Abstract: The present invention relates to overpressure protection systems and methods for use on a production system for transferring hydrocarbons from a well on the seafloor to a vessel floating on the surface of the sea. The production system includes a subsea well in fluid communication with a turret buoy through a production flowline and riser system. The turret buoy is capable of connecting to a swivel located on a floating vessel. The overpressure protection device is positioned upstream of the swivel, to prevent overpressure of the production swivel and downstream components located on the floating vessel. The device may include one or more shut down valves, one or more sensors, an actuator assembly, and a control processor. Each shut down valve and sensor is coupled to a production flowline. Each of the sensors is capable of generating a signal based upon a pressure sensed within the production flowline. The actuator assembly is connected to each of the shut down valves for operating the shut down valves.

Abstract: A marine riser system for transferring fluid between a well on the seafloor and a vessel floating on the surface of the sea. The riser system has a turret buoy capable of connecting to a floating vessel; two or more hybrid risers, each of the hybrid risers having a vertical riser, a riser buoy attached to the upper portion of the vertical riser and a flexible jumper connecting the riser buoy to the turret buoy, and wherein the hybrid risers are secured to the seafloor. A flowline may connect a lower portion of each of the vertical risers to a subsea manifold, which interconnects the flowline and a subsea well. The subsea manifold is capable of controlling the flow to or from a subsea well. The hybrid risers are positioned about the turret buoy so that the turret buoy is horizontally balanced while disconnected from a vessel. In another embodiment, the marine riser system is capable of directing a fluid from the floating vessel to a subsea export flowline.

Abstract: A keel joint protector, which, in certain aspects, includes a body made of flexible material, a central open bore through the body, and the body having a plurality of spaced-apart energy management zones therein for diffusing a force applied to a particular part of the body. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 CFR 1.72(b).

Abstract: A tendon or riser connector has a separate lock-down device that overrides the connector's ability to unlock if the riser or tendon goes slack. The connector has a lock ring that engages a groove profile on a receptacle and is prevented from accidentally unlocking with a cam ring and set of blocks. The blocks are movably positioned between engaged and disengaged positions that correspond to the locked and unlocked positions of the lock ring.

Abstract: Disclosed is a riser comprising a plurality of pipelines. In one example there are three such pipelines, extending from the seabed toward the surface and having an upper end supported at a depth below the sea surface, wherein, in one embodiment a first of said pipelines acts as a central structural core, the other pipelines being arranged around said first pipeline. In another embodiment three pipelines are arranged around a structural core. In each case, the first of said pipelines may be a fluid injection line, said other pipelines being production lines. Also disclosed is a riser having buoyancy along at least a part of its length, said buoyancy resulting in said riser having a generally circular cross-section, the circumference of which being non-contiguous. Methods of installing such risers are also are also described.

Abstract: A pipe string (44) is pulled out by a tug boat (30) from a floating structure (12) such as a production vessel, as pipe sections (54, 56) are connected in series on the vessel, to eventually lay the pipe string in a catenary curve from the vessel to the sea floor and then along the sea floor to a distant subsea well head (86). To save time and cost in coupling the pipe sections, lower fatigue resistant pipe couplings, such as non weld-on couplings (120) that include a threaded sleeve (134), are used to connect pipe sections that will lie in a quiescent zone such as on the sea floor (zone Az), and in a zone (Cz) lying along the middle of the catenary curve. Higher fatigue resistant pipe couplings such as weld-on couplings (150) are used along active zones such as top and bottom zones (Dz, Bz) of the catenary curve.

Abstract: Buoyancy unit for use on a riser for sub sea applications, particularly for great depths, with a clamp 11 to be tensioned around the riser 16, and with a tensioning member 18 to damp the clamp 11. Buoyancy bodies 26, 27 are provided to engage with the clamp 11, said clamp 11 having at least one arched element 12-15 providing an annular structure to enclose the riser and to be pressed thereto with a tensioning strap 18. The buoyancy bodies 26, 27 are attached to the arched segments, The clamp 11 is cast from of a concrete material where at least the outer shell or layer is provided to prevent the intrusion of water, the casting of the clamp preferably containing powdered aplite.

Abstract: A riser tensioner for an offshore floating platform has a frame stationarily mounted to the upper portion of the riser. Pistons and cylinders are spaced circumferentially around the riser and connected between the frame and the floating platform. A tubular guide member is mounted to the floating platform for movement in unison in response to waves and currents. The riser extends through the guide member. A guide roller support is mounted to and extends downward from the frame around the guide member. At least one set of guide rollers is mounted to the guide roller support in rolling engagement with the guide member as the guide member moves in unison with the platform.

Abstract: An underwater buoy for hanging a duct between a sea bed and the surface, the buoy including a frame and a plurality of modular members mounted in the frame, the modular members extending between their two opposite modular-member ends, the frame including a longitudinal body for receiving the extended tubular duct, and retainers mounted on the body for maintaining the modular members substantially parallel to the body. The retainers include two retaining structures spaced from each other along the body. The retaining structures are maintained in a fixed position relative to each other in order to hold at least one modular member.

Abstract: A marine structure comprising a supporting member that comprises a wall at least partially delimiting said supporting member such that an inner side of said wall is arranged to at least partially delimit an inner volume of said supporting member and an outer side of said wall is arranged to face the ambient environment of said supporting member. The marine structure further comprises a drain pipe adapted to guide fluid from said marine structure to a body of water at least partially surrounding said marine structure. At least a portion of said outer side of said wall partially delimits said drain pipe.

Abstract: A cold water pumping system comprises a center tube and a cold water pipe surrounding the center tube. The cold water pipe is supported from a bottom end of the center tube and an impeller is coupled to the bottom end of the center tube. The impeller is operable to move water through the cold water pipe, wherein the cold water pipe is comprised of a plurality of segments. Each segment of the cold water pipe comprises at least two frame sections configured to be coupled together to surround the center tube and a removable skin configured to be inserted throughout the perimeter of the at least two sections.

Abstract: A method and arrangement for well completion and intervention operations where a workover riser 4 projecting from a wellhead 6 and up to a vessel 2 is used, and where the upper portion of the workover riser 4 is designed to be displaced from an upper position to a lowered position favorable for rigging work, where at least the upper displaceable portion of the workover riser 4 essentially follows the heave motion of the vessel 2, whereupon the upper displaceable portion of the workover riser 4 is again raised to its upper position, the workover riser 4 being equipped with a telescoping connection 1.

Abstract: An offshore composite enhanced metallic drilling riser is equipped to enable preloading of the composite shell and the metallic riser. A riser has steel end connectors and a continuous metallic inner liner, encased in a composite shell. A segmented hyperboloid shaped profile is located near each of the end fittings for preloading of the composite and the metallic riser. In one version, both halves of the hyperboloid shape are capable of axial movement by adjusting jack bolts connected to one of the hyperboloid halves. One of the halves is limited in axial movement while the other half moves axially away from the restricted half, the movement simultaneously generates the composite pre-load and the metallic riser pre-load. The other version uses fluid pressure between mating faces of the segments to push them apart.

Abstract: Guide arrangement for marine risers, in particular for offshore oil and gas operations. The guide arrangement has at least one guide structure (21, 22) for a length of riser, a frame assembly (10, 10A-D) for supporting said guide structure, anchor means (11, 12) at the seabed, tether means (13, 14) connecting said frame assembly to said anchor means, and a buoyancy element (1) for keeping said guide structure (21, 22) at a desired level in the sea during operation. The guide structure (21, 22) is pivotably supported by said frame assembly (10, 10A-D) with a pivot axis (21P, 22P) being substantially horizontal.

Abstract: There is disclosed a system comprising a structural element; a transport tool carrying a plurality of VIV and/or drag reduction devices; and an installation tool adapted to remove a VIV and/or drag reduction device from the transport tool and to install the device around the structural element.

Abstract: A method and apparatus for conducting simultaneous drilling and production are provided. The apparatus can include a ship shape floating vessel, wherein the ship shape floating vessel includes at least two drilling derricks, at least two drilling modules, and at least one production module, all situated on the upper surface of the ship shape floating vessel. The drilling modules are adapted for conducting drilling operations; the production module is adapted for conducting production operations. The apparatus can include at least two marine risers, wherein each marine riser depends from a drilling or production module toward a hydrocarbon bearing zone or sea floor and is adapted for conducting drilling and/or production operations; at least one production turret located on the lower surface of the ship shape floating vessel; and at least one production riser, wherein the production riser depends from the production turret, extends toward the sea floor, and is adapted for conducting production operations.

Abstract: A method of installing a subsea structure, such as a hybrid riser tower (300) , is disclosed. The riser .tower comprises a main portion (304) and a buoyancy-portion (302) . When installed, the riser tower extends substantially from the seabed towards the surface with the buoyancy portion attached at a top end. The method comprises taking the riser tower to an installation site in a substantially horizontal configuration with said main portion containing a first fluid and said buoyancy portion containing a second fluid, said second fluid being more dense than said first fluid, and tilting the riser tower such that it takes a substantially vertical configuration, while allowing said first fluid in said elongate portion to interchange with said second fluid in said buoyancy portion. Also disclosed is a suitable apparatus for carrying out the method.

Abstract: A riser assembly and method for providing buoyancy to a riser assembly are disclosed. The riser assembly which is of the type for transporting fluids from a sub-sea flowline to a floating structure comprises a first segment of flexible pipe, a further segment of flexible pipe and a rigid buoyancy support for providing at least one buoyancy element at the support.

Abstract: A known deepwater solution for production risers for extracting oil and gas is the SLOR™ riser. The design of the SLOR™ riser is not compatible with large numbers of risers and thus there is a need for a deep water riser that can be deployed in large numbers, for example 20 to 30 risers. The present invention discloses a support frame that can be used to receive a plurality of risers, which can then be connected to a surface vessel.

Abstract: A riser having a riser body having an interior surface, an exterior surface, and two spaced-apart ends, at least one identification assembly on the riser body, the identification assembly having an assembly body and a wave energizable apparatus in the body, the assembly body having an interior surface, an exterior surface, and a channel therethrough in which is positioned part of the riser body, the assembly body releasably secured on the riser body, and the wave energizable apparatus positioned within the assembly body. This abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims, 37 C.F.R. 1.72(b).

Abstract: A spar platform for use in the offshore drilling or production of fossil fuels includes a hull having a centerwell. An airtight and watertight barrier traverses the centerwell, forming a variable buoyancy compartment in the centerwell. In certain embodiments the centerwell is open at the bottom to the sea, while in certain other embodiments the centerwell is sealed at the bottom. At least one sleeve for accommodating a riser extends through the barrier and the variable buoyancy compartment to the bottom of the centerwell. The sleeve has an open upper end to provide a drain for water accumulating in the centerwell, and it forms an airtight and watertight seal at its juncture with the barrier. In some embodiments, two or more airtight and watertight barriers are provided across the centerwell, defining an airtight and watertight fixed buoyancy chamber between each adjacent pair of barriers.

Abstract: A bend-limiting conduit controls the curvature of a catenary riser extending from the seafloor as it enters the centerwell of a spar-type offshore platform through the keel of the platform. The conduit has a bore dimensioned to receive the riser, and it extends from an upper end constrained within the keel to a lower end disposed below the keel. The conduit has increasing flexibility and weight per unit length from the upper end to the lower end, which results in a lateral load being applied to the riser as it passes through the conduit, thereby causing a gentle and gradual transition in the riser from a curved configuration at the lower end of the conduit, to a straight configuration as it emerges from the upper end of the conduit.

Abstract: A tendon or riser connector has a separate lock-down device that overrides the connector's ability to unlock if the riser or tendon goes slack. The locking device has blocks that are radially actuated through a hole in a receptacle to engage a profile in the connector. When the blocks are pushed in, they prevent the connector from moving downward, and thus prevent any unlocking of the connector. The blocks are secured with pivotable gates that engage and retain the blocks in both positions.

Abstract: A riser support system for use in a body of water comprises a buoyant and ballastable support structure and a plurality of substantially vertical and rigid risers each of which is attached to the inside of the support structure at a location below the center of buoyancy of the support structure and below the surface of the body of water. Usually, each riser passes through the inside of a single tube in the support structure. Typically, the riser support system is used to support a plurality of risers and their surface wellheads inside the hull of an offshore platform, usually in such a manner that the axial movement of the risers and support structure is independent of the axial movement of the hull.

Abstract: A sea vessel exploration and production system is provided, wherein the system includes a drilling station formed from at least one section of a first sea vessel hull; and a docking station, which is also formed from at least one section of a second sea vessel hull. A mooring system suitable for connecting the drilling station to the docking station is also provided. Means for anchoring the vessels to the seafloor, and for attaching them to turret buoys, are also considered. Various exploration and production packages, as well as equipment required to deploy and control a self-standing riser system in either deep or shallow waters, are also described.

Abstract: The invention relates to a bearing element, a universal joint and an offshore construction, comprising such a bearing element.

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 support (1) includes a working deck (2) and floatation members (3) supporting this deck (2). According to the invention, the spacing between the vertical axes (Z) passing through the centre of the floatation members (3) is such that the sum of the moments, taken in relation to the horizontal axis passing through the centre of the support (1) is perpendicular to the swell direction, of the vertical excitation forces of the swell on the floatation members (3) situated on one side of the vertical plane (P) passing through this horizontal axis is equal to the corresponding sum associated with the floatation members (3) situated on the other side of this plane, when the swell period is equal to the period of a swell having this direction and of which the yearly probability of being encountered on the site or the support where it is installed is 1/100.

Abstract: An apparatus for supporting a steel catenary riser (SCR) from a floating structure having a keel includes a flexible support tube or keel sleeve through which the SCR passes. The support tube or keel sleeve includes a pivot mechanism that is lockably received in a receptacle fixed to the floating structure. A method of supporting an SCR from a floating structure includes the steps of inserting a first end of the SCR into a support tube or keel sleeve; fixing the support tube or keel sleeve to the SCR; pulling the support tube or keel sleeve into a receptacle fixed to the floating structure; releasing the support tube or keel sleeve from the SCR; pulling the SCR through the support tube or keel sleeve up to an attachment point on the structure; fixing the SCR to the structure; and fixing the support tube or keel sleeve to the SCR.

Abstract: A tensioner system for a top-tensioned riser in a floating platform includes a hydro-pneumatic tensioner assembly resiliently mounted to the floating platform, and a riser support conductor surrounding the riser coaxially, wherein the support conductor conveys a pull-type tensional force from the hydro-pneumatic tensioner assembly to the riser through a riser conductor coupling assembly that engages the tensioner assembly and the riser support conductor to convey the tensional force. A riser tension joint support assembly conveys the tensional force from the riser support conductor to a riser tension joint on the riser. The tensioner assembly compensates for relative platform motion including pitch, heave, and yaw. Also a reactive load assembly is mounted to the platform and reacts to a two-point dynamic bending moment imposed on the riser support conductor, while resisting riser support conductor rotation.

Abstract: An improved subsea riser for use in oil and gas drilling applications having a cylindrical floatation member adapted for attachment to a blow out preventer. The member may be configured with a plurality of generally evenly spaced dimples, indentations or protrusions about the circumference of the member to provide more streamlined water flow around the riser reducing turbulence and oscillations of the riser. The dimples, indentations or protrusions may be arranged in several ways including icosahedral, dodecahedral, octahedral and other polyhedral configurations.

Abstract: A buoyancy system includes a plurality of buoyancy joints distributed along a riser system. Each joint can include a riser pipe, an external frame disposed around a riser and a vessel, and a buoyant cladding disposed between the vessel and the frame.

Abstract: The current subject matter relates to compliant variable tension risers to connect deep-water subsea wellheads to a single floating platform in wet tree or dry try systems. The variable tension risers allow several subsea wellheads, in water depths from 1220 to 3050 meters, at lateral offsets from one-tenth to twice the depth or more, to tie back to a single floating platform. Also, the current subject matter relates to methods to counter buoyancy and install variable tension risers using a weighted chain ballast line.

Abstract: A deep draft semi submersible structure wherein the semi-submersible has a center of gravity below its center of buoyancy and the structure is a floating vessel with at least three vertically oriented buoyant columns. Each of the vertically oriented buoyant columns have at least one ballasted compartment and the columns are spaced apart at a sufficient distance to reduce vortex induced vibration amplitude. There are at least two connecting structural sealed trusses connected to the columns below sea level, they are positioned to minimize hydrodynamic wave action on the trusses and to transfer shear loads between the columns while remaining transparent to wave and ocean current motion.

Abstract: A riser tensioner for an offshore floating platform has a frame stationarily mounted to the upper portion of the riser. Pistons and cylinders are spaced circumferentially around the riser and connected between the frame and the floating platform. A tubular guide member is mounted to the floating platform for movement in unison in response to waves and currents. The riser extends through the guide member. A guide roller support is mounted to and extends downward from the frame around the guide member. At least one set of guide rollers is mounted to the guide roller support in rolling engagement with the guide member as the guide member moves in unison with the platform.

Abstract: A centralizer system is provided for use in a marine riser system, the centralizer being preferably heat-shrink fitted to an upset portion of a keel joint, the upset portion having tapered sections on the upper and lower ends that gradually blend into the outer diameter of the pipe used as the keel joint, the centralizer preferably comprising axially extending annular grooves in surrounding relationship to the upset portion, the grooves serving to permit forces acting on the centralizer to be redirected or dissipated to thereby prevent excessive buildup on a selected region of the upset portion adjacent the radial grooves.

Abstract: A riser connector connects the upper portion of a riser (12) having a latching enlargement (32) to a receptacle (14) on a vessel (16), so the riser upper end (22) can connect to a fluid coupling (42) leading to a conduit (40) on the vessel. A double-click mechanism (88), with parts on the enlargement and on the receptacle, turns a load ring on the enlargement to latch the enlargement in place when it is lifted to an upper position and lowered to a latched position, and releases it by again lifting and lowering. A cable coupling (24) is temporarily mounted on the top of the riser to enable the riser to be lifted by a cable (26), the cable coupling being later removed to connect the riser upper end to the fluid coupling on the vessel.

Abstract: A vessel for exploration of hydrocarbons includes one or more risers extending from the vessel to the seabed, a hydrocarbon processing unit connected to the one or more risers and to a storage or transport structure for storing the processed hydrocarbons. The vessel is anchored to the seabed, the vessel includes a lifting member for lowering risers vertically towards the sea bed and for connecting a riser with a first end to a subsea hydrocarbon structure, which riser includes a connector on a second end, the vessel having a connector for attaching to the riser connector and for placing the riser in fluid connection with the processing unit.

Abstract: A tendon or riser connector has a separate lock-down device that overrides the connector's ability to unlock if the riser or tendon goes slack. The connector has a lock ring that engages a groove profile on a receptacle and is prevented from accidentally unlocking with a cam ring and set of blocks. The blocks are movably positioned between engaged and disengaged positions that correspond to the locked and unlocked positions of the lock ring.

Abstract: A slip joint for a riser between a well and a floating petroleum installation, for example an oil platform. The slip joint includes, an outer pipe and an inner pipe, the pipes arranged to enable telescopic movement relative to one another in order to compensate for a change in distance between the sea bottom and the platform. The inner pipe is connected to a piston, the piston being operable in response to hydraulic pressure for inflicting a tensile force on riser. The outer diameter of the inner pipe is adapted to the diameter of outer pipe so as to form an annulus between the pipes. The piston is fixedly connected to inner pipe at or close to a downwardly directed end thereof, the annulus and the piston being subjected to hydraulic pressure. A protective sleeve is provided below the piston, which is slippingly arranged within outer pipe.

Abstract: A deep draft semi submersible structure wherein the semi-submersible has a center of gravity below its center of buoyancy and the structure is a floating vessel with at least three vertically oriented buoyant columns. Each of the vertically oriented buoyant columns have at least one ballasted compartment and the columns are spaced apart at a sufficient distance to reduce vortex induced vibration amplitude. There are at least two connecting structural sealed trusses connected to the columns below sea level, they are positioned to minimize hydrodynamic wave action on the trusses and to transfer shear loads between the columns while remaining transparent to wave and ocean current motion.

Abstract: A method and a device for installing a sub-sea riser for an offshore operation, between a base installation disposed on the sea bed and a sea installation protruding above the base installation. The sub-sea riser is provided with a first end and a second end. The method comprises the following stages in the following order: a) the first end of the riser is joined to the sea installation; b) the sub-sea riser is deployed; c) the second end of the riser is guided towards the base installation; d) the second end is coupled to the base installation by releasing the second end and the efforts of the recoil force exerted on the base installation are transferred; e) the second end and the base installation are connected to each other.

Abstract: A water intake riser that can be suspended from a vessel having a riser connected to a riser hanger, which riser hanger includes a first tubular element, a second tubular element to which the riser is connected, a flexible load transfer element joining the tubular elements, and a hose of which the ends are secured to the adjacent ends of the tubular elements.

Abstract: A tendon or riser connector has a separate lock-down device that overrides the connector's ability to unlock if the riser or tendon goes slack. The locking device has blocks that are radially actuated through a hole in a receptacle to engage a profile in the connector. When the blocks are pushed in, they prevent the connector from moving downward, and thus prevent any unlocking of the connector. The blocks are secured with pivotable gates that engage and retain the blocks in both positions.

Abstract: A guide tube for a flexible pipe for transporting hydrocarbons comprising an internal tubular element of a substantially rectilinear section extending along an axis (A) and extended by a free section having a curvature along its length and a wall which is internal with respect to the curvature against which the flexible pipe is accommodated when frictionally carried through guides. The rectilinear section comprises eccentric guides for directing the flexible pipe away from the axis (A) and in a direction opposite to the curvature of the free section such that the pipe is deviated from the internal wall.

Abstract: A shallow water riser extending between a seabed connection and a floating support connection and of a length through the shallow water to be in wave form with at least one and, as illustrated, two wave areas in contact with the seabed. A protective sheath optionally surrounds the riser at the contact regions with the seabed. The upraised wave portions are supported by float elements.

Abstract: A composite tendon comprises a main body of rope type construction. The ends of the tendon body terminate in eye splices for connection to termination connectors. Component strands of the composite tendon may form separate eye splices for connection to the termination connectors. Multiple composite tendons of rope type construction may be joined to a single termination connector. The termination connectors secure one end of the tendon to the seabed and the opposite end thereof to a floating platform.

Abstract: A riser joint keel assembly. A tapered riser joint is connected to a larger diameter outer sleeve through a connection that allows the tapered section and outer sleeve to function as one unit. In the combined design, the outer sleeve provides the required sliding interface between the riser and the guide at the keel of the hull while also providing some of the bending compliance needed to transition from the riser supported in the hull to the riser unsupported below the hull. The tapered section also provides the remaining bending compliance needed for the transition. The connection between the tapered and sleeve sections is a forged, machined ring plate welded to the bottom end of the sleeve, which provides a base for either bolted or threaded type attachment points for the tapered riser joint below the ring plate and the internal riser joint that continues to the surface.

Abstract: An undersea pipe of the riser type providing a connection between a floating support and the sea bottom. The riser has a rigid pipe of the catenary type extending from the floating support to a point of contact with the sea bottom. The catenary riser comprises a lower pipe portion terminating at the point of contact. The apparent weight per unit length in water of the lower pipe portion being at least 25% less than that of the remainder of the pipe constituting the catenary riser.

Abstract: A riser for conveying fluids from a subsea location to a surface vessel comprises an upper section which is located in a confining conduit, said upper section being allowed to deform elastically into a helical configuration against the inside of the confining conduit when subjected to axial compression. The riser further comprises a main section extending below the confining conduit to said subsea location. The riser also comprises a buoyancy arrangement which keeps the main section in tension. This arrangement allows the Christmas tree to be supported directly on the deck of the surface structure and allows the surface structure to support the weight of the tree as well as the tubing which is hung off from the tree.