FPSOs, or floating production storage and offloading facilities, help process and store oil and gas offshore. These vessels retrieve, process, and store oil or gas until a shuttle tanker arrives to transport it or it is pumped to shore via a pipeline. They are usually employed by oil and gas companies to work in varying depths and conditions - one of their biggest advantages is that they are very flexible. They can operate in areas where pipelines aren’t feasible, are quickly mobile, and are usually leased rather than purchased.
FPSO image from NES Fircroft.
History of FPSOs
In 1977, Shell created the first FPSO by converting an oil tanker. At that time, oil and gas could only be retrieved from shallow waters of 160 feet or less and deepwater pipelines were not feasible. Oil fields hundreds of miles from shore also meant no pipelines. The tankers where this oil and gas was stored are called FSOs, or Floating Storage and Offloading units, which were unable to process the oil and gas. FPSOs provided the ability to process oil and gas as well as store and offload it, giving much more value to the vessel.
FPSOs became more popular as onshore oil and gas discoveries declined and production moved offshore. According to Oil & Gas IQ, “There are more than 200 FPSOs today operating around the globe. They're less expensive than traditional offshore oil and gas platforms, more flexible, safer, and time-efficient.” FPSOs receive hydrocarbons from flowlines, flexible or rigid lines connecting from the well, and risers, which are the lines from the seabed to the surface. They have a double hull design to safely store oil or gas until it is transported via ship or pipeline. Gas can be transported or reintroduced to the field to increase production.
At first glance, FPSOs may look like a large tanker, but the easiest way to spot them is to look for the processing equipment on the deck of the vessel. FPSOs can be spread moored by anchoring to multiple points on the seafloor or turret/weathervane by integrating a turret to a single point. Turret anchoring allows a FPSO to move for a favorable angle to wind and waves as needed. A detachable FPSO turret uses both systems to moor the vessel and has a turret that is easily detachable for a hazard like severe weather. Quarters are similar to other offshore facilities, they contain living space for crew to spend long periods of time offshore. Check out our recent article to find out more about what life is like offshore.
FPSO diagram from Energy Maritime Associates.
Why use an FPSO instead of a traditional platform?
In a word: versatility. FPSOs can operate in remote areas at a cheaper price and can connect to any pipeline. They excel at working in smaller fields where permanent installations wouldn’t make sense. While upfront costs for these vessels are higher, they end up being cheaper to use in the long run for many applications. According to Investopedia, “a high-production purpose-built FPSO for a large field offshore of Africa is around $700 to $800 million.” FPSOs are usually leased, providing more flexibility than a fixed asset that can take many years to finance and build. Safety is another plus, as FPSOs can easily disconnect from their subsea assets in severe weather. They can also operate in harsh areas and store a lot of oil and gas, making some fields more viable. FPSOs may also be selected for more environmentally sensitive locations and some mid-range water depth applications.
Glen Lyon FPSO. Image from KBR.
Record breaking FPSOs
Total's Egina has the largest storage capacity of any FPSO at 2.3 million barrels of oil. According to NES Fircroft, “It’s based in the Egina field, 130km off the coast of Nigeria in water depths of 1,600 metres.” At 330 meters long, 60 meters wide, and almost 220,000 metric tons, it’s a huge vessel. Production is up to 208,000 barrels of oil per day from 44 subsea wells to which it’s connected. It was built by Samsung Industries and holds 200 crew. It’s connected to over 150 km of lines and is responsible for almost 10% of Nigeria’s oil production.
Turritella holds the record for deepest oil and gas production unit at more than 2,900 meters or 9,500 feet. Operated by Shell, it was built to operate in the Stones field discovered in 2005 in the Gulf of Mexico. The oil and gas reservoirs are more than 25,000 feet below sea level, according to Shell. SMB Offshore built the vessel, and it was the first FPSO for both companies to be located in the Gulf of Mexico. It has the world’s largest Buoyant Turret Mooring, or disconnectable buoy system, allowing quick disconnection and reconnection in the event of a hurricane. According to NES Fircroft, “It also pioneered the use of an In-line Mooring Connector (ILMC) which allowed it to re-adjust each mooring line tension without affecting any installed device - an innovation now seen in many other vessels.” Check out the video below about the Stones project and the Turritella FPSO.
Video from Shell.
BP’s Glen Lyon has the record for highest oil throughput at 320,000 barrels of oil per day, according to KBR. It also holds the record for largest harsh water FPSO, as it operates at the Quad 204 project in the North Sea. It’s anchored to the seabed and does not have it’s own propulsion, requiring tugs to move it. NES Fircroft lists specifications: “The vessel is 270 metres long by 52 metres wide and weighs 100,000 tonnes. It has a storage capacity of 800,00 barrels of oil and accommodation for up to 140 people.” It operates on a turret mooring system.
Dynamic Positioning
Flexible FPSOs have dynamic positioning systems that allow them to precisely locate over a well or relocate to another field. More purpose-built FPSOs like the Glen Lyon may not have any propulsion. Dynamic positioning also helps when conventional mooring systems may not be available, such as ultra-deep water. OneStep Power tests dynamic positioning DP2 and DP3 systems for fault ride-through to ensure the system can handle a short circuit event and not lose station. Find out more about how we do that on our Services page.
That’s about all for FPSOs! If you want to learn more about other dynamically positioned vessels, check out our article on 22 types of dynamically positioned vessels.
Until next week, Happy Friday!
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