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: A method of lowering a floating body of a floating foundation and carrying a structure projecting above the water surface to an end position located beneath the water level, includes threading, through each of the upwardly projecting tubes, which are secured to the floating body above-through-openings formed in the floating body, a cable or a rod and connecting the cable or rod to a set-in-ground anchor, lowering the floating body, with the uptake devices provided at the free ends of the tubes, to the end position of the floating body beneath the water surface against buoyancy of the floating body, and fixidly securing the cables or rods, in the end position of the floating body, to the floating body and cutting off sections of the cables and rods above fixation points of the cables and rods with the floating body and removing the tubes.

Abstract: An anchor formed of a hollow tube and pivotally attached wings with fluid pressure in the tube being used to expand the wings outwardly. A ring encircles the hollow tube and is attached to the outside surface of the hollow tube to allow for securement of cables to the anchor.

Abstract: A floating platform with motion characteristics for offshore deepwater developments with vertical axial symmetry and decoupling of hydrodynamic design features. A motion-damping skirt (120) is provided around the base of the hull (1), which is configured to provide ease of installation for various umbilicals and risers. A retractable center assembly (300) is used in a lowered position to adjust the center of gravity and metacentric height, reducing wind loads and moments on the structure, providing lateral areas for damping and volume for added mass for roll resistance. The center assembly (300) is used to tune system response in conjunction with the hull damping skirt (120) and fins (121). The center assembly (300) also includes separators (350) below the floating platform deck which serve to add stability to the floating structure by shifting the center of gravity downward, the separators (350) capable of being raised and lowered vertical separators alone or as a unit.

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: 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: A tendon system for anchoring a floating platform to the seabed comprises composite tendon groups including one or more steel tendons in combination with tendons fabricated of synthetic materials. The synthetic composite tendons may be coaxially located within the steel tendons. Tendon resonance is inhibited by exerting damping forces through supplementary tendons/cables connecting a passive or active damping force system to the seabed. In another aspect of the invention, a passive tuned oscillator or an active driven mass oscillator provides damping of platform resonance motions.

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: A method is disclosed for deploying a suction pile anchor in which flood valves are opened on the top of a suction pile and the suction pile anchor is off loaded from the anchor boat and lowered it to the sea floor. The suction pile anchor is set down and the rate of feed is adjusted to match the rate of self-penetration. An ROV with pump capability closes the flood valves on the top of the suction pile and attaches to the pumping port of the suction pile. The pump of the ROV operates to draw down the suction pile to full depth and brings the first load line connection and the attached first end of the load line well below the mudline while the second load connection at the second end of the load line is supported above the mudline. The ROV disconnects from the pump port and connects a mooring line to second the load connection. Another aspect of the present invention is a suction pile system having a suction pile with an ROV compatible pressure port and a flood valve at the top.

Abstract: A method of mooring a vessel to a subsea anchoring element (1) connected to the seabed, and comprising a chain section (3) which is not longer than half the water depth, and which is at or near its free end provided with a coupling member (4), is characterised by the steps of: lowering a multi-strand anchor line (9) from a vessel (8), the multi-strand anchor line (9) being at its free end attached to a connector (10), and attaching the connector (10) to the coupling member (4). The present disclosure also provides an anchor line repair or exchange method comprising the steps of: disconnecting the first multi-strand anchor line (16) from the chain section, lowering a second multi-strand anchor line (9) from a vessel (8), the second multi-strand line (9) being at its free end attached to connector (10), and attaching the connector (10) of the second multi-strand line (9) to the coupling member (4).

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: An offshore floating platform for the drilling and/or production of petroleum products from the seabed includes a production deck and a buoyancy apparatus vertically guided and restrained within the platform. The buoyancy apparatus includes a well deck on its upper surface on which are mounted at least two surface trees. At least two vertical risers are supported by the buoyancy apparatus and are attached to the well deck. Each of the risers is connected to one of the surface trees and extends down through the buoyancy apparatus for connection to a seabed wellhead. At last one tendon assembly secures the buoyancy apparatus to the seabed. The tendon assembly is constructed with at least two concentric tubular tendon elements, and it is attached to the well deck and extends along the vertical centerline of the buoyancy apparatus.

Abstract: A marine platform (and method of installation) provides a plurality of buoys, a platform having a peripheral portion that includes a plurality of attachment positions, one attachment position for each buoy, and an articulating connection that connects each buoy to the platform at a respective attachment position, the connection allowing for sea state induced buoy motions while minimizing effect on the platform. A method of installation places the platform (including oil and gas drilling and/or production facility next to the buoys. Ballasting moves the platform and buoys relative to one another until connections are perfected between each buoy and the platform.

Abstract: Hydrocarbon mooring and transfer system includes a tower resting on the seabed, a vessel containing hydrocarbons, anchoring elements having at least four spaced-apart anchoring members connected via a respective anchor line to the vessel. A hydrocarbon transfer duct extends between a coupling position, located between the bow and stern of the vessel and the tower. The system includes at least six anchoring members, at least four of which are connected to the vessel, the vessel being attachable to at least two different groups consisting of four anchoring members in at least two orientations.

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: A method and apparatus for deployment of mooring systems for buoyant marine structures such as mobile offshore drilling units (MODU's) and for connecting the same to the mooring lines thereof. An anchor handling vessel carries one or more anchors each having a deployment connection and a mooring connection and individually moves each anchor over its stem roller and deploys it to the sea bottom for installation. A handling line is disconnected by ROV from the deployment connection and is moved from the deployment connection to the mooring connection so as to become the main mooring line. Syntactic buoys are then mounted on the main mooring line for elevating it above the sea bottom for recovery. When MODU stationing is desired the anchor handling vessel then recovers the surface buoy and connects to the rig mooring line using a short section of mooring chain. A J-chaser stopper device is then installed in the mooring string and is connected to the mooring line of the MODU by a short section of chain.

Abstract: A tendon which is divided into compartments enclosing therein pressurized gas. A method for transporting a fluid containing tubular body or assembly of bodies above a sea/river bed floor and within a body of water. In addition to the method for transporting the tendon a method of installing and removing an internal pressurized tendon or assembly of tendons in a vertical position in a body of water.

Abstract: An offshore construction includes a floating body (1), at least one anchor line (2) for connecting the floating body to the sea bed, the anchor line being connected to the floating body via a flexible top part (4) which is attached to a connector (5) on the floating body. The connector includes a housing (9) having two mutually perpendicular pivot axes (10, 12) with an elongate tubular member (8) extending in the anchor line direction and a latch mechanism (15) for fixation of the anchor line to the floating body and preventing movement in the direction of the sea bed. The connector includes a rod (13), which can be accommodated within the tubular member. The rod is connected to the flexible top part.

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.

Abstract: A heave suppressed, floating offshore drilling and production platform comprises vertical columns, lateral trusses connecting adjacent columns, a deep-submerged horizontal plate supported from the bottom of the columns by vertical truss legs, and a topside deck supported by the columns. The lateral trusses connect adjacent columns near their lower end to enchance the structural intergrity of the platform. During the launch of the platform and towing in relatively shallow water, the truss legs are stowed in shafts within each column, and the plate is carried just below the lower ends of the columns. After the platform has been floated to the deep water drilling and production site, the truss legs are lowered from the column shafts to lower the plate to a deep draft for reducing the effect of wave forces and to provide heave and vertical motion resistance to the platform.

Abstract: A jack-up platform comprising a deck structure, a column with a base structure and a jack-up system for moving the column and the deck structure relative to each other. The base structure comprises a base and at least three base supporting parts, while the deck structure, starting from at least three spaced coupling places, can be connected by a tensioning apparatus with at least three mutually spaced connecting places on or near the base supporting parts. Before the installation the platform, floating with pulled-up column, is brought to the desired location where the base supporting parts are brought into contact with the floor and the deck structure is raised out of contact with the water. After providing the tensioning apparatus and bringing the deck structure to working height, the tensioning apparatus is tensioned, for instance by slightly further raising the deck structure which is then secured relative to the column.

Abstract: A floating platform for recovery of oil and gas from offshore oil and gas fields includes a hull having a portion located substantially below the water surface, and including a portion thereof which extends above the water surface. The platform is anchored to the seabed by one or more tendons secured to the base of the hull and the seabed. The playload capacity of the floating platform is increased without redesigning the structural design of the hull by attaching a column extension or mounting a detachable buoyancy module to the lower end of the hull for accomodating changing platform pay load requirements.

Abstract: A riser pipe construction for a drilling connection from a drilling vessel to a valve previously provided on a sea floor comprises a riser pipe through which drilling means can be passed by means of which an oil well can be drilled as well as pressure pipes extending along the riser pipe to operate the valve, and floating elements disposed around the riser pipe and the pressure pipes to limit the load on the drilling vessel. The riser pipe and the pressure pipes are built up from modules capable of being coupled together, the floating elements are formed by steel tubular chambers closed so as to be gastight, disposed around the relevant modules and firmly connected thereto. The invention also relates to a riser pipe module.

Abstract: A structural element comprises an elongate body having a longitudinal axis extending along the wavy path. The body is coupled to a support on at least one end. At least a portion of the body extends through an area of fluid flow such that a plane containing the wavy path lies substantially parallel to the direction of flow. In one embodiment, the longitudinal axis extends along a substantially sinusoidal path. Also disclosed is a method of reducing drag on and suppressing vortex induced vibrations in an elongate body disposed in an area of directional fluid flow, comprising the steps of coupling at least one end of the body to a support, forming a longitudinal axis of the body along a wavy path, and orienting the body such that the wavy longitudinal path lies in a plane substantially parallel to the direction of fluid flow.

Abstract: Systems are described for raising production fluid from a source (1) on the seabed comprising a riser (4) having a first, lower, end for connection or connected to the source; a top end support for supporting the riser at or in the vicinity of the sea surface; and an operating device (11) mounted inside the riser (4) for displacement within the riser so that the pump is accessible to an operator for replacement or repair. The operating device (11) may be displaced on a pipe (12) which extends within the riser (4) and to a lower end of which the device (11) is attached. The device (11) may be inter alia an electric pump, a hydraulic pump, a gas injector, a heater or a cleaning device.

Abstract: A method of lowering a floating body of a floating foundation and carrying a structure projecting above the water surface to an end position located beneath the water level, includes threading, through each of the upwardly projecting tubes, which are secured to the floating body above-through-openings formed in the floating body, a cable or a rod and connecting the cable or rod to a set-in-ground anchor, lowering the floating body, with the uptake devices provided at the free ends of the tubes, to the end position of the floating body beneath the water surface against buoyancy of the floating body, and fixidly securing the cables or rods, in the end position of the floating body, to the floating body and cutting off sections of the cables and rods above fixation points of the cables and rods with the floating body and removing the tubes.

Abstract: A semisubmersible multipurpose unit (MPU) having a deck, a multipurpose tower secured to the deck, supports, pontoons connected to the supports with each pontoon adapted for ballast transfer, at least two hawsers connected to the MPU for connecting the MPU to an object at sea having a mooring system, a hawser guidance system to direct each hawser to the object at sea, a crane secured to the deck of a semisubmersible MPU, and at least an 6-point mooring system, wherein the combination of the semisubmersible MPU, hawsers and 6-point mooring system create a global equilibrium between the mooring system of an object at sea and the at least 6-point mooring system and the hawsers have both an elasticity sufficient to accommodate the wave frequency between the object at sea and the MPU and a stiffness adequate to synchronize the average and low frequency movements during a 10-year storm.

Abstract: A method and apparatus for connecting riser between a floating vessel and a subsea structure that reduces the size of the air tanks used and thereby allow closer positioning of the well slots and overall reduction in size of the floating vessel is disclosed. The apparatus includes an inverted hydraulically actuated connector positioned on the subsea structure and oriented to receive and sealingly attach to a complementary end connection member on the lower end of the riser string.

Abstract: The present invention provides a tendon divided into compartment enclosing therein pressurized gas. The invention also relates to a method for transporting a fluid containing tubular body or assembly of bodies above a sea/river bed floor and within a body of water. In addition the invention comprises a method of installing and removing an internal pressurized tendon or assembly of tendons in a vertical position in a body of water.

Abstract: A precast, modular marine structure and method of constructing the same for offshore use, including but not limited to drilling, oil and gas production, and oil storage in a variety of water depths. The marine structure includes an equalized pressure system and concrete modular components cast with at least one cell and a central longitudinal passageway. The equalized pressure system fluidly connects the cell(s) to the adjacent body of water by at least one substantially vertical segmented water column to equalize the hydrostatic pressure differential experienced at a wall of the marine structure. A truss section may be attached to the concrete portion of the marine structure to form a truss spar. A mooring and tether system may be included to maintain the marine structure's station and attitude.

Abstract: An apparatus and method for forming a wellbore casing. A mandrel is used to position a tubular member within a wellbore. The mandrel is then driven into the bottom of the wellbore. The tubular member is then radially expanded by the mandrel.

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

Abstract: A connector in particular intended for use with a tension leg platform is disclosed. The connector comprises a male part (1) and a female part (2), which male part (1) is designed to engage in the female part (2) and the parts are able to engage with one another without any of the parts having to rotate in respect of the other. The female part (2) comprises an abutment ring having an internal continuous downward facing abutment shoulder (4) and the male part (1) has a discontinuous segmented ring (5). Each individual ring segment (8) is limitary independantly movable, both axially and radially, which segmented ring (5) lies slidably against a mandrel abutment (9).

Abstract: A foundation system for tension leg platforms without use of foundation templates, wherein each tendon (5) is directly connected to a socket (9) inside a pile (8), the piles (8) being positioned for driving purpose by a pile-driving template (10) which is employed as a spacing device. The pile-driving template (10) is positioned with the aid of pins (11) that slot into guides (7) built into the well template (6). After the groups of piles (8) needed to anchor a corner of the platform (1) have been driven in, the pile-driving template (10) is withdrawn and repositioned so as to enable the piles for the other group of legs to be driven; this process continues until all of the pile-driving is finished. Alternatively one single pile-driving template (16) may be employed to guide the driving of all the piles (8) thus doing away with the need to reposition the template every time.

Abstract: A connection device for connecting a submerged tubular structure to a floating support structure. The connection device includes first and second tubular connection elements that connect the submerged tubular structure to the floating support structure. The first tubular connection element cooperates with the second tubular connection element to form a first axial abutment in a pulling direction in which the submerged tubular structure is pulled, and a second axial abutment in a direction opposite from the pulling direction. The device further includes a locking and tensioning device that includes at least one actuator secured to the floating support structure and is mounted to pivot on the second tubular connection element about a hinge axis and against the effect of a return spring surrounding the pin so as to enable the first tubular connection element to snap-fasten onto the second tubular connection element.

Abstract: A method and a device for use in the placing of a suction anchor (1) with an attached anchor chain (2) on the ocean bed. The suction anchor (1) and the anchor chain (2) are to be lowered separately to the ocean bed, and be connected at the ocean bed without any use, worth mentioning, of mechanically movable parts or closing mechanisms, the process is to take place by means of gravity and in as few operations and with as few pieces of expensive utility equipment as possible. This is done in that the suction anchor (1) and the anchor chain (2) are connected by means of a guiding element (6) with a lower locking element (7) arranged thereto, and a connecting element (3). The connecting element (3) is positioned at the lower end of the anchor chain (2) and adapted for insertion into the guiding and locking elements (6, 7). The guiding and locking elements (6, 7) are positioned on the side wall (12) of the suction anchor.

Abstract: There is provided a semisubmersible floating platform for use in marine environments. The platform comprises a truss telescopingly mounted to the platform and movable between upper and lower positions with respect to the platform. At least one riser buoyancy member is telescopingly mounted to the platform and movable between upper and lower positions with respect to the platform. For each riser buoyancy member, at least one guide is attached to the truss and adjacent the buoyancy member for guiding and laterally restraining the buoyancy member.

Abstract: A method and apparatus for deployment of mooring systems for buoyant marine structures such as mobile offshore drilling units (MODU's) and for connecting the same to the mooring lines thereof. An anchor handling vessel carries one or more anchors each having a deployment connection and a mooring connection and individually moves each anchor over its stern roller and deploys it to the sea bottom for installation. A handling line is disconnected by ROV from the deployment connection and is moved from the deployment connection to the mooring connection so as to become the main mooring line. Syntactic buoys are then mounted on the main mooring line for elevating it above the sea bottom for recovery. When MODU stationing is desired the anchor handling vessel then recovers the surface buoy and connects to the rig mooring line using a short section of mooring chain. A J-chaser stopper device is then installed in the mooring string and is connected to the mooring line of the MODU by a short section of chain.

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

Abstract: A riser connected by a trunnion mounted/pivoting riser support to a disconnectable body or to a riser table of a permanently connected turret. The trunnion includes a trunnion housing and trunnion pivot. The trunnion housing is arranged to allow a riser to pass through it and up to a vessel turret where the disconnectable body is connected to the turret. The trunnion pivot allows the trunnion housing and riser to pivot about a horizontal axis, allowing a disconnectable body to submerge to the sea floor.

Abstract: A launchable rigid jacket of an offshore platform has a structure including an exterior framing and a plurality of cross-sectional frame sections. The exterior framing has four outside legs, which are spaced apart to define four corners of a trapezoidal cross section. The jacket also includes two launch runners mounted on adjacent parallel outside legs. The cross-sectional frame sections are horizontally positioned at periodic intervals along the height of the jacket and each has a plurality of members, which interconnect the four outside legs and are part of the exterior framing. The exterior framing in total defines an integral launch box for the jacket. A plurality of perpendicularly oriented conductors pass through each cross-sectional frame from the base to the top of the jacket and conductor guides connected to the respective frame sections slidably engage the conductors to laterally support them.

Abstract: A temporary stability module and method for marine structures during construction, transportation and installation is taught. The device and method permit the structure, including platforms, deck and equipment to be constructed in an upright position, towed to an ocean installation site, and installed by ballasting the structure or temporary stability module and subsequent removal of the module.

Abstract: A method and apparatus for deployment of mooring systems for mobile offshore drilling units and for connecting the same to the mooring lines thereof. An anchor handling vessel is provided for transporting at least one suction anchor having a deployment connection and a mooring connection. The, said anchor handling vessel incorporates an anchor deployment mechanism having a handling wire with a quick-disconnect socket connector for accomplishing movement of said suction anchor from the service vessel for line deployment to the sea bottom. After deployment of the suction anchor, disconnecting the handling wire from the deployment connection and moving it to the mooring connection, such that the handling wire becomes the main mooring wire. Connecting buoys with the main mooring wire to position it for recovery. Repeating such procedure for each of the plurality suction anchors and mooring wires of the mobile offshore drilling unit.

Abstract: The present invention discloses a process for installing a floating platform to the ocean floor using a spoolable (preferably composite) tether, comprising installing the spooled tether onto the floating platform; towing the floating platform to a site for installation; unspooling the tether; connecting a bottom end connector of the tether to a foundation on the ocean floor; and connecting a top end connector of the tether to the floating platform. A preferred floating platform is a tension leg platform, and the invention includes a novel tension leg platform (TLP) comprising a spooled tether installed thereon. In a preferred embodiment the foundation is a suction anchor, and the suction anchor is connected to the bottom end connector prior to unspooling the tether and attached to the ocean floor after unspooling the tether. The floating platform may be uninstalled, moved and re-installed according to the invention.

Abstract: A method and apparatus for deployment of mooring systems for buoyant marine structures such as mobile offshore drilling units (MODU's) and for connecting the same to the mooring lines thereof. An anchor handling vessel carries one or more anchors each having a deployment connection and a mooring connection and individually moves each anchor over its stern roller and deploys it to the sea bottom for installation. A handling line is disconnected by ROV from the deployment connection and is moved from the deployment connection to the mooring connection so as to become the main mooring line. Syntactic buoys are then mounted on the main mooring line for elevating it above the sea bottom for recovery. When MODU stationing is desired the anchor handling vessel then recovers the surface buoy and connects to the rig mooring line using a short section of mooring chain. A J-chaser stopper device is then installed in the mooring string and is connected to the mooring line of the MODU by a short section of chain.

Abstract: A mechanism to be applied to an exterior surface of a cylindrical structure for reduction of the effect of Vortex Induce Vibration (VIV) in the cylindrical structure when immersed in flowing fluid. The mechanism is provided with a generally cylindrical column having a central axis, an interior surface corresponding in size and shape to the exterior surface of the cylindrical structure to which the mechanism is to be applied and an outer surface defining a wall thickness. A reduced wall thickness is formed into the outer surface in a pattern to produce a discontinuity that interrupts the lengthwise coherence of vortex shedding of moving fluid from the outer surface when the cylindrical column is attached to the exterior of the cylindrical structure in the flowing fluid. The effect of VIV on the cylindrical structure is effectively reduced.

Abstract: A floating system for very deep water includes a floating structure (1) subject to the external loadings (7, 8, 9) inducing stresses, the floating structure (1) being held in position on the sea bed by one or several tensioned lines (2) made of a material having given mechanical properties. The tensioned line or lines (2) are made of a material that is not very sensitive to fatigue stresses and the tensioned line or lines are sized in a manner independent of the fatigue phenomena associated with the dynamic behavior of the floating system under the effect of external loadings.

Abstract: A method and apparatus for deployment of mooring systems for buoyant marine structure such as mobile offshore drilling units (MODU's) and for connecting the same to the mooring lines thereof. An anchor handling vessel carries one or more anchors each having a deployment connection and a mooring connection and individually moves each anchor over its stern roller and deploys it to the sea bottom for installation. A handling line is disconnected by ROV from the deployment connection and is moved from the deployment connection to the mooring connection so as to become the main mooring line. Syntactic buoys are then mounted on the main mooring line for elevating it above the sea bottom for recovery. When MODU stationing is desired the anchor handling vessel then recovers the surface buoy and connects to the rig mooring line using a short section of mooring chain. A J-chaser stopper device is then installed in the mooring string and is connected to the mooring line of the MODU by a short section of chain.

Abstract: An extended-base tension leg substructure, an offshore platform supported on the substructure and a method for supporting an offshore platform on the substructure are disclosed, where the substructure includes a plurality of support columns disposed about a central axis of the substructure and interconnected by at least one pontoon. Each column comprises an above water and submerged portion. The substructure also includes a plurality of wings or arms radiating from the columns and/or the pontoons, each wing fixedly or removably securing at least one tendon extending from a wing to an anchor on the seabed. The substructure includes an open, wave transparent central zone for improved access to well-related equipment, conduits or the like and the wings minimize translational movement and rotational flex in the substructure reducing fatigue in the tendons and their connections.

Abstract: A bottom connector for the tendon of a tension leg platform uses a latch ring with an outer profile to engage a mating profile in a receptacle on the sea floor. The latch ring moves radially within a housing, relative to the receptacle, between an engaged position and a retracted position. The latch ring engages the receptacle by lowering the connector into the receptacle below the mating profile and then lifting it until the latch ring locks into the receptacle. The latch ring disengages the receptacle by lowering the connector beyond a recess located below the mating profile and then lifting the connector out of the receptacle. As the connector is lifted above the recess, a retaining ring is actuated by the recess to retain the latch ring in its retracted position.