A spar is a marine structure, used for floating oil/gas platforms. Named after navigation channel Spar buoys, spar platforms were developed as an extreme deepwater alternative to conventional platforms. The deep draft design of spars makes them less affected by wind, wave, and currents and allows for both dry tree and subsea production. A spar platform consists of a large-diameter, vertical buoyant

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infi ...

(s) supporting a deck. Spars are permanently anchored to the seabed by way of a spread mooring system composed of either a chain-wire-chain or chain-polyester-chain configuration. The cylinder comprises a number of tanks, the lowest contains ballast, mid-water and/or extracted oil, the upper, air for buoyancy. Helical strakes are fitted to the larger & more recent designs to mitigate the effects of vortex-induced motion. There are three primary types of spars; classic, truss, and cell. A classic spar consists of a tall-height, cylindrical hull, with tanks for heavy ballast located at the bottom of the cylinder. A truss spar comprises 3 parts, a short-height, large-diameter cylindrical hull, atop a

truss A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assembla ...

structure, atop tanks for heavy ballast. A cell spar consists of a cluster of small-diameter cylinders and relatively speaking, extremely cheap to manufacture. Cylinders are either; buoyancy only, or subdivided into buoyancy & ballast. The first spar platform was the

Brent Spar Brent Spar, or Brent E, was a North Sea oil storage and tanker loading buoy in the Brent oilfield, operated by Shell UK. With the completion of a pipeline connection to the oil terminal at Sullom Voe in Shetland, the storage facility had cont ...

. Designed for storage and offloading of crude oil products, it was installed on the UK's Brent Field in June 1976. Shell's attempted deep sea disposal of the platform in the 1990s created a massive environmental backlash by Greenpeace. The spar was eventually dismantled, with ballast used as a foundation for a

quay A wharf, quay (, also ), staith, or staithe is a structure on the shore of a harbour or on the bank of a river or canal where ships may dock to load and unload cargo or passengers. Such a structure includes one or more berths ( mooring locati ...

in Norway. The first spar platform designed for production was the Neptune spar, located in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

, and was installed in September 1996 by Kerr McGee. The first cell-spar platform was Kerr-McGee's Red Hawk spar, (7 of 8m diameter cells). Cell-spar implementation has to date only ever used for one platform. Field-depletion occurred 4 years after production started, Red Hawk was decommissioned in 2014 under the

Bureau of Safety and Environmental Enforcement The Bureau of Safety and Environmental Enforcement (BSEE "Bessie") is an agency under the United States Department of the Interior. Established in 2011, BSEE is the lead agency in charge of improving safety and ensuring environmental protection ...

's " Rigs-to-Reefs" program, at which time it was the deepest floating platform to be decommissioned. The world's deepest production platform is Perdido, a truss spar in the Gulf of Mexico, with a mean water depth of 2,438 meters. It is operated by

Royal Dutch Shell Shell plc is a British multinational oil and gas company headquartered in London, England. Shell is a public limited company with a primary listing on the London Stock Exchange (LSE) and secondary listings on Euronext Amsterdam and the New ...

and was built at a cost of $3 billion.Shell starts production at Perdido
/ref>

References

External links

{{commons category, Spar platforms

- containing detailed diagrams Oil platforms Offshore engineering