A Floating Production, Storage and Offloading vessel (FPSO; also called a "unit" and a "system") is a type of floating tank system used by the offshore oil and gas industry and designed to take all of the oil or gas produced from a nearby platform (s), process it, and store it until the oil or gas can be offloaded onto waiting tankers, or sent through a pipeline. A FSO is a similar system, but without the possibility to do any processing of the oil or gas. Oil has been produced from offshore locations since the 1950s. Originally, all oil platforms sat on the seabed, but as exploration moved to deeper waters and more distant locations in the 1970s, floating production systems came to be used.
Oil produced from offshore production platforms can be transported to the mainland either by pipeline or by tanker. When a tanker solution is chosen, it is necessary to accumulate oil in some form of tank such that an oil tanker is not continuously occupied while sufficient oil is produced to fill the tanker. Often the solution is a decommissioned oil tanker which has been stripped down and equipped with facilities to be connected to a mooring buoy. Oil is accumulated in the FPSO until there is sufficient amount to fill a transport tanker, at which point the transport tanker connects to the stern of the floating storage unit and offloads the oil.
An FPSO have the capability to carry out some form of oil separation process obviating the need for such facilities to be located on an oil platform.
FPSOs are particularly effective in remote or deepwater locations where seabed pipelines are not cost effective. FPSOs eliminate the need to lay expensive long-distance pipelines from the oil well to an onshore terminal. They can also be used economically in smaller oil fields which can be exhausted in a few years and do not justify the expense of installing a fixed oil platform. Once the field is depleted, the FPSO can be moved to a new location.
The world's largest FPSO is the Kizomba A, with a storage capacity of 2.2 million barrels. Built at a cost of over US$800 million by Hyundai Heavy Industries in Ulsan, Korea, it is operated by Esso Exploration Angola (ExxonMobil). Located in 1200 meters (3,940 ft) of water at Deepwater block 15,200 statute miles (320 km) offshore in the Atlantic Ocean from Angola, West Africa, it weighs 81,000 tonnes and is 285 meters long, 63 meters wide, and 32 meters high ((935 ft by 207 ft by 105 ft).