WO2013076298A1

WO2013076298A1 - Floating accomodation

Info

Publication number: WO2013076298A1
Application number: PCT/EP2012/073593
Authority: WO
Inventors: Patrick FERRI
Original assignee: Single Buoy Moorings Inc.
Priority date: 2011-11-25
Filing date: 2012-11-26
Publication date: 2013-05-30

Abstract

A floating accommodation or floating logistic hub (1) for offshore location includes a hull, that has a front section (A) and a rear section (B). The front section includes a turret (2) that is anchored to the sea bed to allowing the hull to weathervane, and on deck (19) of the front section a heliport (3, 4) with a parking area for at least two helicopters. The rear half section (B) includes an accommodation block (14) and an access system for transfer of personnel from and to a personnel transport vessel.

Description

FLOATING ACCOMODATION

Field of the invention

The invention relates to a floating accommodation for offshore location.

Background of the invention

A typical offshore accommodation helicopter base such as the Camelot is fitted with two hydraulically powered Active Heave Compensated (AHC) Telescopic Gangways, offering full redundancy, optimal positioning in all weather conditions and rapid embarkation in emergencies. Designed in Norway for use in the North Sea, it is capable of high frequency quick connection and fast release during crew boat transfer operations.

However, in such configurations there is no sheltered area that can be provided by having an asymmetric or off centre turret. This will enable to naturally position the floating building such that it offers an area with a protecting effect on swell. Further, depending on the size of the floating accommodation, it is needed to have weathervaning systems where a dynamical positioned, a conventionally anchored or spread-moored solution cannot be applied anymore. Summary of the Invention

The object of the present invention is to provide a floating accommodation which can park several helicopters and which is safe and relatively easy to build.

According to the invention, the floating accommodation also known as floating logistic hub (FLH) comprises a hull, said hull having a front (half) section and a rear (half) section, the front section comprising a turret that is anchored to the sea bed to allowing the hull to weathervane and a heliport with a parking area for at least two helicopters. The rear section comprises an accommodation block and an access system for transfer of personnel from and to a personnel transport vessel.

The size of the hull is depending on vessel selection, within a range from an Aframax to an ultra large crude carrier (ULCC).

In an embodiment, the hull of the floating accommodation has a length of at least 50m, and a length-to -width ratio of at least 2 and can be made of a refurbished and converted offshore carrier. Other particularities of the floating building according to the present invention are a recess located in the hull and a fender wall providing additional shielding for high offshore sea states and having the heliport and helicopter storage area covering most of the front half section area of the building.

According to an aspect of the invention, the rear section further comprises a ferry berthing quay.

Brief description of the drawings:

The invention will be further described below in connection with exemplary embodiments with reference to the accompanying drawings, wherein

FIG. 1 shows a top view of an offshore building according to the present invention. FIG. 2 shows a possible layout of the floating accommodation.

FIG. 1 shows the top view of the most interesting layout of an offshore building 1, i.e. a floating accommodation or floating logistic hub, according to the present invention. Main choices and motivation to define such a layout are operation safety and systems uptime:

The floating accommodation 1 comprises on a front section A the turret 2 that can be anchored to the sea bed. The turret 2 is arranged with a weathervaning system that minimizes mooring loads and vessel motions by naturally aligning the vessel with the wind, wave and current.

In an embodiment, the turret 2 is arranged as an external turret to save space in comparison to an internally based turret. This can be applicable for some more stringent sea state conditions, for example like those present in seas near Brazil.

Further, a turret arranged off-centre in the vessel 1 can generate a natural vessel angle with prevailing weather and thus create at the opposite side a more protected lee side sheltered area. This provides some benefits for transportation vessels (personnel transportation ferries) berthing and mooring with the floating accommodation 1. Such transportation vessel is for example a High Speed Personnel Transportation Vessel (HSPTV), but may also relate to any transhipment activities with any type of boats, e.g. supply boats.

Supply boats will either berth side by side, or in tandem depending on berth availability and operation hazard level. The floating accommodation 1 also comprises a heliport 3 with landing and take-off pads or helipads 4. The heliport 3 is located as close as possible to the turret 2, and has a landing/take off area for at least two helicopters. The heliport comprises a parking area as needed for a number of helicopters (at least two) driven by rotation requirements. Further, an air control tower 5 and a maintenance workshop 6 are provided near the heliport 3.

The location of heliport close to the turret is helpful for facing the weather conditions: by locating the heliport 3 close to the turret 2 no vortex effect from an accommodation block on the floating accommodation 1 is present.

Additionally, this location of the heliport 3 allows minimising vessel motions at that location. There is substantially no collision risk during approach and take off. A similar advantage is observed for an air control tower 5 of the heliport 3 : the location close to the turret 2 minimises collision risk with respect to helicopter approach /leaving optimum route.

Further the helipads 4 are arranged in cantilever thus no infrastructure to fly above before landing and take off.

By providing a helicopter in storage position during people transfer away from the landing and take-off pads 4, it allows high frequency round trips carried out in a safe matter.

The heliport 3 will include a maintenance workshop 6 to allow all type of helicopter routine maintenance. On the heliport 3 the maintenance workshop 6 is available for helicopter fleet routine maintenance. This has the advantage to reduce trips back to shore, saving fuel and non productive flying hours.

Also, a separate helicopter spare part warehouse 7 is provided and located within reach of a crane 8 nearby to the maintenance workshop. This warehouse storage is available for helicopter spare parts.

Furthermore the floating accommodation 1 comprises a lay-down area, 9 which is located substantially mid-ship to be used both for heliport 3 and any other activities such as containers storage. In this lay-down area an offshore crane 8 is available for supply boat equipment transfer and helicopter handling issues: spares, lubricant barrels, etc.

Any heavy equipment that is needed for the accommodation blocks can be lifted, stored at and dispatched from this area 9. The offshore crane 8 is rated to suit lifting needs i.e. has a high capacity in accordance with requirements.

Additionally, the floating accommodation 1 is arranged with a supply boat berth 17 under the main crane 8 capable of accommodating high sea going vessels up to 150m. Moreover, the floating accommodation 1 comprises a ferries 13 dedicated quay 11 located in a "protected area" - lee side 12 of the vessel 1. The Floating Logistic Hub arranged on the vessel generates naturally this sheltered zone. A protruding fender wall

10 provides additional sea weather protection to the ferries' berth. The floating accommodation 1 comprises on a rear section B an accommodation block 14 away from the helicopter activity and has the capacity to accommodate 400 people or more. The entire unit may allow for 1500 people transfer per day.

Additionally, the floating accommodation 1 is arranged with measures for flammable fluid transfers from the stern, using supply vessels in tandem: this provides advantages in that hazardous operation is away from the heliport and the fluid supply vessels are moored in the "protected area".

It is advantageous to build an accommodation floating building or floating logistic hub 1 from a refurbished and converted oil tanker or carrier as it allows offshore application and installation location flexibility, and depending on the tanker or carrier selected it is possible to select the deck space for the function needed, the storage capacities requested, the weather shielding for the personnel vessel berth and boarding. Here the front section A relates to the front section of the carrier from bow to about midship, with the external turret 2 being coupled to the bow section. The rear section B of the carrier comprises the section from about midship to the stern.

The weathervaning function, as mentioned above, ensured by an external turret 2 to minimize motions, thus ensures an optimal uptime. Optionally, stern thrusters 15 are enhancing the vessel orientation during helicopter and vessel's activities, thus improving uptime in extreme cases.

The floating accommodation or logistic hub 1 also comprises heliport operations, landing areas and storage area. There are also passengers embark / disembark facilities

11 comprising heave compensated equipments, a maintenance workshop 6, spare part storage 7 and at least one crane 8 for the lifting operations. There are also provided a supply boat berthing facilities 17 and people transportation vessels (900-1500 people Ferries 13) quay 11 for ferries 13 with a capacity of 900-1500 people as well as accommodation for at least 400 persons.

The selected offshore carrier hull will be refurbished and converted to allow for a 30 years design life, thus steel renewal and corrosion protection will be defined accordingly. As a result of the stability study, a major amount of steel may need to be fitted to generate a significant bilge keel 16, 17.

In an embodiment, the hull of the floating accommodation is provided with bilge keel(s) 16, 17 running over at least 25%, preferably at least 50 % of the length of the hull. Bilge keels are arranged in pairs, one on starboard, the other on larboard side.

Bilge keels of such length advantageously improve resistance against rolling of the vessel.

A recess 11, 12 will be created in the back side of the hull to generate a shielded area for High Speed Personnel Transportation Vessel (HSPTV) berth. Also, a protruding wall 10 is arranged to add protection to the HSPTV bow and will minimize the wave height at location.

Thus this maximizes the uptime, which will be confirmed by hydrodynamic stability study.

Additionally or alternatively, a shielded area 20 (indicated by a dashed line) for mooring the HSPTV or a supply vessel may be provided at or within the stern of the floating accommodation vessel. This location may provide enhanced shelter to a vessel mooring in this area. The shielded area may be covered by a deck 19 (construction) above it.

The turret 2 will allow the Floating Logistic Hub to weathervane. Benefits are:

^■ Minimize the mooring loads and vessel motions

^■ Add some general, especially bow stability, which will help the heliport operations

^■ Have the bow facing the weather direction, whatever the condition

^■ Have the helicopter approached leaving route face the wind.

The external turret 2 is not obstructing the main deck. i.e. does not consume space. It is therefore a light structure, and a system suitable for deep water Floating Logistic Hub mooring. To improve and especially control with precision the Floating Logistic Hub orientation, stern thrusters 15 can be fitted to optimize helicopter's activities; in case there is a significant orientation difference between the sea current and the wind direction.

The Floating Logistic Hub will ensure the helicopter airport function in order to dispatch up to 1500 people per day to all platforms within presale fields.

The embarked heliport 3 is designed to comply with national and international regulations. It will be self sufficient and will provide:

^■ The necessary helipads 4 to allow required rotations as presented below

■ Air control tower 5 and radar systems

^■ Maintenance and storage workshop 6, 7

The heliport 3 will include a maintenance workshop 6 to allow all type of helicopter routine maintenance. Of course, the person skilled in the art will appreciate that an assigned footprint of the heliport will be designed in accordance with the selected type of helicopter and the selected / required regulation's obligations.

In an exemplary embodiment, the assigned footprint for the heliport is 25x25m, contiguous to lay down area 9, offshore crane 8 and supply vessel's berthing location 10.

Also, a separate helicopter spare part warehouse 7 is provided and located within the main crane reach 8, nearby to the maintenance workshop 6.

From FPSO (Floating Production, Storage and Offloading) experience, helicopter landing and take off is not a major problem in term of availability. Moreover the FPSO helipads are located oppositely to the turret, thus where the vessel motions are highest. In accordance with invention, a heliport 3 close to turret 2 improves the situation.

A way to be investigated could be to have one helipad heave compensated, if higher availability would be needed.

A side by side berthing area is designed and assigned to incoming/outgoing supply boats. Thanks to the heavy duty offshore crane 8 on the floating accommodation 1, any pieces of equipment, as well as containers can be transferred both ways.

Also, liquid transfer like drilling mud and any none hazardous products can be offloaded/loaded from this location. Supply boat berthing has been located at port side 17, opposite to the turret 2 and thus within the generated protected area 12. Also being within the first half to the Floating Logistic Hub, the motions are minimized.

All liquid (especially hazardous) will be transferred from the stern 15, via floating hoses normally stored onto stern hose reels. Incoming vessels will be either dynamically positioned (DP) or tandem moored to the Floating Logistic Hub.

This allows transshipment in heavy sea state, with waves up to for example 4.5m.

A very suitable location for the HSPTV is in a shielded area in order to minimize the vessel motions and thus maximize he uptime. There are 2 solutions:

Thanks to the off-centre turret 2, the Floating Logistic Hub 1 is arranged to make an angle facing the prevailing weather (winds) and generate naturally a protected cone. Within this area, a recess in the hull and the "fender wall" 10 will provide additional shielding.

From the weathervaning function, the Floating Logistic Hub generate also a naturally protected area at the stern

The primary HSPTV berth consists of a long side quay 11 as per conventional port. Transfer is fast and efficient, accommodating transfer of people up to about 3.5m h_s (Significant Wave Height) and this situation should cover 80% of the time (up to 2.7m h_s).

Transfer will take place thanks to a set of two Offshore Access System (OAS) - offshore hydraulic heave compensated gangways - described in a next paragraph below, as used in the industry under North Sea conditions.

Above the 3.5m and up to 4.5m h_s, (between to 90 and 95% monthly mentioned h_s non- exceedence), the HSPTV will be located behind the Floating Logistic Hub, dynamically positioned. Personnel transfer will take place via a third OAS.

A Hydrodynamic model will be used to evaluate the shielding effect and confirm these scenarios and thus allow a 95% Floating Logistic Hub personnel access uptime.

The Personnel Offshore Access System provides the transfer of personnel from high speed transportation vessel to Floating Logistic Hub. The transfer of personnel will be achieved through the quay 11 located in the hull and detailed in the paragraph above. Walk access from this quay to the accommodation is provided by 2 slopes. Above "acceptable" sea state, defined by the type of HSPTV and FLH motions at berth location, the use of Offshore Transfer System (OTS) will be mandatory [also called Offshore Access System in the industry]. Two of them will be located at both extremities of the quay to ensure efficient people transfer and adequate safety redundancy, a Dynamic Positioned HSPTV could maximize uptime and safety and cope with these offshore access systems.

As a back-up system, a single long reach OAS will be located onto a dedicated platform at the FLH stern. This improves both safety and availability in harsh conditions.

The accommodation block 14, located at the second half of the Floating Logistic Hub will provide full accommodation and living facilities 24/24, 7/7 and 365/365 for 400 people.

As mentioned above, access to them from an HSPTV quay 11 will be by walking external slopes, but can be by protected tunnel if detailed weather analysis demonstrate the need.

People day stand-by from sea arrival to helicopter departure (and reverse) will take place in dedicated rooms within the accommodation, capable to receive the 1500 daily people. Moving personnel from accommodation 14 to heliport 3 will be performed through a protected and dedicated tunnel by identified groups, in accordance with helicopter rotation requirements. The immigration / safety briefing, permitting checking, etc will take place in dedicated rooms for example located on either the Air Control Block Tower block 5 or the accommodation block.

In view of the above, a floating accommodation or Logistic Hub can provide one or more of the following functions for:

receiving and parking several helicopters,

providing helicopter maintenance service warehouse,

storing helicopter maintenance spare parts,

storing helicopter fuel,

providing hotel facilities to the offshore crew under transfer,

loading / offloading berthing quay for high speed transportation ferries,

storing offshore production spares and chemicals, and

storing required fluids and material for offshore drilling activities. Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

Claims

1. Floating accommodation or logistic hub (1) for offshore location comprising a hull, said hull having a front section (A) and a rear section (B), the front section comprising a turret (2) that is anchored to the sea bed to allowing the hull to weathervane, and on deck (19) of the front section a heliport (3, 4) with a parking area for at least two helicopters, the rear half section (B) comprising an accommodation block (14) and an access system for transfer of personnel from and to a personnel transport vessel.

2. Floating accommodation according to claim 1, characterized in that the hull having a length of at least 50 m, and a length- to-width ratio of at least 2.

3. Floating accommodation according to claim 1 or 2, characterized in that the turret (2) is an off center turret.

4. Floating accommodation according to any one of claims 1 to 3, characterized in that the turret (2) is an external center turret placed outside the hull at the bow.

5. Floating accommodation according to any one of the preceding claims 1 to 4, wherein the hull is a refurbished and converted large crude carrier.

6. Floating accommodation according to any one of the preceding claims, characterized in that the hull is provided at one side with a recess (1 1, 12) and a fender wall (10) providing additional shielding for the personnel transport vessel.

7. Floating accommodation according to any one of the preceding claims, characterized in that the heliport area covers most of the front half section (A) of the floating accommodation (1).

8. Floating accommodation according to any one of the preceding claims, characterized in that the hull comprises a recess (12) at a back side (B) of the hull to provide a shielded area for berth of a vessel such as a High Speed Personnel Transportation Vessel (HSPTV).

9. Floating accommodation according to claim 8, characterized in that the recess in the hull comprises a protruding wall (10) extending from the hull.

10. Floating accommodation according to any one of the preceding claims, characterized in that the hull comprises a recess (18) within the stern of the hull to provide a shielded area for berth of at least one vessel.

11. Floating accommodation according to any one of the preceding claims, characterized in that the hull comprises at least one bilge keel (16, 17) on each board, wherein the at least one bilge keel (16, 17) extends over at least 25 % of the length of the hull.

12. Floating accommodation according to any one of the preceding claims, characterized in that the heliport (3, 4) has a landing/take off area (4) for at least two helicopters.

13. Floating accommodation according to claim 12, characterized in that an air control tower block and a maintenance workshop (6) are provided adjacent to the heliport (3).