Abstract: A protective cap assembly uses a heavy corrosion inhibitor fluid in the primary chamber (the central bore of the mandrel or hub) and a lightweight corrosion inhibitor fluid in the zones outside of the mandrel or hub. The protective cap assembly uses a two port hot stab receptacle and connects the first port to the primary chamber and the second port to the secondary inlet port with a secondary inlet check valve. The primary chamber is vented directly to the subsea environment. With the secondary inlet check valve added to the secondary inlet port, the second port of the protective cap assembly is connected directly to the secondary inlet check valve.

Abstract: Techniques and systems to reduce deflection of a riser suspended from offshore platform. A guidance thrust delivery system (GTDS) includes a plurality of thrusters configured to be coupled to a riser of an offshore vessel. Each thruster of the plurality of thrusters is configured to generate a force on the riser of the offshore vessel to control a position of the riser in a subsea environment while the riser is suspended from the offshore vessel and decoupled from a seafloor.

Abstract: A subsea flowline jumper connector includes at least one electronic connector deployed thereon. The sensor may provide data indicative of the connector state during installation and production operations.

Abstract: A cap system for subsea equipment that can be employed on various subsea equipment including but not limited to a vertical monobore tree, a horizontal tree, a wellhead and a tubing head spool. The cap system includes a cap assembly that has the flexibility of installation and retrieval for open water as well as a through a riser with a running tool. The cap assembly also does not require any orientation during installation. The cap system includes a debris cap assembly installable in engagement with the cap assembly. The debris cap assembly interfacing with the cap assembly provides the ability to inject and bleed fluids through a main bore and an annulus bore of the subsea tree independently and without removal of the debris cap assembly and cap assembly.

Abstract: A connector (10) for securing an elongate member such as an umbilical (12) a female receiving member such as an I-tube (14), has an elongate bend stiffening portion (25) and a securing portion (26) connected to the bend stiffening portion and continuous passage (36) extends through the bend stiffening portion and the securing portion. The securing portion has one or more securing members (e.g. steel balls (40)) displaceable radially outwardly into engagement with the inner face of the tube, thereby securing the connector to the I-tube.

Abstract: In one aspect, a method of connecting a riser from an offshore rig to wellhead equipment that includes a first connector is disclosed. The method, in one non-limiting embodiment, includes lowering a riser of sufficient length having a second connector at a lower end thereof adapted to connect to the first connector of the wellhead equipment, wherein the riser is in fluid communication with and is filled with the sea water; closing the riser proximate to the lower end of the riser after lowering the riser; displacing the sea water in the riser with a fluid that is heavier than the sea water to straighten the riser and the second connector; and connecting the second connector to the first connector.

Abstract: A subsea connection system includes a support unit with a first connector and a distribution unit including an external frame to be landed on and supported by the support unit and an inner frame that is movable within the external frame. An outwardly facing connector may be connected via a long umbilical to a remote platform. Nevertheless, a nearby installation may be controlled via a short umbilical from another connector and thus the nearby installation does not require a long umbilical connected to the remote platform.

Abstract: A gooseneck conduit system for use with a telescoping joint of a subsea riser. In one embodiment, a riser telescoping joint includes a tube, and a gooseneck conduit assembly affixed to the tube. The gooseneck conduit assembly includes a plurality of gooseneck conduits and a locking mechanism. The gooseneck conduits extend radially from the tube. The locking mechanism engages a locking pin affixed to the tube to secure the gooseneck conduit assembly to the tube. Each gooseneck conduit couples to an auxiliary fluid line secured to the telescoping joint.

Abstract: Systems, devices, and methods for providing proper spacing and alignment of multi-well modular drilling templates and associated wells are provided. An example embodiment of a system includes a primary well upon which a multi-well modular drilling template is landed, and a second well upon which a specially configured spacer device is landed. The spacer device includes an alignment frame which engages guide arms of the template to force the spacer device into proper axial alignment. The spacer device includes an elongated arm and a guide funnel which provide the proper spacing and proper location for inserting a third well. The third well can be used as the central well for a second multi-well modular drilling template.

Abstract: A gooseneck conduit system for use with a telescoping joint of a subsea riser. In one embodiment, a riser telescoping joint includes a tube and a gooseneck conduit assembly affixed to the tube. The gooseneck conduit assembly includes a gooseneck conduit extending radially from the tube, and a tenon projecting from a rear face of the gooseneck conduit. The width of the tenon increases with distance from the rear face. The riser telescoping joint also includes a mortise channel extending along the length of the tube. The mortise channel is interlocks with the tenon and laterally secures the gooseneck conduit assembly to the tube.

Abstract: A tubular clamp for gripping a tubular is disclosed. In one aspect, a tubular clamp for use with a cutting and lifting system is provided. The tubular clamp is configured to move between an opened position and a closed position. The tubular clamp further includes at least one slip member to permit the clamp to bear the weight of a severed tubular string. Lifting lugs on an outer surface of the clamp permit attachment to a lifting assembly.

Abstract: A releasable guidepost extension is used on the seabed together with a bottom fixed guidepost part. These parts make up a guidepost for use during the lowering of a component from the surface of the water to a subsea structure. The guidepost part includes an upward (in use position) projecting end designed for engagement with a lower (in use position) end of the guidepost extension. The guidepost extension is loosely connected to the bottom fixed guidepost part via a pin and socket part on respective ends. A gap, or clearance, exists between the pin and socket part in the longitudinal direction, and at least one friction forming device arranged in the gap on either the pin part or in the socket part. The friction forming device does not get in contact, or engaged, with the other part unless the guidepost extension is subjected to a lateral force.

Abstract: A cap is lowered onto and secured to a subsea member with an external flange, effecting a seal between the external flange and cap. The cap includes a tubular outer body defining a cavity, and a tubular inner body defining a bore, wherein the lower end of the inner body resides within the cavity. The cap also includes a lower engaging member coupled to the outer body that is radially movable between an inward state and an outward state and configured to alternately engage and disengage at least one of a backside of the external flange. Finally, the cap includes an upper engaging member coupled to the outer body and being radially movable independently of the lower engaging member between an inward state and an outward state and configured to engage and disengage the inner body.

Abstract: Well apparatus comprises a tower, and a support for supporting well intervention, completion, testing, or drilling equipment, the support being attached to the tower and being movable laterally from a parked position on the tower, where preparation of the equipment can be carried out without occupying an operational area where the equipment is to operate on the well, and an operational position in the operational area, and the support being arranged to be lowered or lifted, the apparatus further comprising a guide mechanism for guiding the support so that as the support is - lowered or lifted it is guided along a path involving lateral movement from the parked position to the operational position in the operational area.

Abstract: Apparatuses useable in an offshore drilling installation close to the seabed for controlling well influx within a wellbore are provided. An apparatus includes a centralizer and flow constrictor assembly, a sensor and a controller. The centralizer and flow constrictor assembly are configured to centralize a drill string within a drill riser and regulate a return mud flow. The sensor is located close to the centralizer and flow constrictor assembly and configured to acquire values of at least one parameter related to the return mud flow. The controller is coupled to the centralizer and flow constrictor assembly and the sensor. The controller is configured to control the centralizer and flow constrictor assembly to achieve a value of a control parameter close to a predetermined value, based on the values acquired by the sensor.

Abstract: A device for containing fluid flow from a borehole includes: a containment assembly including a body having a cavity configured to receive a leaking portion of a borehole termination structure extending from the borehole and surround the leaking portion, the cavity configured to be adapted to at least partially conform to a shape of at least one of the leaking portion and the borehole termination structure; and a flow control assembly configured to connect a fluid conduit in fluid communication with the containment assembly and direct downhole fluid into the fluid conduit.

Abstract: A guide funnel for guiding a subsea infrastructure for connection with a subsea wellhead or mandrel profile is provided. The guide funnel comprises a plurality of sections, wherein the sections are collapsible such that the guide funnel can be in an extended state or a collapsed state.

Abstract: The present invention is a method and system for supplying grease to maintain a sealed well during deployment of line, in particular braided electrical wire. The subsea grease cartridge system includes a subsea assembly; first and second grease containers filled with grease; a pump; a switch; and a restoring device to replenish grease containers. The method of operating the grease cartridge system includes: attaching first and second grease containers to the subsea assembly; applying hydraulic pressure to the first grease container; pumping the grease of the first grease container to a grease head; switching hydraulic pressure from the first grease container to the second grease container instantaneously when the first grease container becomes unable to supply grease properly; and pumping the grease of the second grease container to the grease head. The method includes replenishing containers from cartridges and switching back and forth between the filled grease containers.

Abstract: In subsea drilling operations, workover control systems may include deployment of an umbilical from a deepwater drilling vessel. Such an umbilical provides support functions for deepwater drilling operations. In the practice of the invention, a new method, system and apparatus may be employed to deploy the umbilical independently of the drilling riser, which provides commercial and operational advantages. That is, the umbilical may be deployed at a different time than the riser is deployed, and also without intimate close connection from the umbilical to the riser.

Abstract: A system, including a first module (35b) configured to process fluid from a well, wherein the first module (35b) includes a processing device coupleable to a manifold (5), a first access tunnel (4b) extending through the processing device, wherein the access tunnel (4b) is configured to provide access to the manifold (5), a processing input (18a), and a processing output (19a). Further provided is a method of assembling a manifold, including coupling a processing module (35b) to a manifold (5), wherein the processing module comprises an access tunnel (4b) through the processing module (35b) that enables access to the manifold (5) while the processing module (35b) is coupled to the manifold (5).

Abstract: An apparatus for performing well intervention work using coiled tubing. The apparatus includes a structural frame. The upper portion of the frame include two winches for suspending well interventions tools including a coiled tubing injector head. The winches may be selective reciprocated by a hydraulic cylinder to either bring the first or second winch into operative alignment into or out of alignment with a subsea wellhead.

Abstract: Well apparatus comprises a tower, and a support for supporting well intervention, completion, testing, or drilling equipment, the support being attached to the tower and being movable laterally from a parked position on the tower, where preparation of the equipment can be carried out without occupying an operational area where the equipment is to operate on the well, and an operational position in the operational area, and the support being arranged to be lowered or lifted, the apparatus further comprising a guide mechanism for guiding the support so that as the support is—lowered or lifted it is guided along a path involving lateral movement from the parked position to the operational position in the operational area.

Abstract: A fiber optical sensing cable is inserted into an underwater well by: connecting a housing (12A) comprising a coiled or spooled U-shaped fiber optical sensing cable (21) to the wellhead (2) of the well (1) such that an opening (14) in the wall of the housing (12A) is connected to a guide tube (15) extending into the underwater well (1); —inserting the U-shaped nose section (21A) of the fiber optical sensing cable (21) via the opening (14) into the guide tube (15), thereby uncoiling at least part of a pair of substantially parallel sections of the fiber optical sensing cable of which the lower ends are interconnected by the U-shaped nose section; and connecting the upper ends (21B) of the substantially parallel sections of the fiber optical sensing cable to an optical signal transmission and/or receiving unit via e.g. a pair of wet mateable connectors that are connected to a pair of underwater fiber optical transmission cables (14).

Abstract: A subsea oil and/or gas exploitation device including at least one guide member for guiding subsea equipment that is to be landed and connected to the device into a connecting position in relation to the device. The at least one guide member includes an array of projections provided for the purpose of engaging corresponding recesses arranged in a corresponding guide member of the subsea equipment.

Abstract: A system for installation of a subsea module of great length by means of a vessel, using a cable for its installation and/or retrieval, and methods applied therein. The system allows transporting the subsea module on the vessel to a location in the sea and descending the subsea module into the sea at a vertical position for installation on the seabed.

Abstract: A spool piece termination structure to be mounted to a spool piece so as to support a spool piece hub during the connection of the spool piece hub to a corresponding pipeline hub. The termination structure includes a clamping device for clamping together the spool piece hub and pipeline hub, and a base frame openly shaped downwards so as to allow the termination structure to receive a pipeline end section provided with the pipeline hub by lowering the termination structure downwards onto the pipeline end section. A connection arrangement includes such a spool piece termination structure and a method for subsea connection of a pipeline to a spool piece.

Abstract: An apparatus for storing tubulars on a floating semi-submersible drilling or production vessel. The apparatus comprises a storage device for storing tubulars in a submerged position, essentially below a splash zone. The storage device is generally open to the surroundings so that the tubulars are externally exposed to surrounding water. It is also described an apparatus for transporting tubulars between a storage and a derrick on an offshore drilling and/or production platform having a platform deck. The apparatus is situated below the platform deck and is adapted for movement under the platform deck. A method for disassembling a pipe string is also described.

Abstract: An outer wellhead housing has an external locator member initially oriented in a desired direction. An inner wellhead housing lands in the outer wellhead housing. A BOP orientation spool with an external orientation member and an internal orientation member lands on the inner wellhead housing and orients via the external locator member. A tubing hanger with an orientation member and associated tubing hanger running tool with another orientation member lower through the BOP orientation spool and orient as they land in the inner wellhead housing. A production tree with an orientation member on a lower end lands on the inner wellhead housing. The orientation member of the production tree engages the orientation member of the tubing hanger to rotate the tree to a desired orientation.

Abstract: A clamp for supporting a subsea wellhead and attached casing string preparatory to installing same in a well, and slip bowl assembly for running a drill pipe cementing string inside the casing string. The clamp comprises two hinged together clamp halves with a connector to permit the clamp to be locked about a subsea wellhead. Half-circle cutouts in each clamp half form a clamp bore when the clamp is closed. The clamp bore has a grooved profile to mate with a grooved profile on the exterior of the subsea wellhead. When the subsea wellhead is clamped in place, with the clamp resting on the rig floor, a slip bowl assembly having a grooved base plate is placed atop the clamp.

Abstract: The disclosure describes a spoolable compliant guide, a system including a spoolable compliant guide and injector and methods for using the compliant guide, where the guide is designed to connect at one end to the injector and at its other end to a remote installation having a seal and to allow coiled tubing to be inserted into the installation through the seal. Because the guide permits a substantial distance to exist between the injector and the installation seal and functions as a crimp or band resistor for the coiled tubing, the guide enables the injector to be conveniently positioned remote from the installation such as a wellhead and assumes a compliant shape between the injector and the installation allowing dynamic relative movement between them without the use of heave compensators. Thus, for subsea installations, the injector, its control system and coiled tubing reels can all be located on the water's surface for ease of access and maintenance.

Abstract: The disclosure describes a spoolable compliant guide, a system including a spoolable compliant guide and injector and methods for using the compliant guide, where the guide is designed to connect at one end to the injector and at its other end to a remote installation having a seal and to allow coiled tubing to be inserted into the installation through the seal. Because the guide permits a substantial distance to exist between the injector and the installation seal and functions as a crimp or band resistor for the coiled tubing, the guide enables the injector to be conveniently positioned remote from the installation such as a wellhead and assumes a compliant shape between the injector and the installation allowing dynamic relative movement between them without the use of heave compensators. Thus, for subsea installations, the injector, its control system and coiled tubing reels can all be located on the water's surface for ease of access and maintenance.

Abstract: A riser guide is for use on a floating offshore platform, the platform comprises a topsides and a substructure having a lower pontoon, and at least one riser extends from a subsea location to the topsides. A number of riser guides are located in a guide housing which is secured to the platform. Each riser guide comprises a support arm rotatably mounted in the guide housing. A roller for laterally guiding the riser is rotatably mounted in an end of the support arm. A vertically movable wedge which is used for lifting the guide housing is connected to the support arm. During lifting of the guide housing the wedge lifts the support arm and the roller to an inactive position. When installing the riser guides, the guide housing and the riser guides are placed around the riser at the topsides, and lowered down in place by lifting gear connected to the wedges.

Abstract: The disclosure describes a spoolable compliant guide, a system including a spoolable compliant guide and injector and methods for using the compliant guide, where the guide is designed to connect at one end to the injector and at its other end to a remote installation having a seal and to allow coiled tubing to be inserted into the installation through the seal. Because the guide permits a substantial distance to exist between the injector and the installation seal and functions as a crimp or band resistor for the coiled tubing, the guide enables the injector to be conveniently positioned remote from the installation such as a wellhead and assumes a compliant shape between the injector and the installation allowing dynamic relative movement between them without the use of heave compensators. Thus, for subsea installations, the injector, its control system and coiled tubing reels can all be located on the water's surface for ease of access and maintenance.

Abstract: A riser guide system is for use on a floating offshore platform, the platform having a topside and a substructure having a lower pontoon, and at least one riser extends from a subsea location to the topsides. A permanent guide is secured to the pontoon, a primary guide is located in the permanent guide, a secondary guide is located in the primary guide, and riser guides are located in the secondary guide and face the riser. In a method for installing the riser guide system, both the primary guide, the secondary guide and the riser guides are placed around the riser at the topsides, and lowered down to the pontoon.

Abstract: The present invention involves a remote sub sea lubricator assembly for inserting a wireline tool into a sub sea well comprising an elongated tube having an axial passage formed therethrough for receiving the wireline tool. The remote sub sea lubricator is lowered beneath the surface of the sea for connection to a sub sea well. Contained within the lubricator is the wireline tool. Once connected to the sub sea well, the wireline tool is released from the lubricator into the well. The lubricator enables the wireline tool to enter and exit the well without sea water entering the well.

Abstract: A subsea production system and method includes a wellhead field having multiple wellheads and utilizes a stackable guide funnel system for sequential tying back of those wellheads. A storage frame retains several guide funnels that are nestably stacked one upon the other. The guide funnels may be sequentially removed from the frame by a riser connector having a complimentary latching mechanism. The frame is made up of a plurality of guide members that are secured to the exposed tubular conductor of a wellhead. A pair of annular rings surrounds portions of each of the guide members. The upper end of the frame is outwardly flared to assist in landing of the riser connector. The stacked guide funnels are prepositioned at one or more central locations upon the sea floor. The guide funnels are configured at the central location to permit sequential retreival. A riser having a riser connector is lowered to the central location. The riser connector latches onto the uppermost guide funnel within the frame.

Abstract: A remotely installed pressure containing closure having a slight negative buoyancy, and a method for assembly of a slight negative buoyancy remotely installed pressure containing closure, such as a tree cap, on a subsea assembly, having at least one fluid bore, and more preferably a production bore and an annulus bore, wherein the remotely installed pressure containing closure comprises: a guidance ring having a plurality of chambers; optionally, a plurality of orientation pins affixed to the guidance ring for aligning the guidance ring to a funnel; buoyant material disposed in the chambers of the guidance ring to assist in creating a slight negative buoyancy for the remotely installed pressure containing closure; a cylinder connected to the remotely installed pressure containing closure for engaging sealing means on a subsea assembly for sealing at least one seal of at least one fluid bore of said subsea assembly; a debris cover connected to said cylinder to house equipment and cover the fluid bore; a mandre

Abstract: An apparatus for releasably securing a tubular structure of a floating installation to an anchor fixedly secured to an underwater floor has a first connection element mounted at one end of the tubular structure and a second connection element configured at one end to couple with the first connection element. The second connection element includes a pair of guides secured thereto which extend horizontally therefrom. A hinge device connects the second connection element to the anchor such that the second connection element is pivotably connected to the anchor. A plurality of cables connect to both the tubular structure and the anchor, whereby the pair of guides cooperate with the cables such that when the cables are under tension, the cables urge the second connection element to pivot and align with the first connection element.

Abstract: The invention is a device for eliminating the “tripping” of the BOP stack to the surface when switching between drilling and completion modes of operation on a drilling rig. This device is a new apparatus for attaching a BOP guide funnel, which will allow the funnel to be released and/or reattached while the BOP remains subsea on or near the seafloor. The new BOP guide funnel assembly consists of three basic components: a guide funnel, a connector shroud and a parking pile adapter. The guide funnel has a downwardly opening funnel on bottom (used to capture a wellhead) and an upwardly opening smaller funnel on top (used to guide the shroud back into the guide funnel during re-installation of the guide funnel). The connector shroud is permanently attached to the bottom of the BOP stack, surrounding the BOP wellhead connector and holds the guide funnel in place.

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 latching assembly includes a first mating portion and a second mating portion disposed adjacent and rotationally restrained relative to the first mating portion. A first cam member having a first cam profile is mounted on the first mating portion. A second cam member having a second cam profile is mounted on the second mating portion. The second cam profile is adapted to inter-fit with the first cam profile. Torque induced by the cam members when the cam profiles are engaging rotates the first cam member until the first cam profile is inter-fitted with the second cam profile.

Abstract: The invention relates to a system for pull-in and interconnection of two pipelines in subsea position, whereof one first pipeline initially is freely suspended, while one second pipeline for instance is mounted on a bottom based manifold frame. The end section on the first pipeline is provided with a socket-like termination with a front end, which is provided with means (17) for coupling of the terminator (8) to complementary pipe coupling means (29) on the second pipeline (19). The terminator (8) is provided with a laterally directed, longitudinally shaped anchor element (10), and the manifold frame (22) is provided with receiving means (24) for receipt and fixation of the anchor element (10).

Abstract: Apparatus is disclosed for use in lowering an object such as a well pipe through a guide tube suspended from the water surface and onto an upstanding subsea conduit beneath the lower end of the guide tube.

Abstract: A method of providing a cathodic protection to an installed pile is disclosed in which a plurality of anodes are provided on a tendon foundation guide assembly which is attached to a lowering unit and lowered to the pile. The tendon foundation guide assembly is attached to the installed pile and at least one of the anodes is electrically connected to the pile. The tendon foundation guide assembly is then separated from the lowering unit. In another aspect of the invention, a tendon foundation guide assembly is disclosed for deployment upon the top of an installed pile for cathodically protecting the pile and a tendon receptacle inside the pile.

Abstract: A device for mounting a flexible line including a curvature limiter. The device for mounting a flexible line on a structure, including a hollow rigid member forming part of the structure or fixed to the structure, and which the flexible line passes through after having been pulled with the aid of a pull cable fixed to one end of the flexible line, in particular on the end fitting mounted on the latter for connecting it to the structure, and a curvature limiter engaged on the flexible line and secured to fixing means able to interact with fixing means secured to the hollow rigid member for fastening the curvature limiter to the structure.

Abstract: A method of drilling a subsea well involves partial drilling of several wells within a cluster. A base such as a template will have a receptacle. A gimbal mounts to a latching mechanism which in turn releasably latches an outer wellhead housing. The latching mechanism has an upward facing guide funnel. After setting conductor pipe, the well is drilled to a selected depth, an inner wellhead housing and a first string of casing are lowered through the funnel. The running tool for the inner wellhead housing has a funnel retriever which latches to the funnel. After the casing has been cemented, upward movement of the running tool will pull the funnel, latching mechanism and gimbal to the surface.

Abstract: Apparatus having removable posts for guiding subsea well equipment. The apparatus includes a frame for permanent attachment to a well installation. The frame includes outwardly extending legs with each of the legs for receiving an upstanding retrievable guide post. Each leg includes a latching mechanism and a guide foot for receiving an upstanding guide post. The latching mechanism includes a retainer rotatable between a latching position, a latched position and an unlatched position. The latching mechanism preferably includes a handle connected to the retainer with the retainer being rotatably connected to the top of the frame. The retainer may include a beam for engaging a shoulder on the guide post when in the latched position. The handle is in a downward position when the retainer is in the unlatched position prior to the guide post being seated in the guide foot.

Abstract: A guide line attachment for releasably attaching a guide line to a guide post top or other portion of a sub-sea installation has three relatively movable spring loaded concentric sleeves, the relative movement of which can be used to releasably lock the attachment to the guide post top or other portion. Relative movement of the sleeves also activates a latch to releasably lock the sleeves to each other. The attachment may fit inside or outside a guide post top and may be pre-set so that it will or will not automatically relatch on release. The guide post tops have internal or external grooves for engaging the attachment locking means, and specially designed tools may be used to effect remote release sub-sea. The guide line attachment may be used for all stages of the drilling and production of a sub-sea oil well and avoids the present need to cut and replace guide lines at different stages in the life of a sub-sea well.

Abstract: A protective cap (12) can be run onto and retrieved from a subsea wellhead (10) from a floating service vessel. Slidably mounted shear pins (32) in the cylindrical wall (14) of the protective cap (12) allow the cap to be attached by a downward push. Retrieval of the protective cap (12) involves an overpull on the drill string that is sufficient to shear the pins (32) in the cylindrical wall (14).

Abstract: A casing installation system usable with tubular casing having an upper end portion and a lower portion, for anchoring the upper end portion of the casing on an outer casing string secured to a wellhead having a housing, the wellhead housing being positioned at a fixed position over a well, said casing extending upwardly to the wellhead from a location in the well at which location the lower portion of the casing is landed, the upper end of the casing being terminated by a generally annular casing hanger secured to the casing, said outer casing string having an upwardly-facing shoulder, the system also having a locking ring located on the casing hanger and movable thereon in a direction towards the lower end portion of the casing, the locking ring having means for preventing its movement on the casing in a direction away from the lower end portion of the casing in response to a force exerted on the locking ring in said direction away from the lower end of the casing, the locking ring having a downwardly-facin