Abstract: Systems and methods for pressure communication within a hydro-pneumatic cylinder are provided. The hydro-pneumatic cylinder generally includes a rod, a barrel coaxial to the rod, and a piston assembly disposed within the barrel and connected to the rod. The barrel is hollow to define a chamber, and the piston assembly is axially movable within the chamber to stroke the rod relative to the barrel. The hydro-pneumatic cylinder includes: a flow path formed axially through the rod of the cylinder. This flow path may allow for pressure communication between a low-pressure side of the cylinder and a pressure energized lower pin located at a distal end of the rod. The lower pin may be actuated, via this pressure communication to secure the end of the cylinder to a tension ring on a riser.

Abstract: A top interface for subsea riser on offshore, floating vessel has an upper funnel and a co-axial lower funnel in spaced-apart relation. Tension loads on the riser are reacted at the upper funnel while lateral and bending loads are reacted at the lower funnel. The riser top interface may be used with flexible risers or steel catenary risers.

Abstract: A fairlead includes a chain guide support structure and a clump weight engagement member. A clump weight assembly includes a clump weight body, a clump weight coupled to the clump weight body, and a spring housing. The spring housing includes an upper housing wall and at least one spring operatively coupled between the upper housing wall and the clump weight. The clump weight body may be selectively engageable and disengageable with the fairlead to form a fairlead and clump weight assembly. A method of installing and using the clump weight includes engaging the spring housing with the clump weight engagement member, and latching the clump weight body to the clump weight engagement member.

Abstract: A tensioner for maintaining a tensile force in a riser extending from a subsea wellhead assembly to a deck of a floating platform includes a hydro-pneumatic assembly having a first section secured to the deck and a second section secured to a support frame. A pivot joint is coupled to the riser and to the support frame, so that the riser is retained axially static with respect to the support frame and is pivotable with respect to the support frame. A guide assembly has at least two guide elements, the guide elements being axially spaced from each other so that when the deck and the support frame move axially relative to each other, the guide assembly restricts relative rotational movement between the deck and the support frame.

Abstract: A riser tension protector and coiled tubing lift frame assembly including same for use as a backup heave compensator is described. The assembly includes a frame having an upper frame section adapted for attachment to a top drive system and a lower frame section adapted to interface with a flowhead assembly; and a pair of pneumatic cylinders spaced apart from one another. The pneumatic cylinders have a respective cylinder barrel and a piston rod translatable therein, a free end of the piston rods being fixed to the upper frame section and a lower end of the cylinder barrels being fixed relative to the lower frame section.

Abstract: A riser tensioner system for offsetting heave and yaw between the riser and the rig on offshore drilling and production platforms during drilling and production operations. A plurality of hydraulic cylinders are connected by a spider. The spider allows individual cylinders to be disconnected from the riser, suspended in place with equipment integral to the riser system, without cranes, and can be repaired without loosening bolts or screws and without wrenches or torque wrenches. Maintenance can take place on one cylinder without disturbing other cylinders supporting the riser. The cylinders can be oriented in a vertical arranged or slanted in an upper end in an inverted cone or “A” frame orientation.

Abstract: A riser tensioner for maintaining a tensile force on a riser extending through an opening in a deck of a floating platform includes a frame assembly that may be quickly bolted together in the field. The frame assembly includes a plurality of tensioner legs that may be installed on an un-level deck yet still provide a level support of the riser. Lower leg mounting assemblies include a slip ring for mounting directly to the deck and a deck mounting member received in the slip ring at a variable angle and having an upwardly extending shaft passing into a bore in a lower end of a tensioner leg.

Abstract: A tensioner assembly for applying tension to a tubular member, such as a riser, can include an upper latch connected to the tubular member, a platform with a bore, and a lower latch ring. After applying tension to the tubular member, the lower latch ring can be closed around the tubular member so that when the tension is released, the upper latch lands on and engages the lower latch. The assembly can include a locking mechanism that prevents axial movement of the upper latch, relative to the lower latch, after engagement. The upper latch can self-center on the lower latch as it is moved into the latching position.

Abstract: A riser tensioner assembly for supporting risers on an offshore drilling platform includes a frame assembly and a plurality of riser centralizers circumferentially spaced about the frame assembly. The riser centralizers each include a clevis supporting roller for bearing on a riser to limit lateral movement of the riser with respect to the frame assembly. The clevis includes an elongated channel along which the roller is movable to accommodate angular movement of the riser with respect to the frame assembly.

Abstract: A tension frame (2) for its application in a riser system for hydrocarbon exploration and production. The tension frame is (2) installed on a well control unit (5) atop at least one riser (9) in said riser system. The frame is adapted to receive a pressure control unit and hold it in line with the centre of the riser. The tension frame (2) houses at least two pre-installed pressure control equipment units (3, 4) of which one at a time is adapted to be hold at an active position, in which the unit is in line with the centre of the riser, and the other is adapted to be kept in a parked position within the frame.

Abstract: A tensioner assembly for applying tension to a tubular member, such as a riser, can include an upper latch connected to the tubular member, a platform with a bore, and a plurality of lower latch segments, each having a base that is pivotally connected to the platform. After applying tension to the tubular member, the segments pivot inward to form an annular lower latch ring having an inner diameter less than an outer diameter of the upper latch. The assembly can include a locking mechanism that prevents axial movement of the upper latch, relative to the lower latch ring, after engagement. The upper latch can self-center on the lower latch as it is moved into the latching position.

Abstract: A coupler having two degrees of axial freedom couples a hydro-pneumatic cylinder to a tensioner ring of a riser tensioner mounted to a platform. A post extends along an axis of the cylinder and an intermediate sleeve is disposed around the post to form a post annulus. An outer sleeve is secured to the tensioner ring and defines a cavity into which the post and intermediate sleeve are inserted so that an annulus is formed between the sleeve and the outer sleeve. The Outer sleeve is coupled to the intermediate sleeve so that the outer sleeve may pivot on the coupling between the outer sleeve and the intermediate sleeve relative to the intermediate sleeve. The intermediate sleeve is coupled to the post so that the intermediate sleeve may pivot on the coupling between the intermediate sleeve and the post relative to the post.

Abstract: A deep draft semi-submersible production and drilling platform unit with dry trees is described. The platform unit preferably comprises four columns, a ring pontoon, a two-axis symmetrical hull with draft in the range of 100 to 155 feet, top-tensioned risers with push or pull tensioners of preferred combined vertical stiffness of 10% to 30% of the platform water plane stiffness, a wellbay with a well spacing in the range of 12 to 18 feet, a riser guiding system supported by the pontoons or at an elevated level, topside facilities supported by a box type of deck structure, mooring lines, and catenary risers.

Abstract: An apparatus for restraining an assembly suspended by a structure on an offshore platform or vessel, includes a movable carrier configured for controllable movement on a structure of the platform or vessel. A restraining member is movably connected to the carrier via a joint and the restraining member includes an abutment region for abutment with at least one element of the assembly. An assembly-locking device is provided for selectively and releasably locking at least one element of the assembly to the restraining member. A restraining device for a tensioner assembly which is suspended by a structure on an offshore platform or vessel and extending into a moonpool, includes a pair of restraining apparatuses, arranged on opposite sides of the moonpool and individually movable on respective rails by a traction device in interaction with respective racks.

Abstract: A tensioner assembly for applying tension to a tubular member, such as a riser, can include an upper latch connected to the tubular member, a platform with a bore, and a plurality of lower latch segments, each having a base that is pivotally connected to the platform. After applying tension to the tubular member, the segments pivot inward to form an annular lower latch ring having an inner diameter less than an outer diameter of the upper latch. The assembly can include a locking mechanism that prevents axial movement of the upper latch, relative to the lower latch ring, after engagement. The upper latch can self-center on the lower latch as it is moved into the latching position.

Abstract: The present invention generally relates to an apparatus and method for compensating a landing string due to movement of a floating rig platform. In one aspect, a compensation system for use with a landing string is provided. The compensation system includes a slip joint member attachable to the landing string, the slip joint member having an upper portion and a lower portion. The compensation system further includes a first lock assembly configured to connect the upper portion of the slip joint member to a floating rig. Additionally, the compensation system includes a second lock assembly configured to connect the lower portion of the slip joint member to a riser disposed below the floating rig. In another aspect, a method for compensating a landing string due to movement of a floating rig is provided.

Abstract: A tensioning apparatus for applying a substantially constant tension to a workover riser (12) includes a first portion (40) adapted to be coupled to a workover riser, a second portion (44) adapted to be coupled to a marine riser (14) and tensioning means (46) for providing relative movement between the first portion and the second portion to, in use, tension, the workover riser.

Abstract: Systems and methods for controlling movement of an elongated member providing communication between a vessel and a subsea unit are provided. The method can include connecting a positively buoyant member to an elongated member at a first location and connecting a negatively buoyant member to the elongated member at a second location, wherein at least a portion of the negatively buoyant member rests on a seabed when the elongated member is in an operational null position.

Abstract: A riser tensioner system for tensioning a riser at an offshore vessel includes a frame adapted to affix to the vessel. An elongate riser joint is provided for coupling into the riser. The riser joint has an axial flange portion projecting laterally outward therefrom from and extending axially along a length of the riser joint. Ram pistons are arranged about the frame to couple to the riser and to support the riser in tension. Centralizer arms are arranged on the frame to extend into proximity to the flange portion of the riser joint when the riser joint is received through the frame.

Abstract: A riser tensioner for maintaining a tensile force on a riser extending through an opening in a deck of a floating platform includes a frame assembly that may be quickly bolted together in the field. The frame assembly includes a plurality of tensioner legs that may be installed on an un-level deck yet still provide a level support of the riser. Lower leg mounting assemblies include a slip ring for mounting directly to the deck and a deck mounting member received in the slip ring at a variable angle and having an upwardly extending shaft passing into a bore in a lower end of a tensioner leg.

Abstract: An enhanced riser control system may employ electrical tensioners coupled to a drilling riser by wires. The electrical tensioners may provide quick response to a tension controller to handle positioning of the drilling riser. The electrical tensioners of the enhanced riser control system may be combined with hydro-pneumatic tensioners in a riser hybrid tensioning system. A controller within the enhanced riser control system may be configured to distribute tension to electrical tensioners and to control electrical tensioners to adjust the length of the first and second wires. The electrical tensioners may be used, for example, to suppress vortex-induced-vibration (VIV) and control drilling riser recoil.

Abstract: A top-tensioned riser (TTR) is supported by a tensioning system on the deck of a floating platform. The tension ring may include an elastomeric layer which permits small angular and lateral displacements of the tension joint. The tension joint comprises a tapered section to resist the bending moment and shear imposed by the vessel's motion. The riser tension joint may be supported laterally by rollers below the tension ring. The rollers react on the tapered section when the riser strokes up and down. The tapered section may be engineered to maximize the use of the tension joint, and to reduce bending moment and shear loads imposed on the tensioning system. In certain embodiments, there may be a small gap between the rollers and the tapered section. In certain other embodiments, the rollers may be spring-loaded to increase the stability of surface equipment on the upper terminus of the riser.

Abstract: A tension frame (2) for its application in a riser system for hydrocarbon exploration and production. The tension frame is (2) installed on a well control unit (5) atop at least one riser (9) in said riser system. The frame is adapted to receive a pressure control unit and hold it in line with the centre of the riser. The tension frame (2) houses at least two pre-installed pressure control equipment units (3, 4) of which one at a time is adapted to be hold at an active position, in which the unit is in line with the centre of the riser, and the other is adapted to be kept in a parked position within the frame.

Abstract: An improved motion compensator device that includes a compensated framework for various types of well intervention operations where a stable work area is required that is stationary to the sea bed and equipment in the annulus. The device is intended for use on offshore drilling vessels that are primarily either moored or dynamically positioned and therefore subject to the motions created by the sea. The device is designed to compensate for the vertical motion of the rig by means of two steel frame assemblies, pneumatic compensating cylinders, and a load and motion transfer apparatus.

Abstract: A riser tensioner system maintains a tensile force in a riser having an axis and extending from a subsea wellhead assembly through an opening in a floating platform deck. The tensioner includes a plurality of tensioner legs having lower ends mounted to the deck, and upper ends having slots formed therein to receive leg attachment plates having an opening therein through which a tubular support ring passes. A plurality of cylinders extend between the tubular support ring and a tensioner ring and couple to the support ring with cylinder attachment plates through which the tubular support ring passes. An upper end of each cylinder pivots about the mounting point, and a lower end of each cylinder adjustably mounts to the tensioner ring.

Abstract: Riser management systems, apparatus, and methods to maintain a selected range of tension on a plurality of risers extending between subsea well equipment and a floating vessel, are provided. A riser management system can include a mono-buoyancy can platform operably coupled to a plurality of risers extending between subsea well equipment and a moored floating vessel, and a plurality of tensioner units each connected to a top portion of a separate one of the risers to provide tension to each of the risers. The mono-buoyancy can platform can provide tension to each of the risers sufficient to compensate for a relative vertical offset between the risers and the vessel due to vessel movement, which generally affects each of the risers equally, within tolerances, while the tensioner units can simultaneously provide tension to compensate for one or more additional factors which can affect each riser differently.

Abstract: A seafastening apparatus includes a movable frame having an opening configured for receiving and at least partially supporting an equipment unit. A locking device is configured for selective locking and releasing of the equipment unit and hence controlling lateral movements of the equipment unit relative to the apparatus. The locking device includes wires configured for connection to the equipment unit and tensioners configured for controlling the tension in each wire, and a pair of extendible and retractable arms are configured for conveying and guiding at least on of the wires.

Abstract: A push-up tensioner for maintaining a tensile force in a riser having an axis couples to a floating platform and maintains the tensile force while the riser tilts variably from the vertical. The tensioner includes a plurality of cylinders having a lower end pivotally coupled to the deck. The cylinders are substantially perpendicular to the deck in the running position and at an angle to the deck in the tensioning position. After running of the riser, a placement assembly moves the cylinders from the running position to the tensioning position. A tensioner ring is run on the riser proximate to an upper end of the cylinders, and the cylinders are then automatically coupled to the tensioner ring.

Abstract: A riser tensioning system with an individual riser unit on an oil or gas platform. The platform has a traveling trolley structure with at least one trolley bearing and a centralizer. The trolley bearing is coupled to at least one guide rail configured to allow vertical movement of said traveling trolley structure. The traveling trolley structure is coupled to a riser collar configured to support a top of the riser. The riser tensioning system has at least one cylinder coupled to the traveling trolley structure on one end and secured on an opposite end such that the cylinder is adapted to push or pull the traveling trolley structure vertically.

Abstract: A connector assembly that can be used to connect a tension ring to a telescoping joint on a riser by using a lower set of hydraulically actuated dogs. A set of hydraulically actuated hang-off dogs on the connector assembly can be used to connect the tension ring to a diverter housing mounted on a rig. To prevent accidental disengagement of the hang-off dogs, a hydraulically actuated lock ring is used to provide a positive stop against the back of the hang-off dogs.

Abstract: A coupler having two degrees of axial freedom couples a hydro-pneumatic cylinder to a tensioner ring of a riser tensioner mounted to a platform. A post extends along an axis of the cylinder and an intermediate sleeve is disposed around the post to form a post annulus. An outer sleeve is secured to the tensioner ring and defines a cavity into which the post and intermediate sleeve are inserted so that an annulus is formed between the sleeve and the outer sleeve. The Outer sleeve is coupled to the intermediate sleeve so that the outer sleeve may pivot on the coupling between the outer sleeve and the intermediate sleeve relative to the intermediate sleeve. The intermediate sleeve is coupled to the post so that the intermediate sleeve may pivot on the coupling between the intermediate sleeve and the post relative to the post.

Abstract: A heave compensation system that facilitates the transfer of pipe between a floating platform and a snubbing jack. The heave compensation system includes a first end connected to the floating platform and a second end in connection with a traveling slip assembly of the snubbing jack, the heave compensation system is operable between a disengaged position and an engaged position. When the heave compensation system is in the disengaged position the traveling slip assembly moves separate and independent from the movement of the floating platform, and when the heave compensation system is in the engaged position the traveling slip assembly is locked in a constant position relative to the floating platform.

Abstract: A riser tensioner that tensions a riser extending to the seabed from a drilling ship which drills for submarine resources such as oil. The riser tensioner is disposed under a drilling ship to tension a riser used for drilling operation of submarine resources and includes a plurality of cylinders. The riser tensioner further includes: an injection nozzle for injecting water to a surface of a piston rod exposed from each of the cylinders; and a scraper unit which removes salt or seawater from the surface of the piston rod by scrapping the surface of the piston rod to prevent salt from accumulating on the surface of the piston rod.

Abstract: A riser tensioner that includes an oil collecting means and tensions a riser extending to the seabed from a drilling ship which drills for submarine resources. The riser tensioner further includes a piston rod partially inserted into each of the cylinders and reciprocating within the cylinder, a piston seal disposed between a head of the piston rod and a wall of the cylinder to provide fluid sealing, an oil collection passage extending from the head of the piston rod to an outside of the cylinder through the piston rod to allow oil leaking into the cylinder through the piston seal to be discharged from the cylinder to the outside of the cylinder through the oil collection passage, and an oil leakage detection sensor which detects oil leakage positioned on the head of the piston rod.

Abstract: A riser tensioner has an emergency seal and tensions a riser extending to the seabed from a drilling ship which drills for submarine resources such as oil. The riser tensioner is disposed under a drilling ship to tension a riser used for drilling operation of submarine resources and including a plurality of cylinders into which oil is supplied. The riser tensioner further includes a piston rod partially inserted into each of the cylinders and reciprocating within the cylinder, a piston seal disposed between a head of the piston rod and a wall of the cylinder to provide fluid sealing therebetween; an oil leakage detector detecting oil leakage through the piston seal, and an emergency seal disposed in a groove formed at an upper portion of the head of the piston rod to be compressed towards the wall of the cylinder and protrude from the head of the piston rod to prevent oil leakage through the wall of the cylinder when the oil leakage detector detects oil leakage.

Abstract: A push-up tensioner for maintaining a tensile force in a riser having an axis couples to a floating platform and maintains the tensile force while the riser tilts variably from the vertical. The tensioner includes a plurality of cylinders having a lower end pivotally coupled to the deck. The cylinders are substantially perpendicular to the deck in the running position and at an angle to the deck in the tensioning position. After running of the riser, a placement assembly moves the cylinders from the running position to the tensioning position. A tensioner ring is run on the riser proximate to an upper end of the cylinders, and the cylinders are then automatically coupled to the tensioner ring.

Abstract: The disclosure provides a deck tensioning system, supporting multiple risers, that is coupled to an offshore platform and compensated for heave and horizontal movement. Such a tensioning system provides simplified access to the production trees on the risers. The tensioning system provides tensioning for a tensioning deck to which the multiple risers are coupled, while reducing the tensioning cylinders for individual risers. The deck tensioning system further provides a simplified tension flex connector (“TFC”) with an intermediate movable member for each riser. The TFC assists in absorbing and/or adjusting for forces that may cause the tensioning deck to pitch and roll from the interactions between the multiple risers coupled to the tensioning deck as a unitary structure. If a fire or other event causes damage to the tension flex connector, the tension flex connector is designed to maintain a supporting connection with the riser without the intermediate movable member.

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: This method comprises connecting a downstream point (40) of a pipe (24) to a buoy (26) and completely submerging the buoy (26). It comprises deploying in the body of water (12) an intermediate section (30) of the pipe (24) from the downstream point (40) to at least as far as an upstream point (38), anchoring the upstream point (38), and tensioning the intermediate section (30) to keep it vertical. The connecting step includes activating a traction unit (96) to raise the downstream point (40) on the buoy (26). During the connecting step, the buoy (26) is carried in the body of water (12) virtually exclusively by its own floatability.

Abstract: An improved motion compensator device that includes a compensated framework for various types of well intervention operations where a stable work area is required that is stationary to the sea bed and equipment in the annulus. The device is intended for use on offshore drilling vessels that are primarily either moored or dynamically positioned and therefore subject to the motions created by the sea. The device is designed to compensate for the vertical motion of the rig by means of two steel frame assemblies, pneumatic compensating cylinders, and a load and motion transfer apparatus.

Abstract: A tensioner system for an offshore drilling rig for drilling a well with recoil controls is disclosed herein. The tensioner system can include removable independently operable riser tensioner assemblies. Each removable independently operable riser tensioner assembly can include a bidirectional riser recoil valve and a hydraulic cylinder connected thereto. The hydraulic cylinder can power a rod engaged with a clevis and a blind end clevis. The clevis can engage a tension ring on a drilling riser. A fluid containment storage can be connected to the bidirectional riser recoil valve and the hydraulic cylinder, and can have a goose neck for connecting to a flexible jumper. A controller can be connected to the bidirectional riser recoil valve for regulating flow of hydraulic fluid therethrough to control a disconnect process of the drilling riser by controlled raising or lowering of the drilling riser.

Abstract: A riser tensioner configured to apply a tension to a riser. The riser tensioner includes a frame configured to be fixedly attached to the riser; plural cylinder assemblies spaced around the riser, each cylinder assembly having a cylinder and a piston configured to slidably move inside the cylinder, the piston being configured to connect to the frame; a guide roller support stationarily mounted to and extending from the frame; at least one bearing fixedly attached to the guide roller support; and a guide member configured to be in rolling engagement with the at least one bearing as the cylinder moves relative to the frame.

Abstract: An apparatus to restrain a riser tensioner of an offshore drilling rig includes a restraint cone configured to fit within hydraulic cylinders of the riser tensioner, a hoist configured to extend and retract the restraint cone, and a tension member extending from a lower end of the restraint cone, the tension member configured to engage a lower end of the riser tensioner and maintain a wedging action between the restraint cone and the hydraulic cylinders.

Abstract: Hang-off adapters for use in offshore riser systems are provided that seat in a tension ring while allowing for relative rotation between the tension ring and the riser. In one embodiment, the hang-off adapter may comprise a tension ring interface configured to engage an inner landing of a tension ring, the tension ring interface being in the shape of a ring.

Abstract: This method comprises connecting a downstream point (40) of a pipe (24) to a buoy (26) and completely submerging the buoy (26). It comprises deploying in the body of water (12) an intermediate section (30) of the pipe (24) from the downstream point (40) to at least as far as an upstream point (38), anchoring the upstream point (38), and tensioning the intermediate (section (30) to keep it vertical. The height of the buoy (26) is less than 1.5 times its greatest transverse dimension. The method comprises moving the buoy (26) between a remote position and an installed position in line with an anchoring region, keeping the buoy (26) partly submerged on the surface (16) of the body of water.

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: 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 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 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 method for tensioning for oil and natural gas floating platforms and floating vessels using a plurality of self contained dual pressure cylinders for adjusting simultaneously low and high pressures in low pressure and high pressure channels. The method can be used on a floating structure to dampen the effects of sea waves and wind load between casing from a well and the floating structure.