Structure Key Features
The UPB System desgin considers the equipment layout, safety particularly damage stability and explosion modelling, access and egress and the hydrodynamic requirements. The UPB System is a modular design allowing for simplicity and repeatability of construction.
The Buoy
The buoyant structure is over 60 metres in height, excluding a cold vent tower, and is split into three sections:
Upper Section
Air intake, exhaust and vent tower, satellite controls, cold vent tower, and an optional helideck.
Mid Section
Boat landing deck and access / egress shaft.
Submerged Section
22 diameter hull comprising of four decks, which form the main part of the buoyancy chambers:
- Deck 1: control, HVAC, communications, VSD, power distribution and work area
- Deck 2: lube oil, diesel and chemical injection day tanks
- Deck 3: power and utilities
- Deck 4: process, power and utilities
The purpose of the four processing and control decks is to safely control and manage the extraction of hydrocarbons. The structure is designed for safe access and egress for maintenace and is designed to float in the vertical position from shallow draft for simplified towing, installation and decommissioning.
The Tether System
The standard tether arrangement for the UPB System comprises multiple independent tether groups attached to each of 3 or 4 outriggers. The distance of the tether attachment points about the vertical axis of symmetry is set to ensure that the tethers do not come in contact with the buoy and/or risers.
The Gavity Base & Sea Anchoring System
The gravity base is designed to be a single combined unit serving two purposes; tethering of the buoy and storage of hydrocarbons. The configuration of this system is adapted to suit the individual needs of the site.
Fluid Storage
The storage facility is designed as a single unit with a storage capacity of 200,00 bbls of oil at a minimum specific gravity (SG) of 0.76. The unit size is determined by the rate of production, the offloading frequency and the operating philosophy. The fluid storage system serves three key functions:
- to separate oil and water such that oil can be exported
- to maintain the tank fluid at a temperature sufficient to promote oil-water seperation
- to provide the means for export of the seperated crude
The concrete storage tank can also be used to heat heavier crude so that it can be stabilised for export.
Export System
The storage facility forms the gravity anchor for the buoy and the buoy may then also provide support for an export riser to the buoy with floating hoses being held clear by a hold-off tanker pendant.
Offloading can be achieved by a separate export line from the tank via a dedicated offloading buoy to the shuttle tanker or by using the UPB as an offloading buoy and routing the export line via the buoy. These methods are well practised by oil and gas operators with existing seabed storage systems. Control, commencement and termination of off-take from the shuttle tanker is often independent of production and conducted remotely, allowing the UPB System to remain unmmaned throughout this tanker offloading system.
Separate tanker offload studies have allowed for 180,000bbls to be offloaded during winter North Sea conditions and 200,000 bbls offloads in the summer months.
Key Features
| Key Features | |
| Unmanned Production Buoy |
|
| Subsea Storage |
|
| Tethers |
|
| Combined Risers |
|
| Tanker Offload |
|
| Subsea Production Well |
|
| Operations |
|
| Installation |
|