Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B22/00—Buoys
  • B63B22/02—Buoys specially adapted for mooring a vessel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B22/00—Buoys
  • B63B22/02—Buoys specially adapted for mooring a vessel
  • B63B22/021—Buoys specially adapted for mooring a vessel and for transferring fluids, e.g. liquids
  • B63B22/025—Buoys specially adapted for mooring a vessel and for transferring fluids, e.g. liquids and comprising a restoring force in the mooring connection provided by means of weight, float or spring devices

Definitions

• the invention relates to an apparatus for connecting two offshore units and is provided with a coupling element which is, via a first set of coupling means, connectable with the one offshore unit and, via a second set of coupling means, with the other offshore unit, where, further, resetting facilities are present for compensating movements between the two offshore units.
• Such a connecting apparatus is, for instance, used for connecting a tender drilling unit and a wellhead platform or a production platform.
• Such connecting apparatuses generally have a relatively stiff and rigid design, so that they can only be used in relatively mild environmental conditions.
• stretchers i.e. lines with much stretch which are provided between the two offshore units under bias. A result of this is that the two offshore units are pulled towards each other.
• the bias in the stretchers needs to be compensated by the positioning systems of the offshore units, for instance anchor or thruster systems. This often results in additional anchor lines needing to be provided, which requires extra investments and installation time.
• ballast weight is needed.
• a connecting apparatus is inter alia used to couple tankers to offloading stations.
• the ballast weight is suspended from rods which are hingedly connected with an offshore unit.
• the bearing capacity of the offshore unit is reduced considerably.
• the magnitude of the ballast weight is such that the installation thereof cannot take place at sea, but already needs to take place in the harbor in advance.
• the coupling element comprises a frame
• the two sets of coupling means connect the frame with the one and the other offshore unit, respectively, in a manner allowing pivotal movement and rotation
• at least one set of coupling means is provided with a first and a second elongated element, where each elongated element is connected with one of the offshore units via a first construction allowing pivotal movement and rotation and, at a distance from the first one, with the frame via a second construction allowing pivotal movement and rotation, where the first elongated element extends at a distance from the second elongated element between the frame and the one offshore unit
• the resetting facilities comprise a first and a second resilient element, which resilient elements are each stationarily connected with the one offshore unit and force either the first or the second elongated element to a position extending substantially vertically.
• a heavy ballast weight and extra anchor lines can be dispensed with, because a displacement of the two offshore units relative to each other via the frame will result in a pivotal movement and/or rotation of the elongated elements from their position extending substantially vertically.
• This causes resetting forces to be generated in the resilient elements, which forces want to force the elongated elements back to their substantially vertical position, so that horizontal reactive forces are exerted on the frame, which are opposite to the direction of the relative displacement the two offshore units underwent. These reactive forces thus force the offshore units back to the neutral starting position via the frame.
• a special advantage of this construction is that, in contrast to in the known connecting devices with stretchers, extra anchor lines and ballast weights can be dispensed with, so that, in the neutral position, no forces are acting on the connecting apparatus and are, accordingly, no forces are acting between or on the two offshore units.
• An additional advantage is that the connecting apparatus can be installed in a relatively simple and completely controllable manner and on location.
• the apparatus can further be designed such that the frame is provided with a first pair of points of engagement for the elongated elements of the first set of coupling means and with a second pair of points of engagement for the second set of coupling means, while that frame then preferably has a rectangular design, while, each time, an elongated element engages each angular point.
• the two offshore units can be equipped with compensating and resetting facilities.
• the frame is a triangular frame and one of the sets of coupling means is a coupling member comprising a ball hinge, which is located at the location of a first angular point of the triangular frame, while the first elongated element of the other set of coupling means engages a second angular point and the second elongated element engages a third angular point of the triangular frame.
• the provisions to be provided can be minimized, for instance only a ball hinge or even only the possibility to connect a ball hinge with the offshore unit. This is particularly advantageous for offshore units which need to be connected with another offshore unit only once during use.
• a relatively simple yet extremely efficient embodiment can be obtained if at least the elongated elements consist of a steel cable, where it is then further preferred that each steel cable be connected with the respective offshore unit via a winch.
• this offers the possibility to adjust the apparatus, by shortening or lengthening the steel cable, to the respective case of application in a simple manner, both with regard to positioning, i.e. dimensions of the two offshore units, and the manner of compensation of relative displacements between the units, i.e. the setting of the biasing force in the resilient elements, in other words, the spring characteristic of the connecting apparatus.
• the steel cable from its connection with the other offshore unit, via for instance a winch, first runs over a, preferably hinging, wire guide before starting to extend substantially vertically.
• the steel cable is provided with connecting means allowing pivotal movement and rotation for coupling with the frame and with connecting means for coupling with a resilient element. If, further, the connecting means for coupling the steel cable with the frame are at a distance from those with the resilient element, while the part of the steel cable located between the two connecting means runs over a wire guide preferably hingedly connected with the offshore unit, the vertical extension of the steel cable in the neutral position can simply be brought about, while, also, the pivotal movement of the steel cable during the relative movement of the offshore units is accurately controlled and guided.
• the coupling thereof can quickly and efficiently be brought about with a steel cable if the steel cable is interrupted at the location of the connecting means with the frame.
• an elongated element is formed by a rod connected with the respective offshore unit via a hinge pivotable about at least three mutually perpendicular axes, which rod is further connected with the frame via a hinge pivotable about at least three mutually perpendicular axes and with the resilient element optionally via an intermediate element, preferably a steel cable.
• a resilient element is formed by a resilient plastic cable. If this resilient plastic cable is connected with the respective offshore unit via a winch, then a further advantageous setting possibility for the bias and, accordingly, the compensating and resetting action of the apparatus according to the invention is obtained. This setting possibility can be combined with the above-discussed setting possibility of a steel cable coming from a winch, if desired.
• At least one resilient element is formed by a hydropneumatic tensioning unit. This can also be used both in the design with steel cables and that with hinging rods.
• the offshore units to be connected can both be floating units.
• one floating unit and one unit standing on a bottom may be involved.
• the connecting apparatus may, for instance, be used to couple a floating tender drilling unit to a wellhead platform.
• the wellhead platform may be either a floating unit, which kept in place with the aid of an anchor system or tension leg system, or a construction standing on a bottom under water.
• the floating tender drilling unit may be kept in place with the aid of either an anchor system or a dynamic positioning system with propellers or a combination of both.
• the connecting apparatus may be used are, for instance, the connection between a floating tanker and an offloading station or production platform which floats or stands on a bottom under water, or more in particular where offshore units, such as an offshore platform, a barge or a ship need to be placed relatively close together, often temporarily, for carrying out operations.
• Possibilities are units designed as working, crane, drilling, tender, accommodation, storage, production or transport unit and the like. If the one offshore unit is a unit standing on a bottom and the other offshore unit is a floating unit, it is preferred according to an exemplary embodiment of the invention that the frame is arranged to be connected with the offshore unit standing on the bottom by the ball hinge and with the floating offshore unit by the resetting facilities.
• Fig. 1 shows, in side elevational view, a wellhead platform and a tender unit coupled by a connecting apparatus according to the invention
• Fig. 2 shows a top plan view of Fig. 1
• Fig. 3 shows, in perspective, the wellhead platform according to Figs. 1 and 2;
• Fig. 4 shows, in side elevational view, the connecting apparatus in a neutral position where the wellhead platform and the tender unit are in a desired, predetermined relative position;
• Fig. 5 shows, in side elevational view, the connecting apparatus in a position where the wellhead platform and the tender unit have been moved towards each other compared to the neutral position;
• Fig. 6 shows, in side elevational view, the connecting apparatus in a position where the wellhead platform and the tender unit have been moved away from each other compared to the neutral position;
• Fig. 7 shows, in side elevational view, the connecting apparatus in a position where the wellhead platform and the tender unit are in a desired, predetermined relative position
• Fig. 8 shows, in top plan view, the connecting apparatus in a position where the wellhead platform and the tender unit have been rotated relative to each other from the neutral position
• Fig. 9 shows, in top plan view, the connecting apparatus in a position where the wellhead platform and the tender unit have been moved relative to each other from a neutral position, so that a displaced position is taken.
• a floating, anchored offshore unit in the form of a wellhead platform 1 is shown, which is provided with a deck 2 and is anchored to a bottom under water in a manner not shown. Further, Figs. 1-3 show a floating offshore unit 1 in the form of a tender unit 3 moored in a manner not shown near the wellhead platform 1.
• the wellhead platform 1 and the tender unit 3 are mutually coupled by a connecting apparatus 4, which is provided with a relatively rigid triangular frame 5, for instance formed by a rod construction, of which a first angular point bears a ball hinge 6, which is also fixed on the deck 2 of the wellhead platform 1, with which the coupling between the connecting apparatus 4 and the wellhead platform 1 has been brought about.
• the two other angular points of the triangular frame 5 are each connected, via connecting means 7 allowing pivotal movement and rotation, with a steel cable 8, which initially runs substantially horizontal from a winch 9 fixed on the tender unit 3 to a wire guide in the form of a hinging wire pulley 10 also fixed on the tender unit 3 and extends substantially vertically downwards from there to the connecting means 7.
• a further steel cable 12 runs substantially vertically from the connecting means 7 to a wire guide in the form of a hinging wire pulley 11, where a bending of the further steel cable 12 to a substantially horizontal direction takes place.
• the further steel cable 12 is coupled, by connecting means 13, with a resilient plastic cable 14, coming from a winch 15, which is likewise fixed on the tender unit 3.
• the winches 9 the positioning for height of the triangular frame 5 and, with the aid of the winches 15, the bias in the steel cables 8 and 12 and the resilient plastic cables 14 can accurately be set and adjusted to the respective situation of use.
• the coupling of the tender unit 3 with the wellhead platform 1 by means of the connecting apparatus 4 can be brought about in different manners.
• One possibility is to attach the connecting apparatus 4 to the tender unit 3, while the coupling with the wellhead platform 1 is brought about by pulling the angular point of the triangular frame 5 bearing the ball hinge 6 towards the attachment point of the ball joint 6 on the wellhead platform 1 with the aid of a wire.
• the connecting apparatus 4 to attach the connecting apparatus 4 to the tender unit 3 while the coupling with the wellhead platform 1 is brought about by pulling the angular point of the triangular frame 5 bearing the ball hinge 6 towards the attachment point of the ball joint 6 on the wellhead platform 1 with the aid of a wire.
• the deck 2 of the wellhead platform 1 only one possibility for fixing the ball hinge 6 needs to be present.
• Another possibility is to attach the triangular frame 5 and the ball hinge 6 to the wellhead platform 1, while coupling of the wellhead platform 1 with the tender unit 3 takes place via the connecting apparatus 4 by attaching the paid-out steel cables 8 and 12 of the tender unit 3 to the connecting means 7 on the triangular frame 5. Then, the steel cables 8 and 12 and the resilient plastic cables 14 are hauled in to the right length by means of the winches 9 and 15 on the tender unit 3.
• This latter method is preferred because the steel cables 8 and 12 with the resilient cables 14 can offer more room for play via the winches 9 and 15 during coupling of the tender unit and wellhead platform possibly moving relative to each other.
• spring elements 16 indicated by a dashed line in Fig. 2 which can be formed by stretchable plastic wires or a wire or rod with hydropneumatic tensioning unit.
• Fig. 4 shows the neutral position of the connecting apparatus 4 is shown, in which the steel cables 8 and 12 extend substantially straight vertically downwards.
• the tender unit 3 is then at the desired location with respect to the wellhead platform 1.
• Fig. 5 shows the situation which occurs when, for instance, by environmental influences (waves, wind, current, and the like) the wellhead platform 1 and the tender unit 3 have been moved towards each other.
• triangular frame 5 has pressed the steel cables 8 and 12, initially running straight, into a V-shape. Because, in their position assumed in the neutral position (see Fig. 4) the winches 9 and 15 (see Fig. 1) are blocked, the V- shaped deformation of the steel cables 8 and 12 has been brought about by stretching of the plastic cables 14.
• the moving towards each other of the wellhead platform 1 and tender unit 3 is compensated and counteracted by exerting a resetting force in the direction of the neutral position.
• Fig. 6 shows the situation in which the wellhead platform 1 and the tender unit 3 have moved away from each other.
• the steel cables 8 and 12 are again deformed to a V-shape from their initially straight position, albeit opposite to that according to Fig. 5.
• the moving away from each other of the wellhead platform 1 and the tender unit 3 is compensated and counteracted by the resetting action of the connecting apparatus 4.
• Fig. 7 shows the connecting apparatus 4 in top plan view in the neutral position. From this position, for instance as a result of environmental influences, a relative rotation between the wellhead platform 1 and tender unit 3 can occur, for instance to the position shown in Fig. 8.
• the steel cables 8 and 12 will be deformed to a V-shape under tensioning of the plastic cables 14.
• the steel cables 8 and 12 with connecting plastic cables 14 will generate a resetting force in the direction of the neutral position.
• the connecting apparatus is provided with a triangular frame which is connected with one of the offshore units via a ball hinge.
• the frame can also have a different shape than triangular, such as for instance rectangular, square, multi-angular, optionally provided with bent, projecting or receding circumferential parts.
• a winch 9 a hinging wire pulley 10 and a part of a steel cable 8 to the connecting means 7 may be replaced by a rod which is connected with the tender unit 3 by, for instance, a ball hinge at the location where now the hinging wire pulley 10 is located.
• a resilient plastic cable 14 may be replaced by a hydropneumatic tension unit or steel cables may be replaced by plastic cables.
• a different number may be chosen than two steel cables and two plastic cables or the steel cables may be connected with the tender unit without intervention of winches and wire guides.
• two steel cables 8 and 12 have been discussed, it will be clear that this could also be one continuous steel cable.
• the coupling of, for instance, a floating offshore unit and an offshore unit standing on a bottom may be carried out in a similar manner as discussed hereinabove for two floating offshore units.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Excavating Of Shafts Or Tunnels (AREA)
• Bridges Or Land Bridges (AREA)
• Earth Drilling (AREA)
• Joints Allowing Movement (AREA)
• Details Of Connecting Devices For Male And Female Coupling (AREA)

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• 2004
  • 2004-03-12 NL NL1025708A patent/NL1025708C2/nl not_active IP Right Cessation
• 2005
  • 2005-03-03 US US10/592,383 patent/US20070234944A1/en not_active Abandoned
  • 2005-03-03 WO PCT/NL2005/000156 patent/WO2005087579A1/en active Application Filing
  • 2005-03-03 GB GB0618754A patent/GB2428225B/en not_active Expired - Fee Related
  • 2005-03-03 AU AU2005222022A patent/AU2005222022B2/en not_active Ceased
• 2006
  • 2006-09-18 NO NO20064207A patent/NO338121B1/no not_active IP Right Cessation

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