Abstract: The present disclosure provides an improved method and system for loading a topsides onto an offshore structure by functional modules. A module support frame forms a supporting structure to which production modules can be assembled. The production modules are adapted to extract or process hydrocarbons from a hydrocarbon well in an offshore location. One production module is a well bay production module to which other production modules can be coupled, including a drilling support production module, separation production module, export module, and utility module. The module support frame can be loaded onto floating barges and other modules assembled thereto to allow the barges to provide incremental and controlled support during the loading process and for the floatover installation. The barges can be floated out to the offshore structure and loaded onto the offshore structure by methods including a floatover method or with a heavy-lift crane vessel.

Abstract: This method comprises connecting a downstream point (40) of a pipe (24) to a buoy (26) and completely submerging the buoy (26). It comprises deploying in the body of water (12) an intermediate section (30) of the pipe (24) from the downstream point (40) to at least as far as an upstream point (38), anchoring the upstream point (38), and tensioning the intermediate (section (30) to keep it vertical. The height of the buoy (26) is less than 1.5 times its greatest transverse dimension. The method comprises moving the buoy (26) between a remote position and an installed position in line with an anchoring region, keeping the buoy (26) partly submerged on the surface (16) of the body of water.

Abstract: A tendon is assembled in a horizontal orientation using connectors or by welding at a weld station on a barge or other vessel located at or near the installation site of a tension leg platform. During assembly, the tendon is pulled away from the assembly vessel and tensioned by a tug or offshore work vessel. When fully assembled, the tendon may be up-ended in a manner similar to a wet-towed tendon, and then either pre-installed using floats or passed over to a TLP which is on-site and ready to receive tendons.

Abstract: A method and system for transporting an offshore structure such as a wind turbine generator includes a supporting frame in which the offshore structure is assembled on land in an upright configuration. The frame is used for lifting the structure onto a transport vessel, on which it is retained in the upright configuration. At its location of use, the offshore structure is transferred to a pre-prepared foundation. The foundation is provided with a frame which cooperates with the supporting frame. The supporting frame includes a plurality of legs having hydraulically controlled feet. The frame of the foundation includes an equal number of supporting formations on which the feet ultimately rest. The feet are moveable in response to the hydraulic control along a nominally vertical line of action and provide a damping arrangement for the mounting of the offshore structure.

Abstract: A piling barge is disclosed by the present invention. In the piling barge disclosed, a supporting leg includes a supporting arm extended in vertical direction. Differing from the prior art, the supporting leg further includes a supporting base. The supporting base has a transverse section larger than that of the supporting arm, an end of the supporting arm is fixed with the upper surface of the supporting base. The supporting base of the supporting leg having a larger transverse section may receive support from a larger area of mollisol ground and thus provide a larger supporting force for the hull, which enables the piling barge to perform the piling operation on sea areas with mollisol ground. A piling device of the piling barge has pile frame adjusting mechanisms, such as a luffing oil cylinder, a luffing winch mechanism and a turntable, etc., which may adjust the incline angle and the position of the pile frame, therefore the working efficiency of piling operation of the piling barge can be improved.

Abstract: The invention relates to a supporting element (8) for an offshore wind turbine (3), comprising a base body (1) formed by a circular or polygonal basement (4), a shaft (5) with vertical walls and a plurality of vertical cavities (6) extending over the entire height thereof and a slab (2) dispose on the shaft (5) of the base body (1), on which slab (2) a wind turbine (3) is positioned and secured. The base body (1) of the supporting element (8) is produced using sliding formwork, from the basement (4) up to the upper base thereof.

Abstract: A semi-submersible structure. The hull includes four columns that are supported by two pontoons. The columns support the topsides and the topsides structural framing serves as horizontal framing between the columns. A truss frame is attached to the columns. The truss frame preferably includes heave plates. The truss frame extends downward below the pontoons a sufficient distance in the water such that it minimizes motions caused by environmental forces. The hull section and the truss space frame are constructed separately and assembled together at the offshore site where the structure is used for drilling and/or production.

Abstract: The present disclosure provides an improved method and system for loading a topsides onto an offshore structure by functional modules. A module support frame forms a supporting structure to which production modules can be assembled. The production modules are adapted to extract or process hydrocarbons from a hydrocarbon well in an offshore location. One production module is a well bay production module to which other production modules can be coupled, including a drilling support production module, separation production module, export module, and utility module. The module support frame can be loaded onto floating barges and other modules assembled thereto to allow the barges to provide incremental and controlled support during the loading process and for the floatover installation. The barges can be floated out to the offshore structure and loaded onto the offshore structure by methods including a floatover method or with a heavy-lift crane vessel.

Abstract: A method of mating of a buoyant hull with a truss structure while at the installation site of the completed offshore structure. The buoyant hull is moored in place. The truss structure is placed in the water, self upends, and maneuvered near the buoyant hull. The buoyant hull and truss structure are rigged with lines to allow the truss structure to be pulled into engagement with the buoyant hull. The truss structure is lowered to a predetermined depth below the water surface but above the sea floor and the weight is transferred to the lines from the buoyant hull. The truss structure is aligned with the buoyant hull and lines from the buoyant hull are used to pull the truss structure into engagement with the buoyant hull. The truss structure and buoyant hull are rigidly attached together as is customary using grouting and welding.

Abstract: A building over the water, maneuvering methods for the building and hosting sites of the building. The buildings including a superstructure (A) provided a floor structure (1) that is placed over a water surface (2) on which an inhabitable subassembly (3) is positioned, a support (B) sitting on ground (4) positioned under the floor structures (1), and mobile floating docks (C) with variable and controllable buoyancy that includes a load carrying platform (5) positioned under the floor structure (1). The superstructure (A) is held above the water surface (2) by the supports (B), that sit on the ground (4), and respectively carried by the floating docks (C), the superstructure being detachable from the ground (4), and transportable on water on the mobile floating docks (C), thus being possible to reposition the superstructure (A) on ground (4), at a destination of choice.

Abstract: Universal Framed Cofferdam has prefabricated skeletal steel space framing formed from multiple steel vertical pipes and two levels of horizontal diaphragm trusses rigidly connected to pipe columns. Beams of each diaphragm truss are attached to vertical pipes of the framing with rigid moment connections creating a rigid space frame of the perfectly round form that is used as a false work of the Cofferdam. Wales of the Cofferdam and short pieces of the flat sheet piling are attached to the vertical pipes forming a skeleton of the Cellular structure. The Skeleton of the Universal Framed Cofferdam is prefabricated in the convenience of the Dry Dock and than floated to the site. Buoyancy of the framing allows Cofferdam skeleton transportation without using the barge or otherwise necessary floating devices. Once brought to the site of installation Cofferdam skeleton is installed vertically in position and leveled on the bottom of the river bed.

Abstract: The present invention provides a method for installing a hydroelectric turbine at a deployment site on the seabed which involves lowering the turbine and associated base onto the seabed from a vessel using a number of lines, and once on the seabed using these lines to tether the vessel to the base/turbine while telemetry from the base/turbine is analysed.

Abstract: The present invention provides an improved method and system for load-out of a topsides onto at least two float-over barges without requiring an intermediate transportation barge. The topsides and float-over barges create a catamaran system that can be used to install the topsides to an offshore structure, such as a Spar hull, using a float-over method. The load-out process offers several advantages and can be less time-consuming and less expensive than a typical procedure using the intermediate transportation barge.

Abstract: A concrete section of an offshore platform substructure comprises a concrete body with a central opening and at least one guidepost hole extending through a height of the concrete body, wherein a width of the concrete body is greater than the height. An offshore platform substructure comprises a base portion resting on the ocean floor, and a plurality of concrete support sections stacked one on top of another on the base portion. A method of assembling an offshore platform with a concrete substructure comprises locating a guidepost in the ocean floor at a well site, towing a plurality of concrete sections to the well site, sequentially engaging each of the plurality of concrete sections with the guidepost, and sequentially sinking each of the plurality of concrete sections, thereby forming a stack of concrete sections on the ocean floor.

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

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 catamaran lifting apparatus is disclosed for lifting objects in a marine environment. The apparatus includes first and second vessels that are spaced apart during use. A first frame spans between the vessels. A second frame spans between the vessels. The frames are spaced apart and connected to the vessels in a configuration that spaces the vessels apart. The first frame connects to the first vessel with a universal joint and to the second vessel with a hinged connection. The second frame connects to the second vessel with a universal joint and to the first vessel with a hinged or pinned connection. The catamaran hull arrangement provides longitudinal flexibility in a quartering sea state due to the unique universal joint and hinge placement between the frames or trusses and the hulls or barges. Each of the frames extends upwardly in an inverted u-shape, providing a space under the frame and in between the barges that enables a marine vessel to be positioned in between the barges and under the frames.

Abstract: There is disclosed a support means, especially for mounting or dismounting an offshore platform, comprising an articulated bracket which is movable horizontally swinging its two articulated arms. In the case of a rather rough sea a compensating movement in the horizontal direction can be effected by appropriately controlling the articulated arms, wherein the reaction forces acting in the horizontal direction are minimal.

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: 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: The invention concerns a method for mounting a heavy equipment on a floating ship's hull comprising the following steps: (A) securing the equipment to lifting units adapted to be supported on the sea floor, said lifting units being arranged on either side of the equipment; (B) pressing the lifting units on the sea floor; (C) lifting the equipment to shift the ship's hull beneath the equipment; (D) cause the ship's hull to be engaged beneath the equipment in the space defined between the lifting units; (E) lowering the equipment to set it in supported position on the ship's hull; (F) dismantling the units for lifting the equipment; and (G) connecting the equipment to the ship's hull.

Abstract: A catamaran lifting apparatus is disclosed for lifting objects in a marine environment. The apparatus includes first and second vessels that are spaced apart during use. A first frame spans between the vessels. A second frame spans between the vessels. The frames are spaced apart and connected to the vessels in a configuration that spaces the vessels apart. The first frame connects to the first vessel with a universal joint and to the second vessel with a hinged connection. The second frame connects to the second vessel with a universal joint and to the first vessel with a hinged or pinned connection. The catamaran hull arrangement provides longitudinal flexibility in a quartering sea state due to the unique universal joint and hinge placement between the frames or trusses and the hulls or barges. Each of the frames extends upwardly in an inverted u-shape, providing a space under the frame and in between the barges that enables a marine vessel to be positioned in between the barges and under the frames.

Abstract: A system for offloading LNG (liquified natural gas) from a tanker (26) in shallow waters, for regasing, or heating the offloaded LNG to produce gaseous hydrocarbons, or gas, for pressurizing the gas, and for flowing the gas to an onshore station (56), includes a structure that is fixed to the sea floor and projects above the sea surface and aids in mooring the tanker. In one system, the structure that is fixed to the sea floor is a largely cylindrical tower (12) with a mooring yoke (20) rotatably mounted on its upper end. A floating structure (14) such as a barge that weathervanes, has a bow end pivotally connected to a distal end of the yoke, so the barge is held close to the tower but can drift around the tower with changing winds, waves and currents. The tanker is moored to the barge so the barge and tanker form a combination that weathervanes as a combination.

Abstract: A method and a suitable arrangement for installation of a deck structure at an offshore location, where the deck structure is put on a vessel at a location inshore, then transported on the vessel to the offshore location and positioned relative to legs (13) of a jacket or gravity base type support structure standing on the sea bottom, or the legs or columns of a floating substructure, the deck structure having deck legs (5) corresponding to support legs (13) on the support structure, the deck legs (5) each being provided with a jack type of mechanism with an associated piston (1) which is extended into contact with and supported by the top part (3) of the corresponding support leg (13) at the beginning of a procedure for transferring the weight of the deck structure from the vessel to the support legs (13).

Abstract: A system for offloading LNG (liquified natural gas) from a tanker (26) in shallow waters, for regasing, or heating the offloaded LNG to produce gaseous hydrocarbons, or gas, for pressurizing the gas, and for flowing the gas to an onshore station (56), includes a structure that is fixed to the sea floor and projects above the sea surface and aids in mooring the tanker. In one system, the structure that is fixed to the sea floor is a largely cylindrical tower (12) with a mooring yoke (20) rotatably mounted on its upper end. A floating structure (14) such as a barge that weathervanes, has a bow end pivotally connected to a distal end of the yoke, so the barge is held close to the tower but can drift around the tower with changing winds, waves and currents. The tanker is moored to the barge so the barge and tanker form a combination that weathervanes as a combination.

Abstract: A semi-submersible, multicolumn, deep draft, floating offshore oil and gas drilling and production platform comprises a floating hull having an adjustably buoyant base, a plurality of columns vertically upstanding from the base, and an equipment deck that is supported atop the columns when the platform is operationally deployed. Each of the columns comprises a cellular structure that includes a plurality of elongated tubes having a variety of cross-sectional shapes extending from the base to the top of the column. Each of the tubes defines one or more closed compartments. At least one of the compartments has a buoyancy that is fixed, and at least another one of the compartments has a buoyancy that is adjustable. The buoyancy of the compartments and the base can be controllably adjusted with pressurized air to provide a safer and less costly method for deploying the platform for offshore operations.

Abstract: A portable flotation platform is disclosed for use in supporting a load of equipment, hunting dogs, or personnel above the level of a body of water. The platform includes a deck constructed to be of an overall density less than that of water and sized so as to support the load above the level of the water. An anchor extends down to the bottom of the water and up to the deck to hold the deck on station in the water. The deck is provided with a carrying attachment to facilitate the user carrying the deck to a point of deployment at the water. The deck further has anchor storage for carrying the anchor along with the deck to the point of deployment.

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: A method and a suitable arrangement for installation of a deck structure at an offshore location, where the deck structure is put on a vessel at a location inshore, then transported on the vessel to the offshore location and positioned relative to legs (13) of a jacket or gravity base type support structure standing on the sea bottom, or the legs or columns of a floating substructure, the deck structure having deck legs (5) corresponding to support legs (13) on the support structure, the deck legs (5) each being provided with a jack type of mechanism with an associated piston (1) which is extended into contact with and supported by the top part (3) of the corresponding support leg (13) at the beginning of a procedure for transferring the weight of the deck structure from the vessel to the support legs (13).

Abstract: A system for drilling wells includes a plurality of platform modules, which are interconnected to one another on site to form a unitary platform structure. The interconnected platform modules are elevated above a surface on plurality of legs coupled to at least some of the platform modules. The elevated interconnected platform modules support drilling and auxiliary equipment. The system is well adapted for use in arctic, inaccessible, shallow water or environmentally sensitive locations.

Abstract: A method of removing a deck from an offshore structure is provided. An apparatus for carrying out the method is also described.

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 method is described for containing dispersed particulate or soluble matter during contaminated sediment remediation operations in the marine environment. The preferred method comprises the use of a specially designed marine vessel that establishes a negative differential pressure gradient between a defined remediation control zone and the external ambient water environment, thereby preventing the release of contaminants dispersed during the remediation process. The preferred method also includes the use of marine vessels to remove contaminants contained within said control zone and to provide for the management of solids collected in the process.

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: 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 transporter for removing an offshore platform has an oblong structure with a U-shaped cross section, rotatable by ballasting. The transporter is adapted to remove and carry both a jacket and a topsides simultaneously.

Abstract: A connector is provided for removably attaching a space frame to the hull of a floating offshore platform. The connector comprises a socket attached to the hull of the platform. The socket has an open bore therein. A stabbing member is attached to the space frame. The stabbing member has a lower end insertable into the socket. An expandable locking ring is carried by the lower end of the stabbing member. The locking ring comprises a plurality of ring segments for removably seating within the socket bore. A backup ring is slidable along the stabbing member. The backup ring removably mates to the locking ring.

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 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: The method for removing or positioning a structure (103) which is erected on either an underwater bed or anchored to the underwater bed entails the use of a hoisting mechanism. When the structure (103) is being removed, it is detached from the underwater bed. Then, the structure (103) is connected to a hoisting mechanism which is arranged on a separate hoisting vessel (100). The structure is hoisted up by the hoisting mechanism and is attached to a transport vessel (1) in such a manner that it can tilt about a horizontal axis. Then, the structure is tilted into a substantially horizontal position. The structure is positioned in the reverse order.

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: An offshore structure which is resistant to wave, earthquake and ice loads and can be quickly installed and abandoned in response to changing environmental conditions includes a caisson having an upper section and a lower foundation section which are separated by a structural diaphragm. When installed, the lower foundation section extends downwardly a distance from the seafloor to provide sufficient lateral and vertical soil resistance to resist lateral and vertical loads on the structure. The upper section is adapted to support a deck structure. The structural diaphragm is adapted to rest on the seafloor when an offshore structure has been fully installed to enhance the lateral and vertical load carrying capacity of the offshore structure. During installation, the structural diaphragm and a pump are used to form suction in the lower foundation section, thus enhancing the penetration of the lower foundation section into the seafloor.

Abstract: A method and apparatus for the salvage or installation of large multi-ton marine platform includes the use of usually two barges defining a base that can support a large multi-ton load. A lifting assembly is supported by the barge and forms a load transfer interface between the barge and the deck package. Each boom has a lifting end portion that fits a supplemental lifting frame attached to the platform. During removal of the platform from its underlying support (e.g. jacket), there are winches with cables that pull the barges together as the booms lift the supplemental lifting frame and the supported platform. The supplemental frame includes both horizontal and diagonal beams that interface with the platform to transmit load to the lower end of the platform.

Abstract: A method and apparatus for the installation or removal of large multi-ton prefabricated deck packages includes the use of usually two barges defining a base that can support a large multi-ton load. A variable dimensional truss assembly is supported by the barge and forms a load transfer interface between the barge and the deck package. Each boom has a lifting end portion with a roller that fits a receptacle on the package. Tensile connections form attachments between the deck package and barge at a lower elevational position. The variable dimension truss includes at least one member of variable length, in the preferred embodiment being a winch powered cable that can be extended and retracted by winding and unwinding the winch.

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 to transport a deck at sea and install the deck on an offshore substructure. The deck is completely fabricated on a set of deep girders. The deck and deep girders are skidded onto two pontoons. The deck and deep girders are tied down together. A set of jacking units is installed into the deep girders prior to sail out. The complete assembly is towed to the installation site. At the site, the tie downs are removed. The girders are jacked up and the pontoons simultaneously ballasted down until the assembly is supported on the pontoons.

Abstract: A method and apparatus for the installation or removal of large multi-ton prefabricated deck packages (16) includes the use of usually two barges (11, 12) defining a base (13, 14) that can support a large multi-ton load. A variable dimensional truss assembly is supported by the barge and forms a load transfer interface between the barge and the deck package. Each boom (21, 22) has a lifting end portion with a roller (63) that fits a receptacle (75) on the package. Tensile connections form attachments (130-134) between the deck package and barge at a lower elevational position. The variable dimension truss includes at least one member of variable length (130-134), in the preferred embodiment being a winch powered cable (130-134) that can be extended and retracted by winding and unwinding the winch.

Abstract: A mini-jacket is installed using a caisson. The caisson is a tubular pipe that is either pre-existing in the field or specifically installed before hand, such that the bottom end of the caisson is driven into the ocean floor and its top end extends above the water surface. The mini-jacket is a structural frame with pile sleeves at the comers and a caisson sleeve located within the perimeter of the frame. The mini-jacket is configured and installed such that in its installed position its top surface is above water surface while its lower end remains above the ocean floor. During installation, the mini-jacket is lifted and lowered so that its caisson sleeve slides over the caisson. The caisson sleeve has weight bearing plates welded at the top. The mini-jacket is lowered until the weight bearing plates rest on the caisson, thereby transferring the weight of the mini-jacket to the caisson. The caisson alone supports the weight of the mini-jacket during the pile installation.

Abstract: Apparatus for transporting and installing a deck of an offshore oil production comprises a floating barge (10) adapted to support the deck (1) and provided with devices for moving the deck (1). The apparatus includes a support framework (11) for the deck (1) adapted to be placed on the barge (10) and including the devices for moving the deck (1) in the form of at least one rack (21) that can be moved vertically by drive mechanisms (20).