first position; wherein one of the first and second positions corresponds to the open position of the gate and the other position corresponds to the closed position of the gate; and wherein the conduit extends generally longitudinally through the body.

Abstract: A subsea wellhead completion system and method for independently retrieving or deploying a subsea completion with a wellhead housing adapted to be supported on a seabed, a tree atop the wellhead housing with a fine alignment key for aligning the tree with the wellhead housing, a tubing hanger atop the tree with a production and an annular tubing string extending downwardly, numerous ports on the tree, engagable gates to open and close one or more of the ports, a deployable running tool that can manipulate the gates and wherein the tubing hanger is composed of the slidably ignitable gates connected to a way for retracting or extending outer seals of the tubing hanger and provide a blocking position against an inner seal and an unblocking position for fluid communication of the bores with each ports of the tubing hanger tree.

Abstract: A tubing hanger including a tubing hanger body having a tubing string which is adapted to be supported in the bore of the wellhead housing wherein the apparatus comprises a flapper valve disposed in or below the tubing hanger, wherein the valve further comprises a flapper valve having a flapper valve closure member substantially in the form of a concave spherical segment defining an annular valve seat concentric with the tubing for the flapper valve; a flapper plate disposed in the valve chamber for rotatable movement from a valve position in which the flapper plate is removed from the annular valve seat to a valve position in which the flapper plate extends transversely across the flow passage for the flapper valve and forms a sealing engagement with the annular valve seat and the sealing surface is substantially in the form of a convex spherical segment, wherein the convex spherical segment is disposed intermediate between the first and second planar surfaces.

Abstract: A method for attaching subsea manifolds to subsea pipelines which includes attaching a tee member into the pipeline on a vessel, running the portion of the pipeline through support structures which would not pass the manifold, and to an underwater location between the vessel and the ocean floor, then attaching the manifold to the tee section, and then lowering the tee and manifold to the ocean floor.

Abstract: The concentric tubing completion system of the present invention comprises a surface Christmas tree which is located on a surface structure, a tieback connector which is secured to a mudline wellhead that is installed at the upper end of a subsea well bore, a mudline tubing hanger which is supported in the tieback connector, and a pair of concentric tubing strings which are suspended from corresponding tubing hangers in the surface Christmas tree and connected to the mudline tubing hanger. The annulus between the concentric tubing strings communicates with a number of passages in the mudline tubing hanger which are connected to the tubing annulus below the mudline tubing hanger. Thus, lift gas or other fluids may be communicated between the surface christmas tree and the tubing annulus through this annulus between the concentric tubing strings.

Abstract: A wellhead assembly comprises a central bore through the wellhead assembly having a pressure boundary region. A port is provided in the wellhead assembly having an opening in the central bore in the pressure boundary region of the wellhead assembly. The port preferably extends through the high pressure housing into the bore of the wellhead assembly. A first casing string is secured at a first end within the wellhead assembly below the opening of the port in the central bore of the wellhead assembly. A second casing string is secured at a first end within the wellhead assembly above the opening of the port in the central bore of the wellhead assembly. A fluid flowpath is thereby formed comprising the port in the wellhead assembly and an annulus between the first and second casing strings. In this way, access is provided to an annulus within the well.

Abstract: A subsea well uses a shuttle valve for connecting tubing annulus passageways between a riser and a tree of a subsea well. The riser has a connector that lands on an upper end of a tree. The riser connector has a production passage and an annulus port. An internal tree cap is located within the tree. A production passage passes through the internal tree cap and an annulus passage communicates with a top surface of the internal tree cap and the annulus passage of the tree. The shuttle valve is located within a valve receptacle or valve cylinder in an upper end of the annulus passage. A portion of the shuttle valve extends above the upper surface of the internal tree cap so that the shuttle valve opens when the riser connector lands on the top of the internal tree cap. Alternatively, the shuttle valve may be hydraulically actuated.

Abstract: A tubing hanger to facilitate production tubing annulus access including a tubing hanger body having a central bore, a shuttle valve slidably mounted to the tubing hanger body, and at least one annulus access bore through the tubing hanger permitting fluid communication between the central bore and an annulus defined between a production tubing string and a wellbore or casing via the tubing hanger body and the shuttle valve. The shuttle valve may be slidingly movable between an open and a closed position. The tubing hanger may further include a groove enclosed by a filler, the groove providing communication between a plurality of small annulus access bores and a large annulus access bore.

Abstract: An underwater or severe environment electrical connector, comprising first and second connector parts which are to be brought together in longitudinal alignment to establish electrical contact between respective contact portions of the first and second connector parts, the connector parts being relatively rotatable about a longitudinal axis when the connector parts are disconnected, and the contact portions being laterally spaced from said longitudinal axis and being arranged to make said electrical contact when the connector parts are connected, irrespective of the relative rotational positions of the first and second connector parts about said longitudinal axis.

Abstract: A subterranean oil or gas well apparatus is provided. The apparatus includes a single-bore production tubing hanger arranged concentric with a wellhead. The tubing hanger includes a plurality of ports and channels arranged about the tubing hanger to give operators access to the production tubing annulus and provide chemical injection capability. The ports are closable by a sliding valve. The apparatus also includes annulus and production radial-bore stab assemblies between a christmas tree and an internal crossover assembly. The stab assemblies are extendable and retractable between the chirstmas tree and the crossover assembly to allow the retrieval and installation of each independently.

Abstract: The invention is directed to a tubing hanger for a flow completion system which comprises a Christmas tree connected above a wellhead housing that includes a central bore in which the tubing hanger is supported, the tubing hanger comprising a generally annular body; a production bore which extends generally axially through the body; an annulus bore which extends generally axially through the body; the annulus bore comprising a generally lateral first branch which is connected to a generally axial second branch; and a closure member which includes a gate that is moveable generally axially across the first branch between an open position in which a hole in the gate is aligned with the first branch and a closed position in which the hole is offset from the first branch.

Abstract: A tensioning device is disclosed which brings two tubular segments closer together with an intermediate adjustment sleeve. The sleeve is threaded externally and may be accessed internally by a tool to rotate it. The threaded sleeve is secured to the upper tubular in a manner that permits relative rotation. Rotation of the sleeve advances it downwardly in the lower tubular, pulling down the upper tubular secured to the rotating sleeve. The upper tubular translates until a load shoulder hits a support surface in the wellhead to achieve the desired tension in the string.

Abstract: A controls bridge for a flow completion system which comprises a tubing spool having a production outlet, a tubing hanger having a production bore that communicates with the production outlet and at least one service and control conduit extending therethrough, and at least one external service and control line that terminates near the tubing spool, the controls bridge comprising a first body portion; a mechanism for securing the first body portion to the top of the tubing spool and/or the tubing hanger; at least one first coupling member which is adapted to engage a second coupling member that is mounted in the service and control conduit; at least one third coupling member which is adapted to engage a fourth coupling member that is connected to the external service and control line; a bridge line which is connected between the first coupling member and the third coupling member; a first actuator for moving the first coupling member into engagement with the second coupling member; and a second actuator for mo

Abstract: A running tool is used to install a load shoulder and a wear bushing in a subsea wellhead. A subsea wellhead has a locator shoulder, and grooved upper and lower profiles. The running tool has a cylindrical wear bushing that lands on a locator shoulder provided in the bore above a grooved lower profile in a wellhead housing. The running tool also carries a load shoulder ring and a split lock ring. The installation process consists of preparing the tool before running the tool subsea. Flowby ports on the running tool remain open during installation to speed the trip-in operation. The flowby ports are closed by lowering the central mandrel after the running tool lands. Then a portion of the wear bushing is moved downward, which in turn pushes the load shoulder out into the lower grooved profile to retain the load shoulder ring and wear bushing with the wellhead.

Abstract: A connector for tying back a riser from a subsea wellhead to a platform, wherein the wellhead has an internal wellhead housing with external grooves thereon. The connector having a plurality of dog members carried within a cavity which engage the external grooves. The dog members are actuated by axial movement of a piston linked to a cam ring. The connector has a plurality of transfer members located within the cavity to support the dog members and transfer upward loading to the wellhead housing during tension on one side due to bending. Further, the connector has a release ring which forces the dog members out of engagement with the external grooves when the connector is released.

Abstract: A method for drilling and completing oil wells of small intermediate diameter, in particular for application in ultra deep water. The method includes two drilling and running stages. The first stage of drilling and running provides for drilling the well and running at least first and second casings. The second stage provides for drilling and running at least two and more preferably three suspended liners.

Abstract: A well completion system having a spool tree body defining a vertical bore extending therethrough. The vertical bore defines an annular recess adjacent to the lateral production fluid outlet port in the spool tree body. A tubing hanger is connected to the spool tree body. The tubing hanger defines a vertical production bore extending therethrough and has at least a lateral production fluid flow port. The tubing hanger is positioned within the vertical bore such that the lateral production fluid flow port in the tubing hanger is in flow communication with the lateral production fluid outlet port in the spool tree body. There is a removable plug that seals the vertical production bore extending through the tubing hanger above the lateral production fluid outlet port in the spool tree body. A stopper means seals the vertical bore extending through the spool tree body above the removable plug.

Abstract: A connector for tying back a riser from a subsea wellhead to a platform, wherein the wellhead has an internal wellhead housing with external grooves thereon. The connector having a plurality of dog members carried within a cavity which engage the external grooves. The dog members are actuated by axial movement of a piston linked to a cam ring. The connector has a plurality of transfer members located within the cavity to support the dog members and transfer upward loading to the wellhead housing during tension on one side due to bending. Further, the connector has a release ring which forces the dog members out of engagement with the external grooves when the connector is released.

Abstract: A subsea well has a tubing hanger which has an annulus bore and a production bore. A check valve is located in the annulus bore. A running tool runs the tubing hanger on a monobore riser such as a drill string while holding the check valve in the open position. After setting and testing, the running tool is lifted and a blowout preventer is closed around the landing string. The operator monitors the choke and kill line of the drilling riser, which will be in communication with the check valve. If the check valve is leaking, an annulus plug may be installed in the annulus bore. The installation of the annulus plug may be handled by using a retrieval tool configured to align the annulus bore with the landing string passage. A wireline tool may be lowered through the landing string and retrieval tool to retrieve the check valve and install the plug. Alternately, the check valve may remain in the tubing hanger and the plug is set in the annulus bore above it.

Abstract: A method and apparatus for temporarily storing the lower portion of a string of drill pipe in a well which has a cased portion wherein a packer, installed between a storm valve located below the packer and an actuator located above the packer, is set in the annulus between the drill pipe and the well casing, the actuator being designed to close the valve upon initial axial movement of the upper portion of the drill pipe, and then to become disengaged from the lower portion of the set drill pipe allowing the remaining surface suspended drill pipe and actuator to be retrieved as in the case of a floating drill ship or set aside for reconnection and reopening of the storm valve after a storm has passed.

Abstract: A bore selection apparatus (38) is described for facilitating access from a single bore riser to a production bore (34,34a) or annulus bore (36, 36a) without using a wireline-run whipstock. The bore selector apparatus disposed within the bore of a BOP stack (12) and which can be coupled between casing or tubing and a sub-sea test tree. The bore selector apparatus (38) can be actuated from the surface or from an ROV to provide a coupling between the tubing bore (44) and the production bore (34, 34a) or between the tubing bore (44) and the smaller annulus bore (36, 36a).

Abstract: A landing shoulder is provided on a series of collets extending from a frangible ring. The collets are biased into a groove which is itself in a recess in the wellhead housing. Deployment of the landing shoulder in its retracted position allows an additional string of casing to be run which is nominally close to the inside seal bore diameter of the wellhead housing. The ability to add an additional casing string on a wellhead housing of a particular size allows isolation of water-producing zones near the surface in a cost-effective manner where mud used to control water production is recovered. In a subsequent trip after the large casing is hung below the body, a setting tool engages the rings supporting the collets defining the landing shoulder. The hydraulic pressure built up in the setting tool actuates a piston to break a portion of the ring supporting the collets so that they are driven and locked down in a set position where they define a landing shoulder in the bore for a subsequent run of casing.

Abstract: Wellhead completion apparatus includes a wellhead member (11) having an upper supporting shoulder (24) and a lower landing shoulder (26). A running tool (30) is releasably connected to a tubing hanger (36) for lowering and landing the tubing hanger (36) on the wellhead member (11). A fluid coupling (66, 68, 70) is provided between the running tool (30) and the tubing hanger (36). Another fluid coupling (17, 60, 84) is provided between the tubing hanger (36) and the wellhead member (11). The running tool (30) has a body (31) connected to the tubing hanger (36) and an outer sleeve (46) of the running tool (30) is adapted for initial seating on upper supporting shoulder (24) of the wellhead member (11). After the initial seating of sleeve (46) on upper supporting shoulder (24), running tool (30) and tubing hanger (36) are moved downwardly relative to external sleeve (46) for landing of the tubing hanger (36) onto the lower landing shoulder (26) of the wellhead member (11).

Abstract: An adjustable tubular hanger for suspending a tubular string from a wellhead component is provided which includes an elongated body having a lower end adapted to be connected to the tubular string and an upper end portion including a plurality of axial annular grooves formed in the outer diameter surface thereof, each groove defining a downwardly facing support surface, and a support ring adapted to be positioned around the body in one of the grooves, the support ring having an upwardly facing load shoulder for engaging the support surface and a downwardly facing load surface for engaging a support shoulder formed in the wellhead component, whereby the elevation of the tubular hanger within the wellhead component can be adjusted depending on in which groove the support ring is positioned.

Abstract: A lightweight intervention system is described for use with single bore and dual bore intervention operations and which can be used with both horizontal trees and conventional trees and with wellheads without trees mounted thereon. The system is based on a two-part intervention apparatus; the lower part provides the pressure control and consists of an xmas tree or wellhead connector and structural housing in which a sub-sea test tree is located and is coupled to the xmas tree and an upper part, a disconnectable section, attaches to the lower part and consists of a sub-sea test tree latch housed within an xmas tree connector and additional pressure control equipment as required. This general structure can be configured in various ways to create different embodiments for use with horizontal trees and conventional trees which have a single through-bore requirement and a dual bore requirement respectively.

Abstract: Subsea wellhead apparatus is disclosed in which a hanger is adapted to be lowered into and landed in a predetermined orientational and longitudinal position within the bore of a wellhead housing installed on a subsea well in order to suspend a tubing string within the well bore. The hanger has a passageway with one adapted to connect with a tube extending downwardly into the well bore for connection with an operator for a subsurface safety valve in the tubing string, and another end which connects with the outer side of the hanger opposite the bore of the housing. The housing has a passageway therethrough with one end in general alignment with the other end of the passageway in the hanger to form a continuation thereof when the hanger is landed in the housing. A body on the outer side of the housing has passageway means with one end in general alignment with the other end of the housing passageway and another end for connection with a control line external to the housing.

Abstract: A horizontal tree has a vertical bore and a horizontal production passage and is landed in a wellhead housing. A tubing hanger lands in the bore and has a vertical passage and a horizontal passage that aligns with that of the tree. A retrievable first plug seals the vertical passage. A tree cap seals in the tree bore above the tubing hanger and has an axial passage. A retrievable second plug seals the tree cap passage. A vent port extends laterally through the tree cap between its axial passage and outer surface. A pair of seals on the second plug seal above and below the vent port. A tubing annulus passage communicates with the vent port and an annulus passage. The second plug serves as a second pressure barrier to the first plug and blocks the vent port. The annulus passage is sealed from communication with a void between the plugs.

Abstract: A wellhead has, instead of a conventional Christmas tree, a spool tree (34) in which a tubing hanger (54) is landed at a predetermined angular orientation. As the tubing string can be pulled without disturbing the tree, many advantages follow, including access to the production casing hanger (21) for monitoring production casing annulus pressure, and the introduction of larger tools into the well hole without breaching the integrity of the well.

Abstract: An apparatus for use in subsea well completion systems is provided. The apparatus has an isolation sleeve and an extension sleeve. The isolation sleeve has a first end, a second end and a longitudinal axis defined between the first end and the second end. The isolation sleeve has a generally tubular shape. The extension sleeve has a first end attached to the second end of the isolation sleeve to form an assembly comprising the isolation sleeve and the extension sleeve, a second end, and a longitudinal axis that is coaxially aligned with the longitudinal axis of the isolation sleeve. Like the isolation sleeve, the extension sleeve has a generally tubular shape.

Abstract: There are disclosed a wellhead system and a method for use in drilling a subsea well from a jackup platform which includes a wellhead housing which is installed on a surface casing of a subsea well. A first riser having a connector on its lower end is lowered over the upper end of the housing as the connector to land on the housing, and a second riser is lowered through the first riser and connector over and onto the upper end of the wellhead housing to form an upward continuation of the bore of the housing. The connector has locking parts which are movable between outer unlocking position to permit the second riser to be lowered onto and raised from the wellhead housing, and inner positions for locking engagement with the upper end of the housing and lower end of the second riser. A casing hanger is lowered through the second hanger and into landed position within the housing bore for suspending an inner casing string within the surface casing.

Abstract: A subsea wellhead assembly comprises a subsea wellhead, a spool body assembly, a helix, and a tubular bore protector. The spool body assembly is mounted to the wellhead and has an inside surface defining a vertical bore. The spool body assembly has an upper end, a lower end, and a lateral production fluid outlet port. The helix is formed from a tubular member and is positioned in a lower portion of the spool body assembly. The helix has a generally cylindrical outer surface defining an outer diameter and a generally cylindrical inner surface defining an inner diameter, an upper end and a lower end. The tubular member has an organ pipe-shaped cut in the upper end so that the upper end is generally elliptically shaped and forms a pair of arcuate ramps to orient a tubing hanger. The tubular bore protector body has an upper end, a lower end, and a longitudinal axis.

Abstract: A horizontal tree having a vertical bore and a horizontal production passage is landed in a wellhead housing. A tubing hanger lands in the bore and has a vertical passage and a horizontal passage that aligns with that of the tree. A retrievable first plug seals the vertical passage. A tree cap seals in the tree bore above the tubing hanger and has an axial passage. A retrievable second plug having a valve seals the tree cap passage. A vent port extends laterally through the tree cap between its axial passage and outer surface. A pair of seals on the second plug seal above and below the vent port. A tubing annulus passage communicates with the vent port and an annulus passage. The second plug serves as a second pressure barrier to the first plug and blocks the vent port when the valve is closed. The annulus passage is sealed from communication with a void between the plugs. The valve may be opened to release pressure in the void by applying pressure to an upper end of the check valve.

Abstract: A subsea well has a an outer wellhead housing with a tree on an upper end and a tubing hanger landed in the bore of the tree. A tree cap lands on and is secured to the tree. The tree cap has a plurality of production and annulus valves and a dual-bore control pod assembly. The tree has annulus bypass passages which communicate with a tubing annulus on a lower end and upper ports in the tubing hanger on an upper end. Production fluids flow up the tubing hanger bore to the tree cap and circulates through a flowline in the control pod. Access to the tubing annulus is through the annulus passages and tree cap annulus passage to a separate flowline.