An oil platform, oil rig, offshore platform, or oil and/or gas production platform is a large structure with facilities to extract, and process petroleum and natural gas that lie in rock formations beneath the seabed. Many oil platforms will also contain facilities to accommodate their workforce, although it is also common for there to be a separate accommodation platform bridge linked to the production platform. Most commonly, oil platforms engage in activities on the continental shelf, though they can also be used in lakes, inshore waters, and inland seas. Depending on the circumstances, the platform may be fixed to the ocean floor, consist of an artificial island, or float. In some arrangements the main facility may have storage facilities for the processed oil. Remote subsea wells may also be connected to a platform by flow lines and by umbilical connections. These sub-sea solutions may consist of one or more subsea wells or of one or more manifold centres for multiple wells.
Offshore construction is the installation of structures and facilities in a marine environment, usually for the production and transmission of electricity, oil, gas and other resources. It is also called maritime engineering.
A semi-submersible platform is a specialised marine vessel used in offshore roles including as offshore drilling rigs, safety vessels, oil production platforms, and heavy lift cranes. They have good ship stability and seakeeping, better than drillships.
A tension-leg platform (TLP) or extended tension leg platform (ETLP) is a vertically moored floating structure normally used for the offshore production of oil or gas, and is particularly suited for water depths greater than 300 metres and less than 1500 metres. Use of tension-leg platforms has also been proposed for offshore wind turbines.
A gravity-based structure (GBS) is a support structure held in place by gravity, most notably offshore oil platforms. These structures are often constructed in fjords due to their protected area and sufficient depth.
Condeep is a make of gravity-based structure for oil platforms invented and patented by engineer Olav Mo in 1972, which were fabricated by Norwegian Contractors in Stavanger, Norway. Condeep is an abbreviation for concrete deep water structure. A Condeep usually consists of a base of concrete oil storage tanks from which one, three or four concrete shafts rise. The Condeep base always rests on the sea floor, and the shafts rise to about 30 meters above the sea level. The platform deck itself is not a part of the construction.
Bullwinkle was a 1,736 feet (529 m) tall, pile-supported fixed steel oil platform in the Gulf of Mexico. Installed in 1988, the total weight of the platform was 77,000 tons, of which the steel jacket comprises 49,375 tones. At the time of its construction it was the third tallest freestanding structure ever built – shorter than only the CN Tower and the Ostankino Tower – and the tallest in the United States, being 6 ft (1.8 m) taller than the pinnacle of the Sears Tower. Of the total height, 1,352 feet (412 m) are below the waterline. It was located in Green Canyon Block 65, approximately 160 miles (260 km) southwest of New Orleans. Bullwinkle belongs to Fieldwood Energy LLC. The total field development construction cost was US$500,000,000 according to some sources.
A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site.
Marine architecture is the design of architectural and engineering structures which support coastal design, near-shore and off-shore or deep-water planning for many projects such as shipyards, ship transport, coastal management or other marine and/or hydroscape activities. These structures include harbors, lighthouses, marinas, oil platforms, offshore drillings, accommodation platforms and offshore wind farms, floating engineering structures and building architectures or civil seascape developments. Floating structures in deep water may use suction caisson for anchoring.
Offshore drilling is a mechanical process where a wellbore is drilled below the seabed. It is typically carried out in order to explore for and subsequently extract petroleum that lies in rock formations beneath the seabed. Most commonly, the term is used to describe drilling activities on the continental shelf, though the term can also be applied to drilling in lakes, inshore waters and inland seas.
Subsea is fully submerged ocean equipment, operations or applications, especially when some distance offshore, in deep ocean waters, or on the seabed. The term is frequently used in connection with oceanography, marine or ocean engineering, ocean exploration, remotely operated vehicle (ROVs) autonomous underwater vehicles (AUVs), submarine communications or power cables, seafloor mineral mining, oil and gas, and offshore wind power.
"Offshore", when used in relation to hydrocarbons, refers to operations undertaken at, or under the, sea in association with an oil, natural gas or condensate field that is under the seabed, or to activities carried out in relation to such a field. Offshore is part of the upstream sector of the oil and gas industry.
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 compliant tower (CT) is a fixed rig structure normally used for the offshore production of oil or gas. The rig consists of narrow, flexible (compliant) towers and a piled foundation supporting a conventional deck for drilling and production operations. Compliant towers are designed to sustain significant lateral deflections and forces, and are typically used in water depths ranging from 1,500 to 3,000 feet. These structures are considered freestanding but media supported. They demonstrate static stability but have a much greater degree of lateral deformation/flexibility vs land-base structures, up to 2.5% vs 0.5% and are partially supported by buoyancy. It is unknown if these structures could support themselves as built if they were constructed on land. At present the deepest is the Chevron Petronius tower located in water 623m deep.
Deepwater drilling, or deep well drilling, is the process of creating holes in the Earth's crust using a drilling rig for oil extraction under the deep sea. There are approximately 3400 deepwater wells in the Gulf of Mexico with depths greater than 150 meters.
Offshore concrete structures have been in use successfully for about 50 years. They serve the same purpose as their steel counterparts in the oil and gas production and storage. The first concrete oil platform has been installed in the North Sea in the Ekofisk field in 1973 by Phillips Petroleum. Since then 47 major concrete offshore structures have been built.
Suction caissons are a form of fixed platform anchor in the form of an open bottomed tube embedded in the sediment and sealed at the top while in use so that lifting forces generate a pressure differential that holds the caisson down. They have a number of advantages over conventional offshore foundations, mainly being quicker to install than deep foundation piles and being easier to remove during decommissioning. Suction caissons are now used extensively worldwide for anchoring large offshore installations, like oil platforms, offshore drillings and accommodation platforms to the seafloor at great depths. In recent years, suction caissons have also seen usage for offshore wind turbines in shallower waters.
Offshore geotechnical engineering is a sub-field of geotechnical engineering. It is concerned with foundation design, construction, maintenance and decommissioning for human-made structures in the sea. Oil platforms, artificial islands and submarine pipelines are examples of such structures. The seabed has to be able to withstand the weight of these structures and the applied loads. Geohazards must also be taken into account. The need for offshore developments stems from a gradual depletion of hydrocarbon reserves onshore or near the coastlines, as new fields are being developed at greater distances offshore and in deeper water, with a corresponding adaptation of the offshore site investigations. Today, there are more than 7,000 offshore platforms operating at a water depth up to and exceeding 2000 m. A typical field development extends over tens of square kilometers, and may comprise several fixed structures, infield flowlines with an export pipeline either to the shoreline or connected to a regional trunkline.
Offshore embedded anchors are anchors that derive their holding capacity from the frictional, or bearing, resistance of the surrounding soil, as opposed to gravity anchors, which derive their holding capacity largely from their weight. As offshore developments move into deeper waters, gravity-based structures become less economical due to the large size needed and the consequent cost of transportation.
Ocean development refers to the establishing of human activities at sea and use of the ocean, as well as its governance.
