Abstract: A support device is used to facilitate maintenance of a jacking system of a self-elevating drilling or maintenance platform having a plurality of legs supporting the platform in an operating orientation. The platform includes jacking mechanisms associated with the legs to raise and lower the platform using jacking racks on each leg chord. Support devices temporarily support the platform independent of the jacking mechanisms using a rack chock removably clamped in place on each leg with locking teeth on the rack chock meshed with jacking teeth on the leg's jacking rack. In this manner the platform can be temporarily supported by using removable fasteners to secure a rack chock to each leg chord beneath the platform hull, lowering the platform relative to the legs so that the hull rests on a support seat on each support device, and then disengaging the jacking mechanism from the jacking teeth on the legs for maintenance of the jacking system.

Abstract: A semi-submersible floating production vessel which has a ring pontoon. Three main columns extend upwardly from corners of the pontoon and three secondary, minor columns. extend upwardly from centers of the triangle sides. The columns are surrounded with fenders for protecting the columns from impact with floating bodies. The columns support an open frame deck, on which production modules are positioned. The vessel is adapted for semi-permanent mooring with pre-tensioned mooring lines that are attached to swivel padeyes secured on the main columns below the water line. Production and export risers are connected to the vessel below the water line. Compressed air ballast system allows selective emptying of ballast compartments located in the ring pontoon and eliminates the need for a conventional pump room.

Abstract: The invention relates to a floating platform (1) for offshore drilling or production of hydrocarbons, comprising a topsides (2) and a structure (3) having a lower pontoon (4) and columns (5) connecting the pontoon (4) to the topsides (2). Heave motion (S1, S2) of the platform (1) causes a change in the metacentric height (GM) of the platform. To counteract this change in metacentric height, the columns (5) are so adapted that the moment of area inertia of the waterline area of the columns (5) decreases on downward heave motion (S1) and increases on upward heave motion (S2.

Abstract: A Small Waterplane Area MultiHull non-motorized vessel having an upper hull platform located above the design water line of the vessel which is maintained above the surface of a body of water by at least two cylindrical submerged hulls joined thereto by supporting struts. A buoyant core material is contained between inner and outer walls of the submerged hulls which define a cylindrical space in which a rotary propulsive means may be housed. In one embodiment, an engine means is situated . . . means to provide a propulsive force.

Abstract: A bore well in a seabed (27) may be established and/or operated by a drilling barge (10). The barge may be pulled onto a larger vessel (11) and transported to a drilling site. Alternatively, the larger vessel is divided longitudinally into a pair of sub-vessels, which are then re-united at the drilling site, where the barge is pulled into position on the larger vessel. The combined drilling vessel (10, 11) may thereafter be anchored in the desired position relative to the bore well by submerging the larger vessel to rest on the seabed. The barge may be arranged on top of the larger vessel by submerging one end of the larger vessel, towing the barge into a desired position relative to the larger vessel, and raising the submerged end of the larger vessel so as to bring the deck of the larger vessel into contact with the bottom of the barge and to lift the barge out of the water.

Abstract: A lifting vessel (1) consisting of a lower U-shaped pontoon foundation (2a, 2b, 2c), a number of vertical columns (5) attached to the pontoon foundation and extending upwards and through the water surface, and each column (5) being free-standing above the pontoon foundation (2a, 2b, 2c). Methods for positioning, lifting and handling of a platform dock and a platform jacket is also described.

Abstract: In one embodiment of the present invention an offshore construction system is provided. The offshore construction system comprises a work module support vessel having a ballast-down mode, in which a deck of the work module support vessel is submerged, and a ballast-up mode, in which the deck is above water. The system further comprises a pontoon supported work module carried on the deck of the support vessel. The system further comprises a draw connected between the work module and the work module support vessel having a draw-over mode, in which the work module is drawn over the deck, and a remove mode, in which the work module is removed from the deck.

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

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

Abstract: A semi-submersible floating production vessel which has a ring pontoon. Three main columns extend upwardly from corners of the pontoon and three secondary, minor columns extend upwardly from centers of the triangle sides. The columns are surrounded with fenders for protecting the columns from impact with floating bodies. The columns support an open frame deck, on which production modules are positioned. The vessel is adapted for semi-permanent mooring with pre-tensioned mooring lines that are attached to swivel padeyes secured on the main columns below the water line. Production and export risers are connected to the vessel below the water line. Compressed air ballast system allows selective emptying of ballast compartments located in the ring pontoon and eliminates the need for a conventional pump room.

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 mooring system that uses combination traction winch/windlass units is improved by adding an additional fairlead at each combination unit location and by increasing the strength of existing combination units, their foundations and the foundations of associated equipment such as fairleads and turning sheaves. By these relatively simple upgrades, the mooring capabilities of the system can be economically augmented in those situations where additional lines are desired, such as in areas subject to tropical revolving storms. Normal mooring, when there is no threat of hurricanes, has the anchor and chain attached to the floating structure by wire deployed from the traction winch. When storm season threatens, additional anchors attached to chain run over the windlass can be added, allowing the number of lines to be doubled. The additional anchors can be installed if the floating structure is conventionally moored or if it is attached to pre-set moorings.

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

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

Abstract: A working ship (1), comprising a hull (2) provided with driving means and a deck (3). The hull (2) is temporarily submersible. The deck (3) is connected to the hull by using connecting means (8) at an adjustable intermediate distance. The working ship (1) is thus adjustable between a floating position in which the deck (3) is located near the hull and a semi-submerged position in which the hull is located substantially below the water surface and the deck (3) is located above the water surface at a distance from the hull.

Abstract: The drilling vessel includes at least one floating body and a platform which is supported by one or more support columns on the floating body and includes a drilling installation. The vessel is provided with storage provisions for tubular drilling equipment. The storage provisions include one or more shafts which are disposed in one or more of the support columns, extend downwards from the platform and in which a number of items of the drilling equipment can be vertically disposed.

Abstract: An improved lift boat includes a hull, a plurality of legs (preferably three), a plurality of pads, one pad attached to each leg, and a jacking mechanism for moving each upward and downward. Recesses in the hull receive the pads when the lift boat is underway. Preferably, the total bottom surface area of the pads is at least 30% of the surface area of the deck of the lift boat Preferably, the total bottom surface area of the pads is large enough such that, when the boat is loaded to capacity and is jacked up, the pads exert pressure of less than 7 p.s.i. on the sea floor. Preferably, the pads are partially recessed into the hull and extend laterally outward from the hull when the boat is underway to provide increased stability to the lift boat when it is underway.

Abstract: An apparatus for guiding the legs of a lift boat. Continuous track assemblies are used to guide the legs. The assemblies may be placed at any location or in any number vertically along the leg to adequately center the leg. The track assemblies are comprised of link plates 88, link pins, and track pads traveling around idlers. The track assemblies are mounted on rail structures.

Abstract: A method of connecting two or more elongate connection members (105) between the seabed and a floating vessel (106) carrying a connector (102) which is suspended from the vessel by at least two spaced apart suspension members for relative displacement of the connector with respect to the vessel, at least one suspension member being connected to tensioning elements (109, 109′) for exerting an upward force on the connector. The method comprises the steps of: a) attaching one or more connection members to the connector, b) increasing the tensioning force of the tensioning elements, or vice versa, and c) repeating steps a and b until the connection members are installed between the vessel and the seabed.

Abstract: A buoyantly moveable, self-elevating (jack-up) artificial work island or platform self-assembled while floating upon a work body of water by reversibly coupling together a plurality of independently buoyant modular hull components (20, 30), each of which is relatively narrow beam and capable of navigation through relatively narrow waterways. After self-assembly, the work platform is self-elevating upon a plurality of legs (51, 52, 53) to a desired distance above the work body of water. The work platform may be buoyantly moved to subsequent work locations as a unit, or separated into modular hull components each of which may be buoyantly moved separately to the subsequent locations. The work platform may further have a drilling derrick, a hoist, drilling fluid pumps, a rotary table and other equipment associated with earthboring for oil and gas installed thereon. The work platform may be elevated above the water surface a sufficient distance to accomodate operational conditions.

Abstract: A self-elevating drilling unit has dual cantilever assemblies that move longitudinally and transversely in relation to the jack-up platform to allow drilling operation to be performed from two drilling floors. The twin cantilever assemblies permit simultaneous drilling on an 8 feet×8 feet spacing. The cantilever assemblies are retained attached to the platform by a hold down beam that extends over and across the cantilever assemblies. The hold down beam is positioned in a stationary manner on the platform deck. A movable strut that engages the underside of the hold down beam moves along the beam to counteract upward bending forces acting on the beam when the cantilever assemblies are extended from the platform. The cantilever assemblies are made of tubular truss work and can be moved to an infinite number of horizontal positions.

Abstract: A telescoping spar structure designed to be scalable for use with very large floating platforms to relatively small floating platforms includes a platform/hull for supporting a payload; a telescoping spar attached to the platform/hull that includes several interlocking tubes extending from a shallow end to a deep end of the spar, the tubes configured to telescope in and out of adjacent tubes such that the tubes are nestable together in a stowed configuration; a buoyancy chamber attached to the spar between shallow and deep ends of the spar; and, a damping chamber attached to the spar between the buoyancy chamber and the deep end of the spar, the damping chamber including: a first compartment for entraining a volume of water, a second compartment for enclosing deployment ballast, and a release mechanism for jettisoning the deployment ballast from the second compartment after the spar structure is deployed, enabling the platform to rise to an operational height relative to the waterline.

Abstract: An appartus for guiding the legs of a lift boat. Roller assemblies are used to guide the legs. The rollers may be placed at any location or in any number either vertically or around the leg to adequately center the leg. The roller can either have a metal surface that rolls along the leg or be coated with a resilient material. The base of the roller can either be rigidly mounted to the vessel or incorporate resilient material between the roller and the vessel. A means of adjusting the clearance between the leg and roller may be incorporated in the roller assembly.

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

Abstract: A buoyantly moveable, self-elevating (jack-up) artificial work island economically and quickly self-assembled while floating upon work body of water by reversibly coupling together a plurality of independently buoyant modular hull components each of which is of relatively narrow beam and therefore capable of navigation though relatively narrow water-ways. After self-assembly said artificial work island is self-elevating upon a plurality of legs a desired distance above said work body of water. The island may be buoyantly moved to subsequent work locations as a unit or separated into modular hull components each of which may be buoyantly moved separately to the subsequent locations. The island may have a drilling derrick, a hoist, drilling fluid pumps, a rotary table and other equipment associated with earthboring for oil and gas installed thereon.

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: An uncrossed-braced, column stabilized semi-submersible and improved methods of operation of the same are disclosed. The semi-submersible vessel provides necessary strength to resist hydrodynamic forces via a unitized support system. Improved elliptically shaped columns, haunch supports and reinforcing members provide stability and resist transverse forces. A skirt design minimizes the reduced stability at the transition point. Improved deck designs reduce environmental impacts and provide additional support against transverse forces.

Abstract: The invention relates to a semi-submersible vessel designed to operate in harsh environment. The vessel has a twin-hull pontoon structure that supports four corner caissons extending vertically from the pontoons above an operational draft of the vessel. A pair of slender parallel horizontal braces connects each pair of opposing caissons, the braces extending in a general plane perpendicular to longitudinal axes of the pontoons. One of the pair of braces is secured between the forward columns and another of the pair of braces is secured between the aft columns. The braces reduce spreading and torque-induced forces acting on the columns, while not substantially increasing water plane area of the vessel. Each brace has an internal “redundancy” feature, being divided into two independent watertight compartments to continue providing buoyancy to the structure if one of the compartments is breached.

Abstract: A simplified ballast system designed for a tension leg platform from which drilling and/or production activities are to be performed in a body of water provides for rapid deballasting via large capacity dump valve(s) and for ballasting for trim operations by use of an eductor at the bottom of a drain well fluidly connected by drain lines to ballast compartments.

Abstract: The invention relates to a semi-submersible vessel designed to operate in harsh environment. The vessel has a twin-hull pontoon structure that supports four corner caissons extending vertically from the pontoons above an operational draft of the vessel. A pair of slender parallel horizontal braces connects each pair of opposing caissons, the braces extending in a general plane perpendicular to longitudinal axes of the pontoons. One of the pair of braces is secured between the forward columns and another of the pair of braces is secured between the aft columns. The braces reduce spreading and torque-induced forces acting on the columns, while not substantially increasing water plane area of the vessel. Each brace has an internal “redundancy” feature, being divided into two independent watertight compartments to continue providing buoyancy to the structure if one of the compartments is breached.

Abstract: An apparatus and method for installing a deck on an offshore substructure is provided. The apparatus comprises a deck supported by lifting mechanisms that are in turn attached to pontoons. The apparatus floats on the water with the lifting mechanisms compressed until transported to an offshore substructure having an upper end located above the water surface. The lifting mechanisms are then extended and the apparatus moved on the surface of the water to position the deck over the substructure. The deck is then lowered onto the substructure and the pontoons are lifted out of the water.

Abstract: A ship convertible to a floating aircraft runway supported above water level by slender vertical buoyant legs, and capable of remaining stable during inclement weather conditions. The slender buoyant legs lifts the upper hull above the water level by pivoting downwardly from a retracted horizontal configuration to a vertical configuration by shifting ballast. Waterjet propulsion units maintain or change the position of the ship when the legs are in the horizontal or the vertical configuration. The runway has an area sized to launch and land large fixed-wing aircraft in a substantially horizontal direction without a need for a catapult or a landing assist method.

Abstract: An oil drilling barge stabilization system and method provide that an array of substantially vertically-oriented piles is formed in the sea bed to a depth beneath the sea bed that finds solid support. A barge is towed into position over the array of piles, and the barge is partially flooded with ballast to lower it in the water so that a set of cylindrical tubes is positioned to surround top ends of at least some of the piles. Air is then forced into the tubes to force the water out the bottom of the tubes, to create a dry environment for workers. Workers weld the tubes to the piles. The air pressure is removed from the interior of the tubes so that water may again flood the bottom of the tubes. The joints between the tubes and piles secure the barge to the array of piles, even in the face of varying tides, currents, and ice flow conditions. The barge may be used to support oil rigs and a variety of other support facilities.

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).

Abstract: The invention relates to a method for installing anchors on the bottom of the sea. Wires (4) and a suction anchor (2) are attached to a frame (1). Through the centre of the frame's vertical axle a mounting device (6) for an anchor holder (7) is placed. The frame (1) works as a driving ramp for different shaped anchor holders and anchors (5, 15, 20). With the mounting device (6) the anchor penetrates the bottom of the sea at a certain position. A remote operated vehicle (ROV) and/or a hydraulic motor and pump gives a hydraulic torque for boring screwing, pressing and stamping effects. A helical screw-anochor is used for rotary screwing into the bottom of the sea (3). The span and the gradient are varied given to geological data for achieving holding forces. After use the anchor is released with a releasing mechanism (13, 14) and is left on the bottom of the sea.

Abstract: An uncrossed-braced, column stabilized semi-submersible and improved methods of operation of the same are disclosed. The semi-submersible vessel provides necessary strength to resist hydrodynamic forces via a unitized support system. Improved elliptically shaped columns, haunch supports and reinforcing members provide stability and resist transverse forces. A skirt design minimizes the reduced stability at the transition point. Improved deck designs reduce environmental impacts and provide additional support against transverse forces.

Abstract: A vessel with a movable deck. The vessel will contain in one embodiment a catamaran hull having a first pontoon and a second pontoon. The catamaran hull has a platform attached thereto. The vessel also includes a first leg, second leg, and third leg extending vertically from the top side of the platform. The movable deck will contain a first opening, a second opening, and a third opening which has the first, second, and third leg respectively disposed therethrough. The vessel further contains a jacking mechanism that raises and lowers the movable deck relative to the platform. The vessel may further comprise a first thruster nozzle attached to the first pontoon, the first thruster nozzle being movable in a 360 degree phase and a second thruster nozzle attached to the second pontoon, with the second thruster nozzle being movable in a 360 degree phase.

Abstract: A method for converting a semi-submersible drilling or accommodation rig into a dynamically positioned vessel in which the rig has pontoon bodies submergible below a surface of a body of water for producing displacement, support columns extending upright from the pontoon bodies and oriented for intersecting the surface of the body of water to define a waterline area for the rig, and a work deck supported on the support columns and arranged to be disposed at a position above the surface of the body of water. The conversion method includes prefabricating a rig extension in which the rig extension has a pontoon body extension, a work deck extension and a supplemental support structure connecting the work deck extension to the pontoon body extension. The rig extension is then connected to the semi-submersible rig at locations proximate one of the pontoon bodies and at the work deck. Thruster(s) may be optionally added at the pontoon body extension.

Abstract: A precast, modular spar system (10) having a cylindrical open-ended spar of relatively uniform cross section. The spar has a freeboard section (50), a buoyancy section (70), and a ballast section (90). The sections are formed by joining arcuate segments and stacking the sections. A pressurizing system allows for the injection of air into the segments to vary the buoyancy of the modular spar system.

Abstract: A jack up work platform is recited. The work platform comprises a hovercraft vessel outfitted with several jack up legs. The hovercraft can traverse environmentally sensitive terrain such a brackish and freshwater marshes without the need to dig canals that may cause or exacerbate salt water intrusion. Once the drilling or exploration site is reached, the jack up legs may be lowered, lifting the work platform above the surface. Once the vessel is secured on the legs, it may be used like a conventional oil field work platform for drilling, exploration, or construction jobs for which other work platforms or vessels are typically used. The deck of the hovercraft may serve as the work platform or the deck may be provided with a cantilevered work platform extension. The hovercraft will preferably be provided with typical oil field heavy machinery such as a crane for assembly of the legs, and drill stem as well as for work on other structures.

Abstract: A jack-up platform of the type having a buoyant upper barge (10) mounted so that it can be moved along the length of bearing legs (12), mechanical mechanism (18) for moving the legs (12) relative to the barge (10), and submerged storage tank (14) intended to rest on the bottom. The tank (14) has a lower opening (26) allowing the inside of the tank (14) to be placed in contact with the marine environment. The tank defines a bell-shaped/inverted U-shaped cavity confining an air bubble (30) in its upper part. The tank (14) is connected to the lower end of the legs (12) so that it can be moved relative to the barge (10) from the mechanical mechanism (18) for moving the legs.

Abstract: An assembly of a jack-up platform and at least one storage tank, wherein the jack-up platform is floatingly displaceable and can be set up by using legs, in such a manner that the jack-up platform is located at a distance above the water surface, wherein the storage tank is adapted to be placed on a water bedding and includes attaching the legs, in such a manner that the jack-up platform is supported by the storage tank, wherein the storage tank is adapted to receive at least a hydrocarbon compound such as oil, wherein the hydrocarbon compound can be led into and out of the storage tank, wherein during the support of the jack-up platform, the storage tank extends at least partially below the jack-up platform.

Abstract: A system for reducing hydrodynamic drag and vortex-induced-vibration ("VIV") in a bluff hull. In a bluff hull that is designed to be at least partially submerged in a fluid, such as water, the hull has an internal area for holding or transferring fluid. When the hull is beset by a current present in the water, the surface of the bluff hull has an up-current side and a down-current side. The hull surface has at least one opening, preferably a slot-nozzle, for blowing the fluid from the internal fluid area of the bluff hull out of the hull surface and into the surrounding water at a velocity greater than the current velocity, so as to reduce flow separation of the current on the down-current side of the hull surface. Also, preferably, the fluid is blown out of the opening at an angle substantially tangential to the hull surface at the location of the opening and substantially in the direction of the current.

Abstract: In a system for mooring offshore drilling units, a first mooring assembly is installed at a first drilling venue, after which the mobile offshore drilling unit is moored by connection to the mooring lines. A second mooring assembly is installed at a second drilling venue while drilling operations are carried out at the first drilling venue. In this manner the mobile offshore drilling unit can be relocated between successive drilling venues with minimum down time. Less than complete mooring assemblies can be used to temporarily secure the mobile offshore drilling unit.

Abstract: An off-shore oil production platform of the present invention includes an upper barge (1) stretching above the level of the sea. The barge (1) is connected to a completely submerged hollow lower base (3) by partially submerged connecting legs (2) forming a buoyance tank and stretching substantially vertical. The legs (2) along their submerged height includes at least two successive portions (10, 14). A first portion (10) with solid walls delimits a closed space and forms a buoyancy tank. A second portion (14) with openwork sidewall has an interior space open to a surrounding marine environment.

Abstract: Buoyancy unit comprising a body (14) in which there are formed a buoyancy chamber (20) and a chamber (22) which is intended to become filled with water. According to the invention, the wall of the chamber (22) has at least two openings (24, 28), at least one opening of which comprises a nozzle (24, 28) allowing the passage of water between the chamber (22) and the outside, the nozzle being dimensioned in such a way as to appreciably slow the flow of water. The unit may form a buoyancy column intended to hold the deck of a floating rig up out of the water.

Abstract: A submergible vessel for use in shallow-water oil drilling includes a pair of spaced pontoons selectively submergible and raisable in water by the admission and expulsion of water, a main deck, a frame supporting the main deck over the pontoons, and a jacking system for horizontally and vertically translating a packaged drilling rig positioned thereon. The jacking system includes a pair of parallel cantilever beams positioned on the main deck adjacent the stern, vertical jacks for selectively translating the cantilever beams in a vertical direction above the main deck, and horizontal jacks for selectively translating the cantilever beams in a horizontal direction along their longitudinal axes. The deck has an inwardly extending slot formed therein at the stem, and the cantilever beams are positioned on either side of the slot, with their longitudinal axes parallel to the longitudinal axis of the deck.

Abstract: An elevating unit for a jack-up rig provides a pinion gear that rotates upon a support frame for engaging a toothed rack of each leg of the jack-up rig. Each pinion gear is mounted on a gear shaft that extends in opposite directions from a plane of rotation of the gear. First and second roller bearings are mounted upon the frame for supporting the pinion gear at first and second pinion gear shaft end portions. On one shaft end portion, a planetary gear box engages the shaft, the gear box being motor driven. On the opposite side of the shaft end portion a brake hub is attached to the pinion gear shaft and carries a brake drum. A brake band extends about the drum, the band being operable to frictionally engage the brake drum to retard movement of the drum, hub and pinion gear shaft relative to the frame.

Abstract: In a tension-leg mooring system a production platform supporting one or more decks above the water surface for accommodating equipment to process oil, gas, and water recovered from a subsea hydrocarbon formation is mounted on a single water surface piercing column formed by one or more buoyancy tanks located below the water surface. The surface piercing column includes a base structure comprising three or more pontoons extending radially outwardly from the bottom of the surface piercing column. The production platform is secured to the seabed by one or more tendons per pontoon which are secured to the pontoons at one end and anchored to foundation piles embedded in the seabed at the other end.

Abstract: An upper body, forming a large deck which is always above water, and a submerged body, which is always submerged in the water, are disposed in the up-and-down direction with a certain distance therebetween. The upper body and submerged body are connected by a plurality of connecting legs. An outer peripheral portion of the upper body is formed to have a stream-lined configuration symmetric in the up-and-down direction. A middle portion of the upper body is formed to have upper and lower surfaces parallel with one another, except for the outer peripheral portion thereof. The connecting leg may include either a single hollow body or a double hollow body. The submerged body is formed to be approximately a T-shaped in vertical cross-section and has a permanent ballast fixed at bottom and side surfaces of the inside portion thereof. A permanent ballast may also be filled in a lateral connecting body which connects adjacent submerged bodies.