An FPSO (Floating Production, Storage, and Offloading) vessel is a floating facility used in offshore oil and gas production. It processes hydrocarbons, stores oil, and exports processed oil and gas to tankers or pipelines. Below is a breakdown of its typical modules, process units, and equipment for an oil-based FPSO with oil storage, gas export, and water injection capabilities.
1. Hull Modules (Marine Systems)
The hull provides buoyancy, stability, and storage capacity. Key systems include:
1.1 Storage
- Crude oil storage tanks: Store stabilized crude before offloading.
- Slop tanks: Hold process waste or contaminated oil/water.
- Ballast tanks: Maintain vessel stability.
1.2 Marine Systems
- Power generation modules: Diesel or gas turbines.
- Seawater pumps: For cooling and process systems.
- Ballast pumps: For water movement in ballast tanks.
- Inert gas systems: Prevent tank flammability.
- Offloading systems: Loading arms or export hoses.
- Mooring systems: Turret mooring or spread mooring for station-keeping.
To ensure efficient design and operations, P&ID diagrams play a critical role in detailing the FPSO’s process and marine systems. Learn more about P&ID diagrams here.
2. Topside Modules (Process Systems)
2.1 Oil Processing Units
Processes crude oil from the reservoir into stabilized, export-quality oil.
- Separation Train: Separates fluids into oil, gas, and water.
- Primary separators: Three-phase (oil, gas, water).
- Heater treaters: Enhance oil-water separation.
- Dehydration/Desalting units: Remove water and salts.
- Crude oil stabilization: Lowers Reid Vapor Pressure (RVP) for storage.
- Metering skid: Measures oil quality and quantity.
Key Equipment:
- Separators (HP, MP, LP).
- Heat exchangers and heaters.
- Electrostatic coalescers.
- Pumps for export.
2.2 Gas Processing Units
Processes associated gas for export or reinjection.
- Compression units: Increase gas pressure for export or reinjection.
- Gas dehydration: Removes water vapor using TEG (triethylene glycol).
- Gas sweetening: Removes H₂S and CO₂ using amine treatment (if required).
- Gas export: Export-quality gas sent through risers to pipelines.
Key Equipment:
- Gas compressors (centrifugal, reciprocating).
- TEG dehydration package.
- Amine contactor towers.
- Gas coolers and scrubbers.
2.3 Water Injection Units
Used to maintain reservoir pressure and optimize oil recovery.
- Seawater treatment: Removes impurities for reservoir compatibility.
- Filtration and deoxygenation: Prevents reservoir contamination and corrosion.
- High-pressure pumps: Inject treated water into wells.
Key Equipment:
- Seawater lift pumps.
- Filters (media, cartridge).
- Deaeration towers or membrane units.
- High-pressure injection pumps.
2.4 Produced Water Treatment Units
Treats water separated during production for discharge or reinjection.
- Oil removal: Using hydrocyclones or induced gas flotation (IGF).
- Water polishing: Further reduces oil-in-water levels.
Key Equipment:
- Hydrocyclones.
- Induced gas flotation units.
- Degassing vessels.
- Pumps (for water discharge or reinjection).
2.5 Utilities and Support Modules
Support processing and ensure safety and functionality.
- Flare systems: Safely burn excess hydrocarbons.
- Chemical injection systems: Inject corrosion inhibitors, defoamers, etc.
- Power generation: Gas turbines or diesel generators.
- Cooling systems: Heat exchangers, air coolers.
- Control room: Centralized process monitoring.
Key Equipment:
- Flare stacks.
- Chemical storage tanks and metering pumps.
- Heat exchangers and coolers.
- Emergency generators.
3. Riser Balconies or Riser Areas
These are structural platforms located on the hull (typically near the turret or sides of the FPSO). They provide a safe and organized space for handling risers that transport hydrocarbons, water, or gas between the seabed and the FPSO topsides.
3.1 Key Features and Components:
- Riser hang-off points: Secure and support risers at the FPSO interface.
- Types of risers:
- Flexible risers (common for FPSOs).
- Steel catenary risers (SCRs) or hybrid risers (depending on water depth and field design).
- Umbilicals: Carry power, control signals, and chemicals for subsea operations.
- Pull-in winches and tensioners: Assist in connecting risers to the FPSO.
- Riser protection structures: Protect risers from damage due to wave, current, or operational loads.
- Access walkways: Ensure safe inspection and maintenance.
3.2 Key Equipment in the Riser Area
- Riser connectors: For securing risers to the FPSO.
- Manifold block valves: Allow isolation and flow control.
- Pig launchers/receivers: For cleaning subsea pipelines.
- Flowline jumpers: Flexible or rigid connections between risers and manifolds.
- Instrumentation: Pressure, temperature, and flow sensors.
The riser balcony/manifold area is a critical interface that ensures the seamless connection between subsea production and topsides processing. Proper design and maintenance of this area are essential for operational efficiency and safety.
Documenting riser systems requires accurate use of P&ID symbols for equipment and connections. Learn more with our comprehensive article about P&ID symbols.
4. Riser Manifolds
Located on the FPSO topsides near the riser balcony, the riser manifold is where risers terminate and connect to the processing systems. It directs and controls the flow of fluids from the subsea wells to the appropriate process modules (e.g., separators, gas compression units).
4.1. Key Functions:
-
Flow Distribution
- Direct production fluids (oil, gas, and water) to topsides processing equipment.
- Distribute injection fluids (e.g., water, gas, or chemicals) to subsea wells.
-
Flow Control
- Includes valves, chokes, and instrumentation for managing pressure, flow rates, and routing.
-
Pressure Monitoring
- Pressure and temperature sensors to monitor the integrity and efficiency of the production system.
-
Pigging Facilities
- Some manifolds include pigging launchers and receivers for pipeline maintenance.
5. Other Modules and Considerations
5.1 Safety and Emergency Systems
- Fire & gas detection systems.
- Emergency Shutdown Systems (ESD).
- Lifeboats and escape routes.
5.2 Living Quarters
- Accommodation for crew (offices, cabins, helideck).
For large-scale engineering projects like FPSOs, tools like eAI can streamline workflows by bridging the gap between P&ID annotations and cost estimation. Discover how eAI can enhance project engineering.
