Abstract: A support system (12; 12?) for providing horizontal support to a riser (32) extending downward from a cantilever (18) along a well centre and into a body of water comprising a riser interface (48; 48?) and a tether arrangement (50; 50?). The support system (12; 12?) is configured to permit asymmetric placement of the riser interface (48; 48?) relative to the cantilever (18).

Abstract: A positionable emissions control watercraft that may be placed near a serviced watercraft in a location that is away from the risk of falling cargo, while also eliminating a need for a spacer or a spacer barge, and allowing other service watercraft to access the serviced watercraft.

Abstract: A method and equipment for harvesting natural gas from seabed hydrates are disclosed. The preferred equipment includes a mobile riser, a water injection nozzle, a gas collector, a gas separator, a gas compressor, a water pump, and a water boiler. A fraction of produced gas is used to heat water which is in turn injected to seafloor for dissociating gas hydrates. The preferred method of the invention comprises producing natural gas from seabed hydrates using a production ship with a moving riser installed. This method eliminates the need of drilling wells and thus cuts cost of gas production tremendously.

Abstract: In one embodiment, a gas hydrate conversion system is provided comprising a floating factory, an appendage for harvesting a gas hydrate from an oceanic hydrate deposit, and one or more storage tanks. The floating factory comprises one or more heat exchange assemblies, one or more heat pump assemblies and an engine. In another embodiment, a method for harvesting hydrocarbon hydrate deposits is provided, the method comprising providing a gas hydrate conversion system; inducing release of methane from an oceanic hydrate deposit; capturing the methane from a primary methane capture zone and/or a secondary methane capture zone; and converting the methane to hydrogen and carbon.

Abstract: A method of maintaining a substantially fixed orientation of a pressure control device relative to a movable rig can include rotating a body of the pressure control device while the rig rotates. A method of remotely controlling an orientation of a pressure control device relative to a movable rig can include rotating a body of the pressure control device, and controlling the rotation of the body from a location on the rig remote from the body. A pressure control device for use in conjunction with a rig can include a body, a flange, an orientation device which changes a rotational orientation of the body relative to the flange, and an orientation control system which remotely controls the orientation device.

Abstract: In an offshore production system, a semisubmersible supports the risers and provides the service requirements for the wells, while an associated FPSO provides the processing functions and storage of the produced hydrocarbons. As a result, a greater number of risers can be supported in a harsh environment while the turret and swivel requirements of the system are significantly reduced.

Abstract: The invention relates to a device for manufacturing a foundation for a mass located at height, such as the jacket of a wind turbine or a jetty, wherein the foundation comprises a quantity of piles driven into an underwater bottom in a geometric pattern. The device comprises a positioning framework of a number of mutually connected guide tubes arranged in a geometric pattern and adapted to receive and guide a pile to be driven into the underwater bottom, wherein the guide tubes comprise a mechanism with which at least an internal wall part of the guide tubes is displaceable in the radial direction of the guide tubes from a radially inward support position for the pile to a radially more outward position in which the internal wall part substantially releases the pile. The invention also relates to a method and an assembly of a jack-up platform and the device.

Abstract: The invention relates to an undersea connector for connecting an oil installation to the sea bottom, the connector being of the type presenting a first tubular element forming a female portion for fastening to the ocean bottom and a second tubular element forming a male portion for connection to the oil installation, wherein the connector comprises at least one anti-disconnection device for the connector, the device being housed in the female portion and comprising means for positioning the device in a first position in which the connector is capable of being disconnected, or else in a second position in which the connector cannot be disconnected.

Abstract: The present invention is a blowout preventer including a large funnel. The large end of the funnel is placed over a well pipe (or other pipe) through which oil (or other fluid) is blowing out. The small end of the funnel is connected to a return pipe. A high pressure pipe with a smaller diameter is inserted into the well pipe. Air is pumped under high pressure through the high pressure pipe, separating the oil and forcing the oil, that is not kept down in the well pipe by the pressure, up through the return pipe. The funnel can be moved into alignment with the well pipe using positioning arms. A stopper may be forced into the well pipe. There are propellers near an end of the high pressure pipe. There are stacked turbines in the return pipe. There is a gasket with pivoting overlapping plates, to seal the pipe.

Abstract: Flexible hang-off arrangement is provided for a catenary riser suspended from an offshore or inshore platform, which includes floating or fixed platforms, vessels or/and buoys. The bending loads in the top segments of the said riser are reduced by incorporating a pivot at the riser hang-off. Pressure containing welded, bolted, rolled or swaged pipe spools transfer fluids, including hydrocarbons between the riser and the platform. Along significant spool lengths the tangents to the center lines of said spools are orthogonal to and offset from the tangent to the center line of the riser at the hang-off. The said pressure containing spools include arbitrary looped, spiral and helicoidal designs that are subject to torsion.

Abstract: The present invention is a blowout preventer including a large frustoconical funnel. The large end of the funnel is placed over a well pipe (or other pipe) through which oil (or gas or other fluid) is blowing out. The small end of the funnel is connected to a return pipe. A high pressure pipe with a smaller diameter is inserted into the well pipe. Air is pumped under high pressure through the high pressure pipe, separating the oil and forcing the oil, that is not kept down in the well pipe by the pressure, up through the return pipe. The funnel can be moved into alignment with the well pipe using jets. There are sensing devices on moveable arms. A stopper is forced into the well pipe. There are one-way valves in the stopper. There are stacked turbines in the return pipe. There is a gasket with pivoting overlapping plates.

Abstract: A system for developing one or more offshore hydrocarbon fields includes at least one floating hydrocarbon processing unit moored to the seabed and connected to a hydrocarbon reservoir via a riser and a wellhead on the seabed, the unit receiving and processing the hydrocarbon mixture received from the reservoir via the riser, and having equipment to separate the hydrocarbon mixture into oil, water and gas and store them in storage tanks. A gas storage buffer reservoir is placed at a certain distance from and isolated from the hydrocarbon reservoir. A gas export riser is connected to the floating hydrocarbon processing unit and the gas buffer reservoir to export separated gas and inject it into the gas buffer reservoir. A gas riser has one end connected to the gas buffer reservoir and another end connected to the floating gas processing unit for processing gas received from the gas buffer reservoir for enabling transportation to shore.

Abstract: An offshore system allows a vessel (12) to sail to a predetermined sea location (14), quickly set up a loading system and start the transfer of hydrocarbons to or from a pipeline (22), and then quickly disconnect and sail away. The vessel is a DP (dynamic positioning) vessel that does not require mooring or anchor lines, so the only apparatus to install is a conduit (30) that can be picked up by the vessel to extend between a stationary pipe end (24) that lies at the sea floor and the vessel. The conduit includes primarily a flexible hose (70) that extends in a sine wave with two loops (80, 82). The conduit includes a rigid reinforced hose section (34) that is pivotally connected to the sea floor. A chain (114) can be provided with a portion of the chain lying on the sea floor, to help the disconnected hose coupling (42D) remain at a stable position above the sea floor.

Abstract: There is disclosed an offshore vessel mooring and riser inboarding system (12) for a vessel (10) such as an FPSO or FSO. In one embodiment, the system comprises a first mooring element (16) adapted to be located in an offshore environment (18); a riser (20) adapted to be coupled to the first mooring element; a connector assembly (22) 11 adapted to be mounted on the vessel, the connector assembly comprising a second mooring element (28); and a transfer line (32) adapted to be coupled to the riser; wherein the first and second mooring elements are adapted to be connected to facilitate coupling of the riser and the transfer line; and wherein the connector assembly is adapted to permit relative rotation between the vessel and the first mooring element about three mutually perpendicular axes of rotation. This facilitates weathervaning of the vessel relative to the first mooring element, as well as pitch, roll, heave and surge, under applied wind, wave and/or tidal forces.

Abstract: There is disclosed an offshore vessel mooring and riser inboarding system (12) for a vessel (10) such as an FPSO or FSO. In one embodiment, the system comprises a first mooring element (16) adapted to be located in an offshore environment (18); a riser (20) adapted to be coupled to the first mooring element; a connector assembly (22) 11 adapted to be mounted on the vessel, the connector assembly comprising a second mooring element (28); and a transfer line (32) adapted to be coupled to the riser; wherein the first and second mooring elements are adapted to be connected to facilitate coupling of the riser and the transfer line; and wherein the connector assembly is adapted to permit relative rotation between the vessel and the first mooring element about three mutually perpendicular axes of rotation. This facilitates weathervaning of the vessel relative to the first mooring element, as well as pitch, roll, heave and surge, under applied wind, wave and/or tidal forces.

Abstract: A system for supporting multiple-well-site, offshore, hydrocarbon-bearing fields, each well-site has one or more wells. In general, the system first comprises a floating vessel that is relocatable from a first subsea well-site to a second subsea well-site. The system also comprises two separate systems: (1) an operations control system for providing subsea well-site operations such as power and communications; and (2) an intervention system for conducting intervention services to an individual subsea well such as workover services and maintenance services. The operations system may provide control to wells and other subsea equipment at either the first well-site or the second well-site, regardless of the location of the floating vessel. The intervention system may provide workover and/or maintenance to subsea equipment or individual wells at the well-site at which it is located.

Abstract: A method of installing equipment subsea comprising the steps of: assembling the equipment within a frame; submerging in the sea at least a part of an assembly comprising the frame and the equipment; coupling the at least partially submerged assembly to a vessel; transporting the at least partially submerged assembly proximate a subsea installation site; coupling the assembly to an installation device; and installing the equipment at the installation site using the installation device. A frame for supporting equipment is also disclosed wherein the frame is shaped to match the dimensions of the equipment to be supported. The frame comprises at least one clamp having a first half clamp member for releasably engaging a second half clamp member of a second structure and a full clamp member for clamping around and supporting the equipment. The first half clamp member and the full clamp member can be integrally formed.

Abstract: The present invention relates to an underwater rock boring apparatus having differential global positioning system receiver and boring method thereof, new boring technology—a satellite navigation device orients the accurate position of a target—is brought to the underwater boring technology. A differential global positioning system (DGPS) receiver is provided at the body of a boring machine that is installed at the central opening of a self elevation platform (SEP) barge, the location of the boring machine is set to concentricity of the target boring position, and the position of the hull can be controlled without any movement of the boring machine. Then, the barge quickly moves to the next target boring location owing to the operation of a hull moving means so that the construction efficiency of the boring work can be enhanced.

Abstract: A new marine oil production riser system for use in deepwater applications is disclosed. An efficient means for accommodating movements of the host facility, while maintaining riser top tension within the limits for long-term riser performance. Long riser stroke lengths can be accommodated without requiring complex interfacing with the topsides. The riser assembly comprises: a generally extendable substantially non-vertical section having an upper end adapted to be in flow communication with a generally vertical marine riser carried by a facility floating on the surface of a body of water, and having a lower end adapted to be in flow communication with a fluid source on the seafloor; and tensioning means, mechanically connecting the upper end of the marine riser with the lower end of the marine riser, for biasing said ends towards each other.

Abstract: A system and method autonomously clears obstacles and mines from an approach lane. A ship is distantly located from an approach lane spanning a surf zone and beach portion, and the ship has operator control station software in an onboard computer. At least one system delivery vehicle having a storage bay and propulsion system transits from the ship to the approach lane in response to instructions from the operator control station. A line charge is disposed in each bay and has one end coupled to the system delivery vehicle. A line charge delivery vehicle in the bay is connected to another end of the line charge to pull the line charge from the bay and emplace it in a straight path in the approach lane in response to instructions from the operator control station. Explosives in all line charges are detonated to clear the approach lane.

Abstract: A method of connecting a first floating structure to the seabed, includes the steps of: providing a second floating structure, anchored to first and second anchoring points respectively on the sea bed via at least two anchor lines, attaching the second floating structure to the first structure via a pulling device, on the side of the first anchor line, displacing the first floating structure away from the second anchoring point towards the first anchoring point, disconnecting the first anchor line from the second floating structure while maintaining a pulling force on the second anchor line via the pulling device, and attaching the first anchor line to the first floating structure. By interconnecting a temporary buoy to the vessel to be anchored via a tension member, the anchor lines of the buoy and the vessel can remain under tension at all times whereby damage to the anchor lines is prevented.

Abstract: A method and system for sea-based handling/treatment of fluid hydrocarbons (oil) with associated gas include a first separation step in a high-pressure separator (18) installed on the sea bed, from which is output an oil flow containing an essentially predefined percentage of residual gas. The oil containing residual gas is carried through a riser (22) up to a surface vessel/production ship (12), where it is subjected to a second separation step in a second separator (24) incorporated in a low-pressure surface plant on board the vessel (12), this separated residual gas being used as fuel for direct/indirect generation of electric power for the operation of the underwater and above-water sections of the system. Water and gas produced in the first separation step is returned to a suitable reservoir by the use of a multiphase pump.

Abstract: The present invention relates to a subsea system for the production of hydrocarbon reserves. More specifically, the present invention relates to a control wellhead bouy that is used in deepwater operations for offshore hydrocarbon production. In a preferred embodiment, a bouy for supporting equipment for use in a remote offshore well or pipeline includes a hull having a diameter:height ratio of at least 3:1, a mooring system for maintaining the hull in a desired location, and an umbilical providing fluid communication between the hull and the well or pipeline.

Abstract: A system for producing hydrocarbons from a subsea well comprises an unmanned floating platform positioned over the well, the platform including equipment for inserting coiled tubing or wireline tools or the like into the well for servicing, controlling, or conducting other operations in or to the well, a vertical access riser connecting the platform to the well, a control umbilical connecting the platform to the well, a host facility adapted to receive the produced hydrocarbons, and a production pipeline connecting the well to the host facility, the production pipeline including at least one access port between the well and the host facility.

Abstract: A method for carrying out operations on petroleum and gas fields is provided. The method involves using a platform which is located underwater when in working position at a depth where it is not subject to storm waves or under the lower surface of an ice field. The platform is made in the form of a structure which is water-tight and which includes an inner volume in which all the equipment, systems and structures are provided. The platform is directed from the surface using a surface complex which moves on the water or the ice field at the same speed as that of the current or the ice drift in the opposite direction.

Abstract: A semisubmersible multipurpose unit (MPU) having a deck, a multipurpose tower secured to the deck, supports, pontoons connected to the supports with each pontoon adapted for ballast transfer, at least two hawsers connected to the MPU for connecting the MPU to an object at sea having a mooring system, a hawser guidance system to direct each hawser to the object at sea, a crane secured to the deck of a semisubmersible MPU, and at least an 6-point mooring system, wherein the combination of the semisubmersible MPU, hawsers and 6-point mooring system create a global equilibrium between the mooring system of an object at sea and the at least 6-point mooring system and the hawsers have both an elasticity sufficient to accommodate the wave frequency between the object at sea and the MPU and a stiffness adequate to synchronize the average and low frequency movements during a 10-year storm.

Abstract: A semisubmersible multipurpose unit (MPU) having a deck, a multipurpose tower secured to the deck, supports, pontoons connected to the supports with each pontoon adapted for ballast transfer, at least two hawsers connected to the MPU for connecting the MPU to an object at sea having a mooring system, a hawser guidance system to direct each hawser to the object at sea, a crane secured to the deck of a semisubmersible MPU, and at least an 6-point mooring system, wherein the combination of the semisubmersible MPU, hawsers and 6-point mooring system create a global equilibrium between the mooring system of an object at sea and the at least 6-point mooring system and the hawsers have both an elasticity sufficient to accommodate the wave frequency between the object at sea and the MPU and a stiffness adequate to synchronize the average and low frequency movements during a 10-year storm.

Abstract: A surface vessel is anchored almost geostationarily by a turret rotatable relative to the vessel about a vertical axis and having mooring cables extending to the seabed. A well is drilled from a drilling section in the vessel at a distance from the axis of rotation of the turret. The drilling is performed using a drill string through a riser extending from the seabed to the drilling section, which riser can be broken and shut off between the seabed and the vessel. By manipulating (hauling in and slackening) the mooring cables, the vessel is held in position so that the derrick is kept almost geostationary relative to the well during drilling operations. The system includes a surface vessel, a turret rotatable relative to the vessel about a vertical axis and which can be anchored to the seabed by a plurality of mooring cables, and a riser extending from the seabed to the vessel through which the well can be drilled with a drill string from a derrick in a drilling section on board the vessel.

Abstract: For a spar type floating platform having risers passing vertically through the center well of a spar hull, there is provided apparatus for supporting the risers from a gimbaled table supported above the top of the spar hull. The table flexibly is supported by a plurality of non-linear springs attached to the top of the spar hull. The non-linear springs compliantly constrain the table rotationally so that the table is allowed a limited degree of rotational movement with respect to the spar hull in response to wind and current induced environmental loads. Larger capacity non-linear springs are located near the center of the table for supporting the majority of the riser tension, and smaller capacity non-linear springs are located near the perimeter of the table for controlling the rotational stiffness of the table. The riser support table comprises a grid of interconnected beams having openings therebetween through which the risers pass.

Abstract: There are disclosed a wellhead system and a method for use in drilling a subsea well from a jackup platform which includes a wellhead housing which is installed on a surface casing of a subsea well. A first riser having a connector on its lower end is lowered over the upper end of the housing as the connector to land on the housing, and a second riser is lowered through the first riser and connector over and onto the upper end of the wellhead housing to form an upward continuation of the bore of the housing. The connector has locking parts which are movable between outer unlocking position to permit the second riser to be lowered onto and raised from the wellhead housing, and inner positions for locking engagement with the upper end of the housing and lower end of the second riser. A casing hanger is lowered through the second hanger and into landed position within the housing bore for suspending an inner casing string within the surface casing.

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: A system for recovering liquid hydrocarbons from hydrates on an ocean floor includes a vessel, a positioning subsystem coupled to the vessel for holding the vessel in a desired location over a hydrate formation, a hydrate recovery subsystem coupled to the vessel for delivering hydrates from an ocean floor to the vessel and separating gas from hydrates removed from an ocean floor, a gas conversion subsystem coupled to the hydrate recovery subsystem for converting gas to liquids, and a storage and removal subsystem. Excess energy from the gas conversion subsystem is used elsewhere in the system. A method of recovering hydrates from an ocean floor is also provided.

Abstract: The present invention relates to a method and to a system for producing hydrocarbons from marginal offshore fields. The invention includes a baseplate (2) fastened to the bottom and a small-size floating support (9) anchored to the baseplate by tendons (10). The baseplate comprises locations (31) for wellheads (7,8) and at least one receptacle (22,32) for a pumping device (21). The floating support comprises hoisting device allowing workover operations in the wells and maintenance operations on the pumping device to be performed.

Abstract: A well tender system for controlling, separating, storing and offloading well fluids produced from subsea hydrocarbon formations. The system comprises a vertically aligned series of tethered cylindrical tanks which are torsionally stabilized by flexible catenary production riser and export riser bundles, and serviced by separate catenary pipe bundles. Piles are secured to the seabed, each pile assembly being pivotally connected to a lower rigid tendon, which is in turn connected to tendons arranged about the periphery of the interconnected cylindrical tanks.

Abstract: A VASPS (vertical annular separation and pumping system) is integral with a floating production vessel such as a TLP. The head section of the VASPS is located at the deck level of the vessel. The tail section is located at or near the bottom of the body of water. The head and tail sections are in fluid communication by a riser having at least two fluid passageways (conductors). The invention constitutes an improvement on the VASPS unit described and claimed in U.S. Pat. No. 4,900,433.

Abstract: A well tender system for controlling, separating, storing and offloading well fluids produced from subsea hydrocarbon formations. The system comprises a vertically aligned series of tethered cylindrical tanks which are torsionally stabilized by flexible catenary production riser and export riser bundles, and serviced by separate catenary pipe bundles. Piles are secured to the seabed, each pile assembly being pivotally connected to a lower rigid tendon, which is in turn connected to tendons arranged about the periphery of the interconnected cylindrical tanks.

Abstract: A system for controlling, separating, processing and exporting well fluids produced from subsea hydrocarbon formations is disclosed. The subsea well tender system includes a surface buoy supporting one or more decks above the water surface for accommodating equipment to process oil, gas and water recovered from the subsea hydrocarbon formation. The surface buoy includes a surface-piercing central flotation column connected to one or more external floatation tanks located below the water surface. The surface buoy is secured to the seabed by one or more tendons which are anchored to a foundation with piles imbedded in the seabed. The system accommodates multiple versions on the surface buoy configuration.

Abstract: A well tender system for controlling, separating, storing and offloading well fluids produced from subsea hydrocarbon formations. The system comprises a vertically aligned series of tethered cylindrical tanks which are torsionally stabilized by flexible catenary production riser and export riser bundles, and serviced by separate catenary pipe bundles. Piles are secured to the seabed, each pile assembly being pivotally connected to a lower rigid tendon, which is in turn connected to tendons arranged about the periphery of the interconnected cylindrical tanks.

Abstract: A method of extending the working range of a main platform installation for oil deposits at sea involves:(1) positioning a temporary floating station at a location distance from the main platform installation and near to an oil deposit having small individual production capacity;(2) connecting the floating station with at least one well head of said oil deposit;(3) bringing up multi-component effluents from the at least one well head and pumping the effluents to the main platform installation;(4) when production of the effluents from said deposit ends, removing the floating station; and then(5) repositioning the floating station at at least one other oil deposit located at a distant location from said main platform installation to work the at least one other deposit. Also a facility for carrying out this method as described.

Abstract: A method of extending the working range of a main platform installation for oil deposits at sea involves:(1) positioning a temporary floating station at a location distance from the main platform installation and near to an oil deposit having small individual production capacity;(2) connecting the floating station with at least one well head of said oil deposit;(3) bringing up multi-component effluents from the at least one well head and pumping the effluents to the main platform installation;(4) when production of the effluents from said deposit ends, removing the floating station; and then(5) repositioning the floating station at at least one other oil deposit located at a distant location from said main platform installation to work the at least one other deposit. Also a facility for carrying out this method as described.

Abstract: A well tender system for controlling, separating, storing and offloading well fluids produced from subsea hydrocarbon formations. The system comprises a vertically aligned series of tethered cylindrical tanks which are torsionally stabilized by flexible catenary production riser and expert riser bundles, and serviced by separate catenary pipe bundles. Piles are secured to the seabed, each pile assembly being pivotally connected to a lower rigid tendon, which is in turn connected to tendons arranged about the periphery of the interconnected cylindrical tanks.

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 method is described for conducting well operations from a floating platform that may be moved to various locations above subterranean formations. Marine risers that have been previously connected to the platform flex sufficiently to allow this movement. The mobility of the platform allows well drilling, completion, producing, and workover activities to be conducted simultaneously through the risers attached to the platform. The mobility of the platform also allows new wells to be drilled at more preferable locations than those that would be available from a fixed bottom supported well template.

Abstract: A mooring system is provided, which can be rapidly installed and which is of relatively low cost. The system includes a transfer structure attached to a vessel, an anchor line extending from the transfer structure to a chain table near the sea floor, and catenary chains extending from the chain table to the sea floor. A weight hangs from the chain table to help in setting up the system and in mooring a vessel thereafter. The transfer structure includes a platform that can rotate with respect to the vessel, and a direction sensor for controlling a motor that rotates the platform opposite to rotation of the vessel, to avoid twist of the anchor line.

Abstract: A drilling, production and oil storage caisson for use in deep water offshore well operations in which the caisson has such a deep draft that its bottom end is subject only to minimal excitation forces caused by wave, wind and current acting on the caisson, the caisson including a plurality of oil storage compartments, a plurality of water ballast compartments above said oil storage compartments, a through axial passageway through said compartments; a riser system including a plurality of riser pipes in concentric circular arrangement within the through passageway or center well, each of the riser pipes being supported and tensioned by a buoyant flotation unit connected thereto; a drill string extending axially through said passageway between said riser pipes; and mooring lines connected to the bottom portion of the caisson extending therefrom with relatively low scope of 1:1 or less and providing a small watch circle for anchors for said mooring lines, the mooring lines being tensioned so that the mooring li

Abstract: An oil production system for producing oil at an offshore location comprises a floating storage vessel to receive the produced oil, the vessel having means for dynamic positioning and being connectable to a subsea well head by a riser and having means for separating the associated gas from the produced oil and employing the separated gas as fuel for the dynamic positioning.Re-entry of the subsea well is effected by providing the riser with means for effecting a simultaneous stab connection with the production bore and hydraulic control system lines without orientation.

Abstract: The emergency well-control vessel is capable of being moved above an offshore live oil or gas well, over which all normal controls have been lost. The vessel carries special purpose equipments and specially trained personnel for the purpose of bringing the erupted well under control, thereby stopping the pollution of the water body with the ejected formation fluids which form a so-called "plume". Such equipment is adapted to allow the vessel to move over and continue to dispel the plume while simultaneously attempting to regain control of the well. In one aspect, control of the abandoned wellhead and blowout preventers is established with divers working from the vessel or from an auxiliary craft. After control of the blowout preventer stack is confirmed and the same is fully operational, a kill string is lowered through the open blowout preventer stack and as deep down into the well as necessary.

Abstract: A method for drilling wellbores from an offshore platform to penetrate a subterranean formation using a combination of surface drilling techniques and subsea drilling techniques to achieve an improved effectiveness by avoiding the necessity for large conduits communicating the ocean floor and the offshore platform.

Abstract: A drilling ship is maintained over a deep sea well in a drilling position defined by an inner circle and an outer circle having the well as their center. The ship is connected to a set of anchors fastened to the sea bed and adapted, when the ship is subjected to the action of external forces tending to change its position and of not more than a predetermined magnitude, to restrain the ship from moving beyond the confines of the inner circle. The ship is equipped with a set of adjustable propellers adapted, in conjunction with the anchors, to position the ship within the confines of the outer circle when the external forces acting on the ship to change its position exceed the predetermined magnitude. The operation of the propellers is controlled by a computer to which values are fed which are determined by detectors of the position of the ship and of external forces acting upon it.