Offshore drilling

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An oil drilling platform off the coast of Santa Barbara, California - 6 December 2011 Off Shore Drilling Rig, Santa Barbara, CA, 6 December, 2011.JPG
An oil drilling platform off the coast of Santa Barbara, California – 6 December 2011

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.

Contents

Offshore drilling presents environmental challenges, both offshore and onshore from the produced hydrocarbons and the materials used during the drilling operation. Controversies include the ongoing US offshore drilling debate. [1]

There are many different types of facilities from which offshore drilling operations take place. These include bottom founded drilling rigs (jackup barges and swamp barges), combined drilling and production facilities either bottom founded or floating platforms, and deepwater mobile offshore drilling units (MODU) including semi-submersibles or drillships. These are capable of operating in water depths up to 3,000 metres (9,800 ft). In shallower waters the mobile units are anchored to the seabed; however, in water deeper than 1,500 metres (4,900 ft), the semi-submersibles and drillships are maintained at the required drilling location using dynamic positioning.

History

Around 1891, the first submerged oil wells were drilled from platforms built on piles in the fresh waters of the Grand Lake St. Marys in Ohio. The wells were developed by small local companies such as Bryson, Riley Oil, German-American and Banker's Oil. [2]

Around 1896, the first submerged oil wells in salt water were drilled in the portion of the Summerland field extending under the Santa Barbara Channel in California. The wells were drilled from piers extending from land out into the channel. [3] [4]

Other notable early submerged drilling activities occurred on the Canadian side of Lake Erie in the 1900s and Caddo Lake in Louisiana in the 1910s. Shortly thereafter wells were drilled in tidal zones along the Texas and Louisiana gulf coast. The Goose Creek Oil Field near Baytown, Texas is one such example. In the 1920s drilling activities occurred from concrete platforms in Venezuela's Lake Maracaibo. [5]

One of the oldest subsea wells is the Bibi Eibat well, which came on stream in 1923 in Azerbaijan. [6] [ dubious – discuss ] The well was located on an artificial island in a shallow portion of the Caspian Sea. In the early 1930s, the Texas Company developed the first mobile steel barges for drilling in the brackish coastal areas of the Gulf of Mexico.

In 1937, Pure Oil and its partner Superior Oil used a fixed platform to develop a field 1 mile (1.6 km) offshore of Calcasieu Parish, Louisiana in 14 feet (4.3 m) of water.

In 1938, Humble Oil built a mile-long wooden trestle with railway tracks into the sea at McFadden Beach on the Gulf of Mexico, placing a derrick at its end – this was later destroyed by a hurricane. [7]

In 1945, concern for American control of its offshore oil reserves caused President Harry Truman to issue an Executive Order unilaterally extending American territory to the edge of its continental shelf, an act that effectively ended the 3-mile limit "freedom of the seas" regime. [8]

In 1946, Magnolia drilled at a site 18 miles (29 km) off the coast, erecting a platform in 18 feet (5.5 m) of water off St. Mary Parish, Louisiana. [9]

In early 1947, Superior Oil erected a drilling and production platform in 20 feet (6.1 m) of water some 18 miles (29 km) off Vermilion Parish, La. But it was Kerr-Magee, as operator for partners Phillips Petroleum and Stanolind Oil & Gas that completed its historic Ship Shoal Block 32 well in October 1947, months before Superior actually drilled a discovery from their Vermilion platform farther offshore. In any case, that made Kerr-McGee's well the first oil discovery drilled out of sight of land. [10]

When offshore drilling moved into deeper waters of up to 30 metres (98 ft), fixed platform rigs were built, until demands for drilling equipment was needed in the 100 feet (30 m) to 120 metres (390 ft) depth of the Gulf of Mexico, the first jack-up rigs began appearing from specialized offshore drilling contractors. [11]

The first semi-submersible resulted from an unexpected observation in 1961. [12] Blue Water Drilling Company owned and operated the four-column submersible Blue Water Rig No.1 in the Gulf of Mexico for Shell Oil Company. As the pontoons were not sufficiently buoyant to support the weight of the rig and its consumables, it was towed between locations at a draught midway between the top of the pontoons and the underside of the deck. It was noticed that the motions at this draught were very small, and Blue Water Drilling and Shell jointly decided to try operating the rig in the floating mode. The concept of an anchored, stable floating deep-sea platform had been designed and tested back in the 1920s by Edward Robert Armstrong for the purpose of operating aircraft with an invention known as the 'seadrome'. The first purpose-built drilling semi-submersible Ocean Driller was launched in 1963 by ODECO.. Since then, many semi-submersibles have been purpose-designed for the drilling industry mobile offshore fleet.

Comparison of deepwater semi-submersible and drillship. Deepwater drilling systems 2.png
Comparison of deepwater semi-submersible and drillship.

The first offshore drillship was the CUSS 1 developed for the Mohole project to drill into the Earth's crust. [13]

As of June 2010, there were over 620 mobile offshore drilling rigs (jackups, semisubs, drillships, barges, etc.) available for service in the worldwide offshore rig fleet. [14]

One of the world's deepest hubs is currently the Perdido in the Gulf of Mexico, floating in 2,438 meters (7,999 ft) of water. It is operated by Royal Dutch Shell and was built at a cost of $3 billion. [15] The deepest operational platform is the Petrobras America Cascade FPSO in the Walker Ridge 249 field in 2,600 meters (8,500 ft) of water. [16]

Drilling platforms

Offshore drilling is usually done from platforms generically known as mobile offshore drilling units (MODU), which can be of one of several formats, depending on the water depth:

Main offshore fields

Notable offshore fields include:

Challenges

Offshore oil and gas production is more challenging than land-based installations due to the remote and harsher environment. Much of the innovation in the offshore petroleum sector concerns overcoming these challenges, including the need to provide very large production facilities. Production and drilling facilities may be very large and a large investment, such as the Troll A platform standing on a depth of 300 meters (980 ft). [20]

Another type of offshore platform may float with a mooring system to maintain it on location. While a floating system may be lower cost in deeper waters than a fixed platform, the dynamic nature of the platforms introduces many challenges for the drilling and production facilities.

The ocean can add several thousand meters or more to the fluid column. The addition increases the equivalent circulating density and downhole pressures in drilling wells, as well as the energy needed to lift produced fluids for separation on the platform.

The trend today is to conduct more of the production operations subsea, by separating water from oil and re-injecting it rather than pumping it up to a platform, or by flowing to onshore, with no installations visible above the sea. Subsea installations help to exploit resources at progressively deeper waters—locations which had been inaccessible—and overcome challenges posed by sea ice such as in the Barents Sea. One such challenge in shallower environments is seabed gouging by drifting ice features (means of protecting offshore installations against ice action includes burial in the seabed).

Offshore manned facilities also present logistics and human resources challenges. An offshore oil platform is a small community in itself with cafeteria, sleeping quarters, management and other support functions. In the North Sea, staff members are transported by helicopter for a two-week shift. They usually receive higher salary than onshore workers do. Supplies and waste are transported by ship, and the supply deliveries need to be carefully planned because storage space on the platform is limited. Today, much effort goes into relocating as many of the personnel as possible onshore, where management and technical experts are in touch with the platform by video conferencing. An onshore job is also more attractive for the aging workforce in the petroleum industry, at least in the western world. These efforts among others are contained in the established term integrated operations. The increased use of subsea facilities helps achieve the objective of keeping more workers onshore. Subsea facilities are also easier to expand, with new separators or different modules for different oil types, and are not limited by the fixed floor space of an above-water installation.

Effects on the environment

Offshore oil production involves environmental risks, most notably oil spills from oil tankers or pipelines transporting oil from the platform to onshore facilities, and from leaks and accidents on the platform (e.g. Deepwater Horizon oil spill and Ixtoc I oil spill). [21] Produced water is also generated, which is water brought to the surface along with the oil and gas; it is usually highly saline and may include dissolved or unseparated hydrocarbons.

See also

Related Research Articles

<span class="mw-page-title-main">Oil platform</span> Large offshore structure with oil drilling and related facilities

An oil 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 have facilities to accommodate the workers, although it is also common to have 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 facilities may include one or more subsea wells or manifold centres for multiple wells.

<span class="mw-page-title-main">Offshore construction</span> Installation of structures and facilities in a marine environment

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.

<span class="mw-page-title-main">Semi-submersible platform</span> Marine vessel used in offshore roles wtth good stability and seakeeping

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.

<span class="mw-page-title-main">Floating production storage and offloading</span> Vessel used by offshore oil and gas industry

A floating production storage and offloading (FPSO) unit is a floating vessel used by the offshore oil and gas industry for the production and processing of hydrocarbons, and for the storage of oil. An FPSO vessel is designed to receive hydrocarbons produced by itself or from nearby platforms or subsea template, process them, and store oil until it can be offloaded onto a tanker or, less frequently, transported through a pipeline. FPSOs are preferred in frontier offshore regions as they are easy to install, and do not require a local pipeline infrastructure to export oil. FPSOs can be a conversion of an oil tanker or can be a vessel built specially for the application. A vessel used only to store oil is referred to as a floating storage and offloading (FSO) vessel.

<span class="mw-page-title-main">Tension-leg platform</span> Type of offshore platform used in production of oil or gas

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.

The Atlantis oil field is the third largest oil field in the Gulf of Mexico. The field was discovered in 1998 and is located at the Green Canyon blocks 699, 700, 742, 743, and 744 in United States federal waters in the Gulf of Mexico about 130 miles (210 km) from the coast of Louisiana. The oil field lies in water depths ranging from 4,400 to 7,100 feet. The subsea structure of Atlantis has long been the target of safety critics.

<span class="mw-page-title-main">Drillship</span> Vessel fitted for offshore drilling

A drillship is a merchant vessel designed for use in exploratory offshore drilling of new oil and gas wells or for scientific drilling purposes. In recent years the vessels have been used in deepwater and ultra-deepwater applications, equipped with the latest and most advanced dynamic positioning systems.

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.

Subsea technology involves fully submerged ocean equipment, operations, or applications, especially when some distance offshore, in deep ocean waters, or on the seabed. The term subsea 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.

<span class="mw-page-title-main">Jackup rig</span> Type of mobile platform

A jackup rig or a self-elevating unit is a type of mobile platform that consists of a buoyant hull fitted with a number of movable legs, capable of raising its hull over the surface of the sea. The buoyant hull enables transportation of the unit and all attached machinery to a desired location. Once on location the hull is raised to the required elevation above the sea surface supported by the sea bed. The legs of such units may be designed to penetrate the sea bed, may be fitted with enlarged sections or footings, or may be attached to a bottom mat. Generally jackup rigs are not self-propelled and rely on tugs or heavy lift ships for transportation.

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.

<span class="mw-page-title-main">Offshore oil and gas in the United States</span> Large portion of oil and gas supply

Offshore oil and gas in the United States provides a large portion of the nation’s oil and gas supply. Large oil and gas reservoirs are found under the sea offshore from Louisiana, Texas, California, and Alaska. Environmental concerns have prevented or restricted offshore drilling in some areas, and the issue has been hotly debated at the local and national levels.

<span class="mw-page-title-main">Offshore oil and gas in California</span> Drilling in state and federal zones

Offshore oil and gas in California provides a significant portion of the state's petroleum production. Offshore oil and gas has been a contentious issue for decades, first over the question of state versus federal ownership, but since 1969 mostly over questions of resource development versus environmental protection.

North Drilling Company is an Iranian company specialized in drilling oil and gas wells and its services in all regions of Iran and world, to global customers. The company was privatized in June 2009. As of February 2010, Mehr Eghtesad, a quasi-government investment company, owned 20% of its shares on the Tehran Stock Exchange.

<span class="mw-page-title-main">Offshore geotechnical engineering</span> Sub-field of engineering concerned with human-made structures in the sea

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.

<span class="mw-page-title-main">Subsea production system</span> Wells located on the seabed

Subsea production systems are typical wells located on the seabed, shallow or deep water. Generally termed as Floating production system, where the petroleum is extracted at the seabed and the same can be tied back to an already existing production platform or an onshore facility. The oil platform well is drilled by a movable rig and the extracted oil or natural gas is transported by submarine pipeline under the sea and then to rise to a processing facility. It is classified into

The Galata gas field is a natural gas field located on the continental shelf of the Black Sea approximately 25km Southeast of Varna, Bulgaria. The field was the first to be developed offshore Bulgaria, and at peak production provided more than 16% of Bulgaria's domestic gas needs, the platform and associated infrastructure is still the only production facility located in the Bulgarian Black Sea.

Appaloosa is an offshore oil field located in the Mississippi Canyon blocks 459, 460, 503, and 504 of the United States sector of the Gulf of Mexico. It is a part of the Greater Longhorn area. The field is developed by the Italian energy company Eni.

Ocean development refers to the establishing of human activities at sea and use of the ocean, as well as its governance.

References

  1. ↑ Compton, Glenn, 10 Reasons Not to Drill for Oil Offshore of Florida, The Bradenton Times, January 14, 2018
  2. ↑ "Drilling on Grand Lake St Marys in 1891". Energy Global News. 2019-06-30. Retrieved 2020-08-20.
  3. ↑ History of the Offshore Oil and Gas Development in Louisiana at the Mineral Management Services, Dept of the Interior
  4. ↑ "National Ocean Industries Association". Archived from the original on 2010-08-06. Retrieved 2010-06-14.
  5. ↑ "About Offshore Drilling | Engenya GmbH". www.engenya.com. Retrieved 2020-08-24.
  6. ↑ "Oil in Azerbaijan" . Retrieved 20 April 2015.
  7. ↑ Morton, Michael Quentin (June 2016). "Beyond Sight of Land: A History of Oil Exploration in the Gulf of Mexico". GeoExpro. 30 (3): 60–63. Retrieved 8 November 2016.
  8. ↑ "Overview– Convention & Related Agreements". www.un.org. Retrieved 2020-08-20.
  9. ↑ "Offshore Drilling: History and Overview". Offshore Energy. 2010-06-25. Retrieved 2020-08-24.
  10. ↑ "history of offshore oil wells – Google Search" . Retrieved 20 April 2015.
  11. ↑ "About Offshore Drilling". www.engenya.com. Retrieved 2020-08-24.
  12. ↑ Tyler Priest (October 17, 2014). "Offshore at 60: The Blue Water Breakthrough". PennWell . Retrieved October 16, 2021.
  13. ↑ "Géosciences Montpellier – The project Mohole in 1961". www.gm.univ-montp2.fr (in French). Retrieved 2020-08-20.
  14. ↑ "RIGZONE – Offshore Rig Data, Onshore Fleet Analysis". Archived from the original on 8 April 2015. Retrieved 20 April 2015.
  15. ↑ Hays, Kristen (31 March 2010). "UPDATE 1-Shell starts production at Perdido". Reuters . Retrieved 20 April 2015.
  16. ↑ "Off-Shore Drilling". IssolareEnergy Available?.
  17. ↑ "Contracts let for Marjan oil field development. (Saudi Arabian Oil Co. Bids out offshore development contracts) (Saudi Arabia) – MEED Middle East Economic Digest". Archived from the original on 2012-11-05. Retrieved 2011-02-26.
  18. ↑ "Russian Rosneft announces major oil, gas discovery in Arctic Kara Sea". Platts. Retrieved 2017-08-18.
  19. ↑ "Year 2006 National Assessment – Alaska Outer Continental Shelf" (PDF). Dept Interior BEOM. Archived from the original (PDF) on 2012-09-16. Retrieved 2017-08-18.
  20. ↑ Speight, James G. (2014). Handbook of Offshore Oil and Gas Operations. Elsevier. ISBN   978-0-08-087819-5.
  21. ↑ Debate Over Offshore Drilling (internet video). CBS News. 2008. Archived from the original on 2008-08-24. Retrieved 2008-09-27.
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