Abstract: A floating offshore platform, of the type having a buoyancy can disposed within a support structure, includes a can guide assembly that has at least two compliant compression pads that are configured and arranged to provide a non-linear load-versus-deflection characteristic in response to impact loads generated by the impact of the can against the guide assembly. At least one of the compression pads is substantially stiffer (less compliant) than the other pad. The pads are arranged so that the relatively soft pad absorbs the impact load before the relatively stiff pad is engaged. In one embodiment, first, second, and third compression pads are arranged vertically, the upper and lower pads being softer (more compliant) than the middle pad. In another embodiment, a first, relatively soft, compression pad coaxially surrounds a second, relatively stiff compression pad.

Abstract: A buoyancy system to buoy a riser of an offshore oil platform includes buoyancy compartments coupled around an elongated internal beam. The internal beam can withstand loads between the oil platform and the buoyancy system, while the buoyancy compartments provide buoyancy. The internal beam includes an elongated stem, a plurality of webs extending radially outwardly from the stem, and a plurality of transverse flanges attached to the outer edges of the webs.

Abstract: A process for immobilizing metallic sodium in glass form. The process comprises: (A) introducing in a dispersed state, into a reactor, an amount of a vitrified matrix precursor, metallic sodium and iron oxide (Fe2O3) sufficient to ensure oxidation of the metallic sodium; (B) producing a homogeneous mixture of these constituents; (C) heating the mixture to a temperature between 1000–1600° C. to form a molten homogeneous mixture in which the sodium introduced in (A) is converted to sodium oxide; and (D) recovering and cooling the molten mixture to obtain a vitrified matrix having a homogeneous composition, which matrix incorporates the sodium introduced in (A) as a constituent oxide. In a particular embodiment, the process may be used for the containment of metallic sodium containing radioactive elements.

Abstract: A system for stabilizing gravity-based offshore structure anchored in a seabed includes a plurality of upper locking element sets installed in a keel on the bottom of the structure; a plurality of caissons embedded in the seabed; a plurality of inserts, each of which is removably installed in one of the caissons; and a lower locking element set in each of the inserts. Each of the lower locking element sets is lockably engageable with one of the upper locking element sets when the keel is set down on top of the caissons. The inserts are permanently attachable to the keel by a grouting material that may be pumped into the inserts through the keel. The arrangement stabilizes the structure against lateral shear forces, while allowing the structure to be easily removed from the caissons, with the inserts attached to the keel, by the application of a vertical lifting force. The structure may then be moved and installed on a second plurality of caissons embedded at second seabed site.

Abstract: Apparatus for connecting a conduit to a subsea structure includes a frame connectable to the subsea structure by a docking mechanism, a conduit handling mechanism on the frame to facilitate positioning of the conduit for attachment to the subsea structure and a second docking mechanism for attaching a mobile manipulating device to the frame. In use, the mobile manipulating device connects to the conduit by means of a pull-in rope on a winch, and travels under its own power to the subsea structure while paying out the pull-in rope. There, it docks with the frame and the pull-in rope is reeled in by the winch on the mobile manipulating device. The conduit is then connected to the subsea structure by the conduit handling mechanism on the frame. The invention also includes the method of attaching a conduit to a subsea structure using the described apparatus.

Abstract: A buoyancy can for supporting an offshore oil and gas riser includes an axial bore through which the riser extends coaxially, and a radio-axial slot extending through a side of the can and into the axial bore. A pair of spaced-apart support features are disposed coaxially on the riser, and the can includes a pair of corresponding sockets in the axial bore thereof. The sockets are adapted to receive and vertically support respective ones of the support features in a complementary, axial engagement. The can is placed in the water and moved laterally relative to a fully assembled, vertically supported riser such that the riser passes through the radio-axial slot of the can and into the axial bore thereof without the need for disassembly of the upper portion of the riser. The relative vertical positions of the can and riser are then adjusted such that the support features engage and seat within respective ones of their complementary sockets.

Abstract: In a method of and apparatus for offshore mooring, a clamping apparatus includes a clamping mechanism and a pulley. A mooring line connected to an anchor or a pendant line connected to a vessel to be moored extends through the clamping mechanism and around the pulley of the clamping apparatus. The distal end of the line extending through the clamping apparatus is connected to an anchor handling vessel. The anchor handling vessel is employed to apply a predetermined tension to the pendant line and the preset mooring line. A remote operated vehicle is then employed to actuate the clamping apparatus and to disengage the anchor handling vessel.

Abstract: An extendable draft platform, having a deck and buoyancy columns installed in leg wells in the deck for vertical movement from a raised position to a submerged position, includes a connection arrangement for securing the columns to the deck when the columns are in the submerged position. In the connection arrangement, a plurality of first guide elements near the top of each column is engageable by a plurality of complementary second guide elements secured to the deck around each leg well when the column is lowered to its submerged position. A locking mechanism is operable between the columns and the deck when the first guide elements are engaged with the second guide elements. The first and second guide elements may be configured so that the connection between the deck and the columns may be enhanced by over-ballasting the columns and/or by welding the columns to the deck.

Abstract: A spar-type offshore platform includes a buoyant upper hull structure supporting a deck and having lower end in which is received a buoyant lower mooring module. The upper hull structure is connected to the mooring module by connection lines. The upper hull structure is removed from the mooring module by disconnecting the connection lines from the upper hull structure while leaving the connection lines attached to the mooring module and while the mooring module remains moored to the seabed. The mooring module is lowered relative to the upper hull structure, allowing the latter to be moved away. The upper hull structure may be re-positioned over the mooring module, and the mooring module may be hauled upward into engagement with the lower end of the upper hull structure, so that the connection lines can be recovered and re-attached to the upper hull structure.

Abstract: In an Extendable Draft Platform including a deck, a plurality of buoyancy columns installed in column wells in the deck for movement from a raised position to a submerged position, and a heave plate on the bottom of the columns, each of the columns has an upper portion and a lower portion. A helical strake having a radial height H is fixed to the lower portion of each column. The maximum width of the lower column portion is less than the maximum width of the upper column portion by at least 2H, so that the strake can pass through a column well having maximum width that is only slightly greater than that of the upper column portion. A plurality of guide rails is fixed to the lower portion of each column, each extending along the outer periphery of the strake from the upper column portion to the heave plate.

Abstract: In a method of and apparatus for offshore mooring, a clamping apparatus includes a clamping mechanism and a pulley. A mooring line connected to an anchor or a pendant line connected to a vessel to be moored extends through the clamping mechanism and around the pulley of the clamping apparatus. The distal end of the line extending through the clamping apparatus is connected to an anchor handling vessel. The anchor handling vessel is employed to apply a predetermined tension to the pendant line and the preset mooring line. A remote operated vehicle is then employed to actuate the clamping apparatus and to disengage the anchor handling vessel.

Abstract: In a method of and apparatus for offshore mooring, a clamping apparatus includes a clamping mechanism and a pulley. A mooring line connected to an anchor or a pendant line connected to a vessel to be moored extends through the clamping mechanism and around the pulley of the clamping apparatus. The distal end of the line extending through the clamping apparatus is connected to an anchor handling vessel. The anchor handling vessel is employed to apply a predetermined tension to the pendant line and the preset mooring line. A remote operated vehicle is then employed to actuate the clamping apparatus and to disengage the anchor handling vessel.

Abstract: For limiting the lateral buckling of tensile armor plies of an underwater flexible pipe, that can be used in the offshore oil industry, the plies include from the outside inward, at least one external polymer sheath, a first outward retention layer of a defined thickness K1 wound around an upper outer tensile armor ply, at least one second inward retention layer of a defined stiffness K2 wound around each of at least one lower inner tensile armor ply. Stiffness K2 is preferably less than stiffness K1, i.e., the retention layers outward are less stiff. There is then an internal polymer sheath.

Abstract: A device for monitoring the integrity of a flexible pipe used for transporting a pressurized fluid in a terminal end-fitting. The pipe includes an internal pressure sheath, plies of tensile armor wires and an outer sheath fastened to the end-fitting. A monitor of the change in a phenomenon associated with the disorganization of the armor plies as a result of a fracture of several tensile armor wires inside the end-fitting. The monitor detects an increase in the twist in the pipe near the end-fitting. Gas escape from the pipe or strain on the pipe may be measured as such phenomenon.

Abstract: A mechanism to be applied to an exterior surface of a cylindrical structure for the reduction of the effect of Vortex Induced Vibration (VIV) in the cylindrical structure when immersed in flowing fluid, wherein the mechanism includes a generally cylindrical column having a central axis, an interior surface corresponding in size and shape to the exterior surface of the cylindrical structure to which the mechanism is to be applied and an outer surface defining a wall thickness. A reduced wall thickness is formed into the outer surface in a pattern to produce a discontinuity that interrupts the lengthwise coherence of vortex shedding of moving fluid from the outer surface when the cylindrical column is attached to the exterior of the cylindrical structure in the flowing fluid. The effect of VIV on the cylindrical structure is effectively reduced. The result is a submergible cylindrical assembly for positioning in a flowing body of water and having enhanced resistance to VIV.

Abstract: An extendable draft offshore oil and gas drilling and production platform (“EDP”) includes a buoyant deck having a central opening, an adjustably buoyant pontoon, and a single, adjustably buoyant column. The column is mounted upright on the pontoon, and is vertically movable through the central opening of the deck. The deck is supported on an upper end of the column above a body of water for offshore operations. The pontoon, and optionally, the column, have compartments with a buoyancy that is adjustable by pumps or sea water ballast and pressurized air. In one embodiment, the compartments can comprise a plurality of tubes. In another embodiment, a lower end of the column may comprise an open truss structure. The platform combines the advantages of a SPAR platform with those of a deep draft extendable draft platform.

Abstract: A flexible pipe for transporting a fluid comprising an outer sealing polymer sheath, at least a pair of armor wraps helically and long-pitch wound, and a polymer pressure sheath. The pressure sheath consists of an inner tube arranged in an outer tube, and grooves are arranged on at least one of the surfaces opposite the inner and outer tubes.

Abstract: A flexible tubular pipe for hydrocarbon transport, comprising from inside to outside at least a carcass, an inner sheath, tensile armoring plies and an outer sheath, wherein the carcass is formed by winding of at least an anti-corrosive elongated metal element with large cross-section, with successive windings stapled with a thin anti-corrosive metal strip.

Abstract: There is provided a buoyancy system for a structure having at least one component being substantially stationary with respect to the bottom of a water covered area. The system comprises a set of buoyancy modules of engineered materials to apply an identified amount of buoyancy. The set of buoyancy modules is attached to the structure at a set of buoyancy load transfer locations. The set of buoyancy modules comprises layers of the engineered materials. The engineered materials comprise a substantially reinforced axial layer, a substantially reinforced hoop layer; and a leak prevention layer.

Abstract: The invention concerns a method for refrigerating liquefied natural gas under pressure (1), comprising a first step wherein the LNG (1) is cooled, expanded and separated (a) in a first base fraction (4) which is collected, and (b) a first top fraction (3) which is heated, compressed in a compressor (K1) and cooled into a first compressed fraction (5) which is collected; a second compressed fraction (6) is drawn from the fuel gas (5), cooled then mixed with the cooled and expanded LNG (1). The invention is characterised in that it comprises a second step wherein the second compressed fraction (6) is compressed and cooled, and a flux is (8) drawn and cooled, expanded and introduced in the compressor (K1). The invention also describes other embodiments.