Abstract: Method for stabilizing a jack-up platform unit, the unit including a hull, a plurality of legs which are extendible from and/or through the hull and which are arranged to support the platform unit during off-shore operations, and a jacking system arranged to move the legs between a transport position and an operational position, wherein the jacking system is also arranged to move the hull along the plurality of legs between a floating position and an operational position, the method comprising the steps of lowering the plurality of legs until the legs stand on or in the seabed, raising the hull substantially above the sea surface, temporarily applying a preloading on the plurality of legs, further raising the hull to an operational height above the sea surface.

Abstract: At least one handling device is provided having at least one floating member with first and second mutually opposite portions between which a transitional surface at least partially extends defining an interior. The device has an offshore part receiving portion therein to at least partially receive the offshore part. The floating member is simply installed in the offshore part so that it at least partially surrounds its outer surface. The offshore part thus floats on the water for being transported to an intended destination.

Abstract: A jack-up rig for offshore operations comprises a hull. In addition, the rig comprises a support leg moveably coupled to the hull. The support leg has a central axis, an upper end, and a lower end opposite the upper end. Further, the support leg is adapted to be axially raised and lowered relative to the hull. The rig also comprises a ballast tank movably coupled to the support leg. The ballast tank is adapted to be axially raised and lowered relative to the support leg and the hull.

Abstract: A mobile drilling system comprising a top member with a drilling rig positioned thereon. The top member is removably engaged with a foundation member. The foundation member comprises a tower. The top member is moveable and adapted to be elevated out of the water for placement on top of the tower. The tower is preferably of concrete and extends out of the water and above any ice. A method is also described by which the top member is elevated out of the water either by jacking down legs or lifting by interaction with the tower.

Abstract: There is provided a method for the installation of a tidal power plant having a water turbine, which is mounted so it is rotatable on a nacelle, the nacelle being assigned to a coupling device for placement of the tidal power plant on a coupling counterpart on a tower, which carries the tidal power plant during operation.

Abstract: A catamaran-type boat suitable for handling, assembling, and/or transporting off-shore wind turbines, the boat having two side floats constituting a U-shaped floating structure, the open space between the two branches of the U-shape constituted by the two side floats being suitable for receiving a base, the floats being fitted with grippers suitable for gripping the base between the two side floats, and the grippers being suitable for gripping the base and at least two grip levels of different heights.

Abstract: The invention relates to an offshore installation method of a wind power generator and its fabrication segments. A prefabricated wind power generator is finished at a first location, and then carried by a ship to a second location for installation, largely saving installation time. With a tower inserted down through a base to shrink height of the generator, the ship can not only effectively diminish shaking posed by wind and sea waves, advancing steadiness of delivery, but also be one with smaller tonnage to save cost.

Abstract: A device for transporting structures on water, as well as dismounting or installation of the structure(s) includes an elongated tilting frame (8) hingedly connected at a pivoting point (10) to a water vessel (6). The tilting frame (8) holds one or more support cribs (5) designed for being displaceable relative to the tilting frame and possibly relative to each other, the tilting frame further being designed to be able to assume an essentially horizontal or slightly tilted position, corresponding to a transport position, and being designed for being able to be tilted about the hinge connection to an essentially vertical position by suitable means, the vertical position corresponding to a lifting or operating position wherein the structure(s) carried by the support crib(s) may be lifted or lowered up from or down into the water, respectively, or up or down above water level.

Abstract: A method of installing marine equipment, the method including providing a marine apparatus comprising the marine equipment and a buoyancy device including at least a first and a second tank. The first tank containing air and the second tank containing a buoyant liquid having a specific gravity of less than 0.8 g/cm3. The method including providing a template on the seabed and guiding the marine apparatus down onto the template. Also a buoyancy device comprising at least a first and a second tank, the first tank containing a first fluid and the second tank containing a second fluid.

Abstract: The instant disclosure relates to a system and method of constructing drilling and production platforms that are particularly useful in remote, inaccessible and/or environmentally sensitive operating environments. According to one aspect of the invention, an arctic drilling platform is provided wherein various methods and means of interlocking neighboring platform modules are provided. Methods and means for sealing the intersections formed between a plurality of interlocked platform modules are also disclosed. According to further aspects of the invention, improved platform floor plans are provided, and various wellhead cellar layouts and sealing means are also described. Methods and to means of enhancing the usefulness of modular storage platforms are disclosed, and a number of support post installation and removal techniques are also provided.

Abstract: A stabilizing chamber to be used with a mobile offshore unit and a method of manufacturing and stabilizing therewith are disclosed. The stabilizing chamber includes a housing configured to removably receive and retain fluid therein, a first support, and a second support. The first and second supports are attached to the same side of the housing, and at least one of the supports is configured to support the weight of the stabilizing chamber. These supports are then configured to removably connect with the mobile offshore unit. The housing of the stabilizing chamber may be filled with fluid to at least partially submerge the stabilizing chamber. After fluid is received within the stabilizing chamber, the stabilizing chamber may be disconnected from the mobile offshore unit.

Abstract: The present invention refers to a process to permit descent to sea bottom, with the use of two conventional tug boats, of equipment used in submarine field oil field exploration, especially descent of equipment of large size and mass in deep water fields. Equipment is being suspended by a sling, attached to an auxiliary component. This, on its turn, is attached to two cables, each one activated by one of the two tug boats. Connection of the auxiliary component to cables is being made by means of connectors, which are trespassed thru cable openings and attached to auxiliary component by screws, forming a connection, in which connectors may carry out a pivotal movement around holes of auxiliary component. This movement of said connectors almost entirely absorbs oscillations of tug boats caused by waves, without transmitting same to equipment. In this way, both tug boats may lower equipment and cross the so-called resonance area without risk of its occurrence.

Abstract: The invention provides a method for the transport of a civil engineering structure in an aquatic medium. According to this method: at least one float is associated with the civil engineering structure in such a way as to ensure that the said civil engineering structure floats stably in an aquatic medium, the said float surrounding the civil engineering structure and a bottom portion of the civil engineering structure extending below the said float, and the civil engineering structure and the associated float are caused to move in the aquatic medium to a desired position.

Abstract: The invention relates to a method for installing an offshore wind turbine (5) comprising the steps of preparing an offshore foundation (5) for receiving and retaining a part of said wind turbine, moving said wind turbine in substantially vertical (erected) position from an onshore position to a transit position on a barge system (2), transporting said barge system to the site of said offshore foundation (5), moving said wind turbine from said transit position to an installation position on said barge system, positioning said part of the wind turbine in relation to said foundation, and lowering the barge system in relation to the water level so that said part of the wind turbine engages with said prepared offshore foundation (5).

Abstract: A method and vessel for removing or installing an offshore jacket structure in a body of water, the vessel having a generally planar main buoyancy section having the outline of a delta with an extension at the apex and auxiliary buoyancy sections extending transversely of the main buoyancy section at the ends of the base of the delta. The bottom parts of the auxiliary buoyancy sections have a rounded outer surface and contain heavy fixed ballast. The vessel may be rotated as it is brought close to the jacket structure with the auxiliary sections straddling the jacket structure. The vessel is rotated towards the jacket structure while its rounded bottom portion rolls on the seabed. Once the jacket structure is connected securely to the vessel, the vessel is rotated back to the initial position de-ballasting the auxiliary sections before it is brought to the surface.

Abstract: The instant disclosure relates to a system and method of constructing drilling and production platforms that are particularly useful in remote, inaccessible and/or environmentally sensitive operating environments. According to one aspect of the invention, an arctic drilling platform is provided wherein various methods and means of interlocking neighboring platform modules are provided. Methods and means for sealing the intersections formed between a plurality of interlocked platform modules are also disclosed. According to further aspects of the invention, improved platform floor plans are provided, and various wellhead cellar layouts and sealing means are also described. Methods and means of enhancing the usefulness of modular storage platforms are disclosed, and a number of support post installation and removal techniques are also provided.

Abstract: A floating lowering and lifting device (1) includes a floating structure (2) and a lifting unit (3) lowerable from the floating structure (2) towards the sea bed, the lifting unit (3) having a chamber (5) with at least one gas-inlet opening (9) in its wall (27) and an equalization opening (23, 25) in its wall (27), a gas supply (13) being connected to the gas inlet opening (9) The device includes a control element (15) connected to the gas supply (13) for controlling a gas supply rate to the chamber (5), wherein the chamber (5) includes a releasable coupling member (7) for releasably attaching to a load (8).

Abstract: Apparatus (12) for transferring fluid between floating vessels (10, 11) is described, comprising a submerged rigid transfer arm (13) carrying a fluid pipeline (16). The apparatus (12) is provided with thrusters (21) and positioning monitoring means (24). A control system (25) operates the thrusters (21) to move the arm (13) if the position monitoring means (24) shows the arm (13) and the second vessel (11) is outside a given range, to restore the separation to within the range. The pipeline (16) may be located in a tunnel (30) on the arm (13) which opens above the waterline at each end to allow personnel access therein for inspection and maintenance of the pipeline (16).

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 to the seabed. The payload 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 accommodating changing platform payload requirements.

Abstract: A process for the conversion of natural gas to higher hydrocarbons in a system comprising (1) a synthesis gas production unit and (2) a Fischer-Tropsch synthesis unit comprising at least one high shear mixing zone and a reactor vessel wherein the units are located abroad a floatable structure. The process comprises the steps of: (a) converting the natural gas to synthesis gas in the synthesis gas production unit; and (b) converting the synthesis gas to higher hydrocarbons, at an elevated temperature and pressure, in the Fischer-Tropsch synthesis unit by (i) passing synthesis gas and a suspension comprising a particulate Fischer-Tropsch catalyst suspended in a liquid medium through the high shear mixing zone(s) wherein the synthesis gas is broken down into gas bubbles and/or irregularly shaped gas voids which are dispersed in the suspension, and (ii) discharging suspension containing the dispersed gas bubbles and/or irregularly shaped gas voids from the high shear mixing zone(s) into the reactor vessel.

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: Method for transport and installation of objects at sea, particularly relating to transport and installation of obs jects that are part of the infrastructure in oil and gas fields offshore, the object (4) is put in the sea at a suitable location near the shore or in sheltered waters, then towed to the installation site while being suspended in a slender buoyancy unit (5) acting much like a heave compensating unit. Upon arrival at the installation site, the suspension of the object (4) is transferred from the buoyancy unit (5) to a heave compensated winch (3) on a surface vessel (2), preferably the same vessel as used for the preceding towing operation. The winch is used to lower is the object (4) to its destination on the sea bottom or a predetermined location above the sea bottom.

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 device for lifting a seagoing construction such as a drilling rig, which device comprises one or more floater bodies, one or more beam-like lifting members supported movably on a floater body and running parallel or practically parallel to each other, wherein the or each lifting member is supported on at least two support points of the floater body, at least one of which is adjustable in height direction, and the end part of the lifting member lying outside the floater body has a pressure point which is in contact with the construction for lifting, this such that the seagoing construction can be easily connected to the end of the lifting member without this construction suffering damage as a result of the sea swell.

Abstract: A device for positioning and lifting a marine structure, particularly a platform deck, with the use of a U-shaped lifting vessel (1). The device has at least two adjustable lifting frames (12,12), each able to incline towards the middle of the docking area. Each of the lifting frames (12) consists of an upper horizontal lifting beam (13), preferably situated on a level above the top of the lifting vessel (1). The near-vertical part of the lifting frame (16) is connected to the lifting beam (13) in the upper end and in the lower end hinged (21) to the lifting vessel (1). The near-horizontal part of the lifting frame (18) is in one end connected to the lifting beam (13) and in the other end adjustably connected to the lifting vessel (1).

Abstract: An offshore hydrocarbon production system includes a vessel (12) with a turret (16), and a fluid swivel (50) on the turret that is connected to risers (41-43) that extend to the sea floor (26), wherein a drilling/workover rig (60) on the vessel can lower tubing (65) toward the sea floor without danger that the tubing will wrap about the risers when the hull weathervanes. The rig is mounted on the turret. Pipes (54) that extend from the rotatable part of the fluid swivel to fittings (55) on the hull (14), are supported on a gantry (80) that is fixed to the hull and having a gantry middle portion (106) that extends over the turret. The gantry middle portion extends higher than the top (88) of the rig.

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: An offshore well platform is towed in an upright condition to a well site by the use of a temporary flotation device. The flotation device mounts to a portion of the platform and is partially submerged, increasing the ability and buoyancy of the platform. At the site, the engagement of the flotation device shifts to a deploying position. In the deploying position, the ballast of the platform is increased to cause it to more deeply submerge. The flotation device remains at least partially surrounding the platform and floating while the platform moves downwardly relative to it. This provides lateral support if needed to prevent heeling while being submerged. The flotation device is disengageable from the platform when the platform is fully submerged.

Abstract: There is disclosed improved mooring apparatus and method suitable for use with large offshore vessels. To avoid deploying an anchor with a full weight of mooring chain, they are deployed separately. An anchor, such as a suction anchor (1), is fitted with a short chain (C1) with one end permanently connected (6) thereto and its free end temporarily placed in a chain locator (8), which is positioned so as to be accessible after deployment of the anchor to the seabed, minimising the potential for seabed material to cause disruption. The anchor with its short chain is deployed to the seabed and at some stage the free end of a mooring chain (C2) is lowered to and accurately guided (100) into the chain locator, such that both free ends align. A pin (101) is inserted by an ROV to interconnect the two chains, after which the combined mooring chain (C) is tensioned, withdrawing it from the chain locator.

Abstract: An offshore construction system comprises a work module support vessel having a ballast-down mode, in which a deck of the vessel is submerged below the water surface, and a ballast-up mode, in which the deck is disposed above the water surface. The system further comprises an independently floatable, pontoon-supported work module carried on the deck of the support vessel. The system also includes a draw connected between the work module and the work module support vessel. The draw has a draw-over mode, in which the work module is drawn over the deck of the support vessel, and a remove mode, in which the work module is removed from the deck.

Abstract: A platform topsides can be transferred from a substructure to a transporter by ballasting the transporter, locating the transporter underneath the topsides and deballasting the transporter, causing load transfer units of the transporter to lift the topsides off the substructure. Each load transfer unit comprises a compression spring which rests on a layer of particulate material located in a drum, the particulate material in turn rests on a releasable hatch-cover. The springs provide a flexible connection between the transporter and the topsides. During the deballasting of the transporter, the hatch-covers are released to suddenly let out the particulate material from the drums, thereby lowering and relieving the springs, causing a direct contact and a stiff connection between the transporter and the topsides.

Abstract: The invention relates to a method of connecting a first floating structure (1, 16, 25, 41) to the seabed, comprising the steps of: providing a second floating structure (2, 18, 26, 40), anchored to first and second anchoring points (6, 7; 22, 23; 32, 33; 47) respectively on the sea bed via at least two anchor lines (4, 5; 19, 20; 30, 31; 43, 45), attaching the second floating structure to the first structure via a pulling device (13, 24, 35, 46), on the side of the first anchor line, displacing the first floating structure (1, 16, 25, 41) away from the second anchoring point (7; 22, 33, 47) towards the first anchoring point (6, 23, 32), disconnecting the first anchor line (4, 20, 30, 45) from the second floating structure (2, 18, 26, 40) while maintaining a pulling force on the second anchor line (5, 19, 31, 43) via the pulling device, and attaching the first anchor line (4, 20, 30, 45) to the first floating structure (1, 16, 25, 41).

Abstract: The present invention relates to a ball swivel connection/joint intended to be used at anchoring of in particular deep sea water boring rigs and other off-shore platforms but also other heavy units at sea, whereby it comprises a partly spherical wire connection receiving a wire receiving unit a substantially annular link connector as well as a holding element for a fixed or movable fixation of the link connector as well to an annular space arranged in the partly spherical connector, whereby the link connector and the wire receiving unit are rotatably arranged relative each other.

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 of removing a deck from an offshore structure (11) including a deck (13) supported on a jacket (12), includes the following steps: a) positioning a floating vessel (10) around the jacket with respective parts of the vessel on opposite sides of the jacket (12) and trusses (3, 4) extending between the opposite parts of the vessel, b) engaging parts of the trusses (3, 4) with legs (15) of the jacket, c) securing the trusses (3, 4) to the jacket (12), d) relieving the load carried by portions of the legs (15) of the jacket (12), e) cutting through the portions of the legs (15) of the jacket to divide the jacket into a lower part and an upper part carrying the deck, the trusses (3, 4) being secured to the upper part of the jacket (12), f) transferring the weight of the upper part of the jacket (12) and of the deck (13) via the trusses (3, 4) to the floating vessel (10), and g) removing the floating vessel (10), with the trusses (3, 4), the upper part of the jacket (12) and the deck (13) supported thereon,

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 method for fabricating sections of a floating offshore spar type structure and mating the sections offshore. A buoyant hard tank is fabricated vertically. The hard tank is then transported in a vertical orientation to a site where it is mated to a truss section of the spar structure offshore while the hard tank and truss section are both in the vertical orientation. The mated tank and truss sections are then towed in the vertical orientation to the operational site. The hard tank is fabricated with a larger diameter and correspondingly shallower draft than a more traditionally proportioned hard tank.

Abstract: A method for removing a jacket of a drilling or production rig using a vessel provided with a deck includes manoeuvring the vessel close to the jacket, hoisting the jacket, and tilting the jacket relative to a tilting point located close to an edge of the deck of the vessel until the jacket lies on the deck, wherein the side of the jacket directed toward the vessel is supported during the tilting, such that the jacket can be removed in one operation and carried away using the vessel. A vessel with a deck and a device for removing a jacket of a drilling or production rig is also disclosed.

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 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 of constructing SPAR buoys comprising an elongate floating body (1) and a deck structure (2). The elongate body (1) is transported to the mooring site in its horizontal position. During erecting of the floating body (1) by ballasting it with water and alignment with the deck structure (2), the deck structure (2) remains attached to its buoyancy member (7). Hereby the use of large derricks can be avoided which provides a substantial cost reduction. After erecting the floating body, the body (1) may be ballasted to pass below the floating deck structure (2). Alternatively, the deck structure (2) may be deballasted or pulling cables (14) may be used to pull the coupling member (4) of the floating body (1) into contact with the coupling member (12) of the deck construction. Alternatively, the floating body (1) is at its upper ends connected to the deck structure (2) via a pivoting connection (22) such that during coupling the floating body may be hinged against the deck structure (2).

Abstract: A platform topsides (2) can be transferred from a substructure to a transporter (1) by ballasting the transporter (1), locating the transporter underneath the topsides (2) and deballasting the transporter, causing load transfer units of the transporter to lift the topsides (2) off the substructure (3). Each load transfer unit comprises a compression spring (53) which rests on a layer of particulate material (52) located in a drum (51), the particulate material (52) in turn rests on a releasable hatch-cover (58). The springs (53) provide a flexible connection between the transporter (1) and the topsides (2). During the deballasting of the transporter (1), the hatch-covers (58) are released to suddenly let out the particulate material (52) from the drums (51), thereby lowering and relieving the springs (53), causing a direct contact and a stiff connection between the transporter (1) and the topsides (2).

Abstract: The removable pier support system of the present invention comprises a plurality of folding pier support posts. Each post has a platform section having a horizontal base plate for supporting the post on a bed of a body of water. The base plate has a lower surface which in use rests on the bed. An anchoring probe extends from the lower surface of the base plate, and a support arm section extends upwardly from the horizontal base plate. A folding arm section is coupled to the support arm section. The folding arm section is movable between a first position extending upwardly from the support arm section and a second lying adjacent the support arm section. A pivot mechanism couples the support arm section and the folding arm section to one another. The pivot mechanism comprises two sets of cooperating pins and slots with the pins disposed on one section and the slots positioned in the other. The pins are vertically aligned, and include a pivot pin and a locking pin.

Abstract: A marine platform 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.

Abstract: An apparatus and method for the installation of a deck on an offshore substructure. The invention is particularly useful with a floating substructure. Two independent pontoons each have two columns spaced apart from each other that extend upwardly from the pontoons. On each pontoon, a support beam attached to the columns spans the space between the columns. In another embodiment, there is no support beam across the space between the columns. Each pontoon is provided with ballast tanks that allow the pontoons to be selectively ballasted or de-ballasted to control pontoon depth for receiving a deck or installing a deck on an offshore substructure. The pontoons may be ballasted down during transit of the deck such that the main body portion of the pontoons is below significant wave action and the columns present a relatively small water plane area. The pontoons allow the deck to be placed directly above the offshore substructure.

Abstract: A method and apparatus that eliminates the need for a derrick barge to lift the deck into place on a floating offshore structure. A connector is used to connect the transport barge to the floating offshore structure. The connector is a type that allows only relative pitch motions between the transport barge and floating offshore structure in response to sea states acting on the barge and floating offshore structure. The connector is also a type that allows disconnection while large forces are acting on the connector. One or more skidding girders attached to the legs of the deck support the legs of the deck above the skidding surface of the transport barge. A skidding surface on the girders, and complementary skidding surface on the surface of the transport barge and floating offshore structure, allow the deck to be skidded from the barge to the floating offshore structure.

Abstract: An offshore hydrocarbon production system includes a spar (34, 52, 214) that floats at the sea surface, a subsea buoy (26, 154, 200, 210) lying under the spar and hanging from it, and one or more risers (20, 174, 220) that extend up to the subsea buoy and are coupled therethrough to the spar. The subsea buoy is initially negatively buoyant to ballast of the spar and keep it upright, but the subsea buoy can be made positively buoyant so the spar can be moved away and a workover vessel (70) moved over the subsea buoy. The subsea buoy can be coupled to the spar by one or more chains (60, 60A) extending between them, and one or more flexible hoses (60) extending between them.

Abstract: A method for lifting a sea platform with its substructure attached from a seabed and moving that platform to a different location. Use is made of flotation bodies which are filled with water and attached to the substructure. The flotation bodies can be emptied of some water to provide greater flotation and can be rotated around a horizontal axis to facilitate movement of the entire assembly under various sea conditions.

Abstract: An apparatus and method for the installation of a deck on an offshore substructure. The invention is particularly useful with a floating substructure. Two independent pontoons each have two columns spaced apart from each other that extend upwardly from the pontoons. On each pontoon, a support beam attached to the columns spans the space between the columns. Each pontoon is provided with ballast tanks that allow the pontoons to be selectively ballasted or de-ballasted to control pontoon depth for receiving a deck or installing a deck on an offshore substructure. The pontoons may be ballasted down during transit of the deck such that the main body portion of the pontoons is below significant wave action and the columns present a relatively small water plane area. The pontoons allow the deck to be placed directly above the offshore substructure. For a floating substructure, the pontoons are ballasted while the floating substructure is simultaneously de-ballasted to transfer the deck to the floating substructure.

Abstract: A tendon installation for anchoring a semisubmersible platform to a sea bed foundation, wherein said tendons are tensioned by the updrift of the platform. The tendons are prefabricated in dimensions adapted to the depth of the sea bed foundation, expected tension load and in order to be substantially weightless in water. The tendons are connected in groups at each of their ends at a distance corresponding to the distance between anchoring points in the foundation and the platform respectively. The groups of tendons are towed out to the anchoring site and they are positioned vertically above the foundation. The tendons are fastened to the anchoring points in the foundation. The platform is positioned above the groups of tendons and connected to these via wire ropes. The platform is ballasted down onto the tendons under guidance by said wire ropes. The upper ends of the tendons are mounted internally in the legs of the platform.