Abstract: A floating wind turbine platform includes a floatation frame (105) that includes three columns (102, 103) that are coupled to each other with horizontal main beams (115). A wind turbine tower (111) is mounted above a tower support column (102) to simplify the system construction and improve the structural strength. The turbine blades (101) are coupled to a nacelle (125) that rotates on top of the tower (111). The turbine's gearbox generator and other electrical gear can be mounted either traditionally in the nacelle, or lower in the tower (111) or in the top of the tower-supporting column (102). The floatation frame (105) includes a water ballasting system that pumps water between the columns (102, 103) to keep the tower (111) in a 10 vertical alignment regardless of the wind speed. Water-entrapment plates (107) are mounted to the bottoms of the columns (102, 103) to minimize the rotational movement of the floatation frame (105) due to waves.

Abstract: Modular offshore platform systems and associated methods of transport and assembly are disclosed herein. A method of transporting a modular offshore platform to an offshore location in accordance with an embodiment of the disclosure includes transporting towing a first platform portion of the offshore platform to an offshore location and transporting a second platform portion of the offshore platform to the offshore location separately from the first platform portion. The method further includes attaching the second platform portion to the first platform portion at the offshore location, and anchoring at least one of the first and second platform portions to a sea floor at the offshore location.

Abstract: A pontoonless tension leg platform (TLP) has a plurality of buoyant columns connected by an above-water deck support structure. The design eliminates the need for subsea pontoons extending between the surface-piercing columns. In certain embodiments, the buoyancy of the columns is increased by the addition of subsea sections of increased diameter (and/or cross-sectional area) to provide the buoyancy furnished by the pontoons of the TLPs of the prior art. A pontoonless TLP has a smaller subsea projected area in both the horizontal and vertical planes than a conventional multi-column TLP of equivalent load-bearing capacity having pontoons between the columns. This reduction in surface area produces a corresponding reduction in the platform's response to ocean currents and wave action and consequently allows the use of smaller and/or less costly mooring systems.

Abstract: A subsea suction pile crane system comprises a suction pile and a crane mounted on the suction pile. The crane comprises a rotatable mounting surface, a winch, and a boom having a proximal section attached to the rotatable mounting surface such that the boom can pivot with respect to the mounting surface, and a distal section opposite the proximal section. In embodiments, a plurality of suction piles may be sed. The crane system is typically hydraulically operated. A preferred embodiment of the invention may further comprise a remotely operated vehicle comprising a hydraulic power supply operatively coupled to the crane, and a manipulator arm mounted on the distal section of the boom and operatively coupled to the hydraulic power supply.

Abstract: A method of installing an underwater foundation, suitable for use in supporting or anchoring wave or tidal energy capture devices is provided. The method comprises providing a foundation unit (1) equipped with a submersible drilling rig (16); placing the foundation unit (1) on the bed (50) of a body of water at a selected location; activating the submersible drilling rig (16) to drill a plurality of pile holes (56) in the bed of the body of water; and securing the foundation unit (1) to the bed of the body of water by means of piles (54) or tendons, inserted in pile holes (56) and secured to the foundation unit (1). A foundation unit (1) and a submersible drilling rig (16) for use in the method are also provided.

Abstract: A method for coordinating a floating wind turbine installation. The wind turbine installation includes a buoyant body (1), a tower (2) arranged over the buoyant body, a generator (3) mounted on the tower which is rotatable in relation to the wind direction and fitted with a wind rotor (4), and an anchor line arrangement (5) connected to anchors or anchor points on the sea bed. Static heeling, ?s—max, at full wind load on the wind turbine is as low as possible, but preferably less than 8 degrees, and all eigenperiods for the installation are outside the waves' period range. The eigenperiod in pitch, T05 (roll, T04), is preferably less than 80% of the T03 eigenperiod in heave. Moreover, the ratio between T03 and T05 is not close to 0.5 or 1.

Abstract: A floating power generation assembly has at least three floating units (3400) provided with power generation means (3402, 3404) and floating in a body of water. At least one of the three floating units (3400) is a tension leg platform. The assembly also comprises first anchors secured to a surface beneath the water, and first cables (3414, 3416) connecting the buoyant body (3400) to the first anchors. Second anchors are secured to the underwater surface and connected by second cables (3412) to the floating units (3400). The floating units (3400) are arranged substantially at the vertices of at least one triangle or quadrilateral.

Abstract: A mobile, year-round drilling system (MYADS) for drilling offshore wells and/or performing other offshore activities at multiple, successive locations in an arctic or sub-arctic environment is provided. The present invention combines the ability to move to different locations and the strength to resist ice loading when on location and when ice-covering is present in the arctic or sub-arctic environment. The MYADS applies a multiple leg “jack-up” concept in which supporting legs are lowered through a hull to touch down on the seabed and elevate the hull out of the water.

Abstract: A tendon or riser connector has a separate lock-down device that overrides the connector's ability to unlock if the riser or tendon goes slack. The connector has a lock ring that engages a groove profile on a receptacle and is prevented from accidentally unlocking with a cam ring and set of blocks. The blocks are movably positioned between engaged and disengaged positions that correspond to the locked and unlocked positions of the lock ring.

Abstract: A deep water high capacity anchoring system in which the fixing of an anchor structure under compact layers of ocean soil is reached by jetting fluid in rising directions and, simultaneously in a radial and/or perpendicular direction to the external surfaces of said anchor structure injected from its lower extremity, thus guaranteeing anchoring of large size floating structures, related to the petroleum industry, such as stationary production units and oil drilling platforms.

Abstract: A seabed region (18) that lies under a seabed surface area of at least one square meter, is analyzed by an acoustic analysis of the region. Locations of the generation and detection of sound are precisely correlated to the location of a vertical drill hole in the sea bed by mounting an acoustic imaging apparatus (16) that holds acoustic transducers (44, 46), on a carriage (26) that is positioned with respect to the drill hole, using the drill hole as the horizontal position reference. The carriage of the acoustic imager apparatus is clamped to a post that lies in the drill hole. An arm (30 and/or 32) is supported on the carriage through a frame (28), with at least one acoustic generator (44) and one acoustic echo detector (46) mounted on the arm. The arm can be rotated to positions lying about the hole axis (14) to accurately scan a wide area.

Abstract: A leg assembly for a compliant offshore tower provides a structure allowing foundation drive piles to be driven and attached entirely externally to the space frame of the tower, and simultaneously providing restraints on bending forces within the drive pile—flex leg connection structure, allowing for ease of construction and assembly and greater strength and life-expectancy for the structure.

Abstract: The invention relates to a foundation base for mounting wind turbines in an aquatic bed and a method for manufacturing said foundation, formed by a conical structure which is made up of an assembly of columns (1) like generatrices, arranged between an upper apex core (2) and a lower annular footing (3), the constructive mounting of said assembly being carried out on an annular mold (8) which is arranged floating in the water, in which the annular footing (3) is formed, with the attachment thereon of the columns (1), which are held in the constructive formation of the structural assembly by means of a support jig (10).

Abstract: A submerged buoyant floating platform with blocked vertical thrust. Above the platform an electrolyser may be placed inside a hollow container. Under the platform may be a hollow container filled with ballast, connected by pipes or chains to the outer ring of the platform which provide rigidity to the entire structure. A storage tank for the hydrogen produced by the electrolyser may be attached to the hollow container. The entire structure may be anchored with chains attached to bottom weights sitting on the ocean floor. The structure may be used as a support for a tower including a wind turbine. Additional chains attached to the structure bottom weights on the sea floor may link the structure to an aquaculture facility and to floats which hold the cages used in aquaculture. The floats may be linked to additional bottom weights placed on the sea floor.

Abstract: A mooring (10) for connecting an ocean energy capturing device (51) to a seabed (16) is disclosed. The mooring (10) comprises a base (12) adapted for connection to the ocean energy capturing device (51). A plurality of anchor bolts (18) are each connected at a first end to the base (12) and have a second end adapted to be embedded in the seabed (16) for attaching the base (12) to the seabed (16). A method of securing the ocean energy capturing device (51) to the seabed (16) is also disclosed. The method involves passing a tensile transmission line (46) through a guide opening (44) in the base (12) and drawing the tensile transmission line (46) through the guide opening (44) to drag the ocean energy capturing device (51) toward the base (51).

Abstract: An anchor system may reduce stress on anchor cables when an offshore drilling platform weathervanes. The anchor system may hold the platform in a set position above the sea floor during drilling operations. The anchor system includes anchor cables that pass through a split bearing. Clamps may be connected to the bearing to hold the anchor cables in tension.

Abstract: A mounting system is disclosed for mounting structures and equipment, such as wind-electric generators on water. The structure is attached to a carrier, which is attached to a foundation through connecting elements. Buoyancy tanks or the inherent buoyancy of the carrier or the connecting elements are used to maintain a stable position of the carrier in the water. Utilizing connecting elements that transfer pushing and pulling forces, undesirable movements of the carrier are suppressed while requiring only moderate forces on the foundation.

Abstract: An offshore platform includes a buoyant hull comprising three or more interconnected pontoons and a plurality of support columns. The support columns support a deck or structure that supports equipment and/or payloads above a water surface. The support columns extend upwardly from respective ends of the pontoons to the deck or structure supported above the water surface. Anchoring members anchor the platform to the seabed.

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: The invention concerns an assembly for installation of an underwater structure on the sea floor, said sea floor being covered with particles capable of being driven in suspension in the water above said sea floor, the mounting of said underwater installation capable of being implemented by an underwater robot driven by propulsion means, said propulsion means being capable of displacing the sea floor water and said suspended particles around said installation; said assembly comprising means (22, 26) for covering said sea floor surrounding said installation with a protective blanket (10) adapted to confine said particles on said sea floor.

Abstract: A new and improved submarine anchoring cable that includes an outer layer that comprises 20% to 80% polyurethane elastomer, 20% to 80% carbon fiber mixed at a certain ratio. The outer layer is compressed to wrap around an aramid fiber or an ultra-high-molecular-weight polyethylene (UHMWPE) fiber and a core of synthetic fiber rope with molecular malleability, e.g., nylon, nylon66, and the polyester rope. The rope is exposed in a form of a loop from both ends of the cable. Each loop has one or multiple layers of sheath made of aramid fiber, Kelvar fiber or UHMWPE fiber wrapping around the rope near a tie on each end to provide extra friction and withstanding strength. One end of the anchor cable is fixed to the offshore platform and the other end is fixed to each anchor to hold on to the offshore platform within a limited area defined by multiple anchors fastened to the offshore platform.

Abstract: An arrangement for stabilization of a floating foundation, which is arranged to carry a wind-turbine mounted on a tower, is described. The foundation is fixed with a set of mooring cables. First endings of the mooring cables are attached to the foundation at a certain position while second endings of the mooring cables are attached to a floor. There is a second set of mooring-cables, while first endings of the second set of mooring-cables are attached to the foundation near or at its bottom end and while second endings of the second set of mooring-cables are attached to the floor, too.

Abstract: A subsea suction pile crane system comprises a suction pile and a crane mounted on the suction pile. The crane comprises a rotatable mounting surface, a winch, and a boom having a proximal section attached to the rotatable mounting surface such that the boom can pivot with respect to the mounting surface, and a distal section opposite the proximal section. In embodiments, a plurality of suction piles may be used. The crane system is typically hydraulically operated. A preferred embodiment of the invention may further comprise a remotely operated vehicle comprising a hydraulic power supply operatively coupled to the crane, and a manipulator arm mounted on the distal section of the boom and operatively coupled to the hydraulic power supply.

Abstract: A container for underwater placement on a sea, lake or river bottom. The container has openings in the sides, top and bottom and is filled with ballast of large boulders, cobble, crushed coral, cast concrete modules or other materials. The openings allow water and water currents, as well as marine organisms, to pass freely therethrough. Over time, a wide assortment of marine organisms infiltrate and colonize the nooks, crevices and cavities of the ballast, thus utilizing the habitat as they would an artificial reef. One or more hitch points are provided on the container for attaching mooring lines for ships, boats, floating wind turbines or other floating structures, thereby allowing the artificial reef to anchor such structures.

Abstract: The present invention describes an offshore foundation system (10,10a,10b) that is operable for preloading after self-weight installation on a seabed without relying on additional or external ballasts. The foundation system (10,10a,10b) is also operable for extraction by reversing the process of preload operation. In one embodiment, the foundation system (10) comprises a reaction base (20) and suction compartment (60). In another, the foundation system (10a,10b) comprises a plurality of units of reaction base (20) and suction compartments (60), with the units being connected by bridging structures (21). In yet another, the foundation system comprises a reaction base (20) and a plurality of suction compartments (60). A closed-top of the suction compartment (60) projects above the reaction base (20) so that, in use, there is a gap h between a top of a soil plug inside a suction compartment (60) and its closed-top.

Abstract: A tendon top connector for a moored, floating structure such as a tension leg platform, a tension leg buoy or the like has a bowl-shaped extension on the member which transfers the tension of the tendon to the flex connector. A dome-shaped structure at least partially surrounds the bowl-shaped extension but is spaced apart from it to permit at least some rotational movement of the connector. The dome-shaped structure may be attached by clamps or other mounting means to a flange member affixed to the tendon porch. This arrangement provides a load path when the tendon top connector is reverse loaded that extends from the tendon length adjustment joint, through slips, through the bowl-shaped extension, through the dome-shaped structure, through the segmented clamps, and finally into a flange attached to the tendon porch. In this way, detachment of the tendon top connector is prevented if a reverse load is applied such as may occur during extreme metocean conditions.

Abstract: A tendon bottom connector assembly has a receptacle with a bore having an annular locking profile divided into segments by axially extending slots. The connector has a housing that inserts into and locks in the receptacle. The housing and receptacle have mating an anti-rotation elements. The lock ring has an outer surface with an annular locking profile divided into segments by axially extending slots. The lock ring is carried by the housing initially in the installation position with its segments aligned with the slots of the receptacle. This position allows the housing to be fully inserted into the receptacle. An ROV then rotates the ring from the installation position to a locked position, with the segments of the lock ring engaging the segments of the receptacle. Alternately, a split ring with one end fixed rotates the lock ring.

Abstract: The apparatus may include a space frame on which is mounted at least one hydrofoil for generating positive or negative lift. The frame is attachable to underwater equipment such as a turbine. The hydrofoils are adapted to produce negative lift when a flow of liquid passes over them and so in use cause the apparatus and attached equipment to sink to the seabed. The flow of water over the hydrofoils continue to produce negative life and so maintain the apparatus on the seabed. In certain embodiments, the hydrofoils can typically be set to a passive configuration in which they flip over when the current flow changes direction. Furthermore, the hydrofoils are selectively rotatable to provide an angle of attack such that they may be adapted to provide positive lift when it is necessary to remove the apparatus from the water.

Abstract: A mooring system for stabilizing a vessel for handling offshore structures includes at least one mooring unit, a connection mechanism for connecting the mooring unit to the vessel, and a tractive mechanism for stabilizing the vessel by establishing permanent tension in the connection mechanism. Furthermore, the tractive mechanism includes a mechanism for lowering the connected vessel's position in relation to the water level. A method of stabilizing a vessel, a vessel for handling offshore structures and use of a mooring system are also contemplated.

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

Abstract: Subsea oilfield equipment (2), such as an oil and/or gas production template, is installed at the water bottom (16) by means of a submerged installation vessel (1) from which hoisting lines (3A, 3B) are deployed to support the equipment during the installation procedure, which lines (3A,3B) are reeled from at least one hoisting line reeling winch (3A,3B) mounted at the submerged installation vessel (1) to lower the equipment (2) at a desired speed and in a substantially horizontal position onto the water bottom (16).

Abstract: The floating platform of the invention is intended for supporting industrial, commercial, cultural, and dwelling structures and is suitable for deployment in shallow as well as in deep waters, The platform is assembled from prefabricated hollow structural elements in such a way that the unified center of masses of the loads that consist of a plurality of arbitrarily distributed loads of different masses supported by the platform is always maintained in the same position whereby the platform is always maintained in a horizontally counterbalanced position. This is achieved by locally adjusting the buoyancy of the structural elements. Furthermore, the loads are positioned on the platform so that moments created by these loads relative to the aforementioned unified center of masses are equal. This allows maintaining the loads on the platform in equilibrium.

Abstract: A new and improved submarine anchoring cable that includes an outer layer that comprises 20% to 80% polyurethane elastomer, 20% to 80% carbon fiber mixed at a certain ratio. The outer layer is compressed to wrap around an aramid fiber or an ultra-high-molecular-weight polyethylene (UHMWPE) fiber and a core of synthetic fiber rope with molecular malleability, e.g., nylon, nylon66, and the polyester rope. The rope is exposed in a form of a loop from both ends of the cable. Each loop has one or multiple layers of sheath made of aramid fiber, Kelvar fiber or UHMWPE fiber wrapping around the rope near a tie on each end to provide extra friction and withstanding strength. One end of the anchor cable is fixed to the offshore platform and the other end is fixed to each anchor to hold on to the offshore platform within a limited area defined by multiple anchors fastened to the offshore platform.

Abstract: A releasable connector assembly comprising a socket body 2 and a plug body 3. The socket body 2 has a set of channels 15 formed therein and the plug body 3 having a corresponding set of radial tabs 7 formed thereon, the channels 15 forming a keyway for the tabs 7 such that load bearing projections 5, 14 on the bodies are releasably engageable in the manner of a bayonet coupling. The assembly is characterised in that a set of locking pins are provided on the socket member that are extendable into the channels 15 so as, in use, to trap the tabs 7 in undercuts 15k of the channels 15, thereby preventing unintentional release of the plug 3 from the socket 2, and retractable from the channels 15 so as to enable release of the plug 3 from the socket 2.

Abstract: A method for restoring aquatic marsh vegetation in situ on an open body of water, including the steps of (A) floating on the body of water at least one buoyant system which comprises at least one flotation apparatus connected to a matrix, sized and configured to support the vegetation, and water-contacting means for raising and lowering the matrix relative to the surface of the water, (B) suspending marsh vegetation within the matrix, and (C) periodically and repetitively raising and lowering the matrix relative to the surface of the water by action of the water-contacting means so that a varying level of water is provided to at least a portion of a root region of the vegetation.

Abstract: A tendon or riser connector has a separate lock-down device that overrides the connector's ability to unlock if the riser or tendon goes slack. The locking device has blocks that are radially actuated through a hole in a receptacle to engage a profile in the connector. When the blocks are pushed in, they prevent the connector from moving downward, and thus prevent any unlocking of the connector. The blocks are secured with pivotable gates that engage and retain the blocks in both positions.

Abstract: The anchoring device for a floating wind turbine installation, such wind turbine installation comprising a floating cell (7), a tower (8) arranged over the floating cell, a generator (9) mounted on the tower which is rotatable in relation to wind direction and fitted with a wind rotor (10), and an anchor line arrangement (6) connected to anchors or anchoring points on the sea bed. The individual anchor lines (11) are each, at a certain distance from the floating cell (7) at a fixing point (5) on the individual anchor line, connected with double lines (2, 3) slanting outwards and connected to the floating cell (7) in a delta-shaped arrangement.

Abstract: A tendon bottom connector assembly has a receptacle with a bore having an annular locking profile divided into segments by axially extending slots. The connector has a housing that inserts into and locks in the receptacle. The housing and receptacle have mating an anti-rotation elements. The lock ring has an outer surface with an annular locking profile divided into segments by axially extending slots. The lock ring is carried by the housing initially in the installation position with its segments aligned with the slots of the receptacle. This position allows the housing to be fully inserted into the receptacle. An ROV then rotates the ring from the installation position to a locked position, with the segments of the lock ring engaging the segments of the receptacle. Alternately, a split ring with one end fixed rotates the lock ring.

Abstract: A subsea suction pile crane system comprises a suction pile and a crane mounted on the suction pile. The crane comprises a rotatable mounting surface, a winch, and a boom having a proximal section attached to the rotatable mounting surface such that the boom can pivot with respect to the mounting surface, and a distal section opposite the proximal section. In embodiments, a plurality of suction piles may be used. The crane system is typically hydraulically operated. A preferred embodiment of the invention may further comprise a remotely operated vehicle comprising a hydraulic power supply operatively coupled to the crane, and a manipulator arm mounted on the distal section of the boom and operatively coupled to the hydraulic power supply.

Abstract: A submersible and remotely-operable platform system for carrying out repeated operations in a submarine position, and producing electrical energy as either a primary or secondary purpose by means of one or more energy-conversion payload devices installed thereon. The platform and payload devices may be periodically brought to the surface and thence, if necessary, to a shore-based facility for maintenance or refit. In deployment, the platform is preferably engaged to its mooring lines and electrical cables while still on the surface. Simultaneous with controlled flooding of certain of its volumes, the platform is guided to an operational depth and attitude by the action of its winch assemblies upon their engaged mooring lines. Subsea currents energize the platform's payload of energy conversion devices, the electrical output being preferably conveyed via one or more surface-attached cables to an off-board facility for further processing, distribution, or consumption.

Abstract: A spar structure is disclosed for offshore hydrocarbon recovery operations having a vertically oriented elongated floating hull with a buoyant upper section, a ballasted lower section, and a truss member separating the floating hull from the lower ballasted section. A anchoring system connects the hull to the ocean floor and a vertically oriented fairing shaped profile section is presented on the hull.

Abstract: A method for positive locking of a tension leg platform tendon bottom connector C in a tendon receptacle R contained in a tendon foundation pile P, the bottom connector and receptacle having mating locking elements. A vertical space S is provided in the foundation pile between the tendon receptacle and the soil level inside the pile sufficient to allow vertical entry and locking of the bottom connector and receptacle locking elements, and a material M of sufficient density is placed into the space beneath the tendon bottom connector in the tendon receptacle and the soil level inside the pile to limit downward vertical motion of the bottom connector and prevent accidental release of the locking elements. When required, a sufficient amount of the material may be removed to allow the requisite vertical motion of the bottom connector to release the locking elements.

Abstract: A tension leg platform includes a deck supported on the upper ends of three or more columns interconnected at the lower ends thereof by horizontally disposed pontoons. The columns are battered inwardly and upwardly from the pontoons to the deck. Tendons connected at the columns anchor the platform to the seabed. The footprints of the base of the battered columns and the tendons are larger than the footprint of the deck supported on the upper ends of the columns.

Abstract: A seabed region (18) that lies under a seabed surface area of over one square meter, is analyzed by comparing a core sample taken near the middle of the region and/or data from a geotechnical insitu cone penetrometer installed at the middle of the region, to an acoustic analysis of the region. Locations of the acoustic analysis are precisely correlated to the location of the core test sample or cone test by mounting an acoustic imaging apparatus (16) that holds acoustic transducers (44, 46), on a carriage (26) that is positioned on the core drill (12) or cone penetrometer barrel staff. The carriage of the acoustic imager apparatus is clamped to the core drill when the core drill is not rotating. An arm (30 and/or 32) is supported on the carriage through a frame (28), with at least one acoustic generator (44) and one acoustic echo detector (46) mounted on the arm. The arm can be rotated to positions lying about the drill axis (14) to accurately scan a wide area.

Abstract: A method and system for attaching a TLP to its tendons using pull-down lines to rapidly submerge the hull to installation draft while compensating for inherent hull instability during submergence and to provide motion arrest and aid in station keeping. The system includes tensioning devices mounted on the TLP, usually one for each tendon. Each tensioning device is equipped with a pull-down line which is connected to the corresponding tendon. The TLP hull is submerged to lock-off draft by applying tensions to the pull-down lines connected to the top of the tensions, or by a combination of applying tensions to the pull-down lines and ballasting the hull. As the tensioners take in pull-down line, the hull submerges, i.e. the draft increases.

Abstract: The invention relates to a complementary locking system for locking legs to the deck of a jack-up offshore drilling platform. The inventive system comprises the following elements at each leg, namely: at least one assembly comprising plates forming two counter-racks which are intended to be engaged with a leg rack and, on one side of the plates, at least one internal element for connecting the internal edges of the plates, at least one external element for connecting the external edges of the plates and at least one intermediate member for connecting said at least one internal element to said at least one external element. The invention also relates to methods of installing said complementary locking system on the legs of a jack-up offshore drilling platform.

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: An arrangement for anchoring a floating structure comprising a mooring boom 120a, b; 650a, b pivotally arranged at either end, wherein each mooring boom at its free end has a bushing 124a, b: 654a, b through which anchor chains or wires can run. The anchor chain that runs through one of the bushings is fastened to the opposite end of the structure. In addition, for reasons of stability there may be tensioned lines which connect the free ends of both mooring booms to the structure.

Abstract: A deepwater windpower plant (DWP) has a tension leg-type floating platform with an evacuable base for adjusting its buoyancy for installation at ocean depths ranging from 40 meters up to 1.5 kilometers and more. The DWP has a typical offshore wind turbine assembled close to shore which is then towed to a desired installation site on the ocean, and held in place by a gravity anchoring base (GAB), to which an evacuable portion or space of the DWP platform is anchored. The GAB has upwardly extending mooring tethers and a power cable which are brought to the ocean surface by attached buoys. The GAB is sunk to the ocean floor at the installation site under controlled conditions so that the GAB lands flat on the ocean floor. As the GAB sinks to the ocean floor, the mooring tethers and power cable are pulled to the surface by their respective buoys. The GAB is loaded with heavy ballast material that can be dropped from barges on the ocean surface into the upwardly open GAB below the barges.

Abstract: A tendon for mooring a tension leg platform having an uppermost pipe segment with a reduced diameter compared to at least one of the lower pipe segments. The tendon is watertight and sealed from the ocean environment, preferably filled with air at one atmosphere of pressure. One or more interior bulkheads may be included to divide the tendon into multiple compartments. The reduced outer diameter of the uppermost pipe segment provides reduced drag due to waves and currents and accommodates smaller tendon support buoys and vortex fairings, while the greater diameter of the lower pipe segment provides for increased tendon buoyancy.