WO2014073973A1

WO2014073973A1 - Device and method for interconnecting a tanker and a floating terminal

Info

Publication number: WO2014073973A1
Application number: PCT/NO2013/050181
Authority: WO
Inventors: Fredrik Major
Original assignee: Sevan Marine Asa
Priority date: 2012-11-07
Filing date: 2013-10-22
Publication date: 2014-05-15
Also published as: AU2013341863A1; NO336575B1; CN104884346A; NO20121310A1; US20150307161A1

Abstract

A device for connecting a floating vessel such as a tanker (3) and a floating, fixedly orientated, terminal (1), where a floating coupling unit (2) which is provided with a contact portion (211) arranged to be able to bear against a portion of the tanker (3), is shiftably allocated said terminal (1), in that at least two mooring means (24) extend from said terminal (1) via respective shifting devices (23) arranged on the coupling unit (2), and to respective anchors (25) arranged at a distance from said terminal (1) is described. A method for connecting a floating vessel (3) and a terminal (1) for fluids by means of a floating coupling unit (2) is also described.

Description

Device and method for interconnecting a tanker and a floating terminal

The invention relates to a device for interconnecting a tanker, and a floating loading or offloading terminal for fluids, where the terminal is fixedly orientated, and where a floating coupling unit is shiftably associated with said terminal. Further, the invention concerns a method of connecting a tanker and a by means of a floating coupling unit.

Transfer of cargo between a tanker and a floating unit (e.g. a loading or offloading terminal, or production platform) requires comprehensive measures regarding mooring and/or anchoring. The applicant's own patent application NO 20064700 (corresponding to WO 2008082306) describes a mooring system for a conventional tanker, i.e. a tanker without a dynamic positioning system and bow loading equipment, where the tanker is connected to the floating loading/offloading terminal which is fixedly orientated. The tanker is moored in four points, where two of the moorings are connected to the terminal and two moorings are fastened to buoys anchored remote from the terminal. The tanker is then transferred in relation to the terminal by tightening, respectively slackening, of the respective moorings until the tanker has reached the desired position for loading or offloading.

It is necessary to keep a certain distance between the terminal and the tanker during the loading or offloading operation, especially when the operation takes place during rough weather conditions with strong winds, waves and currents. It is therefore difficult to transfer hoses and similar for the transfer of cargo etc. between the terminal and the tanker.

The object of the invention is to remedy or to reduce at least one of the disadvantages of the prior art, or at least to provide a useful alternative to the prior art.

The object is achieved by features stated in the below description and in the following patent claims.

The applicant's own patent application NO 20064700 (corresponding to

WO 2008082306) is in its entirety incorporated as a reference in this description.

In the following, the term "loading terminal" is used for the sake of convenience, although the invention in principle also can be applied during offloading, i.e. when transferring cargo from a tanker and to the terminal for storing or processing there. The invention is also applicable for connecting a ship, such as a tanker, to a production platform, a floating facility for handling liquefied natural gas (FLNG), etc.

To a floating loading terminal which is fixedly oriented by means of suitable anchor and/or propulsion means, typically propulsion machinery with an associated installation for dynamic positioning, there is an associated a floating coupling unit which can be shifted between an inactive position close to the loading terminal and an active position bearing against a portion of the tanker by means of a mooring system. The coupling unit is provided with a ballasting system arranged to vary the net buoyancy of the coupling unit. The coupling unit is provided with an immersed, horizontal portion which at least partly is arranged to extend underneath a bottom portion of the tanker, for example by the coupling unit being generally L-shaped. Said horizontal portion is provided with a generally upward facing contact portion arranged to be able to bear against said bottom portion of the tanker by deballasting the coupling unit after it is placed in the desired position for coupling with the tanker. The coupling unit is provided with mooring means connecting it to at least two mooring points on the loading terminal and to at least two anchoring points remote from the loading terminal via associated winches. The coupling unit may thus be pulled in a desired direction towards or away from the tanker. The mooring means can extend continuously between the loading terminal and to the anchoring points via coupling points on the coupling unit, where the mooring means run over shifting means arranged to pull the coupling unit along the mooring means. In this embodiment it is an advantage if the mooring means are connected to the loading terminal via constant tension means, typically via constant tension winches, to maintain a constant tension in the mooring means independent of tide and wave induced movement in the loading terminal and the coupling unit, and independent of the distance from the coupling unit to the loading terminal. Alternatively, the mooring means may be divided in two, as they extend from mooring winches arranged on the coupling unit. In this embodiment it is also an advantage if the mooring system comprises means for maintaining constant tension in the mooring means, for example by the mooring winches being constant tension winches or that the mooring means connecting the coupling unit to the loading terminal, are connected to constant tension means arranged on the loading terminal. The coupling unit is preferably provided with a vertical portion rising above the body of water and being provided with one or more manipulators arranged to transfer one or more transport lines for connection with or disconnection from a loading/offloading manifold which on a tanker preferably is arranged amidships. At least a portion of the transport lines extending between the loading terminal and the coupling unit is formed of a flexible material such that a fluid communicating connection is maintained between the loading terminal and the coupling unit independent of the position of the coupling unit relative to the loading terminal. The coupling unit may be provided with suitable lifting means for connection with the transport line (s) and possibly other lines extending between the loading terminal and the coupling unit to relieve said lines, typically in the form of one or more protruding crane arms.

The terminal may typically be a floating production, storage and offloading facility (FPSO), more typical a floating facility for handling liquefied natural gas (FLNG).

In a first aspect the invention relates to more specifically a device for interconnecting a tanker and a floating terminal, where said terminal is fixedly orientated, characterized in that a floating coupling unit provided with at least one contact portion is configured for bearing against at least a portion of the tanker, is shiftably associated with said terminal, in that at least two mooring means are configured for extending between the terminal via respective shifting devices arranged on the coupling unit, and respective anchors arranged at a distance from said terminal.

The coupling unit may be provided with a vertical portion rising above a water surface and being provided with means for suspending and/or relocating of one or more line portions extending between said terminal and the coupling unit and is arranged for disconnectable connection with the tanker.

The coupling unit may be provided with a ballasting system.

Said mooring means may comprise a first portion extending between said terminal and the coupling unit, and a second portion extending between the coupling unit and the respective anchor, as each of the mooring means portions are connected to a shifting device arranged on the coupling unit.

The shifting unit may be a constant tension winch. Said first mooring means may be connected to said terminal via respective tensioning devices.

Said terminal may be a floating production, storing and offloading facility (FPSO) or a floating facility for handling liquefied natural gas (FLNG).

In a second aspect, the invention more specifically relates to a method of connecting a tanker and a fixedly oriented terminal, where said terminal is fixedly orientated, and where the method comprises the steps of: mooring the tanker with at least two ship moorings to said terminal and with at least two ship moorings to respective anchors;

shifting the tanker by tightening, possibly slacken, the respective ship moorings until the tanker has arrived at a desired position relative said terminal; characterized in that the method further comprises the steps of: shifting a floating coupling unit by means of shifting devices engaged with at least two mooring means extending from said terminal via respective shifting devices arranged on the coupling unit, and to respective anchors arranged at a distance from said terminal, to supportive contact against a portion of the tanker;

deballasting the coupling unit at least until a submerged, generally horizontal contact portion of the coupling unit is supportively bearing against a portion of the tanker bottom;

connecting the tanker and said terminal in a fluid communicating way by maneuvering an end portion of at least one fluid transport line to connect with a loading/offloading manifold arranged on the tanker.

The method may further comprise the step of: maintaining a prescribed pre-tensioning in the mooring means by activating one or more constant tension winches in a locking engagement with the respective mooring means. In the following, an example of a preferred embodiment is described which is illustrated in the attached drawings, where:

Fig. 1 shows a plan view of a loading terminal provided with a coupling unit according to the invention anchored in a body of water;

Fig. 2 shows in plan view a situation where a tanker is anchored by the loading terminal and the coupling unit bears against the tanker;

Fig. 3 shows in a section view and on a larger scale a side view of the coupling unit connected to the tanker.

In the figures the reference number 1 indicates a loading terminal, typically in the form of a floating facility for handling liquefied natural gas (FLNG), anchored in a body of water 4 by means of several anchoring means 13 extending between said terminal 1 and respective first anchors 131 arranged on a seabed 42 at a distance from the terminal 1.

A floating coupling unit 2 is associated with the terminal 1 as the coupling unit 2 is shiftable relative to the terminal 1 in that the coupling unit 2 is connected with mooring means 24 extending from the terminal 1 via respective shifting devices 23 arranged on the coupling unit 2 and to other anchors 25 arranged at a distance from each other on the seabed 42. The coupling unit 2 is provided with an approximately horizontal, upward facing contact portion 211 arranged to be able to extend underneath a portion of a bottom 31 of a tanker 3. The contact portion 211 is preferably provided with several elastic contact cushions 211a arranged to protect the contact portion 211 and the bottom 31 of the ship. The coupling unit 2 is provided with a ballasting system 26 utilized for raising and lowering the coupling unit 2 in relation to the tanker 3 to contact, respectively clearance, between the contact portion 211 and the bottom 31 of the ship.

A vertical portion 22 of the coupling unit 2 rises above the body of water 4. In the shown embodiment the coupling unit 2 is suitably L-shaped. The vertical portion 22 is provided with fenders 221 arranged for supportive contact against a side 32 of the ship. On the rising, vertical portion 22 of the coupling unit 2 manipulators 27 and lifting devices 28 are arranged, connected to fluid transport and control lines 11, 12 extending from the terminal 1 to the coupling unit 2 and being provided with end portions arranged for connection to a suitable loading manifold 33 on the tanker 3. The manipulators 27 of a type which per se is known, are arranged to maneuver the end portions of said lines 11, 12 during connection and disconnection, and the lifting devices 28 are arranged to hold the portion of the lines 11, 12 extending between the terminal 1 and the coupling unit 2, and prevent these from being overloaded during shifting of the coupling unit 2. The signal line 12 transmits relevant control signals between the terminal 1 and the coupling unit 2 and between the coupling unit 2 and the tanker 3. The control line 12 may also transmit energy for operation of electrical systems on the coupling unit 2.

The shifting devices 23 of the coupling unit 2 are in a first embodiment winches connected to a first mooring mean portion 241 extending between the coupling unit 2 and the terminal 1, respectively a second mooring mean portion 242 extending between the coupling unit 2 and the respective second anchor 25. The winches 23 are preferably constant tension winches.

In a second embodiment the mooring means 24 run uninterrupted between the terminal 1 via the coupling unit 2, where the shifting device 23 is engaged with the mooring means 24, and to the respective second anchor 25. That portion of the mooring means 24 which is engaged with the shifting device 23 may typically be a chain portion running over one or several sprocket wheels (not shown). In this embodiment the mooring means 24 is preferably connected to the terminal 1 via a tensioning device 14, for example a constant tension winch.

The purpose of employing constant tension winches as a shifting device 25 or a tensioning device 14 is to prevent slacking or overtensioning of the coupling unit 2 mooring means 24 when the coupling unit 2 is shifted or is moved vertically due to ballasting, etc.

The tanker 3 is moored by means of ship moorings 34, 34' to the anchors 25, and the terminal 1, respectively, for example as disclosed in NO 20064700.

When the tanker 3 is arranged in the desired position for transferring cargo, the ballasted coupling unit 2 is shifted by means of the shifting devices 23 and the mooring means 24 to alongside contact against the side 32 of the ship as the horizontal portion 21 is extended underneath a portion of the bottom 31 of the ship and the lifting devices 28 are operated such that the lines 11, 12 follow the movement of the coupling unit 2 relative to the terminal 1. The coupling unit 2 is then deballasted such that the contact cushions 21 la on the horizontal, upward facing contact portion 211 are bearing supportively against the bottom 31 of the ship. The lines 11, 12 are connected to the tanker 3, and transfer of fluid between the terminal 1 and the tanker 3 can be carried out.

When the transfer of fluid between the terminal 1 and the tanker 3 has been carried out, the lines 11, 12 are disconnected from the loading/offloading manifold 33 of the tanker 3, the coupling unit 2 is ballasted such that it is released from the bottom 31 of the ship. The coupling unit 2 is then shifted away from the tanker 3 to a position close to the terminal 1.

Claims

1. A device for interconnecting a tanker (3) and a floating terminal (1), where said terminal (1) is fixedly orientated, characterized by

- a floating coupling unit (2) provided with at least one contact portion (211, 22) configured for bearing against at least a portion of the tanker (3);

- at least two mooring means (24) configured for extending between the terminal (1), via respective shifting devices (23) arranged on the coupling unit (2), and respective anchors (25) arranged at a distance from said terminal (1); wherein the coupling unit (2) is shiftably arranged with respect to the terminal.

2. The device of to claim 1, wherein the coupling unit (2) is provided with a vertical portion rising above a water surface (41) and is provided with means for suspending and/or relocating of one or more line portions (11,12) extending between the terminal (1) and the coupling unit (2) and are arranged to disconnectably connect with the tanker (3).

3. The device of claim 1, wherein the coupling unit (2) is provided with a ballasting system (26).

4. The device of claim 1, wherein said mooring means (24) comprise a first portion

(241) extending between the terminal (1) and the coupling unit (2), and a second portion

(242) extending between the coupling unit (2) and the respective anchor (25), as each of the mooring means portions (241, 242) are connected to a shifting device (23) arranged on the coupling unit (2).

5. The device of claim 4, wherein the shifting device (23) is a constant tension winch.

6. The device of claim 1, wherein said first mooring means (24) are connected to the terminal (1) via respective tensioning devices (14).

7. The device of any one of claims 1-6, wherein the terminal is a floating production, storage and offloading facility (FPSO) or a floating facility for handling liquefied natural gas (FLNG).

8. The device of any one of the claims 1-7, wherein the terminal (1) is fixedly oriented by means of suitable anchoring means (12, 131) and/or propulsion machinery connected to facilities for dynamic positioning.

9. A method of interconnecting a tanker (3) and a fixedly orientated terminal (1), comprising the steps of:

- mooring the tanker (3) with at least two ship moorings (34) to the terminal (1) and with at least two ship moorings (34') to respective anchors (25),

- shifting the tanker (3) by tightening, possibly slacken, the respective ship moorings (34, 34') until the tanker (3) has arrived at a desired position relative to the terminal (1), characterized in that the method further comprises: shifting a floating coupling unit (2) by means of shifting devices (23) in engagement with at least two mooring means (24) extending from the terminal (1) via respective shifting devices (23) arranged on the coupling unit (2), and to respective anchors (25) arranged at a distance from the terminal (1), to supporting contact against a portion of the tanker (3);

10. The method of claim 9, further comprising the subsequent steps of:

- deballasting the coupling unit (2) at least until a submerged, generally horizontal contact portion (211) of the coupling unit (2) is supportingly bearing against a portion of the bottom (31) of the tanker (3); and

- connecting the tanker (3) and said terminal (1) in a fluid communicating way by maneuvering an end portion of at least one fluid transport line (1) to connecting with a loading/offloading manifold (33) arranged on the tanker (3).

11. The method of claim 8,further comprising the step of maintaining a prescribed pre-tensioning in the mooring means (24) by activating one or more constant tension winches (23; 14) in a locking engagement with the respective mooring means (241, 242; 24).