Abstract: A tendon for an offshore floating platform has a tubular section formed of joints of steel pipe secured together. The tubular section has an interior sealed from sea water to provide buoyancy. A composite fiber section is secured to a lower end of the tubular section. The composite fiber section is formed of non metallic fibers and has a solid interior.

Abstract: A closed system drill string compensator having a hydraulic fluid accumulator, at least one air pressure vessel, and a piston and a piston rod slidably engaged within a cylinder. The drill string compensator provides tensioning force for supporting a drill string and permits the drilling vessel to remain connected to the drill string during ocean level changes caused by wave action or ocean heave. In one embodiment, the accumulator surrounds the cylinder and at least one air pressure vessel is radially disposed around the accumulator and the cylinder. In another embodiment, the accumulator surrounds the cylinder and includes two ports, one port for permitting fluid communication between the cylinder and the accumulator and a second port for permitting fluid communication between the accumulator and the air pressure vessel, the first port including a shut-off valve disposed therein. Methods of compensating a drill string are also disclosed.

Abstract: A buoyancy module comprises a multi-layer outer protective shell that has an exterior surface and an interior surface. A first layer of foam buoyancy material is located adjacent to the interior surface. A second layer of foam buoyancy material that includes macrospheres and syntactic foam is surrounded by the first layer of foam buoyancy material. The multi-layer outer protective shell can include a layer of fiberglass backed by a fibrous plastic liner. In this embodiment, the layer of fiberglass provides the exterior surface of the multi-layer outer protective shell, while the fibrous plastic liner provides the interior surface of the protective shell. The second layer of foam buoyancy material can be a precast material. The precast material can include for example macrospheres and syntactic foam. The first layer of foam buoyancy material is preferably a stronger layer than the second layer of foam buoyancy material.

Abstract: The invention relates to flexible risers for transfer of hydrocarbons between a sea bed installation and a vessel (10) floating at the sea surface. The riser (18) is provided with means (20) for protecting the riser (18) from impacts. The protection means (20) covers at least the upper part of the riser (18) and is retractable to an inactive position. When in operation, the riser protection means (20) is either suspended from the vessel (10) or from a submerged turret buoy, forming part of a mooring system for the vessel (10).

Abstract: A new marine oil production riser system for use in deepwater applications is disclosed. An efficient means for accommodating movements of the host facility, while maintaining riser top tension within the limits for long-term riser performance. Long riser stroke lengths can be accommodated without requiring complex interfacing with the topsides. The riser assembly comprises: a generally extendable substantially non-vertical section having an upper end adapted to be in flow communication with a generally vertical marine riser carried by a facility floating on the surface of a body of water, and having a lower end adapted to be in flow communication with a fluid source on the seafloor; and tensioning means, mechanically connecting the upper end of the marine riser with the lower end of the marine riser, for biasing said ends towards each other.

Abstract: There is provided a buoyancy system for a structure having at least one component being substantially stationary with respect to the bottom of a water covered area. The system comprises a set of buoyancy modules of engineered materials to apply an identified amount of buoyancy. The set of buoyancy modules is attached to the structure at a set of buoyancy load transfer locations. The set of buoyancy modules comprises layers of the engineered materials. The engineered materials comprise a substantially reinforced axial layer, a substantially reinforced hoop layer; and a leak prevention layer.

Abstract: Method intended for automatic control of an underwater pipe for connecting the lower end of the pipe to a wellhead, wherein the following stages are carried out: Stage 1: determining a mathematical model expressing the position of the lower end of the pipe as a function of the position of the upper end of the pipe, Stage 2: determining a reference path leading to the wellhead, Stage 3: from the mathematical model determined in stage 1, determining control laws allowing to control the path of the lower end of the pipe, Stage 4: applying determined motions to the upper end of the pipe so that the position of the lower end is as close as possible to the reference path determined in stage 2.

Abstract: A top tensioned riser extends substantially vertically from a platform hull to the seabottom. The riser includes length adjustment at its upper end and is detachably connected to an anchor pile at its lower end. Riser tension is monitored via load cells incorporated in the riser porch. The riser is connected to one or more import/export flowlines or pipelines.

Abstract: A buoyancy can for supporting an offshore oil and gas riser includes an axial bore through which the riser extends coaxially, and a radio-axial slot extending through a side of the can and into the axial bore. A pair of spaced-apart support features are disposed coaxially on the riser, and the can includes a pair of corresponding sockets in the axial bore thereof. The sockets are adapted to receive and vertically support respective ones of the support features in a complementary, axial engagement. The can is placed in the water and moved laterally relative to a fully assembled, vertically supported riser such that the riser passes through the radio-axial slot of the can and into the axial bore thereof without the need for disassembly of the upper portion of the riser. The relative vertical positions of the can and riser are then adjusted such that the support features engage and seat within respective ones of their complementary sockets.

Abstract: A conduit structure (44) connects subsea oil wells to a floating structure (12) such as a vessel, in shallow water, the conduit structure providing a low cost and reliable fluid connection during drift of the vessel. The conduit structure includes a seafloor riser support (50) with a lower end (52) fixed to the seafloor and an upper end (54) lying a plurality of meters above the seafloor. A flexible pipe or hose (46) extends in a double catenary curve from the top of the seafloor riser support, at a downward incline away from the seafloor riser support and then at an upward incline to the floating structure. A rigid pipe (70) can extend along a plurality of meters of the height of the riser support to minimize the required length of flexible hose and facilitate installation.

Abstract: Expandable and contractible buoyancy modules are assembled to the risers of a deepwater exploration spar or other offshore structure to provide an upwardly directed buoyancy force to offset at least a portion of the weight of the riser. The buoyancy modules have a fabricated pressure tight expandable and contractible envelope composed of rubber or rubber-like material which is mounted onto a tubular member having a central passage for receiving the riser to be supported. The tubular member projects beyond the respective upper and lower ends of the envelope and defines upper and lower riser joint connectors and buoyancy module travel stops which secure the buoyancy module to the riser and provide for force transmission from the buoyancy module to selected locations along the length of the riser or to the upper end of the riser.

Abstract: A deep water support platform, suitable for use as a hydrocarbon exploration or production facility in very deep waters of 10,000 ft or more is presented. The platform is attached to the floor of the ocean with a buoyant pile that includes buoyant members attached about the periphery of the pile. The buoyant pile and buoyant members include tubular members that can be filled with water, oil, air or other materials to produce a structure that has improved buoyancy and stability over prior platforms. Embodiments include configurations of buoyant members that have constant and equal diameter and spacing, and other configurations where the diameter and/or spacing of the buoyant members changes along the pile. In addition, the buoyant members are arranged about the pile to reduce vortex induced vibrations on the platform by interfering with current flow about the support structure.

Abstract: This invention relates to a marine riser system for transferring fluid between a plurality of mutually separated locations on the seabed and a vessel (1) on the surface of the sea. The riser system comprises a submerged buoy (2), a plurality of risers suspended from the buoy (2) to the location on the sea bed and a plurality of flexible conduits (8) extending from the vessel to the submerged buoy (2). Connectors (7) carried by the submerged buoy (2) connect the flexible conduits (8) to the risers (6), each connector being remotely operable to disconnect all the flexible conduits from the risera. A central tether (5) may be provided during an installation phase only, until the risers (6) are in place and hold the buoy (2) by their own tension. Alternatively, the tether (5) may remain in place, and tensioned to limit vertical motion of the buoy.

Abstract: The method relates to a riser comprising a main tube and auxiliary lines. Each tubular element forming the auxiliary lines is fastened at one end by a complete link with the central tube and at the other end by a link allowing a longitudinal play J with the central tube. The method provides adjustment of play J so that, on the one hand, during conventional drilling operations, the elements forming the auxiliary lines slide in relation to the central tube and, on the other hand, during show control or testing operations, the elements forming the auxiliary lines form hyperstatic assemblies with the central tube. The method thus allows to prevent buckling of the peripheral lines when they are under pressure because they work under hyperstatic conditions.

Abstract: A vessel (1) comprises a rotatable turret (14) and a supporting structure (3) over or on the turret for supporting a swivel (5). The swivel comprising an inner and an outer ring (21, 21?; 22, 22?) which can rotate with respect to each other and which define at least one fluid distribution path from a geostationary fluid riser (19) connected to one ring (22, 22?) to a product outflow pipe (18) connected to the other ring (21, 21?). A rig (2) is mounted over the turret area above or below the swivel (5), and a substantially rigid pipe extends from the rig, through a moonpool of the turret towards the sea bed, the rigid pipe being in line with the swivel.

Abstract: A system for providing motion compensation of a platform attached to an ocean floor. The platform is operatively associated with a riser extending from a subterranean well. The system comprises a frame member positioned on the platform and a deck slidably attached to the frame member, and wherein the deck is attached to the riser. The system further comprises a moving device for moving the frame member relative to the deck. In one of the preferred embodiments, the frame member contains a plurality of guide post and wherein the deck is slidably mounted on the guide post so that the frame member is movable relative to the deck. The moving device may comprise a cylinder member operatively attached to the frame member and a piston operatively attached to the deck and wherein the system further comprises a pressurized recharging vessel configured to direct a pneumatic supply to the cylinder member, and a gas delivery mechanism for keeping the cylinder member within a pressure range.

Abstract: A method for installing a pile anchor into the sea floor that enhances the holding capacity of the pile anchor. The pile anchor is installed at an inclined angle with respect to the sea floor, with the top of the anchor inclined in a direction opposite the lateral load applied to the anchor.

Abstract: A frame and system for adding buoyancy to a riser used in connection with floating platforms is provided which, in some example embodiments, includes a stem attached to multiple supports which include flanges arranged to take impact and abrasion loads off an internal buoyancy module. An air management system is also provided.

Abstract: A method of connecting a first floating structure to the seabed, includes the steps of: providing a second floating structure, anchored to first and second anchoring points respectively on the sea bed via at least two anchor lines, attaching the second floating structure to the first structure via a pulling device, on the side of the first anchor line, displacing the first floating structure away from the second anchoring point towards the first anchoring point, disconnecting the first anchor line from the second floating structure while maintaining a pulling force on the second anchor line via the pulling device, and attaching the first anchor line to the first floating structure. By interconnecting a temporary buoy to the vessel to be anchored via a tension member, the anchor lines of the buoy and the vessel can remain under tension at all times whereby damage to the anchor lines is prevented.

Abstract: A semi-submersible floating platform for offshore drilling and/or production of petroleum product from the seabed includes a base having a first moon pool; a plurality of vertical outer buoyancy columns extending upwardly from the base; a deck structure supported by the buoyancy columns and having a second moon pool; a central columnar buoyancy apparatus having a lower portion guided within the first moon pool and an upper portion guided within the second moon pool; and at least one vertical riser passing through the buoyancy apparatus. Each riser has a lower portion that is horizontally restrained within the buoyancy apparatus below the center of gravity thereof. In a preferred embodiment, the platform includes at least two vertical risers attached to a single buoyancy apparatus.

Abstract: An apparatus for providing an indication of relative movement between sheave assemblies of a riser tensioner that has a sensor target connectable to one of the sheave assemblies, a senor tube cooperative with said sensor target and suitable for interconnection to the other of the sheave assemblies, a metallic member positioned within the sensor tube and suspended by the sensor target, and a an ultrasonic sensor cooperative with the sensor tube so as to sense a distance that the metallic member moves within the sensor tube in relation to relative movement between the sensor target and the sensor tube.

Abstract: Pipe for great water depths allowing transfer of a fluid between a floating support and a point situated below and at a distance from the water surface, characterized in that it comprises: at least one flexible part connected at one of its ends to the point situated below the surface, at least one rigid part connected to the flexible part at one of its ends and to the floating support at the second end, the rigid part being held up onto the floating support by holding means allowing this part to be essentially tensioned under the effect of its own weight.

Abstract: In one example embodiment, a floating deep draft caisson vessel for drilling and production is provided. The vessel comprises an outer hull, wherein the outer hull has a hollow centerwell. The vessel further comprises a centerwell buoy guided within the centerwell. At least one tendon assembly secures the centerwell buoy to the sea floor and the tendon assembly is attached along essentially the centerline of the centerwell buoy.

Abstract: An arrangement for transferring loads by means of one or more hydraulic cylinder-like actuators (19, 26, 40) in order to establish and maintain tension in a riser (1) of the type typically used in offshore petroleum production, where the riser (1) constitutes a connection between the sea bed (2) and an installation (4) on or near the surface of the sea (6), and where the required pressure difference between the pressure side(s) (18, 42) and the depressurised side(s) (17, 46) of the actuator(s) (19, 29, 40) is constituted by a hydrostatic pressure difference.

Abstract: A semi-submersible floating platform for offshore drilling and/or production of petroleum product from the seabed includes a base having a first moon pool; a plurality of vertical outer buoyancy columns extending upwardly from the base; a deck structure supported by the buoyancy columns and having a second moon pool; a central columnar buoyancy apparatus having a lower portion guided within the first moon pool and an upper portion guided within the second moon pool; and at least one vertical riser passing through the buoyancy apparatus. Each riser has a lower portion that is horizontally restrained within the buoyancy apparatus below the center of gravity thereof. In a preferred embodiment, the platform includes at least two vertical risers attached to a single buoyancy apparatus.

Abstract: A riser support system for use in a body of water comprises a buoyant and ballastable support structure and a plurality of substantially vertical and rigid risers each of which is attached to the inside of the support structure at a location below the center of buoyancy of the support structure and below the surface of the body of water. Usually, each riser passes through the inside of a single tube in the support structure. Typically, the riser support system is used to support a plurality of risers and their surface wellheads inside the hull of an offshore platform, usually in such a manner that the axial movement of the risers and support structure is independent of the axially movement of the hull. By attaching the risers at a location below the center of buoyancy of the riser support structure, riser load adds to instead of decreases inherent stability and therefore the structural payload efficiency of the overall floating platform is improved.

Abstract: A steel catenary riser (SCR) system includes a tensioning mechanism on a floating facility that controllably applies a substantially constant tension to an SCR that is fluidly coupled to the facility by a flexible jumper conduit. More specifically, the system includes a tensioning device located on the floating facility; and an SCR having an upper portion, which, in the preferred embodiment, extends above the surface of the body of water. The upper portion of the SCR is connected to the tensioning device by a connection element, such as a cable, chain, rope, or wire, whereby tension is controllably applied from the tensioning device to the SCR. A flexible jumper conduit is fluidly connected between the upper portion of the SCR and the floating facility for conducting fluid from the SCR to the floating facility.

Abstract: A cylindrical buoyancy unit is composed of separate sections which are held together to surround a marine object such as a riser or pipe with additional conduits. The sections combine to define an internal cavity which is shaped to conform with the marine object. Each unit section is a thermosetting resin composite with a bulk interior of syntactic foam and an outer layer of different characteristics and an intermediate reinforcement layer. The intermediate layer is disposed close to the outer layer and is mechanically embedded but not tightly bonded into the structure. The intermediate layer is made as a mesh of high strength polymer fibers.

Abstract: A loading arrangement includes a riser that extends from a subsea structure to a coupling element for coupling the riser to a vessel. The coupling element includes a buoy body which is connected to a retention member via a flexible connection part. The retention member, such as a submerged buoy, is attached to anchor lines which at or near their end parts are provided with buoy. The connection part, which can be a cable or a frame structure has a relatively high tensile strength to anchor the vessel to the sea bed and to prevent drift of the vessel when tension is exerted on the connection part and the anchor line.

Abstract: A receptacle 20 is removably secured to hull 12 of an offshore structure 10, and supports an elongate member 14, which may be a riser string, extending downward to the sea bed or to another structure. The elongate member 14 includes a tapered supporting surface 18, which may be provided on a tapered stress joint or flex joint 16. The receptacle 20 includes a mounting bracket 22 secured to the structure 10, and a basket housing 30 which has a tapered interior surface 34 for mating engagement with the exterior surface 18. According to the method, the mounting bracket is fixed to the structure, and the receptacle basket positioned about the elongate member and the assembly then positioned for being supported on the bracket. The supporting surface on the basket may be arranged for positioning the elongate member at a selected azimuth and declination relative to the offshore structure.

Abstract: A vessel includes a riser and/or tendon tensioning construction. A connector, such as an arm or deck structure, is suspended from cables movable relative to cable guides. The connector carries two or more risers and/or tendons extending from a subsea structure to above water level. The free ends of the cables are attached to weights for exerting a tensioning force on the risers, which are substantially decoupled from pitch, roll and heave motions of the vessel.

Abstract: The invention relates to a bed to surface connection for an underwater pipeline (11), resting on the seabed, in particular at great depth, of the hybrid tower type, comprising a static base (151-152) resting on the bed. According to the invention said pipeline (11), resting on the seabed is connected by means of a flexible pipeline element (12) with an elbow bend, to a vertical riser (5), the bottom end of which is fixed with relation to said base.

Abstract: The present invention relates to systems and methods for prevention of clashing between multiple conduits spaced closely together and to methods of installation of multiple conduits at the same time. Various aspects of the invention are provided involving separating the at least two transfer conduits, and allowing relative motion between the at least two transfer conduits.

Abstract: An arrangement for transferring loads by means of one or more hydraulic cylinder-like actuators (19, 26, 40) in order to establish and maintain tension in a riser (1) of the type typically used in offshore petroleum production, where the riser (1) constitutes a connection between the sea bed (2) and an installation (4) on or near the surface of the sea (6), and where the required pressure difference between the pressure side(s) (18, 42) and the depressurised side(s) (17, 46) of the actuator(s) (19, 29, 40) is constituted by a hydrostatic pressure difference.

Abstract: A buoyancy system to buoy a riser of an offshore oil platform includes buoyancy compartments coupled around an elongated internal beam. The internal beam can withstand loads between the oil platform and the buoyancy system, while the buoyancy compartments provide buoyancy. The internal beam includes an elongated stem, a plurality of webs extending radially outwardly from the stem, and a plurality of transverse flanges attached to the outer edges of the webs.

Abstract: A floating offshore construction (1) comprising a suspension gear (7) for suspending a riser construction (6). The suspension gear comprises a guide which extends adjacent the water surface during use, with a float (12) disposed therein for axial movement. The float comprises coupling means (13) for coupling to a riser construction. The invention also relates to a float.

Abstract: Keel joint assemblies are described that permit a degree of rotational movement of a riser within the keel of a floating vessel and greatly reduce the amount of stress and strain that is placed upon the riser, as well. Keel joint assemblies described provide a limiting joint between the riser and the keel opening that permits some angular rotation of the riser with respect to the floating vessel. Additionally, the limiting joint permits the riser to move upwardly and downwardly within the keel opening, but centralizes the riser with respect to the keel opening so that the riser cannot move horizontally with respect to the keel opening. In described embodiments, the limiting joint is provided by a single annular joint that allows that riser to move angularly with respect to the can. In some embodiments, the keel joint assembly incorporates a cylindrical stiffening can that radially surrounds a portion of the riser and is disposed within the keel opening.

Abstract: The present invention provides a metal lined composite riser section for use in offshore applications featuring a traplock metal-to-composite interface to secure a plurality of structural composite overwrap layers about a metal liner assembly. Each traplock is formed with at least one annular groove or channel which has been made in the exterior surface of the metal liner assembly. The annular trap grooves may be of various geometries and may be arranged adjacent to each other to form a traplock having 2 to 8 or any number of grooves required to ensure proper adhesion between the composite overwrap layers and the metal liner assembly. A number of structural composite overwrap layers are secured about the assembly by building up alternating combinations of helical and hoop fiber windings to form a composite material. The present invention also provides a method of making composite riser sections using either a mandrel or counterweights to facilitate the composite fiber winding process.

Abstract: The invention relates to a marine riser tower (112, 114) having a plurality of rigid metallic conduits bundled together with a metallic tubular core. The conduits may include production lines for hydrocarbons (P), water injection lines (W), and/or gas lift lines (G). A production line or gas lift line is located within the core, while the water injection line is located outside the core.

Abstract: A protective element for a riser segment, comprising an elongated buffer body, at least one foot connected with the buffer body, the at least one foot being provided with an engagement part arranged to engage on a main pipe of a riser segment, the distance between the engagement part of the foot and the buffer body being such that in mounted condition the part of the buffer body located farthest from the main pipe is located farther from the main pipe than auxiliary pipe elements arranged on the main pipe.

Abstract: A bottom-to-surface link with at least one underwater pipe having a portion with a substantially constant diameter and one or more floats in a string, the floats constituting cans surrounding the pipe and being located in a float zone around the top underwater portion of the pipe. The pipe is held at the surface by a guide device, preferably on a floating float support. The link includes at least one stabilizer situated in the top portion of the pipe. The link is arranged so that the bottom portion of the float zone, is preferably on or level with the lowest float and a transition zone is between the floats and the substantially constant diameter portion of the pipe.

Abstract: A floating offshore platform configuration is provided, which decouples pitch, roll, and heave motions from acting on tensioned risers and accommodates the angular displacement induced by floating offshore platform surge and/or sway excursion without inducing bending in the riser at its entrance to the floating offshore platform. The risers are guided by an inner structure that is tethered from the sea floor and centered inside an outer hull structure. Outer hull structure heave, pitch and roll motions are substantially isolated from acting on the inner structure through a connection mechanism, and each riser is allowed to individually expand or contract.

Abstract: A steel catenary riser (SCR) system includes a tensioning mechanism on a floating facility that controllably applies a substantially constant tension to an SCR that is fluidly coupled to the facility by a flexible jumper conduit. More specifically, the system includes a tensioning device located on the floating facility; and an SCR having an upper portion, which, in the preferred embodiment, extends above the surface of the body of water. The upper portion of the SCR is connected to the tensioning device by a connection element, such as a cable, chain, rope, or wire, whereby tension is controllably applied from the tensioning device to the SCR. A flexible jumper conduit is fluidly connected between the upper portion of the SCR and the floating facility for conducting fluid from the SCR to the floating facility.

Abstract: An apparatus for transferring hydrocarbons from a subsea source to a vessel, wherein the risers are suspended from a rotating body and communicate with a swivel unit including a number of swivel rings having outlets connected to a pipe system on the vessel. The apparatus includes a block arranged between the risers and the swivel unit and provided with interior ducts for connection of the risers with respective swivel rings, and a device for selective closing of the ducts are arranged between the risers and the swivel unit. The device is integrated in the block. In an advantageous embodiment, the block is also provided with a device for selective interconnection of two or more of the ducts in the block.

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: A substantially rigid riser to offshore platform connector and a process of using the connector allows a riser to be preloaded and adjustably positioned relative to the offshore platform. The connector allows the riser tensile load to be limited by preloading and adjustably positioning the connector. In the preferred embodiment, hydraulic cylinders are used to preload the connector as well as to partially or fully support the riser during maintenance or repair procedures.

Abstract: Apparatus and methods for environments subject to vortex induced vibration. The system includes a shroud having a number of perforations, with the shroud encircling the flowing-fluid element less than 100%. The system further includes a separation member for attaching the shroud to the flowing-fluid element.

Abstract: Where a submarine wellhead is coupled to a floating vessel by a riser in the form of a flexible hose, vessel movements subject the riser to excessive strains where the riser is tethered ask to the vessel. In accordance with the invention, these strains are reduced by pivoting the riser tether about a horizontal axis, and optionally also about a vertical axis. Giving the riser tether at least one degree of rotational freedom is surprisingly beneficial in reducing riser strains, and consequently in reducing the probability of premature failure of the riser.

Abstract: Systems and methods for time, and labor efficient construction and production of subsea wells include a surface blowout preventer stack, a high pressure riser, and a drill thru Xmas tree. The systems may further comprise a subsea shut off and disconnect device.

Abstract: A stress joint for a subsea riser has a reduced diameter intermediate section to reduce bending stresses on the connection between the stress joint and the riser as well as the subsea equipment. The stress joint having a riser joint with a threaded upper end for connection to a riser string. Attached to a lower end of the riser joint is an upper transition section that tapers from the diameter of the riser joint to a reduced diameter. An intermediate section below the upper transition section has a reduced outer diameter. A lower transition section connects the lower end of the intermediate section to the subsea equipment. The lower transition section is tapered from a reduced diameter to a larger diameter to ensure a firm connection with the subsea equipment.