Abstract: Subsea well arrangement for offshore production of oil or gas, comprising a wellhead, a christmas tree mounted on the wellhead and at least one riser for connection with a production vessel at the sea surface. At the top of the christmas tree there is provided a swivel device communicating with the christmas tree, and the swivel device is provided with preferably laterally directed connecting members for risers or hoses and for an umbilical or control cable.

Abstract: An accumulator for use in deepwater operational and control systems which uses a differential between a high pressure ambient pressure source such as sea water pressure and a low pressure source such as a chamber holding vacuum or atmospheric pressure to provide storage and delivery of hydraulic power for operation of equipment.

Abstract: The present invention relates to a well head system, especially in connection with high pressure wells, and in order to reduce the weight of steel involved, as well as avoiding unnecessary equipement in the well head, it is according to the present invention suggested a casing programme based on liners, having the same pressure integrity as the casing on which the well head is mounted.

Abstract: The present invention provides apparatus and method for killing or suppressing a subsea wellbore. The system includes a pressure intensifier adjacent the wellhead. The output of the pressure intensifier is coupled to a “kill” inlet at the wellhead equipment. Power is supplied from the surface to the pressure intensifier, which increases the pressure by a known multiple, usually 3 to 5, and supplies the high pressure fluid to the wellbore. A control unit at the surface controls the operation of the pressure intensifier in response to the predefined criteria or programmed instructions. One or more sensors provide measurements to the control unit of the wellbore conditions, which are used to determine the timing of activation of the pressure intensifier.

Abstract: A subsea wellhead assembly is disclosed with an extension spool secured thereto and an in line tree assembly locked within the extension spool. Ball valves are disposed within the vertical bores of the in line tree assembly. Valve actuators are disposed radially on the extension spool with a cylindrical sleeve mounted coaxially around the one end of the actuator and rotatable relatively to the actuator about the common axis of the actuator and the sleeve, so that, when the actuator engages with the corresponding ball valve, the sleeve bridges the gap between the extension spool and the in line tree assembly to lock the in line tree assembly to the extension spool.

Abstract: A wellhead cap assembly (10) includes a high security barrier (16) for installation onto a wellhead (12) containing any leakage safely and for permitting the installation of a subsea xmas tree onto the wellhead (12) whilst, simultaneously, providing means for containing full pressure control during rectification of the leak. The barrier (16) is provided by an internal tree cap which allows pressure between the top of the tubing hanger (34) and the underside of the tree cap (16) to be monitored by pressure monitoring means (20) via a port (29) in the assembly (10) and, in addition, in the event the presence of well bore fluids is detected indicating that leakage has occurred, the cap assembly allows intervention in order to rectify the leakage.

Abstract: A caisson gate valve (10) fitting within an outer casing (12) extending downwardly from a subsea wellhead below the sea floor is disclosed. The gate valve (10) includes a valve body or block (14) having an axial bore or flow passage (16) therethrough and a transverse cavity (18) in body (14) which extends through the body (14) to provide open ends (19) for cavity (18). Covers (60, 66) are mounted over the open ends (19) of cavity (18). A gate carrier (24) has an oval opening (26) which receives a gate member (28) having a gate opening (30) therein for movement between open and closed positions relative to the flow passage (16). A pair of opposed stems or pistons (32, 34) extend from gate carrier (28) for actuation of gate carrier (24) and valve member (28) between open and closed positions relative to flow passage (16). Fluid chambers (36, 38) adjacent pistons (32, 34) provide pressurized fluid for actuation of gate carrier (24) and gate member (28) therein.

Abstract: A connector device for connecting a wellhead christmas tree assembly to a wellhead wherein the device comprises a cylindrical body adapted to be placed in sleeved relationship to the wellhead and having means for attaching a wellhead christmas tree assembly in coaxial relation therewith. The cylindrical body member is further provided with a plurality of lateral openings in equiangular relationship with respect to the axis of the body member. The connector further includes a plurality of locking dogs, each having a toothed front face in conforming configuration with the wellhead exterior and each disposed in a different one of the lateral openings. The connector also includes a first drive means comprising a locking sleeve with an internal camming surface for interacting with a matching cam surface on the back face of each of the locking dogs and adapted by an actuator to drive the locking dogs into locking engagement with the wellhead.

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: A single bore riser system is disclosed which is based on a dual bore completion tree. An eccentric offset sub is coupled to the top of the tree and which can be sealed by BOP pipe rams. The completion tree has a main bore and an auxiliary bore with ball valves located in the respective bores. A remotely actuatable annulus plug is located in the bottom of the annulus bore and is moveable between a first position allowing fluid flow through the annulus bore and a second position sealing the annulus bore to provide control of various operations. Embodiments of the invention are described.

Abstract: An improved sub-sea Xmas tree consists of a wellhead connector, a cylindrical structural housing and a tree cap mounted on top of the housing. A dual bore sub-sea completion test tree is disposed in the housing and it has a main production bore with serial ball valves for controlling fluid flow in the production flow path of an annuus bore with a ball valve therein. The ball valves are independently and remotely actuatable by a remotely operated vehicle (ROV) override system to control communication through the Xmas tree and to comply with various regulatory standards. A cross-over valve is provided between the main bore and the annulus bore to allow fluid passage for well kill operations.

Abstract: A casing hanger assembly is disclosed which includes a bottom member which centralizes a casing string within a casing head and a top member of a conventional slip-type casing hanger design. The bottom member functions to rigidly centralize the casing string inside the casing head while absorbing any side bending load induced by movements of the casing string. The top member, set on top of the bottom centralizer member, supports and transfers the weight of the casing string to the casing head.

Abstract: The invention relates to a method and equipment to assist the flow of offshore production of hydrocarbon mixtures containing a high concentration of gas. A primary separating vessel is used and production is diverted to it. This vessel is designed to allow primary separate of the gas, which flows to the gathering center via a special line. Within the primary separating vessel there is a U-shaped length of pipe whose arms are connected to two flow lines which extend to the gathering center. A mechanical interface driven by high pressure gas periodically travels along these lines, carrying with it to the gathering center the volume of liquid phase which has accumulated in the lines. If liquid phase passes into the gas flow line, a mechanical interface can be passed along this line to remove the volume of liquid which has accumulated within it.

Abstract: A pressure balanced connector is provided for connecting a choke and kill line to a subsea wellhead. The connector bears the separation forces applied by the line pressure with a pressure balancing chamber that is in constant fluid communication with the choke and kill line. The forces applied on the pressure balancing chamber hold a latching mechanism for the connector in place on the wellhead. The latching mechanism does not require precise positioning with the wellhead to make the connection.

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: A subsea wellhead assembly has a tubular housing having a sidewall, an axial bore, and a housing lateral passage extending from the bore through the sidewall. A blocking sleeve fits around the housing to block the housing lateral passage while drilling through the housing. A tubing hanger is secured to a string of tubing and landed in the housing. The tubing hanger has a vertical passage which communicates with the tubing and a tubing lateral passage which extends from the vertical passage and registers with the housing lateral passage. A lower annulus port is in the sidewall of the housing below the lower seal and leads to a tubing annulus. An upper annulus port is in the sidewall of the housing above the upper seal and leads to the bore of the housing. A tree block having a central opening for receiving the housing is lowered over the housing after removal of the blocking sleeve.

Abstract: An adjustable wellhead connector is secured to the lower end of a BOP and riser assembly and has a housing which surrounds a groove profile on the upper outer surface of a first wellhead housing. The housing has a window on its inner surface which contains a removable first locking member. The first locking member has a groove profile on its inner diameter which mates with the groove profile on the first wellhead housing. The first locking member is movable between inner and outer radial positions which correspond to locked and unlocked positions, respectively. The first locking member is moved by a hydraulic system contained within the housing. The wellhead connector may be readily adapted to connect to a second wellhead housing having a different outer diameter than the first wellhead housing by replacing the first locking member with a second locking member. The second locking member enables the wellhead connector to connect a riser to the second wellhead housing.

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 well production assembly includes a production tree which has a lateral production passage extending laterally from a vertical bore of the tree. A tubing hanger, also having a lateral production passage, lands in the tree, with the lateral passages registering with each other. The junction of the lateral passages has flat, tapered sealed areas which mate with one another. An annulus passage extends vertically through the tubing hanger offset from and parallel to the tubing hanger vertical production passage. The annulus passage also has a lateral passage which registers with the lateral passage formed in the tree. The annulus lateral passages have a flat seal area at their junction. The tubing hanger has a downward facing hydraulic connector which registers with an upward facing hydraulic connector located on a shoulder formed in the bore. Once mated, the connectors provide hydraulic or other auxiliary fluid communication to downhole equipment.

Abstract: A subsea production system that facilitates the cost effective development of offshore hydrocarbon reserves. The system includes a template base, a wellhead assembly, a saddle manifold, flowlines, a subsea tree assembly, and a control center. The system facilitates phased development by allowing control over timing for the installation of system components and by providing extendibility to additional wells developed after installation of the system.

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: A connector assembly includes first and second connector parts. The first connector part has a bearing portion and the second connector part is connectable with the first connector part. A carriage comprises an abutment which is disposed against the first connector part and the carriage is reciprocatable between a forward position for connecting the connector parts and a retracted position for disconnecting the connector parts. A bias is provided for biasing the bearing against the abutment. The bearing portion and the abutment cooperate to permit pivoting of the first connector part in response to a force in any lateral direction on the first connector part. The first connector part may include a weakened portion providing a reduced resistance to shear. The connector assembly may also form part of a wellhead assembly.

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: 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: 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: 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: 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 lightweight intervention apparatus is described for use with a single bore intervention operation and which is suitable for use with a sub-sea horizontal tree with a tree cap and integral ball valve. The lightweight intervention apparatus is adapted to be coupled to the horizontal tree and that when so coupled the integral ball valve within the tree can be actuated via the intervention apparatus and cycled between an open and a closed position. The annulus line within the horizontal tree is adapted to be coupled through the lightweight intervention apparatus to a separate annulus line such that the annulus line is separate from the main bore to facilitate control of the annulus for certain well functions. A significant advantage of this arrangement is that the internal diameter of the main bore is not reduced in any way by apparatus or equipment for separating the annulus line from the main bore so that full bore diameter may be used.

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 plug is provided which is specially adapted for statically setting a plug portion within an internal profile formed in a wellhead. In an illustrated preferred embodiment, the plug portion is set by application of fluid pressure to a running tool portion. When set in the profile, the plug portion is secured statically relative to the profile, thereby permitting advantageous utilization of a metal-to-metal seal on the plug portion. The plug portion includes features which maintain its set configuration in the profile. The running tool portion includes multiple pistons which enhance operation of the running tool portion. A disclosed verification tool provides an indication that the plug portion has been properly set.

Abstract: A lightweight ROV deployable tree cap (28) for deployment on a subsea production hub (10) of a subsea tree. A tree cap (28) has a lightweight body (30) with parallel planar sides and including suitable openings and slots for mounting of the various operating elements. A seal plate structure (64) includes a piston (66) connected to a seal plate (68) having a pair of downwardly projecting tubular seal members (70, 72) for fitting within the production bore (13) and annulus bore (15) of the tree hub (10) in a sealed landed position. Fluid pressure is applied to fluid line (96) to urge piston (66) and seal plate (68) downwardly into sealing landed position. For removal or retrieval of tree cap (28) from the installed position on subsea tree hub (10), fluid pressure is applied through fluid lines (108, 110) for the upward movement of seal plate (68) and tubular seal members (70, 72) from sealing relation with production bore (13) and annulus bore (15).

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 wellhead structure having a subsea wellhead (10) connected to the lower end of a collet connector (30). A blowout preventer stack (8) is connected to the upper end of the collet connector (30) and a marine riser (13) is connected to the upper end of the blowout preventer stack (8). The wellhead (10) has an outer wellhead housing (12) fixed to the seabed (B) and an inner wellhead housing (14) supported within the outer wellhead housing (12). Upper hub (16) of outer wellhead housing (12) has an outer profile for mating in a releasably locked position with the collet connector (30). External tensile and bending loads are transmitted directly from the marine riser (13) and blowout preventer stack (8) to the outer wellhead housing (12) along load path L2 bypassing inner wellhead housing (14). One embodiment (FIGS. 5 and 6) shows an inner wellhead housing (14B) extending above the outer wellhead housing (12B) and adapted for separate connection to a small connector (30C) shown in FIG.

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.

Abstract: Wellhead equipment includes a body having a drilling conduit passage, whereby drilling conduit is passed through the body. Polymer sealing elements are disposed within the body and disposed in relation to the passage to seal off well pressure. A circulation passage extends through the body in the vicinity of the polymer sealing elements. The circulation passage has an inlet and an outlet whereby warm fluid is circulated through the circulation passage from the inlet to the outlet thereby raising the temperature of the polymer sealing elements to improve their cold weather performance.

Abstract: A monobore completion/intervention riser system for providing a conduit for communication fluids and wireline tools between a surface vessel and a subsea well having a tubing hanger located therein, the tubing hanger including a production bore and an annulus bore, wherein wireline tools may be lowered through a riser bore 48 to either the tubing hanger production bore 68 or the tubing hanger annulus bore 70 through operation of a bore selector 56, and fluids may be produced from the well to the surface vessel through the production bore 52, 60, 64, 68 and the riser bore 48 by sealing off the annulus bore 66, 70.

Abstract: A pressure compensated plug for use with subsea trees is described in which a reservoir of compressible fluid is located from a cavity within a horizontal tree (10) whereby allowing temperature induced volume changes to be absorbed by the compressible fluid without resulting in significant increase in pressure. This is achieved by providing a pressure compensation apparatus (80) in the cavity, the apparatus comprising a housing (82) with a floating piston (86) in a chamber (84). The lower face (96) of the chamber is exposed to compressible fluid in the form of an inert gas, such as nitrogen, which is pre-charged at the surface to the appropriate hydrostatic pressure of the seabed. The volume of gas trapped between the lower piston face and the lower face of the cylinder forms the gas reservoir (94). A compensation cylinder can be attached to the upper section of the lower plug (70) and run and retrieved at the same time as the plug, thereby reducing the number of intervention runs.

Abstract: An adjustable casing hanger for suspending a casing string from a wellhead is provided which includes an elongated tubular body having a lower end adapted to be connected to the casing 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, whereby the elevation of the casing hanger within the wellhead can be adjusted depending on in which groove the support ring is positioned.

Abstract: A dual bore completion sub-sea test tree (10) is described which has main bore (18) and an auxiliary or annulus bore (20). Two identical ball valves (22, 24) are located in series within the main bore (18) and two smaller identical ball valves (26, 28) are located in series in the annulus bore (20). The ball valves (22, 24, 26, 28) are operated by respective independent control lines acting on the operating mechanisms of the respective valves within the test tree (10) to move the valves between open and closed positions to allow or deny communication through the respective bores (18, 20). The completion sub-sea test tree (10) provides isolation of the main bore (18) and/or the annulus bore (20) when required by application of hydraulic pressure to assist closure to spring forces sufficient to cut coil tubing in the event of an emergency situation requiring rapid disconnect.

Abstract: A drilling, production, test, and oil storage caisson for use in deep water offshore well operations. Separate low pressure and high pressure drilling risers are independently supported on buoyancy modules. Multiple drilling and production risers are left in the water and connected to the drilling rig and well(s) as needed to prevent the need for the raising and lowering of different risers during the various steps involved in beginning and completing wells. Surface and lower BOP stacks are utilized. Means for controlling the accelerations and velocity of the drilling riser buoyancy modules in the event of riser failure is provided. A subsea tree with dual master valves allows for production directly through a vertical production riser, flowline, to the production manifold on the caisson. A twisted tubing production riser is formed from three strings of tubing that are used for the flowline, annulus, and conduit for control lines.

Abstract: The internal tree cap of this invention has an isolation sleeve that stabs into a receptacle in the upper end of the tubing hanger. A seal on the exterior of the isolation sleeve seals an inner void within the isolation sleeve from an outer void. The inner void is the area between the tubing hanger wireline plug and the tree cap. The outer void is an area surrounding the tubing hanger above the tubing hanger upper seal and below the tree cap seal. The internal tree cap may have a bore and an upper crown plug that is wireline retrievable. Fluid will be trapped in the inner void when the isolation sleeve is stabbed into the receptacle above the tubing hanger. To allow displacement of the fluid when landing the upper crown plug, or when landing the upper crown plug and internal tree cap together, a vent passage leads through the tubing hanger to the outer void. This vent passage is preferably controlled by a metal sealing needle valve which is shut by an ROV or diver.

Abstract: A lower casing hanger including a cylindrical block with two holes is landed on a shoulder in the bore of a wellhead housing. The first hole has shoulders that are inclined relative to the axis of the housing. The second hole is smooth and has a constant diameter. A first string of casing is run through the first hole and a C-shaped annular slips is placed around the casing. The outer surface of the slips has shoulders for engaging the shoulders on the lower casing hanger. The casing is lowered until the shoulders engage, thereby preventing further downward movement of the casing. An upper casing hanger then is placed on top of the lower casing hanger. The upper casing hanger has two holes that align with the holes in the lower casing hanger. The second hole has shoulders that mate with exterior shoulders on a second slips. A second string of casing is run through the second hole and the second slips is placed around the second casing.

Abstract: A tool is employed to shift an external valve sleeve on an outer wellhead housing at a subsea location. The tool has an engaging member that moves between upper and lower positions. The tool has a locking member that locks to the inner wellhead housing with the engaging member sliding over the outer wellhead housing. In one embodiment, the tool also is employed to run the inner wellhead housing and preload it. The engaging member moves to a lower position to shift the valve sleeve after the inner wellhead housing has been preloaded by the tool. In another embodiment, the tool is lowered over a previously installed inner wellhead housing to retrieve the valve sleeve for repair or replacement.

Abstract: An offshore well is stabilized by at least three cables connected on one end to hydraulically powered cable tensions on the well casing at a location substantially below the surface of the body of water in which the well is located and on an opposite end to a respective anchor pile on the bottom body of water. The cables are equally tensioned by the hydraulically powered cylinder and are subsequently retained in taut condition by mechanical retainers.

Abstract: A sealing assembly (40) for fitting between an upper wellhead connector (12) and a lower wellhead housing or hub 14. Upper wellhead connector (12) has a downwardly facing frusto-conical sealing surface (32) and wellhead housing (14) has an upwardly facing frusto-conical sealing surface (34). Sealing assembly (40) includes a metal ring (42) having annular grooves (58) therein to receive elastomeric sealing elements (60) therein. Elastomeric sealing elements (60) have extending lips (62) for contacting and sealing against adjacent sealing surfaces (32, 34) spaced from opposed frusto-conical surfaces (54, 56) on the metal ring (42) to provide elastomeric seals for the sealing surfaces (32, 34) of wellhead connector (12) and wellhead housing (14).

Abstract: A consumable probe is installed in an elbow zone of a well. The consumable probe is subject to ablation caused by abrasive particles suspended in the fluid being transported by the conduit. As the probe is ablated pressure sensitive chambers will be exposed and the pressure in the conduit will pressurize the pressure sensitive chambers and signal a readout station in a position remote from the location of the probe in the conduit.

Abstract: There are disclosed two embodiments of subsea wellhead apparatus each of which includes a subsea wellhead housing installed at the ocean floor, a casing hanger connectable to the to the upper end of a casing string and supported in the bore of the housing to suspend the casing string in the well bore, and a tubing hanger connectable to the upper end of a tubing string and also supported within the housing bore above the casing hanger for suspending the tubing string within the casing string. A primary valve and a secondary backup valve are installed in series for controlling a passageway in the tubing hanger, and during the completion process, with an additional passageway in a Christmas tree which is installed on the head above the tubing hanger.

Abstract: A tensioning system for a tieback string of casing between a subsea wellhead and a surface wellhead employs hydraulic pressure. A mandrel is connected into the tieback string. A casing hanger mounts to the mandrel and an internal gripping member between the casing hanger and the mandrel allows upward movement of the mandrel relative to the casing hanger but prevents downward movement. The operator lowers the string into the well with the casing hanger in an extended upward position and secures the tieback. The operator then closes the blowout preventer and applies hydraulic pressure in the annulus below the blowout preventer. Seals seal the casing hanger to the surface wellhead and also seal the inner diameter of the casing hanger to the running conduit. The hydraulic pressure forces the casing hanger down onto an internal landing shoulder in the surface wellhead.

Abstract: A subsea wellhead system is used in areas which have shallow water producing sands. A first string of casing extends from the sea floor through a section of conductor pipe and below the conductor pipe to a point above the water sand. An external wellhead housing having flow ports is supported at the upper end of the conductor pipe. A valve sleeve is located on the exterior of the external wellhead housing. The valve sleeve is movable to a closed position, closing the flow ports. A second string of casing is installed to a point below the water producing formation. An internal wellhead housing is secured to the upper end of the second string of casing, which lands within the external wellhead housing. During cementing of the second string of casing the flow ports are open. After cementing, the valve sleeve is moved to the closed position.

Abstract: A mudline casing hanger mechanism is set forth which is particularly intended for use in installing multiple casings which are assembled from a jack-up rig at the surface to the mudline support system of the present disclosure. This utilizes multiple casings which are arranged concentric one within the other and assembles the string of casing joints to the present support structure. This is especially useful when several casing strings are established from a rig temporarily at the location and extend to the mudline. The rig is subsequently moved and the several casing strings above the mudline are disconnected to enable the well to be shut in. All the weight of the well is transferred by casing hangers as set forth so all the weight is supported at the mudline. Later, a different platform is typically installed and the casing strings are reestablished from the mudline to the platform above the water.