EP3172125B1

EP3172125B1 - A tandem reel assembly

Info

Publication number: EP3172125B1
Application number: EP15728126.2A
Authority: EP
Inventors: James Straker; Malcolm Smith
Original assignee: Techflow Marine Ltd
Current assignee: Techflow Marine Ltd
Priority date: 2014-07-25
Filing date: 2015-06-08
Publication date: 2018-11-28
Anticipated expiration: 2035-06-08
Also published as: GB201413261D0; EP3172125A1; WO2016012747A1; GB2528674A

Description

The present invention relates generally to the field of oil and gas production, and towards offloading and storage facilities. In particular, the present invention relates to a reel assembly comprising combined mooring and offloading means utilising a single storage reel.

Introduction

A floating production, storage and offloading (FPSO) unit is a floating vessel used by the offshore oil and gas industry for the processing of hydrocarbons and for storage of oil. An FPSO vessel is designed to receive hydrocarbons produced from nearby platforms or subsea template, process them, and store oil until it can be offloaded onto a tanker or, less frequently, transported through a pipeline. FPSOs are preferred in frontier offshore regions as they are easy to install, and do not require a local pipeline infrastructure to export oil. FPSO's can be a conversion of an oil tanker or can be a vessel built specially for the application. A simplified FPSO 10 and offloading tanker 12 is shown in Figure 1, where the tanker 12 is moored to the FPSO 10 via a hawser 14, and the hose string 16 provides a fluid connection between the FPSO 10 and the tanker 12 allowing, for example, crude oil, LNG or condensate to be transferred from the FPSO to the tanker.
The offloading of crude oil (but also condensate and LNG) from an FPSO vessel to a shuttle tanker is often facilitated via an offloading system 18, such as a Tandem Mooring & Offloading system, that is integrated into the hull of the FPSO 10. The Tandem Mooring & Offloading system may consist of at least two rotating reels 20 and 22. One reel 20 may accommodate a mooring hawser 14, and the other reel 22 may accommodate the offloading hose 16.
A side, front and top view of a typical hawser storage reel are illustrated in Figure 2 (a), (b) and (c), respectively. The mooring hawser string 14 can be deployed overboard the FPSO 10 and connected to the shuttle tanker 12 to facilitate the tandem mooring process. The mooring system 20 may be integrated into the hull of the FPSO 10, comprising, for example, a rotating reel 24, i.e. a Hawser Storage Reel, accommodating a mooring hawser 14 and connection point mooring hook 26. The mooring hawser string 14 may comprise an FPSO inboard chafe chain master link, a chafe chain, a mooring hawser and shuttle tanker chafe chain. The mooring hawser connection system, which securely connects the mooring hawser string to the hull, may comprise a mooring hook, a reel connection link adapted to interface with the chafe chain master link. During use, the FPSO inboard chafe chain and chafe chain master link are deployed from the hawser storage reel 24 so that the reel connection link facilitates the master link connection at the mooring hook that is integrated into the hull. The mooring hawser string 14 and shuttle tanker chafe chain may then be deployed overboard the FPSO 10 and are connected to the shuttle tanker 12.
Figure 3 (a), (b) and (c) illustrates a side, front and top view of a typical offloading hose storage reel 22, where the hose string 16 can be deployed overboard the FPSO 10 and connected to the shuttle tanker 12 to facilitate the tandem offloading process. The offloading system 22 may be integrated into the hull of the FPSO 10, comprising, for example, a rotating reel 28 accommodating an offloading hose string 16. The hose string end connection may be connected to the offloading reel 28 via a "gooseneck" connection 30 and secured by a bolted flange. Typically, the offloading hose 16 is stored on the reel drum of the rotating reel 28 in a single or double layer. During use, the offloading hose 16 is deployed from the offloading system 22 overboard the FPSO 10 and connected to the shuttle tanker 12.
In order to be able to provide both mooring and offloading systems at the FPSO 10, the mooring system 20 and the offloading system 22 may be located at the bow or stern of the FPSO 10, whereby the mooring system is positioned such that the hawser string 14 is in line with the centre line of the FPSO 10. The offloading system 22 may be positioned on the port or starboard side of the mooring system 20. A typical arrangement of a tandem mooring and offloading system 18 is illustrated in Figure 4 (a), (b) and (c).
To facilitate the tandem mooring and offloading operation, the FPSO 10 firstly deploys and connects the mooring system 20 from the FPSO 10 to the shuttle tanker 12. In the next step, the offloading system 22 deploys the offloading hose 16 for connection to the shuttle tanker 12. Crude oil, condensate, fluid medium, LNG etc. may then be transferred through the offloading hose 16 to the shuttle tanker 12. On completion of the fluid transfer, the offloading system 22 recovers the offloading hose 16 to the FPSO hose reel 28. The mooring system 20 then recovers the mooring hawser 14 to the FPSO hawser reel 24.
It is clear that the two distinct functions of mooring and offloading currently require two independent reel systems powered and controlled by two independent drive and control systems. In addition, the two systems each require a separate reel support structure and access facilities, consequently utilising an exorbitant area of deck space, either at the bow or stern of the FPSO 10.
A method and apparatus for performing continuous tubing operations is disclosed, for example, in document US2010/0314132A1 . Here, a motor driven spool is adapted to deploy and retrieve multiple separate strings of continuous tubing, wherein a level-wind assembly us utilised to direct the continuous tubing overboard. In addition, document WO97/35759 descloses another example of a multiple-reel assembly for at least two groups of flexible lines adapted to transfer fluid and utilities between a vessel and the sea-bed or another vessel or a platform. However, both reel assemblies are simply storage reels for the continuous tubing that do not provide any additional functionality.
Accordingly, it is an object of the present invention to provide a reel assembly fully functional for mooring and offloading, but having a significantly reduced number of component parts.

Summary of the Invention

Preferred embodiment(s) of the invention seek to overcome one or more of the above disadvantages of the prior art.
According to a first embodiment of the invention there is provided a reel assembly comprising the features of claim 1.:
This provides the advantage of a significantly reduced number of component parts, consequently requiring a greatly reduced deck space, either bow or stern of the FPSO. In addition, the current invention provides the advantage that only one motor drive is required to control the mooring and offloading operation, further reducing overall weight of the system, costs of manufacture and maintenance, and potentially reducing the running cost of the tandem mooring and offloading system.
Advantageously, a first flexible string may be connected to said first string connector and wound in a first direction around said at least one first support drum portion. A second flexible string may be connected to said second string connector and wound in a second direction, opposite to said first direction, around said at least one second support drum portion.
This provides the advantage that the operation of one function (e.g. mooring) minimises the risk of the other string to accidentally unwind from the storage reel.
A reel assembly according to claim 3, wherein said first direction is clockwise and said second direction is anticlockwise.
Preferably, the first flexible string may be a hawser string, and the first string connector may be adapted to releasably engage with said hawser string. Advantageously, said first string connector may be adapted to operably engage with a mooring point.
Preferably, said second flexible string may be an offloading hose string adapted to conduct fluid between said first end portion and a second end portion of said second flexible string.
Advantageously, said at least one first support drum portion may comprise a first string end fastener adapted to selectively fasten a second end portion of said first flexible string, and said at least one second support drum portion may comprise a second string end fastener adapted to selectively fasten said second end portion of said second flexible string.
Advantageously, the reel assembly may further comprise a monitor system, operably coupled to said reel assembly, and adapted to monitor at least one or more of a string load, support drum speed and direction, and the extent of unwinding of said first and/or second flexible string.
Preferably, the reel assembly may further comprise at least one audible and/or visual indicator adapted to indicate a predetermined condition of said reel assembly.

Brief Description of the Drawings

Preferred embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:

Figure 1 (prior art) shows a simplified offshore setup for an offloading FPSO in engagement with a tanker;
Figure 2 (prior art) shows a (a) side, (b) front and (c) top view of a known mooring system;
Figure 3 (prior art) shows a (a) side, (b) front and (c) top view of a known offloading system;
Figure 4 (prior art) shows a (a) side, (b) front and (c) top view of a typical arrangement of a tandem mooring and offloading system;
Figure 5 illustrates a front view of a preferred embodiment of the tandem reel assembly of the present invention;
Figure 6 illustrates a top view of the preferred embodiment of the tandem reel assembly of the present invention;
Figure 7 illustrates a side view of the preferred embodiment of the tandem reel assembly of the present invention;
Figure 8 (a) to (d) illustrates a schematic sequence of operation for deploying and connecting a hawser to a shuttle tanker, where the arrows indicates the direction of rotation of the reel;
Figure 9 (e) to (h) illustrates the continued sequence of operation from Figure 8 for deploying and connecting an offloading hose to a shuttle tanker;
Figure 10 (i) to (m) illustrates the continued sequence of operation from Figure 9 for disconnecting and recovering the offloading hose and hawser from the shuttle tanker.

Detailed description of the preferred embodiment(s)

The exemplary embodiments of this invention will be described in relation to offshore offloading of hydrocarbon fluid. However, it should be appreciated that, in general, the system and method of this invention will work equally well for any other suitable offloading system offshore and onshore and any suitable fluid medium.
Referring now to Figures 5, 6 and 7, a front, side and top view of a preferred embodiment of the reel assembly 100 is shown. In the preferred embodiment, i.e. for use on FPSO's, the reel assembly 100 comprises a support structure 102 adapted to be securely installed at bow or stern of an FPSO, a support drum 104 that is rotatably coupled to the support structure 102, e.g. via an axle 106 of the support structure 102. A motor 108 is operably coupled to the support structure 102 so as to rotatably engage the support drum 104, i.e. selectively drive the support drum clockwise and anti-clockwise. A gear mechanism (not shown) may be coupled between the motor 108 and the support drum 104, so as to allow additional control of the power output of the motor 108. A controller (not shown) is coupled to the motor allowing either manual operation of the reel assembly 100, or providing a pre-programmed sequence of rotating the support drum 104 at a predetermined rotational speed and direction. It is understood by the person skilled in the art that any suitable type of motor 108 and controller (not shown) can be used to drive the reel assembly 100.
The support drum 104 has a hawser support portion, adapted to accommodate the hawser string 112, and an offloading support portion 114, adapted to accommodate the offloading hose string 116. Both, hawser and offloading hose support portions 110, 114, are coaxial with the support drum 104 and support structure axle 106. In this preferred example, the hawser support portion 110 of the support drum 104 has a larger diameter than the offloading support portion 114 of the support drum 104, so as to allow for the considerable larger diameter of the offloading hose 116 compared to the hawser string 112. The step in diameter between the hawser support portion 110 and the offloading support portion 114 provides a spacial separation between the hawser support portion 110 and the offloading support portion 114. In addition, circumferential dividers 118, 120 and 122 are provided at both ends of the support drum 104 and between the hawser support portion 110 and the offloading support portion 114.
A "gooseneck" connector 124 is further provided at the offloading support portion 114 of the support drum 104, allowing the offloading hose 116 to be operably connected to the reel assembly 100. The "gooseneck" connector 124 is aligned so as to allow the offloading hose 116 to be wound clockwise around the support drum 104.
A hawser connector 126 is provided at the hawser support portion 110 of the support drum 104, allowing the hawser string (e.g. chafe chain section) 112 to be operably connected to the support drum 104. In particular, the hawser string is wound anticlockwise around the support drum 104. The hawser connector 126 is further adapted to operably engage with a mooring hook installed at the FPSO deck, i.e. when the hawser string is unwound from the support drum 104, the end section of the hawser automatically disconnects from the hawser connector 126 and connectingly engages with the mooring hook of the FPSO.
It is understood by the person skilled in the art that any suitable diameter may be used for the hawser support portion 110 and the offloading support portion 114, i.e. also including equal diameters for both the hawser support portion 110 and the offloading support portion 114 depending on the intended use of the reel assembly 100.
Referring now to Figures 8 to 10, an example operation of the reel assembly 100 of the present invention is described. The sequence of steps may be controlled manually, e.g. an operator controlling the motor and rotational direction of the reel, or automatically, for example, via a pre-installed software program. The controller may be interfaced (wire connection or wireless) to external sensors adapted to determine, for example, the rotational speed and direction, as well as the load on either the hawser string 112 or the offline hose 116. Audible or visual indicators (not shown) may be installed on the reel assembly 100 to provide audible and/or visual signals indicating, for example, the operational status of the reel assembly 100. The controller may further comprise a data logger system adapted to record data from the external sensors, as well as, monitor the data with respect to predetermined thresholds (e.g. safety thresholds).
When a shuttle tanker 12 approaches an FPSO 10 in order to offload, for example, hydrocarbons stored in the FPSO 10, the support tanker 12 is first tandem-moored to the FPSO 10 in order to secure the tanker shuttle 12 to the FPSO 10. As shown in Figure 8 (a) to (d), a firing line 128 connected to the hawser string 112 (i.e. hawser tag line 130, hawser messenger line 132, outboard chafe chain 134, hawser 136 and inboard chafe chain 138) is first propelled towards the shuttle tanker 12 from which the hawser tag line 130 is pulled towards and secured to a chain stopper 140 and traction winch 142 of the shuttle tanker 12. The motor 108 is then actuated to rotate the support drum 104 of the reel assembly 100 in an anti-clockwise direction (viewed from the motor drive side), unwinding the hawser string 112 and moving the hawser messenger line 132 and connected outboard chafe chain 134 and hawser 136 across to the shuttle tanker 12 (utilising the traction winch 142). During this step, a hose pull-in line 144 is connected to the outboard chafe chain 134 and pulled across to the shuttle tanker 12, where it is operably coupled to a hose pull-in winch 146. The outboard chafe chain 134 is secured to the chain stopper 140 of the shuttle tanker 12 and the inboard chafe chain 138 is secured to the mooring point of the FPSO 10.
As shown in Figures 9 (e) to (h) (a continuation of the steps shown in Figure 8), the shuttle tanker 12 then manoeuvres to stand off distance from the FPSO 10. In the next step, the motor 108 is actuated to rotate the support drum 104 in a clockwise direction (viewed from the motor drive side) and the offloading hose 116, connected to the hose pull-in line 144, is transferred to the shuttle tanker 12, and the motor drive 108 is stopped. The offloading hose 116 is then coupled to the hose connection 148 of the shuttle tanker 12 and the offloading of the hydrocarbons is started.
After the offloading is completed, the hose recovery step is initiated by actuating the motor drive 108 rotating the support drum 104 anticlockwise (viewed from the motor drive side) and pulling in the offloading hose 116 back toward the FPSO 10. The end portion of the offloading hose 116 is then secured to the support drum 104 utilising, for example, a fastener 125 (see Figure 5).
As shown in Figure 10 (i) to (m), the motor drive 108 is stopped and the inboard chafe chain is reconnected to the hawser connector 126 (see Figure 6).
In the next step, the motor drive is actuated to rotate the support drum 104 in a clockwise direction (viewed from the motor drive side) pulling in the hawser string 112 and attached hose pick-up line 144, followed by the messenger line 132. The tag line 130 and firing line 128 are then released overboard the shuttle tanker 12 and pulled across to the FPSO 10. The motor drive 108 is stopped and the end point of the hawser string 112 is secured to the FPSO 10.
Due to the combined functions an offloading hose reel and a hawser reel, the reel assembly 100 of the present invention may be used under the name "HOWSER REEL".
It will be appreciated by persons skilled in the art that the above embodiment has been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departing from the scope of the invention as defined by the appended claims.

Claims

A reel assembly (100) for a Floating Production and Offloading (FPSO) unit, comprising:
a reel support structure (102) adapted to be securely installed on said FPSO;

a cylindrical support drum (104), rotatably coupled to said reel support structure (102);

a motor drive (108), operably coupled to said reel support structure (102) and said cylindrical support drum (104), adapted to selectively rotate said cylindrical support drum (104) in a clockwise and anticlockwise direction;

a mooring point, provided on the FPSO;

said cylindrical support drum (104) further comprising:
at least one first support drum portion (110), coaxial with said cylindrical support drum (104) and adapted to operably accommodate a hawser string (112);

at least one second support drum portion (114), coaxial with said cylindrical support drum (104) and adapted to operably accommodate a offloading hose string (116), and

at least one circumferential divider (120), coaxial with said cylindrical support drum and adapted to divide said at least one first support drum portion (110) and said at least one second support drum portion (114), wherein said first (110) and second support drum portions (114) comprise respective first (126) and second string connectors (124), each adapted to releasably connect to a first end portion of respective hawser (112) and offloading hose strings (116), and characterised in that said first string connector (126) is further adapted to operably engage with said mooring point, so as to automatically disconnect said first end portion of said hawser string (112) from said string connector (126) and connectingly engage with said mooring point.
A reel assembly (100) according to claim 1, wherein said hawser string (112) is connected to said first string connector (126) and wound in a first direction around said at least one first support drum portion (110).
A reel assembly (100) according to any one of the preceding claims, wherein said offloading hose string (116) is connected to said second string connector (124) and wound in a second direction, opposite to said first direction, around said at least one second support drum portion (114).
A reel assembly (100) according to claim 3, wherein said first direction is clockwise and said second direction is anticlockwise.
A reel assembly (100) according to any one of the preceding claims, wherein said first string connector (126) is adapted to releasably engage with said hawser string (112).
A reel assembly (100) according to any one of the preceding claims, wherein said offloading hose (116) string is adapted to conduct fluid between said first end portion and a second end portion of said offloading hose string (116).
A reel assembly (100) according to any one of the preceding claims, wherein said at least one first support drum portion (110) comprises a first string end fastener adapted to selectively fasten a second end portion of said hawser string (112).
A reel assembly (100) according to any one of the preceding claims, wherein said at least one second support drum portion (114) comprises a second string end fastener (125) adapted to selectively fasten said second end portion of said offloading hose string (116).
A reel assembly (100) according to any one of the preceding claims, further comprising a monitor system, operably coupled to said reel assembly (100), adapted to monitor at least one or more of a string load, support drum speed and direction, and the extent of unwinding of said hawser (112) or offloading hose string (116).
A reel assembly (100) according to any one of the preceding claims, further comprising at least one audible and/or visual indicator adapted to indicate a predetermined condition of said reel assembly (100).