FPSOs are classified into the following types.
- Floating storage and offloading (FSO)
- Floating production storage and offloading (FPSO)
- Floating drilling production storage and offloading (FDPSO)
- Floating storage regasification unit (FSRU)
FPSO (Floating Production Storage and Offloading) produces crude oil and gas at sea. Treated oil is transferred to cargo tanks in the FPSO ship’s hull. Treated gas is used as fuel for on-board power generation, and excess gas is either re-injected back into the subsea reservoirs or exported via a pipeline to shore. Water that is produced during production is discharged overboard, within the environmental limits. Alternatively, water may be injected into the reservoirs.
Demand for FPSO is expected to grow, as major infrastructure for deep-water oil/gas production that is forecasted to continue increasing.
A floating storage and offloading unit (FSO) is essentially a FPSO without the capability for oil or gas processing. Most FSOs are converted single hull supertankers. An example is Knock Nevis, ex Seawise Giant, which for many years was the world’s largest ship. It was converted into an FSO for offshore use before being scrapped.
What’s the need for a FPSO ?
The FPSO concept allows oil companies to produce oil in more remote areas and in deeper water than would have been economically possible with other technology, like fixed piled structures. Furthermore, it has storage capacity for the treated crude oil produced and is equipped with an offloading system to transfer the crude oil to shuttle tankers for shipment to refineries, rather than requiring a pipeline to transport oil to shore.
One of the typical features of an FPSO is the turret mooring system, which is usually fitted inside and integrated into the FPSO’s hull. The turret is moored to the seabed with chains, wires and anchors and has bearings allowing free and unrestricted 360° rotation of the FPSO around the turret (“weathervaning”). The FPSO will normally lay head to the prevailing environment.
The living quarters provide accommodation for offshore personnel and contain the temporary refuge, (emergency) control rooms, offices, and dining & recreation lounges.
FPSO Operations encompass the following activities:
- Oil, water and gas separation
- Gas treatment, gas injection, gas lift, gas metering and gas export.
- Oil storage, oil metering, offloading, shuttle tanker management
- Water treatment
- Supply, operations, inspection and maintenance of subsea moorings, flow lines and riser systems
- Duty Holder of the FPSO Facility and the subsea pipelines
- Logistics including: supply vessels, helicopters, guard vessels
- Asset Integrity and Maintenance of all systems and equipment
- Safety and Environmental Management
- Crew training & competency.
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