WO1996007583A1

WO1996007583A1 - Method and device for offshore oil transfer

Info

Publication number: WO1996007583A1
Application number: PCT/NO1995/000152
Authority: WO
Inventors: Asbjørn LØVGREN; Claes W. Olsen
Original assignee: Marine Consulting Group A.S
Priority date: 1994-09-09
Filing date: 1995-09-06
Publication date: 1996-03-14
Also published as: NO943361L; EP0777600A1; DE69514368D1; NO943361D0; AU3534895A; NO300676B1; JPH10507709A; EP0777600B1

Abstract

Method and device for connection of two units offshore with the purpose of oil transfer, thereby transferring a hawser between the units and, depending on the need, locking at least one end of the hawser by means of a locking device (12) in a combined roller fairlead (1) arranged on one of the units, to chain links connected to one end, and to connect an oil hose between the units, whereby the end of the oil hose on one of the units is connected with a ball link (6) allowing free movement of the hose suspending from the ball link, whereby the hose is adapted to be coiled on a hose barrel (5) and the ball link is secured to the barrel and connected with the piping system of one of the units through the axis of the barrel.

Description

Method and device for offshore oil transfer

The present invention is related to a method and a s connecting device for offshore oil transfer between two units. Transfer of oil offshore today is accomplished accor¬ ding to different principles, such as submerged tower, by means of a buoy etc. Increasingly a transfer system is used comprising shuttle tankers equipped with the submerged turret loading system 0 (ST ) or the submerged turret production system (STP).

When loading with such a system (STL), a stationary ship is used as a storage tank. The oil is in between loaded to a second shuttle tanker. The ship rests with is bow towards the weather and the shuttle tanker is connected to the stern of the s ship. During production (STP) the storing space aboard the ship may be limited and the oil therefore is transferred more or less continuously to the second shuttle tanker.

Shuttle tankers, however, also have the need for connection to other systems, such as bow loading system (BLS), 0 which claims adaptation of the tankers specifically also for such systems.

Construction of shuttle tankers adapted for use with several of the known systems, however, demands as of today comprehensive structural devices aboard each shuttle tanker and 5 also comprehensive and many manual operations before and after loading. Such operation are time consuming and therefore under specific circumstances also may be connected with hazard for people and equipment.

The connecting system according to the present inven- o tion ensures that shuttle tankers quickly and safe may be connected to different loading systems comprise a minimum of quickly performed manual operations. To provide the ships with multi use properties loading and unloading is performed in the same area of the ship, which to a high extent provides possibi- 5 lity for use of few components and few manual operations for connecting and disconnecting, enduring only a short time. The system according to the present invention is defined with the features stated in the claims.

In the drawing, figure 1 discloses a side view of the stern of a shuttle tanker, comprising the system according to the present invention, figure 2 discloses a side view of the combined rolling hawser and chain lock device according to the present invention and figure 3 discloses a ground view of the device in s figure 2.

Shuttle tankers constructed with the system according to the present invention are used in connection with the loading from a normal bow loading system station (BLS) by reversing the vessel up to the loading station, the stern thereby is given a o somewhat bowlike shape. The stern is hold up against the weather during loading by means of the positioning system of the ship. At stations constructed according to the STL and STP systems, the bow of the ship is placed up against the weather and loading to another shuttle tanker is made by connecting this to the stern. s The system according to the invention comprises a roll hawser with chain locks for safe mooring to an unloading station, respectively another vessel, and a host barrel hose barrel ensuring that the hose is exposed to a minimum of physical stress by the use of ball shaped couplings. 0 When connecting the ship to an oil loading system station (OLS) the oil hoses pulled up from the seabed by means of a hawser running through the fairlead 1 in a known manner and further to the pulling winch 8.

The oil hose thereafter is connected in a known way to 5 a standard tail part on the outer end of the house 4, usually made as a flange coupling. The house 6 is coiled up on a barrel 5 having a horizontal axis. The barrel thereafter is rotated in such a way that the coiled hose 5 runs out until the inner end of the hose 4, which is connected with the barrel 5 by means of o a ball link 6, is situated in a preferred position, such as in the axial horizontal plane of the barrel. The barrel 5 thereafter is locked in this position.

The ball link 6 is connected to the barrel and by means of pipe 7 further connected with the pipe 1 the center axis of 5 the barrel, from which connection is established through this pipe to one side of the barrel 5. By means of a swivel the connection thereby is established to the piping system of the ship. Based on the ball link 6 the house freely can be moved in all directions without forces being created in the hose or the coupling.

The roll hawser 1 and the barrel 5 are arranged in the stern of the ship, the roll hawser preferably at the platform deck of the ship. Ship provided for STL respectively STP s couplings have the bridge arranged ahead of these installations of security reasons. A multi use ship of the type described here thereafter have all installations for connection arranged in the stern.

The fairlead 1 is such that it functions as a normal o fairlead where hawsers, buoys, wires and chains freely may run through and between vertically arranged rolls 1 and on horizontal rolls 3.

By loading from a single point mooring station (SPM) the tanker must be moored to a tower or a buoy. The mooring s hawser 9 from the tower of the buoy is pulled aboard on the shuttle tanker by means of a forerunner 10 and the pulling winch 8. A chain 11 having standard length is connected in between the forerunner 10 and the hawser 9. The forerunner 10 is pulled through the roll fairlead 1 until a sufficient number of chain loops are placed in a locking mechanism 12 in the roll fairlead 1. Thereafter the locking mechanism 12 is activated and the shuttle tanker is moored in such a way that the oil house may be connected as described above.

By unloading from a STL/STP-ship a shuttle tanker is moored to the ship with a corresponding hawser having a chain 11 between the forerunner and the hawser 10. At the other end of the hawser, aboard the ship, some chain links are inserted to lock those chain links by means of the locking mechanism 12 of the fairlead 1. When the leading chain length 11 is aboard the shuttle tanker.

When the system is not used, the leading chain length 11 is stored in a specially designed box on the platform deck, between the roller fairlead 1 and a winch 13 for the hawser. The chain length 11 is secured to the hawser as such, which is stored on the hawser winch 13. With the other end of the hawser, some chain links are connected which are used for locking in the locking mechanism 12.

The hawser winch 13 comprises two parts which can operated independently. On one part of the hawser winch 13 therefore the hawser 9 and the chain links are arranged and on the other part of the barrel a forerunner is arranged.

When connecting the shuttle tanker to a STL/STP-ship the forerunner is let out and shut out by means of an air canon.

5 The forerunner is connected with the chain length 11 by means of a swivel. On the shuttle tanker the forerunner is pulled in and later also the chain length 11 and simultaneously the hawser is coiled off from the hawser winch 13. After the chain links are secured with the' locking mechanism 12 aboard the ship, the chain o length aboard the shuttle tanker is locked.

A method as described above to a very high extent simplifies the operations as opposed to what is used today, where the mooring is made by means of a separate winch where the hawser is secured to the axis of the winch by means of a oveable link. s The mooring forces are, with the device according to the present invention, transferred to the locking mechanism 12 of the roller fairlead. Of this reason only one hawser winch 13 is needed.

Upon proper mooring the house barrel 5 gives out the o house 4, the end piece of which is connected with the manifold of the shuttle tanker. The hose barrel 5 is again locked in such a way that the ball link 6 is arranged in the horizontal plane of the barrel axis. In this way the hose may be freely moved without causing any forces to the house or the coupling. 5

0

5

Claims

P a t e n t C l a i m s

1. Method for connection between two units offshore s with the purpose of oil transfer, CHARACTERIZED IN transferring a hawser between the units and, depending on the need, locking at least one end of the hawser by means of a locking device (12) in a combined roller fairlead (1) arranged on one of the units, to chain links connected to one end, and to connect an oil hose o between the units, whereby the end of the oil hose on one of the units is connected with a ball link (6) allowing free movement of the hose suspending from the ball link, whereby the hose is adapted to be coiled on a hose barrel (5) and the ball link is secured to the barrel and connected with the piping system of one of the units through the axis of the barrel.

2. Method according to claim 1, CHARACTERIZED IN connecting to a mooring station of the single point mooring type by pulling the hawser aboard the one unit with a forerunner and locking the chain length between the hawser and the forerunner by means of the locking mechanism (12) of the roller fairlead (1).

3. Method according to claim 1, CHARACTERIZED IN connecting to an oil loading system station by pulling an oil hose up from the seabed by means of a hawser to the roller fairlead (1) by means of a pulling winch (8) to connect the oil hose to the end piece on the barrel hose and to let out the hose from the barrel (5) until the hose (4) from the barrel suspends freely down from the ball link (6) of the barrel.

4. Method according to claim 1, CHARACTERIZED IN connecting a shuttle tanker by guiding a forerunner on the hawser from the hawser winch (13) to the tanker, whereafter a chain length connected to the hawser may be secured aboard the shuttle tanker and the chain length are locked by means of the locking mechanism (13), to the roller fairlead (1).

5. Connecting device for oil transfer between two units offshore, CHARACTERIZED IN the device comprising a roller fairlead (1) having horizontal an vertical rollers (3, 2) and a locking mechanism (12) for locking of chain links to the roller fairlead (1) and a hose barrel (5) comprising a hose (4) having its inner end connected with a ball link (6) being connected with the piping system of the ship, by means of a radially arranged pipe to an axially arranged pipe in the barrel and further with a swivel to the piping system.

6. Device according to claim 5, CHARACTERIZED IN the chain links being arranged closest to the winch on the indepen¬ dently movably part of a hawser winch (13) and being secured to the tail end of the hawser, the leading end of the hawser being connected with a chain length (11) arranged between the roller fairlead (1) and the hawser winch (13), and that the second part of the hawser winch having coiled up a forerunner being connected with the leading chain length, adapted to be shut over to another unit, such as a shuttle tanker.