Abstract: A remotely operated vehicle-mounted pump is used to pump water from a suction pile, causing the suction pile to sink into the seabed of the ocean. The remotely operated vehicle exhibits a first mating member, and the pile exhibits a second mating member. The mating members define a channeled interface, channeling the first and second mating members to a common axis.

Abstract: An apparatus for manipulating an object located proximate an underwater floor is disclosed, in a preferred embodiment comprising a foundation implantable in the underwater floor; a lifting frame extending between the foundation; and a multiplicity of slings mounted adjacent to each other and attached to the lifting frame such that each of the slings is suspended in a cradle-like configuration from the lifting frame. Each of the slings further comprises a top surface facing away from the underwater floor and a padding material mounted proximate the top surface of each sling. The foundation may further comprise suction piles. A monitoring system comprising instrumentation may also be used to aid in guiding the load transfer of the object from the floor to the lifting frame.

Abstract: A floating offshore structure has a buoyant hull with sufficient fixed ballast to place the center of gravity of the floating structure below the center of buoyancy of the hull. A support structure coupled to an upper end of the hull supports and elevates a superstructure above the water surface. A soft tendon is attached between the hull and the seafloor. A vertical stiffness of the soft tendon results in the floating structure having a heave natural period of at least twenty seconds.

Abstract: An installation for producing oil from an off-shore deposit has a semi-submersible platform, at least one riser connecting the platform to the sea bed, and devices for tensioning the riser. The tensioning devices include, for each riser, at least one submerged float connected to a point on the main run of the riser for hauling it towards the surface, and a mechanism for hauling the riser. The mechanism is installed on the platform and applied to the top end of the riser.

Abstract: A floating construction (11) such as for instance a SPAR buoy, which is connected to the seabed (32) by tethers and/or risers (15, 16). At the top part the floating construction (11) comprises a displacement member (17′) mounted on a mounting frame (17). Two risers (15, 16) and/or tethers that are placed on respective sides of a vertical center line (22) of the mounting frame (17) are connected to the displacement members for causing oppositely directed and substantially equal displacements thereof upon tilting and/or the sideways excursion of the floating body (11). Hereby a substantially similar tension in the connecting elements (15, 16) is maintained. In one embodiment displacement member comprises a pivotable arm (5) or pivotable deck structure connected near the upper end of the floating body to provide a dry tree. Alternatively the displacement member may comprise pressure fluid cylinders (39) or a cable construction (51, 52).

Abstract: An installation for producing oil from an off-shore deposit has a semi-submersible platform, at least one riser connecting the platform to the sea bed, and devices for tensioning the riser. The tensioning devices include, for each riser, at least one submerged float connected to a point on the main run of the riser for hauling it towards the surface, and a mechanism for hauling the riser. The mechanism is installed on the platform and applied to the top end of the riser.

Abstract: An uplift spring assembly to compensate for hull deflection at a main bearing of a mooring turret is disclosed. Elastomeric pads are used to react turret uplift because of their properties of large deflections and resistance to cold weather. Tie rods are provided to transmit the uplift loads into the elastomeric pads. The elastomeric pads react the uplift loads in compression. The assembly arrangement prevents the elastomeric pads from reacting tension loads.

Abstract: A support structure is disclosed for use in drilling and production operations having one end positioned above a body of water and another end below the body of water on a bed. The support structure includes a base and a jacket structure having at least three jacket legs and support members for supporting a structure, such as a deck. The base has at least four cylindrical base legs engageably positioned in a generally rectangular pattern on the bed and a base frame connected to the cylindrical base legs. The cylindrical base legs start and terminate below the body of water. The jacket has a first jacket leg, a second jacket leg, a third jacket leg. The first, second, and third jacket legs start below the body of water and terminate above the body of water and are positioned with the support members for supporting a structure above the body of water. The first jacket leg is attached to one of the cylindrical base legs and the second jacket leg is attached to another of the cylindrical base legs.

Abstract: An anchoring system for the production of hydrocarbons at sea by employing a moored production vessel or ship in which the ship is equipped with a mooring apparatus, preferably at the bow portion, and with at least one connection unit for a production riser from the seabed. Included is an anchor located at the seabed, as well as at least one anchor line adapted to connect the anchor to the mooring apparatus on the ship. There being provided a permanent anchor, preferably in the form of a suction anchor, gravitation anchor, or pile anchor. The anchor being provided with a swivel mechanism for the anchoring line, preferably with a buoyant body attached at a middle portion of the anchoring line, and whereby the riser is in the form of at least one flexible hose, the lower end of which is connected to said swivel mechanism. The flexible hose contains at least two passages for hydrocarbons and possibly other fluids.

Abstract: A method for transporting petroleum products in deep water from the seabed up to a floating or semi-submersible surface structure wherein at least one rigid and straight hybrid riser extends vertically. The hybrid riser has a rigid central hollow tubular structure surrounded by a cylindrical block of syntactic material which provides buoyancy and thermal insulation for the riser. A plurality of rigid pipelines are embedded in the syntactic material and surround the central tubular structure for receiving petroleum products from wells on the sea bed. The bottom of the riser is connected to a suction or gravity anchor at the sea bed. A submerged float is attached to the top of the riser and exerts an upward vertical force thereon. Flexible pipelines connect the rigid pipelines in the riser to the floating or semi-submersible structure.

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 the pile (8), said piles (8) being positioned for driving purpose by means of a pile-driving template (10) which is employed as a spacing device is described. 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 method of installing a foundation for a tension leg platform is described that eliminates the foundation template as a permanent, load bearing part of the foundation. As an embodiment of the invention, piles are installed by, for example, being driven into the ocean floor so that each pile is secured to the ocean floor, but is unsecured to any other structure that is on the ocean floor. A tension leg platform is coupled via tendon structures to the piles so that anchoring load paths are defined from the tension leg platform to the ocean floor in a plurality of generally vertical paths extending in axial alignment through the tendon structures to the pile and the ocean floor. Each of the tendon structure to pile anchoring systems is substantially independent of one another.

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 spar platform is disclosed having a deck supported by a buoyant tank assembly having a first buoyant section connected to the deck and defining a central moonpool and a second buoyant section disposed beneath and axially vertically aligned with the first buoyant section. A buoyant section spacing structure connects the first and second buoyant sections in a manner providing a horizontally extending vertical gap therebetween and a counterweight spacing structure connects the counterweight to the buoyant tank assembly. A flexjoint receptacle connected to the exterior base of the second buoyant section receives a receptacle connection on the exterior of the riser to support a catenary section of the riser between the receptacle connection and the seafloor. An exterior section of the riser mounts to the exterior of the second buoyant section and an ingress section passes through the horizontally extending vertical gap to the moonpool.

Abstract: An earthquake-compliant offshore platform for use in regions of strong earthquakes is disclosed in which the natural vibrational period of the jacket structure is preferably in the range of about 4 seconds to about 8 seconds, which is between the primary excitation period of earthquake energy and the primary storm wave period. The earthquake-compliant jacket structure is lighter than a conventional steel battered jacket for the same location and conditions and has a constant cross-section. The vibrational period of the earthquake compliant platform can be tuned by altering structural stiffness or mass.

Abstract: A compliant offshore platform wherein the sole foundation support for platform loads not provided by seawater buoyancy is provided by traditional skirt piles rigidly attached to the platform base near the ocean floor. Lateral flexibility of the platform is enhanced by the introduction of unbraced portal frames located throughout the platform framing in such a way as to facilitate lateral shearing displacements within the platform framing to the extent that the required compliant characteristics are obtained for the sway mode (first structural mode) of vibration while at the same time allowing the overturning moments generated by wind, wave, and current loads to be resisted by the vertical forces within the platform legs and platform foundation. The addition of these portal framed sections at selected locations into an otherwise traditional jacket provides a framing system with improved fundamental modes of vibration as are required for compliant structural behavior.

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: A mudmat assembly for supporting a portion of a subsea offshore platform on a soft, unconsolidated underwater surface is described. The mudmat assembly includes at least one fiberglass plank, a mudline framing plane that is attached to and provides support for the fiberglass plank, and integral framing beams attached to and providing support for the fiberglass plank. The fiberglass mudmat assembly of the present invention requires minimal cathodic protection, has a high flexural strength, and is lighter than conventional mudmats.

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 buoyancy assembly suitable for supporting, either alone or in combination, a load deck or other marine body, said assembly comprising: i) a first portion adapted to be connected to or form an integral part of the marine body, said portion incorporating a piston; ii) a second portion adapted to envelope the piston and thus create a variable volume chamber, the first and second portions being moveable with respect to each other; iii) sealing means adapted to form a fluid tight seal between the piston and the second portion; iv) a constant pressure source adapted to maintain a constant pressure within the variable volume chamber; v) tether means adapted to tether the second portion to the sea bed; wherein the buoyance assembly is adapted such that displacement of the marine body from its hydrostatic equilibrium position results in the generation of a restoring force, upwards or downwards, tending to restore equilibrium.

Abstract: A floating offshore drilling/producing structure. The structure is formed from a plurality of closely spaced vertically oriented buoyant columns on which one or more modules or decks may be placed to support process equipment, a drilling rig, utilities, and accommodations for personnel. The columns are held in the spaced relationship by a plurality of horizontal plates spaced along the length of the columns and vertical plates located near the bottom of the columns and near the top of the columns. Drilling and/or producing is accomplished through risers located approximately in the center of the structure. The structure includes fixed ballast, an oil storage area, and voids and variable ballast for offsetting the lighter weight of the stored oil. The columns have a smaller water plane area than the horizontal plates.

Abstract: A bottom-founded offshore structure in relatively shallow waters is protected against sliding. It uses at least one pile and a suction pump inside the pile. The pile has a length-to-diameter ratio such as to achieve sufficient pile imbedment with the selected suction pump. A dedicated pile lowering and lifting device lowers and lifts the pile as needed. Guides allow the pile's vertical motion and limit its rotational motion during imbedment and extraction. A stop device limits the vertical motion of the pile's top rim during pile extraction. The pile is reusable, light weight, easy to install and to extract, self-contained, and economical in relationship to its high holding power when imbedded.

Abstract: An improved spar for offshore hydrocarbon recovery operations is disclosed having a vertically oriented elongated floating hull with a buoyant upper section and a ballasted lower section and an anchoring system connecting the hull to the ocean floor. The hull of the spar is provided with a vertically oriented, rotatable fairing whereby low drag VIV suppression protects the spar.

Abstract: A deepwater riser assembly is disclosed for a riser connecting subsea equipment to a surface wellhead. A buoyancy can assembly provides an open ended buoyancy can tube which surrounds the upper end of the riser and an upper seal which effectively closes the annulus between the riser and the buoyancy can tube. A load transfer connection in the buoyancy can assembly then connects the riser to buoyancy can tube. A pressure charging system communicates with the annulus between the riser and the buoyancy can tube below the upper seal. Injecting gas into this annulus then provides support to the riser.

Abstract: A dual phase riser flotation system contains a number of passive phase buoyancy modules of syntactic foam contained within an outer skin, and a number of active phase buoyancy modules which are similar to air canisters in that they may be inflated or deflated as required to provide levels of buoyancy. The passive phase buoyancy modules may contain tubes filled with air, a compressed gas such as nitrogen, or evacuated to provide additional buoyancy. Charge and discharge valves connect gas flow lines to a manifold system serving the active phase buoyancy modules.

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 the pile (8), said piles (8) being positioned for driving purpose by means of a pile-driving template (10) which is employed as a spacing device is described. 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: The platform comprises a buoyant sub-structure comprising a base and a plurality of columns upstanding from said base, a buoyant deck-hull mounted on the columns and means for ballasting and deballasting at least the base of said sub-structure. It further comprises means for tangentially guiding said deck-hull on said columns during deployment of the platform into a predetermined configuration by ballasting of the sub-structure while the deck-hull is floating and means for locking said deck-hull to the columns in said predetermined configuration.

Abstract: A passive anchor latching mechanism which allows its user to attach a moog line to an anchor without using a secondary mechanism such as a remotely operated vehicle to attach the cable or anchor wire to the anchor. The passive anchor latching mechanism comprises three elements: (1) a latch ring which may have a tether line removably coupled thereto; (2) an anchor post extending vertically upward from the top of the anchor; and (3) a crown line attached to the anchor and buoyed at the water's surface. The latch ring consist of a tail which attaches to the mooring line and a ring which slides downward along the crown line. The anchor post has an anchor collar coupled thereto which forms an annulus groove with the anchor post. The annulus grove latches the ring of the latch ring to the anchor post while the tail of the latch ring prevents the ring from detaching from the anchor post and riding backward up the anchor post once the latch ring is latched.

Abstract: A pumpskid comprises a frame adapted for connection to a remotely operated vehicle for positioning thereby. A male connector mounted on the frame is adapted for engagement with the suction port on a suction anchor. Clamping apparatus is provided for securing the male connector in engagement with the suction port of the suction anchor and thereby clamping the pumpskid in engagement with the suction anchor. A pump mounted on the frame is connected in fluid communication with the male connector by piping sections which include a port open to the surrounding sea. Valves and valve actuators are provided for causing the pump to cause water flow out of or into the suction anchor, as required.

Abstract: In a method of and apparatus for anchor installation, a plate anchor is mounted at the bottom of a suction follower comprising a hollow cylinder having an open lower insertion end and a closable upper suspension end. The suction follower and the anchor secured thereto are engaged with the sea floor, whereupon water is pumped out of the suction follower causing the suction follower and the anchor to penetrate into the sea floor to a predetermined depth. The anchor is then disengaged from the suction follower, whereupon water is pumped into the suction follower to disengage the suction follower from the sea floor for recovery to the surface, leaving the anchor embedded in the sea floor. The plate anchor may comprise first and second plate members, the second plate member pivoting relative to the first plate member to prevent upward movement of the anchor.

Abstract: A quick connect/disconnect system for an offshore oil/gas production platform is facilitated by a submerged connection header for the platform. The platform comprises a vessel with a connection bay on vessel bottom. The vessel has the ability to be ballasted to position the connection bay either for connection or for transport toward and away from the connection header. The connection header houses the production lines and control lines and is positively buoyed and held in place by tension cables extending from the header bottom to the ocean floor. The quick connect/disconnect system comprises couplers for the production lines and control lines and devices for releasably linking the header to the vessel bay whereby the vessel may be held in a state of positive buoyancy by appropriately deballasting the vessel.

Abstract: The present invention relates to an apparatus and methods for coupling objects that are displaced from one another. In particular, the present invention relates to an apparatus and methods for providing a connection member, for coupling objects that are displaced from one another, that is able to adapt to changing operating conditions. The connection member is a composite tubular that responds to pressure changes such that when the internal pressure of the composite tubular is changed, the length of the tubular proportionally changes, thereby enabling the composite tubular to do useful work.

Abstract: A process comprising: fixing a first end of a tendon to an anchor; lowering the anchor to the sea floor; securing the anchor to the sea floor; fixing a second end of the tendon to the platform. A tendon comprising: a flexible line that extends from the TLP to the anchor, wherein the flexible line comprises a top end and a bottom end; an attacher of the top end of the flexible line to the TLP; and an attacher of the bottom end of the flexible line to the anchor. A platform comprising: a platform for floating on the surface of the sea; an anchor for attachment to the sea floor; and a flexible tendon for securing the platform to the anchor.

Abstract: A pile for anchoring a floating structure in deep water includes an elongated body provided with a tapered pointed tip at the lower end thereof and a closure disc at the upper end thereof. A plurality of radially and axially extending fins are secured to the pile adjacent the upper end thereof. The elongated body of the pile is filled with material having a high specific gravity distributed in such a manner that the center of gravity of the pile is located well below its center of buoyancy. The process for installing the pile uses the potential energy generated by the free fall of the pile from a vessel in order to ensure that the pile penetrates the ocean floor.

Abstract: A dampening device for dampening the vertical wave-induced motion component of a floating structure. The dampener projects in the form of a skirt down below the bottom of the floating structure (11) and consists of a plurality of channels (47) which extend substantially horizontally and converge from an inlet opening (27, 28, 36, 37, 38) to an outlet opening (16, 46) leading away from the floating structure (11). When the structure (11) moves downwards water is forced from the underside through the channels (47) and creates a jet effect which acts with dampening effect on the vertical motion of the structure.

Abstract: A maritime dock structure including a plurality of hollow modules each having a buoyancy force associated therewith. A plurality of anchors are coupled to the modules and embedded in an underwater bed. Each anchor opposes the buoyancy force of its associated module as well as lateral forces and load forces directed into the underwater bed.

Abstract: A riser arrangement increases the stability and/or decreases sensitivity to vortex induced vibration of risers of a riser system including steel tubular lines, SCRIBS and flexible hose risers leading to a floating storage/production vessel. A cross-link is placed between two or more steel tubular lines in order to enhance the stability of the riser system. Devices are coupled to the steel tubular lines for increasing their tension in order to increase the natural frequency of vibration in order to reduce sensitivity to vortex induced vibration.

Abstract: A subsea production system that facilitates the cost effective development of offshore hydrocarbon reserves. The system includes a template base, a wellhead assembly, a saddle manifold, flowlines, a subsea tree assembly, and a control center. The system facilitates phased development by allowing control over timing for the installation of system components and by providing extendibility to additional wells developed after installation of the system.

Abstract: A connector unit is disclosed which comprises a shaft, a plurality of collet fingers, and a sleeve. The plurality of collet fingers are peripherally positioned against the generally cylindrical outside surface of the shaft adjacent the lower end of the shaft. The sleeve has an upper end, a lower end, and a generally cylindrical inside surface positioned peripherally around the shaft. The sleeve is provided with a radially inwardly extending annular flange extending from its inside surface between its upper end and its lower end which forms a seal with the generally cylindrical outside surface of the shaft. An upper annular chamber is formed between the generally cylindrical outside surface of the shaft and the generally cylindrical inside surface of the sleeve above the radially inwardly extending flange and a lower annular chamber is formed between the generally cylindrical outside surface of the shaft and the generally cylindrical inside surface of the sleeve below the radially inwardly extending flange.

Abstract: An offshore oil or gas well riser system which forms a connection between the well head and a surface vessel. The system has a first riser section which extends vertically and is essentially rigid and a second riser section which is made of a flexible material to accommodate movements of the surface vessel. The first riser section has buoyancy means attached to its upper end to support at least partly the weight of the first riser section, and the first and second riser sections have corresponding first and second bores which provide a continuous path between the surface vessel and the well head. The profile of the flexible second riser section is variable to provide a smooth continuous path through its corresponding second bore and such that the path does not extend below the upper end of the first riser section.

Abstract: A method for assembling a cluster platform in a body of water, by embedding a plurality of conductors in soil underlying the body of water; wet welding in the body of water at least one bracing element between the plurality of conductors, wherein the bracing element is wet welded to at least a first conductor of the plurality of conductors at a first elevation and wet welded to at least a second conductor of the plurality of conductors at a second elevation different from the first elevation; securing a deck atop the plurality of conductors.

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 the pile (8), said piles (8) being positioned for driving purpose by means of a pile-driving template (10) which is employed as a spacing device is described. 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: An offshore system is provided of the type that includes riser pipes (30) extending up from the seafloor (44) to a tall and narrow caisson (12) at the sea surface, with the caisson moored by mooring lines (34) extending to the seafloor and anchored thereat, which minimizes bending of the upper portion of the riser pipes when the caisson drifts in severe weather. Although the caisson has a Ballasted lower end and buoyant upper end to keep its axis (20) vertical, a device is provided for applying a horizontal force (54) to a location along the caisson that is vertically spaced from the upper ends of the mooring lines, to tilt the caisson so the axis of the caisson is parallel to portions (82) of the riser pipes lying immediately below the caisson. In one arrangement, a second set of mooring lines (60) is provided, that have upper ends coupled to second locations (64) along the caisson that are vertically spaced from the upper ends of the first mooring lines.

Abstract: An undersea telescopic joint for a riser system is connected to a drilling vessel with a plurality of tensioners. The joint has a bearing with inner and outer annular mating members. A cap seals the outer member to the joint. The outer member closely receives and is axially movable relative to the inner member. A flat thrust bearing is located in a chamber between the two members. The members are sealed to one another with upper and lower swivel seals. A passage communicates hydraulic fluid to the chamber. The bearing has a pressure gage which registers with a passage that extends between the swivel seals. The chamber is filled with hydraulic fluid so that the two members are separated and the drilling vessel may rotate easily. The gage is used to detect whether the primary swivel seal is leaking.

Abstract: A deep water platform, suitable for use as a hydrocarbon exploration or production facility in very deep offshore waters, and a method of constructing the same are shown. The platform is positioned on top of a buoyant leg structure. During normal drilling operations the platform is anchored by a gravity base tethered with pre-tensioned cables to the buoyant leg structure. According to the invention, the gravity base is retractable to permit the platform to be moved from site to site within a drilling region. Long distance relocation is also possible by retracting the gravity base, disassembling the platform, transporting the component parts, and reassembling the rig in a new location.

Abstract: A process comprising: attaching a first end of a chain to the tendon; securing a second end of the chain to the platform. A mechanism comprising: a chain which is attached to the tendon; and a stopper for attaching the chain to the platform. A tension-leg platform (TLP) comprising: a platform for production operations which floats on the surface of the sea; an anchor which attaches to the sea floor; a flexible tendon which connects to the anchor on the sea floor; and a mechanism for attaching the flexible tendon to the platform.

Abstract: A variable-buoyancy marine riser and a method for providing and adjusting the buoyancy for such a riser. The riser is comprised of a main riser conduit on which a plurality of cans are affixed. A slurry of buoyant material, e.g. small, hollow spheres, is pumped into the cans to displace the seawater therein and give buoyancy to the riser. When it is desired to reduce the buoyancy of the riser, the spheres are removed by merely opening the cans and allowing the surrounding seawater to displace the spheres from the cans.

Abstract: A mudmat in which the bearing plates of the mudmat are fabricated of a non-corrosive, man-made structural material such as plastic. The plates, formed of such a material, are lightweight, easily fabricated and generally less expensive than the prior art plates and their associated support structure. In one preferred embodiment, the plates are formed of extruded polyvinyl chloride (PVC) or a fiber reinforced composite such as thermoset resin reinforced with glass fibers (GRP). The individual plates are supported by standard frame members. The PVC or GRP plates are of such a size, shape and weight that they can easily be transported to, assembled and attached to the offshore jacket at the jacket fabrication site. Being formed of such materials, the plates are corrosion resistant, eliminating the need for cathodic protection.

Abstract: A process comprising: generating a stabilizing moment, before the platform is secured and tensioned to the sea floor, wherein the generating vertically aligns the central axis of the TLP; and reducing the size of the TLP in the wave zone, after a tendon of the platform is secured to the sea floor. A device comprising: a generator of a stabilizing moment, before the platform is secured and tensioned to the sea floor, wherein the generator vertically aligns the central axis of the TLP; and a reducer of the size of the TLP in the wave zone, after a tendon of the platform is secured to the sea floor.

Abstract: In a method of and apparatus for anchor installation, a plate anchor is mounted at the bottom of a suction follower comprising a hollow cylinder having an open lower insertion end and a closable upper suspension end. The suction follower and the anchor secured thereto are engaged with the sea floor, whereupon water is pumped out of the suction follower causing the suction follower and the anchor to penetrate into the sea floor to a predetermined depth. The anchor is then disengaged from the suction follower, whereupon water is pumped into the suction follower to disengage the suction follower from the sea floor for recovery to the surface, leaving the anchor embedded in the sea floor.