Abstract: An apparatus for changing a drilling tool for a drilling rig is described, where the drilling rig comprises a drill tower supporting a drill pipe. The apparatus for changing a drilling tool has a drilling tool changer assembly moveable between a storage position and an exchange position, and the drilling tool changer assembly supports a rotatable carousel assembly. The rotatable carousel assembly is capable of being removed from the drilling tool changer assembly and capable of replacement on the drilling tool changer in the same angular position with respect to the drill pipe as when removed. The rotatable carousel assembly has a plurality of bit adaptors for holding drilling tools and is selectively rotatable to bring a selected drilling tool into coaxial alignment with the drill pipe when the drilling tool changer assembly supporting the rotatable carousel assembly is moved into the exchange position.

Abstract: A method is disclosed for semi-automatic or automatic control of a system for changing drilling tools for a drilling rig that includes a drill tower supporting a drill string with a drill pipe at a lowermost end, and a drilling tool changer assembly having a rotatable carousel assembly with a plurality of bit adaptors for holding drilling tools. The method includes removing a first drilling tool attached to the drill pipe and attaching a second drilling tool held in the rotatable carousel assembly to the drill pipe. The method may selectively be performed semi-automatically or automatically via a control system operatively coupled to the drilling rig.

Abstract: An apparatus and methods for installation of an offshore platform for supporting equipment installations is provided. The apparatus includes a vertical compression assembly and a counteracting tensioning tendon system. The vertical compression assembly may comprise multiple compression members, a column truss, or other configurations.

Abstract: Systems and processes for subsea marine managed pressure operations. One system includes a modified riser joint configured to fluidly connect inline with one or more riser joints. The modified riser joint and the one or more riser joints are connected to form a riser connecting a floating vessel with a wellhead. The system further includes a subsea pressure management sub-system configured to be operatively and fluidly connected to the modified riser joint at a subsea location.

Abstract: A wellhead monitoring system includes a conversion assembly, the conversion assembly including an actuator element for modifying an operating mode of a valve from manual to remote. The system also includes one or more sensors, associated at least one of a fracturing tree or the conversion assembly, the one or more sensors obtaining wellhead operating conditions. The system further includes a control unit, adapted to receive information from the one or more sensors, the control unit presenting the information, on a display, and transmitting the information to a remote system for analysis.

Abstract: An apparatus for changing a drilling tool for a drilling rig is described, where the drilling rig comprises a drill tower supporting a drill pipe. The apparatus for changing a drilling tool has a drilling tool changer assembly moveable between a storage position and an exchange position, and the drilling tool changer assembly supports a rotatable carousel assembly. The rotatable carousel assembly is capable of being removed from the drilling tool changer assembly and capable of replacement on the drilling tool changer in the same angular position with respect to the drill pipe as when removed. The rotatable carousel assembly has a plurality of bit adaptors for holding drilling tools and is selectively rotatable to bring a selected drilling tool into coaxial alignment with the drill pipe when the drilling tool changer assembly supporting the rotatable carousel assembly is moved into the exchange position.

Abstract: A platform assembly for providing a work area around a well riser is disclosed. The platform assembly comprises a platform configured to be attached to the well riser. The platform assembly further comprises a plurality of tensioning means for supporting the platform relative to a vessel and for supporting the riser. At least part of tensioning means is configured to change in length relative to another part of tensioning means responsive to angular motion of the riser and the vessel.

Abstract: A subsea valve system for use in a subsea landing string includes a subsea valve and an external manifold in fluid communication with the subsea valve. The external manifold includes a cylinder, a split manifold piston, an above bore inlet that is configured to be exposed to an above bore pressure, a below bore inlet that is configured to be exposed to a below bore pressure, and an open chamber outlet. The split manifold piston is configured to move within the cylinder to fluidly couple the above bore inlet to the open chamber outlet to enable pump through functionality while a respective force exerted on the manifold piston by the above bore pressure is greater than a respective force exerted on the manifold piston by the below bore pressure.

Abstract: An inflatable packer system for an annular blowout preventer (BOP) includes an inflatable bladder configured to be positioned within a housing of the annular BOP and to inflate upon receipt of a fluid within the inflatable bladder. The inflatable bladder may be an annular structure that is configured to circumferentially surround a bore of the annular BOP.

Abstract: A subsea assembly includes a housing having a flange interface for interfacing with a flange of a process fluid carrying component, wherein the housing is configured such that boltheads or nuts exerting a fastening force on the subsea assembly when mounted to the process fluid carrying component are spaced from the flange interface so that the dimensions of the housing of the subsea assembly at the flange interface are not affected by a space required for a bolthead or nut fastening tool.

Abstract: Embodiments of the present disclosure include a remote well servicing system including a control unit and a remote servicing manifold. The control unit further includes a service fluid source and a control system. The remote servicing manifold further includes a fluid input line coupled to the service fluid source, a fluid output line couplable to a well component, and a valve coupled to the fluid input line and the fluid output line, wherein the valve, when actuated, places the fluid input line in fluid communication with the fluid output line and permits delivery of a service fluid from the service fluid source to the well component. The remote servicing manifold also includes a control line coupling the valve and the control system wherein the control system controls actuation of the valve via the control line.

Abstract: A horizontal connection system including: a first holding unit, to which a first hub is fixed; a second holding unit, to which a second hub is fixed; a heat bank including a casing with a rear part secured to the first holding unit and a front part releasably connectable to the rear part; and a clamp connector secured to the first holding unit and received inside the heat bank. The parts of the casing are temporarily fixed to each other by connecting members extending between the parts on the outside thereof. The front part of the casing is provided with fastening members configured to come into engagement with associated fastening members on the second holding unit, to thereby allow the front part to be secured to the second holding unit, when the front part and the second holding unit are brought into contact with each other.

Abstract: Techniques and systems to provide pressure reduction of a fluid, for example, from a well. A device includes an input configured to be fluidly coupled to a well control device. The device also includes an output configured to be to be fluidly coupled to the well control device. The device further includes at least one valve configured to alter a pressure of a fluid received at the input and transmitted from the output.

Abstract: A system for connecting flow interface equipment to a subsea tree or manifold is disclosed. The system relates to an apparatus adapted to inject fluids into a well having a flow bore. The system includes a connection apparatus adapted to land a conduit on a subsea tree or manifold and to connect the conduit of the connection apparatus to an access port or choke body of the tree or manifold.

Abstract: An underwater connector includes a first component and a second component, wherein the components are operable to be coupled together in operation in a first coupled state, and operable to be mutually spatially separated in a second uncoupled state. The first and second components each include communication arrangements which are operable to provide wireless communication between the first and second components when in their first coupled state. The first and second components include a power transfer arrangement for transmitting power between the first and second components. The power transfer arrangement includes inductive coupling devices and/or capacitive coupling devices, wherein the power transfer arrangement is implemented substantially as an annulus, for example circular, elliptical, or polygonal, on the first and second components together with the communication arrangements being disposed within the annulus and/or around a periphery of the annulus.

Abstract: A handling device (1) for an installable and retrievable subsea apparatus (2) to engage a docking device (3) on a subsea installation, the docking device (3) having a pair of engagement members (4, 5). The device (1) is provided with a top member (6) and a pair of engagement arms (7, 8) depending therefrom to extend along the outside of the apparatus (2). Each of the arms (7, 8) at a free end thereof is provided with a hook (7?, 8?) configured to engage in releasable way the engagement members (4; 5). A rotatable handle (9) is located above the top member (6) and has an integral or linked stem (10) which extends through the top member (6) and is pivotally linked to a top region of the apparatus (2). The handle (9) is able to operate the engagement arms (7, 8) relative to the engagement members (4,5).

Abstract: An ROV-mountable flush and sample skid is described that reduces the project cost and deliveries, and also improves HSE risk during Subsea Pump installation campaigns. The ROV skid can be configured as part of a standard ROV tooling across different projects. The tool also reduces the total pump module installation weight that is important in deepwater applications. The ROV-mountable flushing and sampling skid is mounted to an ROV and deployed to a subsea location to provide flushing of and sampling of barrier oil from a barrier oil supply jumper from an subsea umbilical termination assembly. The Subsea pump flushing and sampling ROV skid includes of a set of flush accumulators with enough capacity to flush the installed jumpers clean, and also one or more sample accumulators configured to sample the barrier oil after the flushing has been performed.

Abstract: Systems and methods for drilling multiple wells include a landing template, the landing template having at least two through bores. Each through bore extends from a first face of the landing template to an opposite second face of the landing template. A skirt conductor is secured to the landing template, the skirt conductor operable to be driven into a sea floor so that the landing template is proximate to a mudline. A bore separator guide has a drill bit guide sized to register with one of the through bores. The bore separator guide is moveable to align with each of the at least two through bores one at a time.

Abstract: A dual-BOP or multi-BOP self-standing riser configuration is disclosed, including at least a riser or another similarly fixed tubular structure disposed in communication with an associated drilling vessel and a subsurface well. The system supplements the traditional mud-line level BOP with one or more additional near-surface BOPs, which are tensioned using an adjustable buoyancy chamber rather than by means of a vessel-born tensioning device.

Abstract: A system for connecting flow interface equipment to a subsea tree or manifold is disclosed. The system relates to an apparatus adapted to inject fluids into a well having a flow bore. The system includes a connection apparatus adapted to land a conduit on a subsea tree or manifold and to connect the conduit of the connection apparatus to an access port or choke body of the tree or manifold.

Abstract: According to one aspect, an apparatus is adapted to be operably coupled to a subsea blowout preventer and includes a first tubular member defining an internal passage, and a second tubular member extending within the internal passage. A sealing assembly is disposed radially between the first and second tubular members, and includes a sealing element. The second tubular member covers the sealing element and thus facilitates protecting the sealing element from any fluid flow through the internal passage. According to another aspect, a sealing element of a connector is protected before engaging the connector with a subsea casing. The connector is engaged with the casing while the sealing element is protected so that the sealing element is fluidically isolated from any fluid flow through the connector. The sealing element sealingly engages the casing.

Abstract: A drilling system including a drill head. The drill head defines a drill head bore and includes a drill head bore closure device. An inner core barrel and an inner core barrel retrieval device may be passed through the interior of the drill string and the drill head bore when the drill head is connected with the drill string and the drill head bore closure device is actuated to an open position. A method of wireline core drilling which includes passing an inner core barrel retrieval device through the drill head bore and into the interior of the drill string when the drill head is connected with the drill string, and removing an inner core barrel and the inner core barrel retrieval device from the interior of the drill string through the drill head bore when the drill head is connected with the drill string.

Abstract: A system for connecting flow interface equipment to a subsea manifold is disclosed. The system relates particularly to an apparatus adapted to inject fluids into a well having a flow bore. The system includes a connection apparatus adapted to land a conduit means on a subsea manifold and to connect a conduit means of the connection apparatus to a choke body of the manifold.

Abstract: According to one aspect, an apparatus is adapted to be operably coupled to a subsea blowout preventer and includes a first tubular member defining an internal passage, and a second tubular member extending within the internal passage. A sealing assembly is disposed radially between the first and second tubular members, and includes a sealing element. The second tubular member covers the sealing element and thus facilitates protecting the sealing element from any fluid flow through the internal passage. According to another aspect, a sealing element of a connector is protected before engaging the connector with a subsea casing. The connector is engaged with the casing while the sealing element is protected so that the sealing element is fluidically isolated from any fluid flow through the connector. The sealing element sealingly engages the casing.

Abstract: There is provided a subsea system for increasing pressure and/or flow rate in a flow line, the subsea system being arranged in fluid communication with said flow line which receives fluid from at least one fluid source. The subsea system comprises at least one compressor or pump and at least one subsea cooler which is arranged in the flow line in series with the at least one compressor. The subsea system further comprises a recirculation line which is configured such that at least a portion of the fluid flowing in the flow line downstream the at least one compressor and the at least one subsea cooler may be recirculated back to the flow line upstream the at least one compressor and the at least one subsea cooler such that the recirculating line can be used for capacity regulation of the at least one compressor and cleaning of the at least one subsea cooler.

Abstract: A system (10) for managed pressure drilling, or for workover of a hydrocarbon well with a wellhead, the system comprising a floating structure that is located in a body of water (41). A method is also described for connecting up the system for managed pressure drilling or well workover. The floating structure comprises a drill floor (13) and a work deck (14) that is movably arranged in an essentially vertical direction in relation to the drill floor. The system further comprises a riser (28) and a slip joint (32) that is connected to the underside of the work floor and to the upper end of the riser such that the work deck can be moved relative to the riser. The riser extends from the slip joint down to a wellhead valve device (40) arranged on the wellhead of the hydrocarbon well. The floating arrangement also comprises heave-compensated riser tensioners (17) which are connected to the slip joint such that the riser is held under tension.

Abstract: A method of installing an off-shore tidal hydroelectric turbine generator is described. The method provides for a number of safety features, ensuring that all components are safe to handle during the installation operation, and also ensuring that the turbine will not start spinning during the installation operation.

Abstract: A method of monitoring a subsea pipeline system connecting one or more wells to a floating production system, wherein the pipeline system is at least partially flexible, the method comprises installing a continuous optical fiber distributed sensor as part of the pipeline system, the sensor capable of providing a distributed measurement of temperature, vibration, pressure or strain, or any combination thereof; using the sensor to obtain a distributed measurement of temperature, vibration, pressure and/or strain along at least part of the pipeline system indexed to a length thereof; and using the distributed measurement to predict the actual condition of the fluid, the pipeline system and/or the adjacent sea water using a model.

Abstract: The present invention relates to a managed pressure and/or temperature drilling system (300) and method. In one embodiment, a method for drilling a wellbore into a gas hydrates formation is disclosed. The method includes drilling the wellbore into the gas hydrates formation; returning gas hydrates cuttings to a surface of the wellbore and/or a drilling rig while controlling a temperature and/or a pressure of the cuttings to prevent or control disassociation of the hydrates cuttings.

Abstract: A pressure equalizer for an underwater vessel can include a pneumatic reservoir and a pressure compensating valve (PCV). The PCV can be in fluid communication with the surrounding underwater environment and the vessel interior, and in selective fluid communication with the reservoir. The PCV can further include a valve body and a valve plug. As the PCV opens, the plug moves within the body to establish a path of fluid communication from the reservoir, through the PCV to the vessel interior, to allow flow of high pressure compressible fluid from the reservoir into the interior to pressurize the vessel interior. As the vessel interior pressure equalizes with the surrounding environment, the plug moves within the body to close the fluid communication path with the reservoir, thereby stopping the flow of compressible fluid into the vessel interior to maintain the equalized pressure.

Abstract: Several, preferably three, deflection elements are placed and fixed around the wellhead, preferably in equal circumferential distances around the wellhead. For each deflection element a guiding cable is lowered with its head end from one or several, preferably three workspaces in the direction of the wellhead. Each guiding cable is looped with its head end through the corresponding deflection element, wherein each deflection element forms a point of reversal. Each guiding cable is pulled back with its head end side to the corresponding workspace while in return additional guiding cable is supplied and passed through the corresponding deflection element. A sealing element which is fastened to each guiding cable is lowered in the direction of the wellhead by pulling the guiding cables at their head end sides upwards and, in return, supplying the guiding cables in the direction of the wellhead on the lowering side.

Abstract: A riser for use in boring a subsea wellbore having a gooseneck assembly connected onto the riser. The gooseneck assembly has an outlet that couples with a flowline on the riser and a connector assembly that selectively decouples the gooseneck assembly from the flowline. A release member, such as a wire, cable, or rod, is attached to the connector so the connector assembly can be actuated by manipulating the release member from a remote location.

Abstract: A method and apparatus are described for containing an oil spill caused by a subsea blowout, (i.e., a source of pollution located on a floor of an ocean, (e.g., a defective blowout preventer (BOP) that caused the oil spill)). A cylindrical containment assembly may be positioned such that a wall of the cylindrical containment assembly circumvents a portion of a floor of an ocean where the subsea blowout occurred. At least one mud flap may be configured to selectively protrude from the wall or retract into the wall when activated to control the depth that the cylindrical containment assembly sinks to below the ocean floor. A valve assembly may be positioned on the top perimeter of the wall. The top perimeter of the wall may have the same diameter as the outer perimeter of the valve assembly.

Abstract: A method and apparatus are described for containing an oil spill caused by a subsea blowout. A blowout preventer (BOP) stack, located on a floor of an ocean, may be circumvented with a hollow wall of a cylindrical containment assembly. The containment assembly may be reinforced by filling the wall with cement. A valve assembly having a hollow cavity may be positioned on a top perimeter of the wall and may be reinforced by filling the cavity with cement. Alternatively, a cylindrical containment assembly may be positioned such that a wall of the assembly circumvents a portion of a floor of an ocean where a subsea blowout occurred and at least one of oil or gas is spewing into the ocean. The wall may be reinforced with cement, a valve assembly may be positioned on a top perimeter of the wall, and the valve assembly may be reinforced with cement.

Abstract: An arrangement related to subsea electric power distributing AC-system and adapted for a subsea application. The arrangement is enclosed in a watertight casing. The casing exposes a main power input connection, adapted for watertight co-ordination with a first subsea cable and a main power output connection, adapted for a watertight co-ordination with a second subsea cable. The second subsea cable is adapted for a power supply to an AC-current and AC-voltage adapted device. The arrangement includes interconnected: a voltage regulator connected to the first cable, and a NO-load switching unit connected to the second cable, and a control unit. The control unit is adapted, in a first operative mode, to regulate the output AC-voltage from the voltage regulator towards and to zero, or at least almost to zero, and in a second subsequent operative mode, to bring the NO-load switching unit from an ON-position to an OFF-position or vice versa.

Abstract: A dual-BOP or multi-BOP self-standing riser configuration is disclosed, including at least a riser or another similarly fixed tubular structure disposed in communication with an associated drilling vessel and a subsurface well. The system supplements the traditional mud-line level BOP with one or more additional near-surface BOPs, which are tensioned using an adjustable buoyancy chamber rather than by means of a vessel-born tensioning device.

Abstract: A method and apparatus are described for stopping oil and/or gas from spewing from a defective blowout preventer (BOP) stack located on a floor of an ocean by entombing the defective BOP stack. A containment assembly, which is lowered below a surface of the ocean, includes a hollow wall and a large diameter high pressure valve mounted on an upper opening of the containment assembly. The large diameter high pressure valve is maintained in an open position. The containment assembly is positioned on a portion of the ocean floor such that a hollow inner cavity of the containment assembly circumvents the defective BOP stack. The hollow wall is filled with reinforcement material via a first set of valves, and the hollow inner cavity is filled with reinforcement material via a second set of valves. The upper opening may also then be filled with reinforcement material.

Abstract: A riser for use in boring a subsea wellbore having a gooseneck assembly connected onto the riser. The gooseneck assembly has an outlet that couples with a flowline on the riser and a connector assembly that selectively decouples the gooseneck assembly from the flowline. A release member, such as a wire, cable, or rod, is attached to the connector so the connector assembly can be actuated by manipulating the release member from a remote location.

Abstract: The present invention generally relates to methods and apparatus for subsea well intervention operations, including retrieval of a wellhead from a subsea well. In one aspect, a method of performing an operation in a subsea well is provided. The method comprising the step of positioning a tool proximate a subsea wellhead. The tool has at least one grip member and the tool is attached to a downhole assembly. The method also comprising the step of clamping the tool to the subsea wellhead by moving the at least one grip member into engagement with a profile on the subsea wellhead. The method further comprising the step of applying an upward force to the tool thereby enhancing the grip between the grip member and the profile on the subsea wellhead. Additionally, the method comprising the step of performing the operation in the subsea well by utilizing the downhole assembly. In another aspect, an apparatus for use in a subsea well is provided.

Abstract: The present invention is directed to an insulation shroud with internal support structure. In one illustrative embodiment, the insulation shroud includes a body adapted to be positioned around a subsea component, the body including an insulating material having an internal support structure positioned therein and a door.

Abstract: The present invention relates to overpressure protection systems and methods for use on a production system for transferring hydrocarbons from a well on the seafloor to a vessel floating on the surface of the sea. The production system includes a subsea well in fluid communication with a turret buoy through a production flowline and riser system. The turret buoy is capable of connecting to a swivel located on a floating vessel. The overpressure protection device is positioned upstream of the swivel, to prevent overpressure of the production swivel and downstream components located on the floating vessel. The device may include one or more shut down valves, one or more sensors, an actuator assembly, and a control processor. Each shut down valve and sensor is coupled to a production flowline. Each of the sensors is capable of generating a signal based upon a pressure sensed within the production flowline. The actuator assembly is connected to each of the shut down valves for operating the shut down valves.

Abstract: A submersible process environment for sub-sea processing is provided. Such environment can include a modular encapsulated unit having an interior volume and one or more processing units disposed therein, a first valve in fluid communication with the interior and exterior of the unit, and a second valve in fluid communication with the interior and exterior of the unit. The first valve and the second valve can be in fluid communication with the processing unit, and the processing unit can receive a fluid from the first valve and discharges the fluid to the second valve.

Abstract: A method of insulating pipeline bundles used in recovering hydrocarbons from wells is disclosed. A polymeric substance, such as an orthophosphate ester, is injected into the annulus between a carrier pipe and the hydrocarbon conveying tubulars. A ferric salt, such as ferric sulphate, may be added as a gelling agent. The mixture results in a gel having a dynamic viscosity of greater than (1000) PaS. The gel insulates the inner hydrocarbon-conveying tubulars from the surrounding seawater thus helping to maintain the relatively high temperature therewithin. This in turn reduces the likelihood for chemicals, such as hydrates, to be precipitated out of the oil phase.

Abstract: A method and system for performing intervention and workover operations on a subsea well are provided, as well as an adapter for connecting a lower end portion of a conduit extending from a vessel with an upper portion of a lower marine riser package associated with a subsea tree. The method includes providing a lower marine riser package connected to an upper portion of a subsea tree associated with a subsea well, and a conduit extending from a vessel toward the lower marine riser package. The conduit is connected to the lower marine riser package with an adapter. A portion of a conduit bore of the conduit above the adapter is sealed from a chamber in the adapter, and a portion of a bore extending through the lower marine riser package is sealed from the chamber. The adapter is opened for access to the chamber from the sea.

Abstract: A subsea drilling system comprises a pressurized drilling capsule that is sealed against the subsea environment and houses equipment for manipulating a drillstring that extends through an opening in the drilling capsule to the exterior of the capsule. A drilling fluid handling assembly is contained within the drilling capsule that communicates drilling fluid through the drillstring and returns the drilling fluid to the water's surface via a drilling fluid conduit. A seafloor unit engages the seafloor and the drilling capsule to position the drilling capsule relative to the seafloor, and includes an opening for passing the drillstring into the seafloor. A pressurized transport unit is movable between the drilling capsule and a support vessel at or near the water's surface for delivering personnel and supplies to the drilling capsule. A method of drilling using the subsea drilling system is disclosed.

Abstract: A ROV-deployable gas hydrate diverter comprising a body having a circular disc shape with a center hole, and a handle attached to and protruding from a surface of the body, wherein the handle is adapted to be grasped by the grasping arm of an ROV to facilitate installation of the gas hydrate diverter over a subsea wellhead.

Abstract: A subsea gas compressor module having a housing comprising a sealing element generally defining within the pressure housing a first compartment holding as compressor and a second compartment holding an electric motor, the compressor and motor being driveably connected by at least one shaft. The first compartment is connected to an inlet line and an outlet line for sealing hydro carbon gas and for discharging gas. The second compartment has magnetic bearings for supporting the at least one shaft, and a pressure and volume regulator is fluidly connected to the second compartment and a gas supply, and includes elements for sensing respective pressures in the inlet and outlet lines whereby, based on the magnitude of sensed pressure, the pressure and volume regulator controls the pressure at which gas is injected into the second compartment.

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

Abstract: A drilling placed on the seabed and arranged for drilling of oil and gas wells is remote controlled from a light drilling vessel (2) through pipes and signal cables (3). The main structure of the drilling rig is made up of two cylindrical structures (1 and 10), in connection with which there is provided a number of cylindrical silos (8) for storing drill pipe magazines (23). A complete drilling module (17) can be lowered and retrieved through hatchways (11) at the top of the first cylindrical structure 10 The drilling rig is anchored to a foundation frame (7) by hydraulic legs (9). A cylindrical skirt (34) encloses the BOP (33) to prevent pollution of the environment.

Abstract: A stiffener fixation assembly fixed to the outer cover of a flexible tube, the flexible tube being in contact with a stiffener in an I-tube, at the end of which a bell mouth may be fixed, whereby the stiffener fixation assembly is located between the outer surface of the flexible tube and the inner wall of a centralizer and comprises rotary pieces that are axially movable with respect to the inner wall of the I-tube and capable of eliminating the relative movement between the flexible tube and the stiffener.