Abstract: Pipe for great water depths allowing transfer of a fluid between a floating support (1) and a point situated below and at a distance from the water surface, characterized in that it comprises:

Abstract: A universal catenary riser support that can be designed to accommodate all riser pipe diameters typically considered for production of offshore hydrocarbons and allows the catenary riser to exit from the vessel at any azimuth angle and at a wide range of angles from the vertical. The support structure at the keel of the offshore structure is provided with a receptacle to receive a curved riser segment. The curved riser segment is adapted to be received in the receptacle. The curved riser is also adapted to receive a vertical riser section through the offshore structure. Relative motions between the catenary riser and the offshore structure are accommodated by a tapered section of riser or flexible joint attached to the curved riser section. A removable plug may be provided in the curved riser section to prevent water from entering the catenary riser during installation in the offshore structure.

Abstract: The invention relates to a production riser system wherein the riser (1), at the touchdown point (5), has a bottom flexjoint (8) so that the dynamic motion of the riser (1) is absorbed by angular excursion (9) of the flexjoint (8) and not by the interaction of the sag bend (10) with the seabed (6). The surface end of the riser may be fixed, or coupled by a second flexjoint to a production and storage vessel.

Abstract: This application discloses a method of extracting hydrocarbons from a submarine well, which is characterized in that a displacement fluid, e.g. water, is injected under pressure into the submarine well, or into a reservoir connected to the submarine well, from a submerged buoy or from a submerged part of a buoy. Typically, the injection fluid is rawwater. A buoy is also disclosed which comprises an upper section (2) arranged to extend above the sea level; and a lower, submerged section (1), characterized in that the lower, submerged section comprises means for providing a displacement fluid under pressure to an output which is connected or is connectable to a submarine well.

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: The present invention relates to a subsea system for the production of hydrocarbon reserves. More specifically, the present invention relates to a subsea system in economically and technically challenging environments. Still more specifically, the present invention relates to a control wellhead buoy that is used in deepwater operations for offshore hydrocarbon production.

Abstract: An exemplary floatable vessel is described having an upper tower section with a reduced diameter or width and an affixed lower base section having an enlarged diameter or width. The lower section contains weighted ballast distributed upon its lower floor. The lower section also includes flotation tanks which can be filled with air to raise the vessel in the water such that portions of the lower section are raised above the water line. Alternatively, the flotation tanks can be flooded to dispose the lower section and a portion of the upper section below the water level. The upper tower section of the vessel supports a deck structure upon which rig components can be constructed or secured. The tower section includes flotation tanks as well. In preferred embodiments, these tanks are variable tanks that can be partially filled with air and partially flooded with water.

Abstract: The riser system includes a small diameter riser that can be disconnected from the subsea BOP/wellhead assembly to obtain access to the wellbore for large diameter casing while continuously maintaining a hydrostatic head to control the well. The riser system further includes a large diameter riser joint having one end connected to the BOP/wellhead assembly and one or more hydraulic conduits extending from the BOP/wellhead assembly to the small diameter riser which extends to the surface. The small diameter riser has a first position where the small diameter riser is aligned and connected to the other end of the riser joint and a second position where the small diameter riser is non-aligned and unconnected with the large diameter riser joint. The riser system further includes a shifter which moves the small diameter riser from the first position to the second position. Downhole operations are conducted through the small diameter riser in the first position.

Abstract: A tension member comprising a plurality of fiber filaments (21) gathered into a plurality of strands (20). The filaments (21) run close together, and a protective sheath (16) is provided around the strands. Each strand (20) is coated on the exterior thereof with a sheath (22) of a material having a low friction coefficient, permitting the strands (20) to move longitudinally in relation to one another and independently of each other.

Abstract: A device for fitting a stiffening sleeve which is located at the end of an oil pipe onto a bearing structure. The device comprises an internal hollow tube fixed on the bearing structure, the tube having an internal diameter slightly greater than the diameter of the cylindrical wall of the stiffener, and two support/centering devices, respectively a lower device formed by retractable balls and an upper device formed by a conical collar, the devices interacting with the cylindrical wall of the stiffener and a conical bearing surface at the top of the tube in order to support/center the stiffener.

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 connection between a riser and a receptacle of a floating platform may be preloaded to reduce fatigue. The platform has a receptacle with upper and lower grooved profiles. A hanger is connected to the upper end of the riser. The hanger has a latch that engages the lower grooved profile in the receptacle to resist downward pull of the riser. A tieback connection inserts from above into the receptacle. The tieback connection has an outer member that lands on the hanger. The outer member has a latch that engages the upper grooved profile. The tieback connection also has an inner member with a set of internal threads. Threads on the inner member engage threads on the latch, rotating the inner member relative to the outer member exerts an outward force on the tieback connection latch. As the latch is pushed into the tieback grooved profile, a downward preload force is created, which passes to the hanger latch.

Abstract: In one embodiment of the invention, there is provided a drilling unit comprising a floating drilling rig, a subsea wellhead, and a riser connecting the subsea drilling rig with the subsea wellhead. A floatation collar encircles the riser so as to reduce deck load on the floating drilling rig. The floatation collar comprises a hollow fabric body filled with gas. The floatation collar has a longitudinal axis and is formed from a sidewall body having a longitudinally extending slit extending through the sidewall body. The slit enables the floatation collar to be transversely mounted onto the marine riser.

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: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a circumferentially shaped channel positioned on its upper end. An annularly shaped ring is placed over the circumferentially shaped channel and sealed in place by a frangible weld. A tether line attaches to the annularly shaped ring and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight.

Abstract: A universal catenary riser support that can be designed to accommodate all riser pipe diameters typically considered for production of offshore hydrocarbons and allows the catenary riser to exit from the vessel at any azimuth angle and at a wide range of angles from the vertical. The support structure at the keel of the offshore structure is provided with a receptacle to receive a curved riser segment. The curved riser segment is adapted to be received in the receptacle. The curved riser is also adapted to receive a vertical riser section through the offshore structure. Relative motions between the catenary riser and the offshore structure are accommodated by a tapered section of riser or flexible joint attached to the curved riser section. A removable plug may be provided in the curved riser section to prevent water from entering the catenary riser during installation in the offshore structure.

Abstract: A method for assembling and delivering a drivepipe to a drill site, the method having the following steps: assembling the drivepipe at a shoreline assembly station; attaching floatation devices to the drivepipe and floating the drivepipe in the ocean; towing the drivepipe with tow vessels to a drill site; delivering the drivepipe in a horizontal orientation to a drilling vessel at the drill site; attaching a upper end of the drivepipe to the drilling vessel and detaching the tow vessels from the drivepipe; pivoting the drivepipe about its point of attachment to the drilling vessel until the drivepipe is vertically oriented; deactivating the buoyancy function of the floatation devices attached to the drivepipe; removing the floatation devices from the drivepipe; equipping the drivepipe with a driving mechanism; and lowering the drivepipe with a running string from the drilling vessel to the sea bed.

Abstract: A connection device for connecting a submerged tubular structure to a floating support structure, said connection device comprising a first tubular connection element and a second tubular connection element concentric with said first element, the connection elements being connected respectively to one end of the submerged tubular structure, the first tubular connection element being provided firstly with a first shoulder serving to co-operate with a corresponding first abutment face of the second tubular connection element to form a first axial abutment in a pulling direction in which the submerged tubular structure is pulled, and secondly with a second shoulder serving to co-operate with a corresponding second abutment face of the second tubular connection element to form a second axial abutment in a direction opposite from the pulling direction, locking and tensioning means being mounted between the first and second tubular connection elements to act, by putting the first and second shoulders simultaneously

Abstract: A semi-submersible vessel 10 adapted to resist heave motion that includes a plurality of support columns 16, each of which has an upper end 19 and a lower end 23. A deck 39 is interconnected between the plurality of support columns 16 at locations upon the columns 16 proximate the upper ends 19 thereof. The deck 39 is a box-shaped structure. A ring-pontoon 43 is connected to the plurality of support columns 16 at locations proximate the lower ends 23 of each of the columns 16. Each support column 16 has a longitudinal axis 29 that is inclined upwardly and inwardly from the ring-pontoon 43 to the deck 39 and the longitudinal axis is oriented substantially radially from a center point 13 of the vessel 10. An angle of columnar inclination of the support columns 16 approaches at least five degrees from vertical. The ring-pontoon 43 is rectangular-shaped, and in one variation, is substantially square-shaped and has corner pontoon portions 49 interconnected by elongate pontoon portions 56.

Abstract: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a circumferentially shaped channel positioned on its upper end. An annularly shaped ring is placed over the circumferentially shaped channel and sealed in place by a frangible weld. A tether line attaches to the annularly shaped ring and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight.

Abstract: A riser system connecting a oil or gas well head and a surface vessel comprises a first riser section maintained substantially vertically under tension, attached for example by a tension cable to a constant load tensioner means mounted on the vessel, and a flexible second riser section arranged above the first riser, the second riser being able to flex to accommodate movements in the surface vessel. The second riser section includes a curvature limiter, achieved for example by making the riser from a material of variable stiffness along the riser's length. An emergency disconnect valve is provided between the lower riser section and the upper flexible section. An alternative curvature limiter comprises a plurality of discrete collars which are connected together and surround the outer diameter of the second riser.

Abstract: The invention is a system used for production of petroleum effluents situated at great water depths. The system includes an intermediate floating station situated below the surface at a depth selected according to the pressure of the effluent at the outlet of wellheads situated on the station, production risers communicating with the well to be worked, an anchor including production risers, a pump situated on the floating station which transfers the effluent to a processing or destination site, a transfer which transfers the effluent between the floating station, the water bottom and a final platform or a processing plant, and an energy source providing necessary energy to the various equipments installed on the floating station.

Abstract: A drilling unit comprises a floating drilling rig, a subsea wellhead, and a riser connecting the subsea drilling rig with the subsea wellhead. A floatation collar encircles the riser so as to reduce deck load on the floating drilling rig. The floatation collar comprises a hollow fabric body filled with gas. The floatation collar has a longitudinal axis and is formed from a sidewall body having a longitudinally extending slit extending through the sidewall body. The slit enables the floatation collar to be transversely mounted onto the marine riser.

Abstract: An arrangement and method are disclosed for providing a fluid flow path between a seabed supply of hydrocarbons and a turret moored storage vessel. A steel catenary riser interface buoy provides support for a steel catenary riser and the lower end of a flexible riser. This arrangement allows both risers to be pre-installed prior to arrival of the storage vessel or other floating storage facility. A turret interface buoy, secured to an upper end of the flexible riser is used in the installation process as well as in the hook-up of the riser system to the storage vessel.

Abstract: A production riser that provides the benefits of a slug catcher, riser based gas lift, and multiphase meter in a single device and is suited to both shallow and deep-water oil/gas field developments. The riser is formed from a pipe within a pipe. The inner pipe provides the path for the production fluids. Perforations are provided near the base and top of the inner pipe. The top of the annulus between the pipes is closed and is in fluid communication with a gas supply/compression system via an isolation control valve/choke. The bottom of the annulus is closed. Three sets of pressure and temperature transducer transmitters are installed at the top, center, and base of the riser through the outer pipe wall.

Abstract: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a vertical channel positioned on its exterior. A cover plate is placed over the vertical channel and sealed in place by a frangible weld. A tether line attaches to the cover plate and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight. Further ascension of the buoyancy tank or housings, causes the frangible weld joints to break and peel back the cover plate, exposing the vertical channels.

Abstract: A ship type floating oil production system for access to subsea wells through installation of surface wellheads on a ship type surface vessel on the sea comprises a cylindrical turret moored to a seabed is located within a moon pool formed in the ship type surface vessel such that the ship type surface vessel is freely rotatable about the cylindrical turret. A plurality of riser pipes have a rigid structure and extend downward to subsea wells through the cylindrical turret, and each riser pipe is provided at its top portion with a surface wellhead including valves of the riser pipe. Accordingly, workover operations can be facilitated as needed by running workover tools through the surface wellhead of the corresponding riser pipe through use of a work-over-rig installed on the ship type surface vessel.

Abstract: An offshore hydrocarbon production system includes a spar (34, 52, 214) that floats at the sea surface, a subsea buoy (26, 154, 200, 210) lying under the spar and hanging from it, and one or more risers (20, 174, 220) that extend up to the subsea buoy and are coupled therethrough to the spar. The subsea buoy is initially negatively buoyant to ballast of the spar and keep it upright, but the subsea buoy can be made positively buoyant so the spar can be moved away and a workover vessel (70) moved over the subsea buoy. The subsea buoy can be coupled to the spar by one or more chains (60, 60A) extending between them, and one or more flexible hoses (60) extending between them.

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: An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a vertical channel positioned on its exterior. A cover plate is placed over the vertical channel and sealed in place by a frangible weld. A tether line attaches to the cover plate and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight. Further ascension of the buoyancy tank or housings, causes the frangible weld joints to break and peel back the cover plate, exposing the vertical channels.

Abstract: A vessel includes a swivel assembly wherein each swivel is individually connected to a support structure with the swivels not being interconnected in a weight-bearing manner, and piping extending within a central space of the swivel assembly having individual pipe segments which can be disconnected for removal of one swivel in the radial direction.

Abstract: A riser guide and support mechanism for a floating vessel, and particularly a spar type structure, where the buoyancy can stem extends nearly the entire length of the floating vessel. A riser centralizing element is provided on the riser near the lower end of the buoyancy guide stem. Riser bend limiting elements are positioned on the riser so as to extend above and below the riser centralizing element. Since the buoyancy cans and buoyancy can stem are not required to rotate relative to the stem guides on the floating vessel, the stem guides can be formed from pipe sections that provide a much larger bearing area than is customary.

Abstract: There are disclosed two embodiments of a connector for use in supporting a riser from cable which extend about sheaves intermediate the riser and a tensioning device located on a floating rig above a subsea wellhead to which the lower end of the riser is to be anchored. Each connector is of such construction that the cable may be advanced through an opening in a body of the connector in order that the wear point on the cable where it passes over the sheave may be changed from time to time without having to detach and reattached it from and to the riser.