Abstract: A marine structure situated in a seabed having mooring means designed to provide resistance to the environmental forces acting on the structure. Weights are attached to the mooring means at a distance above the seabed so that the weights do not touch the seabed during normal operating conditions. When extreme environmental loads move the structure a certain distance leeward of its original locations, the weights on leeward mooring means contact the seabed, significantly and immediately increasing the restoring force provided by the mooring means.

Abstract: A tether system for a semisubmersible work platform which may be based on deep water, comprising a number of pontoon elements mounted in a frame configuration, upright columns and a work deck for exploitation of oil or gas fields below the sea bottom. The system comprises a sea bed anchor template, which is provided with receptacle means for tendons, running up to connectors at the work platform. The receptacle means in the sea bed anchor template are located along a circular track on which a carrier can move. The carrier has sheave means for one or more handling line for a tendon which is provided with a running collar. The connectors for the upper ends of said tendons are located at the outside of the columns.

Abstract: A lean-to well protector apparatus for use on offshore wells having a generally vertical upstanding conductor pipe extending between the sea bed and the water surface includes a pair of jacket legs defining a plane that is angularly oriented with respect to the conductor pipe forming an acute angle therewith. A first plurality of structural chord members interconnects the jacket legs and can occupy the plane defined by the jacket legs. The first plurality of chord members and the jacket legs form a truss that leans towards the conductor pipe during operation of the offshore well. A first clamp connector is positioned at the middle portion of the conductor pipe and a second clamp connector is positioned at the upper portion of the conductor pipe generally near the water surface area. A second plurality of structural chord members interconnects the conductor pipe with the truss at the clamp connectors.

Abstract: A riser system includes inflatable buoyancy bladders and a near surface disconnect so that a drilling vessel can rapidly disconnect from the riser leaving the riser in a freestanding buoyant position.

Abstract: A Kevlar.RTM. rope termination in which the rope is passed through an opening in a tension leg termination, is divided and laid over a rigid pin, being sealed around the pin with a resin. A flexible bearing member is located between the rope covered pin and a rigid support member contiguous with the inside of the termination, adjacent to the opening so that the rope covered pin can easily rotate within the bearing member without kinking the rope.

Abstract: A motion absorbing docking assembly for use in subsea docking operations. A tubular docking pile receives a pile head assembly in which a retractable pile head is positioned. When the pile head is impacted by a docking guide on a jacket being lowered into place, axially spaced shock cells having a common central support member absorb the relative motion between the pile head and the docking pile. This arrangement provides for absorption of twice the distance that each individual shock cell is capable of absorbing by itself.

Abstract: A tension leg platform top connector will connect a tendon to the platform. The top connector has a housing with a bore containing a conical shoulder. Several segments locate on the conical shoulder and will slide between an upper retracted position to an engaged position. In the engaged position, threads on the interior of the segments will engage threads formed on the exterior of the tendon. A cam plate will slide the segments down when the cam plate is rotated. A guide ring mounts outward of the segments. The guide ring has fingers that engage slots in the backs of each of the segments. The fingers and vertical slots allow the segments to move axially, but prevent them from rotating relative to the guide ring. A clutch ring applies a frictional force to the guide ring to resist rotation until the segments engage the tendon threads.

Abstract: A latching mechanism comprises a cam operated pivoting member within a first cylinder. The member has a lug which can project through an aperture in the cylinder. The cylinder slides into a second cylinder which has a corresponding aperture to receive the projected lug.The pivotting member has no internal axis of pivot. Instead it has a rolling axis depending on the position of the cam and a rocking axis about a shoulder of the member in contact with the interior wall of the first cylinder.This results in a small, light-weight structure.

Abstract: A guide base for a sub-sea well is formed in two parts, an annular portion fixed to a conductor housing and a retrievable portion surrounding and releasably attached to the annular portion. The retrievable portion can be recovered and used elsewhere if a well is suspended or abandoned or changed for another type of guide base after drilling and before completion. A trawler board deflector can also replace the retrievable guide base portion, and a retrievable protective cap may be placed on the well head housing of a suspended well. A hydraulically-operated multi-purpose tool may be used for placing or retrieving any of the retrievable items.

Abstract: A Kelly bar adapter for use with earth anchor driving machinery is disclosed. The adapter allows for pivotal connection of an earth anchor or earth anchor extension rod thereto. Thus, a vertically hanging Kelly rod may be attached to an earth anchor or its associated extension rod while the same is diagonally extending out of the ground. A tool for removing earth anchors having an integral eyelet or an eyelet which is threaded onto an earth anchor is also disclosed.

Abstract: A floating drilling and production unit comprising two independently floating bodies: (1) an outer, larger, substantially cylindrical buoyant caisson with an enlarged skirt around its lower perimeter to dampen sea-induced motions and (2) a wellhead buoy captured within the central well of the outer caisson. The outer caisson supports the weight of the drilling platform, machinery, storage and living quarters and is ballasted and anchored in a manner similar to a conventional semisubmersible vessel. The constant tension buoy supports the wellheads of completed wells and is held in a constant position relative to the ocean floor much like a tension leg platform by the production risers of completed wells, tendons, or a combination of tendons and risers. Production risers are kept taut by the buoyancy of the constant tension buoy. The constant tension buoy has a tapered shape that minimizes contact and interaction between the wellhead buoy and the caisson.

Abstract: An offshore harbor including a first support structure firmly fixed to the sea bed, a first flat slab supported by the first support structure, and a plurality of vertical sidewalls resting on the first slab and being joined together to form a hollow shell which defines an inside portion. The inside portion of the shell houses a portion of the sea, and one of the plurality of vertical sidewalls is provided with an opening so that the inside portion of the hollow shell is in communication with the rest of the sea through the opening. The offshore harbor further includes an assembly of blocks disposed on the first flat slab between an edge thereof and one of the vertical sidewalls. The assembly of blocks includes a plurality of horizontal layers stacked upon each other to form a staircase configuration.

Abstract: A lightweight, high modulus mooring element for a tension leg platform comprises a pretensioned composite member in fixed attachment to and surrounded by a metallic tubular member in compression prestress. The hybrid composite assembly offers significant cost and weight savings over an all steel mooring system for use in deep water tension leg platform mooring.

Abstract: A floating structure to support maritime operations is constituted by a metallic platform, in the shape of an internally open square (10) floating in the ocean being moored to the bottom of the ocean by a cable system (C.sub.1, C.sub.2, C.sub.3 . . . C.sub.n) tied to a pile system (E.sub.1, E.sub.2, E.sub.3 . . . E.sub.n). It retains in its interior a portion of the sea which is communicated to the outside ocean through an opening (11) in the walls of the said metallic platform (10) in such a way that, in that confined part of the ocean, the support boats to the sea work, may be moored due to the fact the interior of the open square is calm in respect to the rough sea outside the structure (10).

Abstract: A method and apparatus for offshore support structures utilizes a hollow pile disposed within one leg of a three-legged structure to support an offshore platform, wherein the hollow pile is fixedly secured to the tubular leg within which it is disposed.

Abstract: The semi-submersible platform comprises a submersible lower hull including a plurality of spaced-apart hull segments. A wave-transparent stabilizing superstructure extends from the lower hull. An upper hull is supported by the superstructure. A wellhead system is suspended from the platform. A catenary mooring system moors the platform to the seabed, and plurality of risers connect the individual wellheads on the platform to the wellbores in the seabed.

Abstract: A marine platform comprising a deck supported by a tower composed of a rigid fixed structure of the jacket type anchored to the sea floor, an oscillating structure supported by and connected to the fixed structure by flexible piles anchored in the lower part of the fixed structure and arranged on the periphery of the oscillating structure, and by a shear device, the oscillating structure being equipped with a floater. In one embodiment the connection between the fixed and oscillating structures is located in a zone between 30 and 60% of the water depth from the water level. The shear device consisting of at least one set of pairs of structural elements placed obliquely or perpendicularly with respect to the axis of the tower between a lower part of the upper structure and an upper part of the lower structure or of the base and allowing transmission of shear forces and torsional moments between the two parts.

Abstract: A new and improved shock absorber mechanism and method for use on the leg structure of a jack-up offshore drilling rig is disclosed. The shock absorbing mechanism is designed to be mounted on the bottom of each existing leg of a drilling rig and comprises a pointed piston member which is positioned on the bottom of the leg structure, wherein the piston member projects downward through the can/footing of the rig leg and is held in place by a resilient tension member which is designed to absorb shock forces during vertical/axial impact of the leg structure when contact is made with the ocean floor.

Abstract: In an anchoring arrangement for releasable anchoring of the legs of a marine tension leg platform in a foundation on the sea floor, the lower ends of the tension legs with an end head (1) are lowered into a cylindrical anchoring casing (4). For anchoring the leg in the foundation, locking elements (7) are provided at the tension leg insertion end of casing (4), on the inside of the cylindrical casing wall, for cooperation with bosses (2) on tension leg head (1). Anchoring casing (4) is, furthermore, on the outside of its cylindrical wall, at the insertion end, provided with further bosses/grooves (10). The latter are intended for cooperation with bosses (14,15) and grooves which are provided on the inside of a cylindrical steel ring (13), which is intended to be integrallly moulded into the foundation on the sea floor. Over the end edges of casing (4) and the cylindrical integral ring (13) a locking ring (16) is provided on a contact face to provide additional fixation of the anchoring.

Abstract: A floating drilling and production unit comprising two independently floating bodies: (1) an outer, larger, substantially cylindrical buoyant caisson with an enlarged skirt wellhead buoy captured within the central well of the outer caisson. The outer caison supports the weight of the drilling platform, machinery, storage and living quarters and is ballasted and anchored in a manner similar to a conventional semisubmersible vessel. The constant tension buoy supports the wellheads of completed wells and is held in a constant position relative to the ocean floor much like a tension leg platform by the production risers of completed wells, tendons, or a combination of tendons and risers. Production risers are kept taut by the buoyancy of the constant tension buoy. The constant tension buoy has a tapered shape that minimizes contact and interaction between the wellhead buoy and the caisson. Thus, the wellhead buoy is substantially unaffected by sea-induced motions of the bouyant caisson.

Abstract: A method of measuring the shear modulus profile of a seabed floor using one or more bottom shear modulus profilers, each having a seisometer package to measure the seabed motion in three dimensions and a sensor for measuring the pressure at the seabed floor, placed on or below the seabed floor, and a means for converting the measurements derived therefrom into a shear modulus profile.

Abstract: A rotating lug anchor connector (10) is disclosed for anchoring the tether (12) of tension leg platform (14) to the sea floor. The connector includes an anchor latch assembly (18) which is mounted on the lower end of the tether. The assembly includes a ring (50) from which three lugs (58) extend. The ring is secured to the tether through an elastomeric assembly (36) which permits the tether to pivot about a pivot point (28) relative to the ring. Guide surfaces on members (74, 76, 78) of the receptacle assembly (20) guide the lugs downward along vertical slots (104) and beneath notches (92) in the members. Upward movement of the tether engages the lugs and notches to secure the tether to the sea floor. For release the tether is lowered to move the lugs in an alignment with the vertical slots for removal.

Abstract: An anchorage line comprising a large number of successive elements interconnected in an articulated way and each including a closed watertight tube delimitating an interior volume full of air. The anchorage line comprises a shallow depth extremity providing the link with a floating vehicle and a very deep anchorage extremity providing anchorage on an ocean bottom. The floatability of the anchorage line varies according to its length. The tubular essential parts of the anchorage line have a wall thickness related to their diameter and which is thicker the nearer these parts are to the anchorage extremity of the line. The anchorage line may be assembled on site and put in place by a suitable device.

Abstract: In a flexible tension leg member an adjustable spacer is provided between the coaxial tension leg members joined in the member.

Abstract: A tension leg platform has a flexible tension leg member comprising upper and lower tension leg elements and a casing within which the upper and lower tension leg elements are flexibly joined. The platform has a vertical shaft wall in which the casing is supported and a first packing which seals between the casing and the shaft wall. Swingable claws releasably interconnect the upper tension leg element to the casing, and a second packing surrounds the upper tension leg element and releasably seals between the upper tension leg element and the shaft wall. The second packing comprises a hollow cylinder with a coupling flange on the lower end thereof, and a coupling flange on the casing. The claws releasably secure together the flanges and are operated by vertical movement of the cylinder.

Abstract: A tension leg platform for drilling and/or production, processing and transporting hydrycarbons from sub sea wells or installations, and methods for installation of such platform. The platform comprises in operational position the following: a working platform which has position above the sea level, a buoyant body (1) which is connected with the underside of the platform and has substantially position below the surface, and a number of tension legs (13) which connect the buoyant body (1) with a fundament anchored to the sea bed. The invention is characterized in that the lower parts of the tension legs (13) in per se known fashion are anchored to the fundament (14) and at their upper ends are controlled in guides (20, 21) on the outside of the buoyant body and are attached to the buoyant body (1) above or just below the water line.

Abstract: Method and apparatus to stabilize a columnar platform for deepwater offshore applications. An added mass stabilizer system is utilized to control first order heave, pitch, roll, surge and sway motions of the floating platform. The stabilizer is suspended beneath the platform by a set of tendons a sufficient distance to (1) enter a quiescent zone beneath the action of waves and currents, (2) provide a sufficiently long movement arm to resist pitch and roll torquing, and (3) incorporate sufficient flexibility into the suspension system to avoid shock loads. The stabilizer is sized to (a) provide sufficient submerged weight to maintain the tendons in constant tension and, (b) create adequate added mass (actual stabilizer weight plus mass of water moved by the stabilizer) to provide the desired control of first order motions. A secondary mooring system such as a spring-buoy mooring or dynamic positioning system can be provided to control drift produced by higher order motions and first order yaw.

Abstract: The floating structure comprises one or more catenary mooring cables for anchoring the structure to the seabed. An extensible dynamic tensioner system is provided for maintaining a predetermined dynamic tension in each mooring cable, as the structure responds to cyclic wave forces, and for increasing the natural periods of oscillation of the pitch, roll, heave, surge, sway, and yaw motions of the moored floating structure by reducing the spring stiffness of the mooring system. A motion damping system is coupled between the dynamic tensioner system and the structure for damping the linear and angular displacements of the structure relative to the tensioned cables. The damping system selectively applies frictional forces against a movable member in the tensioner system. The movable member does not move relative to the cables.

Abstract: An offshore subsea well includes a wellhead to which is connected an elongated somewhat flexible riser extending to the sea surface. The riser pipe is unstayed and is buoyed at least partially by a buoyancy member connected to the riser between the sea surface and the wellhead. Flow control valves and well access components are disposed at the upper end of the riser pipe and extend only a few feet above the sea surface during a normal or calm sea condition. A production fluid flowline returns to the sea floor alongisde the riser for extension to a central platform for the reservoir. The well support system provides for a low cost surface disposed Christmas tree arrangement which does not require a fixed support platform. The buoyancy member is preferably an annular can which is connected to an upper end of an elastically bendable section of the riser and which supports a tower for a work platform and hazards to navigation aids.

Abstract: The invention relates to an arrangement in an offshore platform (1a), comprising a deck structure (1) which is supported above the water surface (5) by means of a column structure (14, 2) which in turn rests on and is connected to a foundation (3) on the sea bottom (4). In order to provide a compliant platform structure which is not dependent upon guylines preventing free traffic around and at the platform (1a), the column structure (14, 2) comprises at least one hollow column (2), in the cavity (2a) of which there is provided at least one tension means (7) which at its first end is connected to the foundation (3), and which at the second end is connected to the column (2). The foundation (3) can be preinstalled at the sea bottom (4), or might constitute a part of the offshore platform (1a) such that the latter mounted on the sea bed (4) as a gathered unit.

Abstract: The floating structure has limited heave oscillations. A long member has a lower end coupled to the seabed. An extensible tensioner is coupled between a platform deck and the upper end of the long member. The tensioner suspends the upper end of said long member and applies a predetermined tension thereto. The tensioner includes anti-heave force-exerting means for exerting downward-acting forces on the floating structure.

Abstract: According to the invention a steel tube is prestressed longitudinally. This prestress is advantageously exerted by cables (20) extending along the tube (10) either inside the tube or outside the tube, and prevented from moving transversely relative to the tube, said cables being constituted by fibers (of glass, of carbon, or of other inorganic materials), having a breaking strength which is greater than that of steel. Such a structure is particularly applicable to anchoring a taut line type oil production platform (200) at sea. In this case, the advantages of inorganic fibers and of steel are combined, thereby taking advantage of the very high breaking strength in traction of the fibers in order to prestress the steel which can then be subjected to much lower stress than the fibers, thus considerably reducing the elongation of the anchor lines.

Abstract: A method and apparatus for offshore support structures utilize a central support having three legs interconnected with an outrigger support structure comprised of at least two legs and at least one hollow pile is disposed within at least one leg of the central support, the hollow pile being fixedly secured to the tubular leg within which it is disposed.

Abstract: A mobile marine drilling assembly has a horizontally disposed pontoon which floats on or is submerged below the surface of a marine environment. A first vertically disposed column is secured to the pontoon and extends upwardly therefrom. A work platform has an opening through which the column extends, and the platform overlies the pontoon and is vertically movable relative thereto along the column. A jack system is operably connected with the work platform and with the column for jacking the work platform along the column between a first position wherein the pontoon floats on the surface of the marine environment and a second position wherein the pontoon is disposed a substantial distance below the surface of the marine environment. An anchor is secured to the floor of the marine environment.

Abstract: The floating structure has a structural frame and a long member which has a lower end anchored to the seabed. The structural frame has limited heave motion relative to the long member. An extensible tensioner is between the frame and the long member. Mechanical brakes apply braking forces against the long member only when the floating structure heaves up. The brakes are inactive when the floating structure heaves down.

Abstract: A releasable latch-type connector for a tension leg platform tether. A tether portion of the latch is provided with an annularly arranged set of shear lugs. The tether portion of the latch is adapted to be received within a generally cylindrical second portion of the latch. The second portion of the latch is also provided with an annularly arranged set of shear lugs. The two sets of shear lugs are arranged so that the tether portion of the latch may be inserted into the second portion of the latch and then rotated and lifted to cause the two sets of shear lugs to come into abutment, preventing further withdrawal of the tether portion of the latch. This connector is particularly well suited for securing the lower end of a tension leg platform tether to a foundation on the ocean bottom.

Abstract: An offshore well test platform system is positionable above one or more underwater wells and comprises a submerged buoy restrained below the surface of the water by a plurality of laterally extending, tensioned cables, a platform structure removably connected to a submerged buoy with an upper portion that extends above the surface of the water, and a flexible riser that connects the well to a well test platform deck above the surface of the water.

Abstract: A platform consisting of a rigid structure supporting the deck, floats fixed to the lower part of the rigid structure, and flexible structure formed of piles fixed by their upper ends to the rigid structure and to the floats and by their lower ends to a base provided on the seabed, the piles being held under tension.

Abstract: A resilient unit able to accomodate a large movement comprises a stack of elastomeric bearing units arranged to be loaded in series and to deform primarily in shear. Preferably a plurality of the stacks are provided in a nested configuration and interconnected in series to enable even greater movements to be accommodated.The resilient unit is particularly suitable for use on an offshore platform to accommodate movement between the platform and a riser pipe while also maintaining a tension loading in the riser pipe.

Abstract: A man portable (80 lbs) surface piercing structure which can be installed shallow water (nominally 10 ft) from a small boat without divers assistance. The structure is comprised of two separate assemblies, a mast and a foundation. The mast is joined to its foundation by a mechanical latch and release mechanism which is internal to the mast.

Abstract: An improved platform comprising several columns at least partially submerged in service, wherein, over at least a submerged portion of at least one column, the section defined by the intersection of this portion with a horizontal plane decreases when the depth increases.

Abstract: A subsea landing base including a plurality of guide posts interconnected to a housing support structure including an upper annular plate, a lower annular plate, an annular control plate supported on the upper annular plate and rotatable thereon, a connection between the control plate to a landing ring to actuate the landing ring between housing supporting position and expanded position, rotation of the control plate to one of its positions of running, released and landed and locked, and a tool for rotation of the control plate and for retrieval of the landing base.

Abstract: Described herein are a system for securing and tensioning the tethers 12 of a tension leg platform 10 and a TLP installation method incorporating such a system. The tethers 12 preferably extend upward from the ocean bottom 16 to a position slightly below the bottom of the unballasted TLP hull 20. At least one tether tensioning tool 26 is situated within the hull 20 for lowering a tether extender 22 to each tether 12 and then biasing each tether-tether extender unit upward to tension the tether 12. The use of a removeable tensioning tool 26 avoids the need for a dedicated tensioning system for each tether 12. The tensioning system 28 of the present invention permits use of a simplified method for installing a TLP 10. Because the tethers 12 extend to an elevation which, at least initially, is below the draft of the TLP hull 20, the tethers 12 may be installed offshore prior to hull installation.

Abstract: A node intersection between circular columns and pontoon members at a tendon-moored semisubmersible offshore platform. The pontoon members have a box shape, defined by vertical side walls, a horizontal deck and a horizontal bottom skin, joined together into a foursided frame, via the columns. The node intersection comprises vertical bulkheads within the lower ends of the columns, forming internally intersecting continuations of the vertical sidewalls.

Abstract: A tension leg floating platform for offshore drilling has a plurality of tendons extending from the sea floor to the platform in tension. The upper connector for each tendon includes a housing with a conical shoulder located therein. A terminal segment on the upper end of each tendon extends through the housing. Dogs are carried on the shoulder of the housing, each having threads on the interior for mating threads formed on the terminal segment. A cam ring moves the dogs from an outer retracted position to an inner engaged position. The cam ring also will rotate the dogs relative to the terminal to mesh the threads of the dogs with the threads of the terminal segment.

Abstract: An improved tension leg joint with a first or receptacle member having an opening to receive the second or tension leg member end, the first member opening includes an internal recess including an upper downwardly facing shoulder and a lower shoulder, the second member end includes a latching element carried on a lower upwardly facing shoulder of the second member and normally biased outward so that it moves into the internal recess of the first member when the second member end is inserted therein sufficiently far so that the latching element moves past the downwardly facing shoulder, and a release sleeve movable within the first member recess and having means for releasably engaging the latching element when it is moved into the interior of the release sleeve subsequent lifting of the second member and its latching element causes the release sleeve to be raised to engage the downwardly facing recess shoulder and allow the latching element to pass thereby in its upward movement without coming into latching e

Abstract: Method and apparatus for retrieving a running tool/guideframe assembly without the use of winch wires. A portion or each guidepost assembly can be unlatched from the seafloor-mounted template to permit that portion to be retrieved using the guidewires. The unlatchable portion of the guidepost system is formed with a load support that engages and supports the running tool/guideframe assembly so that the assembly is retrieved concurrently with the unlatchable portions of the guidepost assemblies.

Abstract: Both an offshore platform mating system and method are disclosed in which adjacent first and second jacket sections are provided with a plurality of corresponding docking poles and receptacles, respectively. Alignment of the adjacent jacket sections is facilitated by using at least one extended or lead docking pole on the first jacket section which projects further toward the second jacket section than do the other docking poles and is thus the first to engage one of the horizontally aligned receptacles when the first and second jacket sections vertically approach. Mating procedures for the first and second jacket sections continue with rotational alignment of the first and second jacket sections about the lead docking pole which acts as a pivot while alignment of the other receptacles is adjusted with respect to the other docking poles.

Abstract: An offshore drilling/production platform equipped with a retractable work deck. A light weight work deck constructed of tubular steel with plate steel attachment plates welded thereto. A plurality of variously configured removable panels can be bolted in a configuration that can provide the work surface needed to accomplish the tasks of installing wellhead equipment, inspecting the below deck regions of the platform or performing maintenance on such portions. A plurality of removable and foldable handrail sections are installed about the periphery of the configured work surface. The work deck can be retracted to a position immediately adjacent the lowermost fixed deck to protect it from wind and waves when not in use.

Abstract: A reversible mechanical coupling to be clamped in a suitable seat by means of clamping levers and wedges, in which the clamping levers are pivoted to arms rigid with said wedges by two lateral pivots which are inserted through vertical slots in said arms and are retained at the lower end of said slots by the narrow but forcible mouth of springs of tuning-fork shape mounted in correspondence with said slots, said clamping levers being also provided with laterally projecting pegs which are inserted in suitably shaped guides provided in protection casins interposed between the clamping levers and fixed to the coupling body.