Abstract: A free standing riser system includes a riser, a subsea intervention unit, and an umbilical line. The riser includes interconnected joints linked to one another, a lower-end of the riser being coupled to a wellhead and an upper-end of the riser enclosed in a buoy assembly, including a terminal, the riser being maintained in an erect, substantially vertical position. The subsea intervention unit is provided above the riser, and includes three connections: one connection to the terminal of the riser, one connection to a flexible jumper that is connected to a FPU, and one connection that provides a vertical conveyance to an intervention rig.

Abstract: A technique for monitoring and evaluating parameters related to the use of a compliant guide system in intervention operations. A compliant guide enables movement of a conveyance within its interior and is coupled between a subsea installation and a surface vessel. A sensor system is provided with sensors deployed in subsea locations to detect operational parameters related to operation of the compliant guide. A control system is coupled to the sensor system to receive data output from the sensor system.

Abstract: Methods for deploying a subsea blowout preventer stack system comprising a lower marine riser package, a blowout preventer stack with a first ram blowout preventer, and an additional blowout preventer package releasably coupled to the blowout preventer stack and comprising a second ram blowout preventer. The subsea blowout preventer stack assembly can be deployed by coupling a drilling riser to the lower marine riser package that is releasably connected to the blowout preventer stack. The lower marine riser package and blowout preventer stack are then toward a subsea wellhead and then landed on the additional blowout preventer package that is coupled to the subsea wellhead.

Abstract: A system comprising a surface installation in position above a plurality of subsea wells disposed within the watch circle of the surface installation. A plurality of flowlines directly couple at least one of the plurality of subsea wells to the surface installation. A control station, a hydraulic power unit, and an injection unit are disposed on the surface installation. A distribution body is disposed on the seafloor and is coupled to each of the control station, hydraulic power unit, and the injection unit via one or more umbilicals. A first wellhead component is disposed on one of the subsea wells and is coupled to the distribution body via one or more flying leads that provide electrical, hydraulic, and fluid communication. A second wellhead component is disposed on another one of the subsea wells and coupled to the distribution body via one or more flying leads that provide electrical, hydraulic, and fluid communication.

Abstract: The invention relates to a riser pipe section (1) comprising a main tube (2), at least one auxiliary line element (3) arranged substantially parallel to said tube (2), the ends of the main tube comprising connection means allowing longitudinal stresses to be transmitted and the ends of the auxiliary line element comprising linking means allowing longitudinal stresses to be transmitted, said linking means comprising at least one locking pin (14).

Abstract: Systems and methods for drilling a well bore in a subsea formation from an offshore structure positioned on a water surface with a drill string that is suspended from the structure and includes a bottom hole assembly adapted to form a top hole portion of the well bore. A drilling fluid source on the offshore structure supplies drilling fluid through the drill string to the bottom hole assembly where the drilling fluid exits from the bottom hole assembly during drilling and returns up the well bore. A suction module is disposed at the sea floor and collects the drilling fluid emerging from the well bore. A pump module is disposed on a return line, which is in fluid communication with the suction module, at a position below the water surface and above the sea floor. The pump module is operable to receive drilling fluid from the suction module and pump the drilling fluid through the return pipe to the same offshore structure or a different offshore structure.

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 disclosure provides an improved design for a pull tube sleeved stress joint and associated pull tube for managing stresses on a catenary riser for a floating offshore structure. The pull tube sleeve stress joint includes at least one sleeve surrounding a length of the pull tube with an annular gap between the sleeve and pull tube and a link ring therebetween. For embodiments having a plurality of sleeves, a first sleeve can be spaced by an annular first gap from the pull tube and coupled thereto with a first ring between the pull tube and the first sleeve, and a second sleeve can be spaced by an annular second gap from the first sleeve and coupled thereto with a second ring between the first sleeve and the second sleeve. Both pull tube and sleeves can be made with regular pipe segments welded together with regular girth welds.

Abstract: A tubular assembly comprising a first iron based tubular having a first non-cladded inner surface; and a second iron based tubular having a second non-cladded inner surface, wherein the first tubular is connected to the second tubular using a non-iron based bonding material. Preferably, the non-iron based bonding material has a lower crack growth rate than the iron based tubulars.

Abstract: A tieback connector connects a tieback conduit from an offshore platform to a subsea wellhead assembly. The tieback connector has a mandrel that is connected to a string of tieback conduit and a sleeve and load ring that are carried by the mandrel. The load ring is radially expansible and has a conical portion with internal threads. The load ring has an external grooved profile that engages an internal grooved profile in the subsea assembly. The mandrel is rotatable relative to the sleeve while in its lower position, causing the load ring to further expand outward into engagement with the internal profile. A locking member is carried below the load ring on an exterior cam surface of the mandrel. The cam surface moves the locking member outward when the mandrel moves downward into engagement with an internal profile in the subsea assembly.

Abstract: A downhole deployment system comprises a spoolable tubular member (76) adapted to be coupled to a subsea assembly and to extend to surface level. The deployment system also comprises a spoolable support member (96) adapted to extend through the spoolable tubular member (76) and into a wellbore. The spoolable tubular member (76) may define a conduit between the subsea assembly and the surface and the spoolable support member (96) may be utilised to extend through this defined conduit and into a wellbore, for example to deploy a tool into a wellbore, to engage a downhole tool or other object, for example for activation, retrieval or the like.

Abstract: A drilling system employing a main tubular having a plurality of fluid inlet and outlet conduits positioned thereon and a concentric inner tubular having a plurality seals for sealing the annular space between the concentric inner and main tubulars. The fluid inlet and outlet conduits work in cooperation with the annular seals to selectively open and close for effective management of pressure within the tubulars.

Abstract: A system for mitigating slugging in the conveyance of hydrocarbons in a flowline includes a first portion of flowline that extends substantially longitudinally along a declining surface. The first flowline portion carries multiphase hydrocarbons. A second portion of flowline extends upward from adjacent the first portion of flowline, and is in fluid communication with the first portion of flowline. A slug-mitigating region is between the first and second portions of flowline so slug-mitigating assembly receives the hydrocarbons from the first portion of flowline and conveys the hydrocarbons to the second portion of flowline. The slug-mitigating region has consecutively joined tubular segments that are each arcuate along a predetermined arcuate angle, with substantially uniform cross-sections. The first portion of flowline can be a subsea flowline extending along a sea floor, and the second portion of flowline can be a riser.

Abstract: The invention relates to a safety joint (10; 100; 200) for a riser consisting of two telescoping parts that are arranged to break in the event of a predetermined axial tension load. The joint also comprises means (21, 41; 121, 141; 221, 241) for closing the passage in the joint in the event of fracture where the means are activated by means of the forces generated during the separation.

Abstract: A technique for subsea intervention operations enables pressure control to be accomplished at the surface while borehole fluid control is exercised at the seabed. A compliant guide extends between a subsea well installation and a surface location, such as a surface intervention vessel. A buffer fluid is deployed within the compliant guide to maintain the borehole fluids proximate the seabed. The buffer fluid also enables pressure control over the buffer fluid and the borehole fluid to be performed from the surface. Additionally, a flexible conveyance can be used to move intervention tools through the compliant guide.

Abstract: The riser pipe section comprises a main tube 22 and auxiliary line elements 23 arranged parallel to tube 22. The ends of the main tube comprise connectors 20a and 20b allowing longitudinal stresses to be transmitted. The ends of auxiliary line elements 23 comprise connectors 20c and 20d. Auxiliary line elements 23 consist of two parts 23a and 23b assembled by an adjustment device 23c or 30 allowing the axial length of each auxiliary line element to be adjusted.

Abstract: The present invention relates to the marine drilling risers and other submerged hulls, and methods and apparatuses for reducing vibration and drag in the drilling risers when they are beset by ocean currents, for instance elastic swivel devices for use in orienting a riser in a desired direction for boundary layer control applications.

Abstract: A tensioner for an offshore structure has inner and outer barrels engaging each other for movement between retracted and extended positions. The barrels are filled with gas pressure. A primary seal is located between the inner and outer barrels at the open end of the inner barrel. An annular lubricant reservoir is mounted to an interior wall surface of the inner barrel at the open end of the inner barrel. A lubricant port extends from the lubricant reservoir through the inner barrel to a high pressure side of the primary seal for dispensing lubricant between the inner and outer barrels. A fill tube leads from the reservoir to the exterior of the inner barrel for replenishing lubricant.

Abstract: An offshore drilling riser joint has a central riser pipe, a number of auxiliary lines mounted around it, and a buoyancy module assembly of a buoyant material. A pair of upper thrust sleeves slide over two of the auxiliary lines, each of the upper thrust sleeves having a flange in contact with an upper end of the buoyancy module assembly. Each of the upper thrust sleeves transfer upward thrust imposed by the buoyancy module assembly to an upper support flange mounted to the central riser pipe. A pair of lower thrust sleeves slide over two of the auxiliary lines. Each lower thrust sleeve has a lower thrust flange that is engaged by a lower end of the buoyancy module assembly. Each of the lower thrust sleeves transfer weight of the buoyancy module assembly while out of water to a lower support flange mounted to the central riser pipe.

Abstract: A riser tensioner has inner and outer cylindrical barrels that telescopingly engage each other. A small external tank is mounted outside of the barrels for communicating a small quantity of hydraulic fluid the seals between the inner and outer barrels. The external tank allows the internal volume of the cylinder rod assembly to be used for gas storage and reduces the need for accumulators. The fluid level in the external tank is checked via a sight glass, and the tank is isolated from the cylinder assembly by a combination of check and three-way valves, which allows easier access to the working fluid, and allows the addition or removal of high pressure fluid to the system without a high pressure fluid cart.

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.

Abstract: There is disclosed an umbilical assembly comprising at least one elongated umbilical element, and at least one light weight, high strength reinforcing rod.

Abstract: An improved subsea manifold system that is capable of being used in an early production system for producing hydrocarbons from a plurality of wells from a common riser system. The subsea manifold is able to control the fluid from a multiple of subsea wet-tree wells while at the same time giving the operator the option to isolate production from a single subsea well for production evaluation. The subsea manifold also includes a pigging loop which enables efficient pigging of the flowline(s) of the early production system.

Abstract: An offshore system allows a vessel (12) to sail to a predetermined sea location (14), quickly set up a loading system and start the transfer of hydrocarbons to or from a pipeline (22), and then quickly disconnect and sail away. The vessel is a DP (dynamic positioning) vessel that does not require mooring or anchor lines, so the only apparatus to install is a conduit (30) that can be picked up by the vessel to extend between a stationary pipe end (24) that lies at the sea floor and the vessel. The conduit includes primarily a flexible hose (70) that extends in a sine wave with two loops (80, 82). The conduit includes a rigid reinforced hose section (34) that is pivotally connected to the sea floor. A chain (114) can be provided with a portion of the chain lying on the sea floor, to help the disconnected hose coupling (42D) remain at a stable position above the sea floor.

Abstract: A marine riser system for transferring fluid between a well on the seafloor and a vessel floating on the surface of the sea. The riser system has a turret buoy capable of connecting to a floating vessel; two or more hybrid risers, each of the hybrid risers having a vertical riser, a riser buoy attached to the upper portion of the vertical riser and a flexible jumper connecting the riser buoy to the turret buoy, and wherein the hybrid risers are secured to the seafloor. A flowline may connect a lower portion of each of the vertical risers to a subsea manifold, which interconnects the flowline and a subsea well. The subsea manifold is capable of controlling the flow to or from a subsea well. The hybrid risers are positioned about the turret buoy so that the turret buoy is horizontally balanced while disconnected from a vessel. In another embodiment, the marine riser system is capable of directing a fluid from the floating vessel to a subsea export flowline.

Abstract: A curvature limiter for a hydrocarbon transferring subsea system comprising a flexible tubular member through which an intermediate portion of the flexible hydrocarbon pipe passes. The flexible tubular member has a plurality of successive, substantially cylindrical sections which are hingedly mounted with respect to each other. At a predetermined maximum displacement thereof, the tubular member defining a mean plane in such a way that the flexible tubular member forms a mean curvature having the predetermined curvature radius of this mean plane.

Abstract: A subsea intervention system is disclosed comprising a floating vessel and a source of coiled tubing at the floating vessel. The system includes a seabed installation including a wellhead and compliant guide having one end operatively connected to the floating vessel and the second end operatively connected to the seabed installation. The compliant guide provides a conduit between the floating vessel and the wellhead for the coiled tubing. At least one injector is present at the floating vessel for inserting the coiled tubing into the compliant guide, and a carousel is proximate the wellhead which comprises a plurality of chambers with intervention tools in at least two of those chambers. The system may also include a plurality of sensing units that are disposed at spaced intervals along the compliant guide to monitor various aspects of the compliant guide and to transmit that information to a repositioning system.

Abstract: The invention relates to a riser pipe section comprising a main tube (2), at least one auxiliary line element (3) substantially parallel to said main tube (2) and at least two fastening means (7, 8) that connect the ends of said element (3) to main tube (2). The section is characterized in that fastening means (7, 8) allow longitudinal stresses to be transmitted from said element (3) to main tube (2) and in that at least one of fastening means (7, 8) allows at least a rotating motion of said element (3) in relation to said main tube (2), the rotating motion following an axis perpendicular to the plane passing through axis (4) of the main tube and through the axis of auxiliary line element (3).

Abstract: A thermal insulating packer fluid contains at least one water superabsorbent polymer and optionally water and/or brine, and a viscosifying polymer. The composition is capable of inhibiting unwanted heat loss from production tubing or uncontrolled heat transfer to outer annuli. The viscosity of the composition is sufficient to reduce the convection flow velocity within the annulus.

Abstract: The current subject matter relates to compliant variable tension risers to connect deep-water subsea wellheads to a single floating platform in wet tree or dry try systems. The variable tension risers allow several subsea wellheads, in water depths from 1220 to 3050 meters, at lateral offsets from one-tenth to twice the depth or more, to tie back to a single floating platform. Also, the current subject matter relates to methods to counter buoyancy and install variable tension risers using a weighted chain ballast line.

Abstract: A pipe string (44) is pulled out by a tug boat (30) from a floating structure (12) such as a production vessel, as pipe sections (54, 56) are connected in series on the vessel, to eventually lay the pipe string in a catenary curve from the vessel to the sea floor and then along the sea floor to a distant subsea well head (86). To save time and cost in coupling the pipe sections, lower fatigue resistant pipe couplings, such as non weld-on couplings (120) that include a threaded sleeve (134), are used to connect pipe sections that will lie in a quiescent zone such as on the sea floor (zone Az), and in a zone (Cz) lying along the middle of the catenary curve. Higher fatigue resistant pipe couplings such as weld-on couplings (150) are used along active zones such as top and bottom zones (Dz, Bz) of the catenary curve.

Abstract: A tieback connection between an offshore production platform and a wellhead on the sea floor has a riser and a tubular expandable and contractable member within the riser. The expandable and contractable member compensates for axial movement within the riser while maintaining axial tension in the riser. The expandable and contractable member is of uni-body construction having a wall configured to correspondingly expand and contract to compensate for the riser movement. In cross section, the member wall comprises folds formable by alternating slots formed into the inner and outer wall surface or an undulating surface.

Abstract: In an offshore drilling facility, apparatus is disclosed comprising: a drilling floor centralizer for receiving the upper end of a string of drilling riser sections; a moonpool centralizer for receiving another portion of the drilling riser; and at least one roto-track, removably and rotationally carried by at least one of the pin end of one drilling riser section and the box end of the adjacent drilling riser section, for extending the outer diameter of each of the adjacent ends to the outer diameter of the adjacent drilling risers sections intermediate the ends of the drilling riser sections.

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 utility line connector assembly having a male stab having a central bore with a port that communicates with a second bore in a receptacle where the stab is fixedly inserted into a receiving female opening in the receptacle, the receptacle has an L shaped opening with a protruding partial spherical pocket, a ring groove for sealing said stab to a riser package, and where the stab and receptacle are placed between a lower marine riser and the blow out preventer in fluid communication therebetween. The stab and receptacle may be sealed with ring seals and the assembly may be used in riser auxiliary line connections, sub sea production tree connections, drape hose connections and surface bop auxiliary line connections.

Abstract: A device and method for the reduction of vortex-induced vibration of a deepwater riser. A device for attachment to a structure, which is subject to movement relative to a fluid surrounding the structure, for reducing vortex-induced vibration effects on the structure, the device comprising: a flexible netting (4) interconnecting a plurality of relatively inflexible members comprising a plurality of elongate members (3) and a plurality of spacer members (6), wherein each elongate member has a first cuter boundary and each spacer member has a second outer boundary wherein the second boundary extends radially outward of the first outer boundary relative to the netting, over at least: a substantial portion of the boundary.

Abstract: A method for managing hydrates in a subsea production system is provided. The system has at least one producing subsea well, a jumper for delivering produced fluids from the subsea well to a manifold, a production line for delivering produced fluids to a production gathering facility, and an umbilical for delivering chemicals to the manifold. The subsea well has been shut in, leaving produced fluids in a substantially uninhibited state. The method generally comprises the steps of pumping a displacement fluid into the chemical injection tubing, pumping the displacement fluid through a chemical injection tubing provided in the umbilical, further pumping the displacement fluid through the manifold and into the production line, and pumping the displacement fluid through the production line so as to displace the produced fluids before hydrate formation may begin. Preferably, a chemical inhibitor is placed in the chemical injection tubing before the displacement fluid is pumped into the chemical injection tubing.

Abstract: A riser for connection between a vessel and a fixed connection point on the seabed, in the form of an “L”, where the bottom riser arm is connected to the fixed point (2) on the seabed and the top riser arm (3) is connected to the vessel at the point (4). An elastic element (5) is connected to the bend (6) between the riser's arms and an anchoring point (7) on the seabed.

Abstract: A riser is connected to subsea well equipment and extends to a vessel. A tubular conductor is mounted stationarily to and around the riser, the conductor passing through an opening in the vessel. A set of rollers is mounted to the vessel around the opening for engagement with the conductor as the vessel moves relative to the riser. Hydro-pneumatic cylinder units are connected between the riser and the vessel for applying tension to the riser. An external flange is located on a lower portion of the conductor. A shock absorber is positioned around the conductor and mounted to the vessel for movement relative to the conductor. The shock absorber absorbs shock when the cylinder units are in an extreme stroke position.

Abstract: A riser assembly includes a rotating control housing connected between an upper portion and a lower portion of a riser assembly, and a packing element rotatable with respect to the rotating control housing, wherein the packing element is configured to isolate an annulus of the lower portion from the upper portion when a drillstring is engaged through the packing element, and wherein the packing element is configured to be retrieved and replaced through the upper portion.

Abstract: There is disclosed an offshore vessel mooring and riser inboarding system (12) for a vessel (10) such as an FPSO or FSO. In one embodiment, the system comprises a first mooring element (16) adapted to be located in an offshore environment (18); a riser (20) adapted to be coupled to the first mooring element; a connector assembly (22) 11 adapted to be mounted on the vessel, the connector assembly comprising a second mooring element (28); and a transfer line (32) adapted to be coupled to the riser; wherein the first and second mooring elements are adapted to be connected to facilitate coupling of the riser and the transfer line; and wherein the connector assembly is adapted to permit relative rotation between the vessel and the first mooring element about three mutually perpendicular axes of rotation. This facilitates weathervaning of the vessel relative to the first mooring element, as well as pitch, roll, heave and surge, under applied wind, wave and/or tidal forces.

Abstract: A corrosion-resistant alloy tube is formed and bonded to a pre-machined steel alloy rod to form a riser tensioner cylinder rod. During assembly, an epoxy is injected into an annular space between the tube and rod and then cured. The bonded tube is ground to a desired surface finish prior to installation and utilizes a double seal arrangement that prevents external pressure or corrosive fluids from entering the cured epoxy in the annular space.

Abstract: A connector for connecting sections of drilling riser pipe wherein a first riser contains a pin assembly with an external first grooved profile and a second riser contains a housing assembly. An internal split pivoting latch segment assembly carried by the housing assembly contains a second grooved profile adapted to mate to the first grooved profile and a split actuation ring movably carried by the housing assembly forces the second grooved profile of the latch segment assembly into engagement with the first grooved profile of the pin assembly. A plurality of retraction links engage an upper edge of the latch segment assembly to disengage the second grooved profile of the latch segment assembly from the first grooved profile of the pin assembly if the risers are to be disconnected.

Abstract: A riser disconnect and support mechanism for flexible risers and umbilicals on an offshore structure with low under keel clearance. A main body portion includes an inverted and truncated conical or convex section substantially at the center of the main body portion. The main body portion and conical section receive risers therethrough by means of a plurality of conduits through the main body portion and conical section. A plurality of projections extend radially outward from the main body portion. A plurality of arch-shaped riser supports are provided on each projection to support risers and/or umbilical lines and control their bending radii. The projections extend out from the main body portion at a distance that allows the portions of the risers below the main body portion to hang at an angle and bend radius in accordance with the design tolerances of the risers to prevent buckling or damage due to excessive bending while keeping the risers from contacting the sea floor.

Abstract: An arrangement and method for integrating a high pressure riser sleeve from the upper end of a high pressure drilling and workover riser terminated by an upper BOP close to sea level in one end and by a sub-sea blowout preventer BOP or a low riser package LRP close to the seabed in the lower end. The high pressure riser sleeve being installed, connected and integrated to the high pressure drilling and workover riser and extending up to and above the drill floor, inside a low pressure drilling riser slip joint which is connected to the drilling and workover riser. This relates to offshore drilling and well activities preformed from a floating drilling or workover rig or vessel. Operations can be switched from drilling with jointed drillpipe in a conventional manner, into performing underbalanced wireline and/or coiled tubing activities with full well pressure, much more effectively than with prior art.

Abstract: A pipeline (20) that lies primarily in the sea and that is formed of multiple steel pipe sections connected in tandem at pipe joints, includes a protective coating around the pipe sections and around the pipe joints. Each pipe section is first covered, at an onshore facility, by an initial coating (30, 32) that extends along at least 80% of the pipe section length while leaving its ends uncovered, to leave gripping areas (40, 42) where the steel of the pipe is uncovered so the pipe can be clamped by tools such as those with steel jaws to position and slide it axially, or turn it, or prevent it from turning. After a pair of pipe sections are connected, a completion coating (50) is applied around the pipe joint to leave the pipeline with a coating around all of it.

Abstract: Disclosed are compliant variable tension risers (106) to connect deep-water subsea wellheads (102) to a single floating platform (104). The variable tension risers (106) allow several subsea wellheads (102), in water depths from 4,000 to 10,000 feet, at lateral offsets from one-tenth to one-half of the depth, to tie back to a single floating dry tree semi-submersible platform (104).

Abstract: An aluminum riser assembly has a plurality of riser joints connectable together to form a riser string. When upper and lower joints are assembled, clamps support auxiliary pipes for carrying hydraulic lines. A drive rotates a sleeve rotatably supported on the upper joint, and the sleeve rotates a union nut rotatably disposed on the upper joint. As the union nut rotates, it moves axially along the riser joint and threads onto the lower joint. The union nut is tightened until it engages an external collar to complete the coupling between the upper and lower riser joints. The entire process can then be repeated for additional upper riser joints to make up a riser string.

Abstract: A method and a device for installing a sub-sea riser for an offshore operation, between a base installation disposed on the sea bed and a sea installation protruding above the base installation. The sub-sea riser is provided with a first end and a second end. The method comprises the following stages in the following order: a) the first end of the riser is joined to the sea installation; b) the sub-sea riser is deployed; c) the second end of the riser is guided towards the base installation; d) the second end is coupled to the base installation by releasing the second end and the efforts of the recoil force exerted on the base installation are transferred; e) the second end and the base installation are connected to each other.

Abstract: There is disclosed a system comprising a structural element; at least one strake holder connected to the structural element; and at least one flexible helical strake connected to the at least one strake holder.