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Offshore platform in the Gulf of Mexico
Offshore platform in the Gulf of Mexico


An oil platform or oil rig is a large structure used to house workers and machinery needed to drill and/or produce oil and natural gas through wells in the ocean bed. The Gulf of Mexico ( Spanish: Golfo de México) is the ninth largest Body of water in the world Petroleum ( L petroleum, from Greek πετρέλαιον, lit Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, Depending on the circumstances, the platform may be attached to the ocean floor, consist of an artificial island, or be floating. An artificial island is an Island that has been constructed by humans rather than formed by natural means 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

Generally, oil platforms are located on the continental shelf, though as technology improves, drilling and production in deeper waters becomes both feasible and profitable. The continental shelf is the extended perimeter of each Continent and associated Coastal plain, which is covered during interglacial periods such A typical platform may have around thirty wellheads located on the platform and directional drilling allows reservoirs to be accessed at both different depths and at remote positions up to 5 miles (8 kilometres) from the platform. Directional drilling (or slant drilling) is the practice of drilling non-vertical wells It can be broken down into three main groups Oilfield Directional A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States The kilometre ( American spelling: kilometer) symbol km is a unit of Length in the Metric system, equal to one thousand

Many platforms also have remote wellheads attached by umbilical connections, these may be single wells or a manifold centre for multiple wells. An umbilical cable or umbilical is a cable which supplies required consumables to an apparatus

Contents

History

The Thames Sea Forts of World War II are considered the direct predecessors of modern offshore oil platforms, having been pre-constructed in a very short time, they were then floated to their location and placed on the shallow bottom of the Thames estuary. The Maunsell Sea Forts were small fortified towers built in the Thames and Mersey estuaries during the Second World War to help defend the United Kingdom The Thames ( is a major River flowing through southern England. [1][2] In 1938, the Superior Oil company constructed the first offshore oil platform off the Gulf Coast of Louisiana. Superior Oil Company (1921–1984 was an independent American oil company that is now part of ExxonMobil. The State of Louisiana ( or, État de Louisiane, pronounced) is a state located in the southern region of the United States of America

Types

Larger lake- and sea-based oil platforms and oil rigs are some of the largest moveable man-made structures in the world. There are several distinct types[3] of platforms and rigs:

Fixed Platforms

These platforms are built on concrete and/or steel legs anchored directly onto the seabed, supporting a deck with space for drilling rigs, production facilities and crew quarters. A Fixed Platform is a type of offshore platform used for the production of oil or gas. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Such platforms are, by virtue of their immobility, designed for very long term use (for instance the Hibernia platform). Hibernia is the name of a petroleum field located in the North Atlantic Ocean, approximately 315 kilometres east-southeast of St Various types of structure are used, steel jacket, concrete caisson, floating steel and even floating concrete. In Geotechnical engineering, a caisson is a retaining watertight structure used for example to work on the foundations of a Bridge pier, Steel jackets are vertical sections made of tubular steel members, and are usually piled into the seabed. Concrete caisson structures, pioneered by the Condeep concept, often have in-built oil storage in tanks below the sea surface and these tanks were often used as a flotation capability, allowing them to be built close to shore (Norwegian fjords and Scottish firths are popular because they are sheltered and deep enough) and then floated to their final position where they are sunk to the seabed. Condeep (abbr concrete deep water structure) refers to a make of Gravity base structure for Oil platforms developed and fabricated by Norwegian Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional A fjord or fiord (fjɔːd|fiːɔːd or fiːɔːd is a long narrow Inlet with steep sides created in a valley carved by glacial activity. Scotland ( Gaelic: Alba) is a Country in northwest Europethat occupies the northern third of the island of Great Britain. Firth is the Lowland Scots word used to denote various coastal waters in Scotland. Fixed platforms are economically feasible for installation in water depths up to about 1,700 feet (520 m).

A fixed platform base under construction on a Louisiana river
A fixed platform base under construction on a Louisiana river

Compliant Towers

These platforms consist of narrow, flexible towers and a piled foundation supporting a conventional deck for drilling and production operations. A compliant tower (CT is a fixed rig structure normally used for the offshore production of Oil or gas. Compliant towers are designed to sustain significant lateral deflections and forces, and are typically used in water depths ranging from 1,500 and 3,000 feet (450 and 900 m).

Semi-submersible Platform

These platforms have legs of sufficient buoyancy to cause the structure to float, but of weight sufficient to keep the structure upright. A Semi-submersible platform or rig, is a mobile structure used for drilling for Oil and Natural gas in offshore environments In Physics, buoyancy ( BrE IPA: /ˈbɔɪənsi/ is the upward Force on an object produced by the surrounding liquid or gas in which it is Semi-submersible rigs can be moved from place to place; can be ballasted up or down by altering the amount of flooding in buoyancy tanks; they are generally anchored by cable anchors during drilling operations, though they can also be kept in place by the use of dynamic positioning. Dynamic positioning (DP is a computer controlled system to automatically maintain a Vessel 's position and heading by using her own propellers and thrusters Semi-submersible can be used in depths from 200 to 6,000 feet (60 to 1,800 m).

Jack-up Platforms

Jackups, as the name suggests, are platforms that can be jacked up above the sea using legs which can be lowered like jacks. A jack-up rig is a type of mobile offshore oil and gas drilling platform that is able to stand still on the sea floor, resting on a number of supporting legs These platforms, used in relatively low depths, are designed to move from place to place, and then anchor themselves by deploying the jack-like legs.

Drillships

A drillship is a maritime vessel that has been fitted with drilling apparatus. A drillship is a maritime vessel that has been fitted with drilling apparatus It is most often used for exploratory drilling of new oil or gas wells in deep water but can also be used for scientific drilling. It is often built on a modified tanker hull and outfitted with a dynamic positioning system to maintain its position over the well. Dynamic positioning (DP is a computer controlled system to automatically maintain a Vessel 's position and heading by using her own propellers and thrusters

Floating production systems

FPSOs are large ships equipped with processing facilities and moored to a location for a long period. 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 The main types of floating production systems are FPSO (floating production, storage, and offloading system), FSO (floating storage and offloading system), and FSU (floating storage unit). 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 These ships do not actually drill for oil or gas.

Tension-leg platform

TLPs consist of floating rigs tethered to the seabed in a manner that eliminates most vertical movement of the structure. A Tension-leg platform or Extended Tension Leg Platform (ETLP is a vertically moored floating structure normally used for the offshore production of oil or TLPS are used in water depths up to about 6,000 feet (2,000 m). The "conventional" TLP is a 4-column design which looks similar to a semisubmersible. Proprietary versions include the Seastar and MOSES mini TLPs; they are relatively low cost, used in water depths between 600 and 3,500 feet (200 and 1,100 m). Mini TLPs can also be used as utility, satellite or early production platforms for larger deepwater discoveries.

A 'Statfjord' Gravity base structure under construction in Norway. Almost all of the structure will end up submerged.
A 'Statfjord' Gravity base structure under construction in Norway. A gravity base structure (GBS is a support structure held in place by Gravity. Norway ( Norwegian: Norge ( Bokmål) or Noreg ( Nynorsk) officially the Kingdom of Norway, is a Constitutional Almost all of the structure will end up submerged.

SPAR Platforms

Spars are moored to the seabed like the TLP, but whereas the TLP has vertical tension tethers the Spar has more conventional mooring lines. A SPAR, named for logs used as buoys in shipping and moored in place vertically is a type of floating Oil platform typically used in very deep waters Spars have been designed in three configurations: the "conventional" one-piece cylindrical hull, the "truss spar" where the midsection is composed of truss elements connecting the upper buoyant hull (called a hard tank) with the bottom soft tank containing permanent ballast, and the "cell spar" which is built from multiple vertical cylinders. The Spar may be more economical to build for small and medium sized rigs than the TLP, and has more inherent stability than a TLP since it has a large counterweight at the bottom and does not depend on the mooring to hold it upright. It also has the ability, by use of chain-jacks attached to the mooring lines, to move horizontally over the oil field. The first production spar was Kerr-McGee's Neptune, which is a floating production facility anchored in 1,930 feet (588 m) in the Gulf of Mexico, however spars (such as Brent Spar) were previously used as FSOs. Brent Spar or Brent E was a North Sea oil storage and tanker loading Buoy in the Brent oilfield, operated by Shell UK Dominion Oil's Devil's Tower is located in 5,610 feet (1,710 m) of water, in the Gulf of Mexico, and is the world's deepest spar. Devil's Tower is a deep-water oil and gas production Spar Oil platform located in the Gulf of Mexico and named after Devils Tower National Monument The first Truss spars were Kerr-McGee's Boomvang and Nansen. The first (and only) cell spar is Kerr-McGee's Red Hawk.

Normally unmanned installations

These installations (sometimes called toadstools), are small platforms, consisting of little more than a well bay, helipad and emergency shelter. A Normally Unmanned Installation (NUI is a type of offshore facility that is designed to be operated remotely without the constant presence of personnel A well bay is an area of an Oil platform where the Christmas trees and Wellheads are located The word helipad is a portmanteau meaning helicopter landing pad, a landing area for Helicopters Though helicopters can usually land anywhere flat a fabricated They are designed for operate remotely under normal operations, only to be visited occasionally for routine maintenance or well work. A well intervention, or 'well work' is any operation carried out on a oil or gas well during, or at the end of its productive life that alters the state of the well and or

Especially large examples

The Petronius Platform is an oil platform in the Gulf of Mexico, which stands 2,000 feet above the ocean floor. Petronius is a deepwater Compliant tower Oil platform operated by Chevron Corporation and Marathon Oil in the The Gulf of Mexico ( Spanish: Golfo de México) is the ninth largest Body of water in the world A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit Depending on the criteria it may be the world's tallest structure. While determining the world's tallest structure has generally been straightforward the definition of the world's tallest building or the

The Hibernia platform is the world's largest oil and gas platform, located on the Jeanne D'Arc basin, in the Atlantic Ocean off the coast of Newfoundland. Hibernia is the name of a petroleum field located in the North Atlantic Ocean, approximately 315 kilometres east-southeast of St Newfoundland and Labrador (ˈnuːfɨn(dlənd ən(d ˈlæbrəˌdɔr (Terre-Neuve-et-Labrador is a province of Canada, the tenth and latest to join the Confederation The Gravity Base Structure (GBS), which sits on the ocean floor, is 364 feet high and has storage capacity for 1. A gravity base structure (GBS is a support structure held in place by Gravity. 3 million barrels of crude oil in its 278. 8 foot high caisson (Dorel Iosif). The platform acts as a small concrete island with serrated outer edges designed to withstand the impact of an iceberg. An iceberg is a large piece of freshwater Ice that has broken off from a snow-formed Glacier or Ice shelf and is floating in open water The GBS contains production storage tanks and the remainder of the void space is filled with ballast with the entire structure weighing in at 1. 2 million tons. Units of mass There are three similar units of Mass called the ton: Long ton (simply ton in countries such as the United The platform stands 734 feet high, which is half the height of New York's Empire State Building (1473) and 108 feet taller than the Calgary Tower (626. 6 feet).

Maintenance and supply

A typical oil production platform is self-sufficient in energy and water needs, housing electrical generation, water desalinators and all of the equipment necessary to process oil and gas such that it can be either delivered directly onshore by pipeline or to a Floating Storage Unit and/or tanker loading facility. Elements in the oil/gas production process include wellhead, production manifold, production separator, glycol process to dry gas, gas compressors, water injection pumps, oil/gas export metering and main oil line pumps. A wellhead is piece of equipment that exists atop (the exposed area above ground of a well A separator for Petroleum production is a large drum designed to separate Production fluids into their constituent components of oil, gas and A diol or glycol is a Chemical compound containing two Hydroxyl groups (-OH groups Vicinal diols have hydroxyl groups attached to adjacent atoms A gas compressor is a mechanical device that increases the Pressure of a Gas by reducing its Volume. The water injection method used in oil production is where Water is injected back into the reservoir usually to increase Pressure and thereby All production facilities are designed to have minimal environmental impact.

Larger platforms are assisted by smaller ESVs (emergency support vessels) like the British Iolair that are summoned when something has gone wrong, e. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The Iolair ( Gaelic for eagle is a semi-submersible vessel that served as an Emergency Support Vessel (ESV g. when a search and rescue operation is required. For the TV series of this title see Search and Rescue (TV series. During normal operations, PSVs (platform supply vessels) keep the platforms provisioned and supplied, and AHTS vessels can also supply them, as well as tow them to location and serve as standby rescue and firefighting vessels. Anchor Handling Tug Supply (AHTS vessels can supply Oil rigs tow them to location anchor them up and in a few cases serve as an Emergency Rescue and Recovery Vessel (ERRV

Crew

The size and composition of the crew of an offshore installation will vary greatly from platform to platform. Because of the cost intensive nature of operating an offshore platform, it is important to maximise productivity by ensuring work continues 24 hours a day. This means that there are essentially two complete crews on board at a time, one for day shift and the other for night shift. Crews will also change out at regular intervals, nominally two weeks.

Essential personnel

Not all of these personnel are present on every platform, on smaller platforms workers will be responsible for several areas. The names shown are not industry-wide.

Incidental personnel

Drawbacks

Risks

A typical offshore Oil/Gas platform.
A typical offshore Oil/Gas platform.

The nature of their operation — extraction of volatile substances sometimes under extreme pressure in a hostile environment — has risk and accidents and tragedies occasionally occur. In July 1988, 167 people died when Occidental Petroleum's Piper Alpha offshore production platform, on the Piper field in the North Sea, exploded after a gas leak. Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) Occidental Petroleum Corporation (" Oxy " is an international Oil and Gas exploration and production company with operations in the United Piper Alpha was a North Sea oil production platform operated by Occidental Petroleum (Caledonia Ltd. The North Sea is a marginal, Epeiric sea of the Atlantic Ocean on the European Continental shelf. The accident greatly accelerated the practice of providing living accommodations on separate rigs, away from those used for extraction.

However, this was, in itself, a hazardous environment. In March 1980, the 'flotel' (floating hotel) platform Alexander Kielland capsized in a storm in the North Sea with the loss of 123 lives. Year 1980 ( MCMLXXX) was a Leap year starting on Tuesday (link displays the 1980 Gregorian calendar) Flotel, a Portmanteau of the terms '''flo'''ating ho'''tel''', refers to the installation of living quarters on top of Rafts The North Sea is a marginal, Epeiric sea of the Atlantic Ocean on the European Continental shelf.

Given the number of grievances and conspiracy theories that involve the oil business, and the importance of gas/oil platforms to the economy, platforms in the United States are believed to be potential terrorist targets. Agencies and military units responsible for maritime counterterrorism in the US (Coast Guard, Navy SEALs, Marine Recon) often train for platform raids. United States Marine Corps Force Reconnaissance detachments or FORECON units are special-purposes units roughly analogous to the U

Ecological effects

In British waters, the cost of removing all platform rig structures entirely was estimated in 1995 at $345 billion, and the cost of removing all structures including pipelines — a so-called "clean sea" approach — at $621 billion.

Further effects are the leaching of heavy metals that accumulate in buoyancy tanks into water; and risks associated with their disposal. There has been concern expressed at the practice of partially demolishing offshore rigs to the point that ships can traverse across their site; there have been instances of fishery vessels snagging nets on the remaining structures. For the fishing industry and the practice of fishing see Fishing. Proposals for the disposal at sea of the Brent Spar, a 449 ft tall storage buoy (another true function of that which is termed an oil rig), was for a time in 1996 an environmental cause célèbre in the UK after Greenpeace occupied the floating structure. Brent Spar or Brent E was a North Sea oil storage and tanker loading Buoy in the Brent oilfield, operated by Shell UK Year 1996 ( MCMXCVI) was a Leap year starting on Monday (link will display full 1996 Gregorian calendar) A cause célèbre (plural causes célèbres, French famous case) is Greenpeace, originally known as the Greenpeace Foundation, was founded in Vancouver, British Columbia, Canada in 1972 The event led to a reconsideration of disposal policy in the UK and Europe.

In the United States, Marine Biologist Milton Love has proposed that oil platforms off the California coast be retained as artificial reefs, instead of being dismantled (at great cost), because he has found them to be havens for many of the species of fish which are otherwise declining in the region, in the course of 11 years of research. An artificial reef is a man-made underwater structure typically built for the purpose of promoting marine life in areas of generally featureless bottom Love is funded mainly by government agencies, but also in small part by the California Artificial Reef Enhancement Program. NOAA has said it is considering this course of action, but wants money to study the effects of the rigs in detail. The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the

In the Gulf of Mexico, more than 200 platforms have been similarly converted. The Gulf of Mexico ( Spanish: Golfo de México) is the ninth largest Body of water in the world In 2002, an oil rig exploded just offshore near New Orleans.

Tallest oil platforms

Depth records have been published[3]. The tallest rigid structure oil platform is the floating Magnolia ETLP which is about 1,500 metres (5,000 ft). Magnolia is an offshore oil drilling and production Extended Tension Leg Platform in the Gulf of Mexico. Non-floating platforms are:

See also

References

  1. ^ Project Redsand
  2. ^ 11.2 Azerbaijan's Oil History Brief Oil Chronology since 1920 ­ Part 2 by Mir-Yusif Mir-Babayev
  3. ^ a b [1] Poster illustrating different oil platform types and records

External links


Dictionary

oil platform

-noun

  1. A large structure used to house workers and machinery needed to drill and then produce oil and natural gas in the ocean.
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