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{{short description|Mechanical process where a wellbore is drilled below the seabed}}
{{Refimprove|date=April 2010}} [[File:Off Shore Drilling Rig, Santa Barbara, CA, 6 December, 2011.JPG|thumb|An oil drilling platform off the coast of Santa Barbara, CA - 6 December, 2011]]
[[File:Holstein at Dusk.jpg|300px|thumb|Holstein, an oil drilling platform at Green Canyon in the [[Gulf of Mexico]], approximately 100 miles from land.]]
'''Offshore drilling''' refers to a mechanical process where a [[wellbore]] is drilled through the seabed. It is typically carried out in order to explore for and subsequently extract [[petroleum]] which 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.
'''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 sea|inland seas]].


Offshore drilling presents environmental challenges, both from the produced hydrocarbons and the materials used during the drilling operation. Controversies include the ongoing [[US offshore drilling debate]].
Offshore drilling presents all 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]].<ref>Compton, Glenn, [http://thebradentontimes.com/reasons-not-to-drill-for-oil-offshore-of-florida-p19415-137.htm 10 Reasons Not to Drill for Oil Offshore of Florida], ''The Bradenton Times'', January 14, 2018</ref>


There are many different types of facilities from which offshore drilling operations take place. These include bottom founded drilling rigs ([[Jackup rig|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 and drillships. These are capable of operating in water depths up to {{convert|3000|m|ft}}. In shallower waters the mobile units are anchored to the seabed, however in deeper water (more than {{convert|1500|m|ft}} the [[Semi-submersible|semisubmersibles]] or [[drillship]]s are maintained at the required drilling location using [[dynamic positioning]].
There are many different types of facilities from which offshore drilling operations take place. These include bottom founded drilling rigs ([[Jackup rig|jackup barges]] and swamp [[Barge|barges]]), combined drilling and production facilities either bottom founded or floating platforms, and deepwater mobile offshore drilling units (MODU) including [[Semi-submersible platform|semi-submersible]]s or [[drillship]]s. These are capable of operating in water depths up to {{convert|3000|m|ft}}. In shallower waters the mobile units are anchored to the seabed; however, in water deeper than {{convert|1500|m|ft}}, the semi-submersibles and drillships are maintained at the required drilling location using [[dynamic positioning]].


==History==
==History==
[[File:Offshore oil well drilling platform, Continental Oil Co., C.A.T.C., Gulf of Mexico.jpg|left|thumb|Offshore oil well drilling platform, Continental Oil Co., Gulf of Mexico, 1955.]]
Around 1891, the first submerged oil wells were drilled from platforms built on piles in the fresh waters of the [[Grand Lake St. Marys]] (a.k.a. Mercer County Reservoir) in [[Ohio]]. The wells were developed by small local companies such as Bryson, Riley Oil, German-American and Banker's Oil. By 1893 it was discovered that workers offshore quickly adopted the mentality of a homosexual and began to fornicate with one another, a practice that still exists in the industry today, much to the displeasure of many of the 'takers'.
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.<ref>{{Cite web|date=2019-06-30|title=Drilling on Grand Lake St Marys in 1891|url=http://www.energyglobalnews.com/drilling-on-grand-lake-st-marys-in-1891/|access-date=2020-08-20|website=Energy Global News}}</ref>


Around 1896, the first submerged oil wells in salt water were drilled in the portion of the [[Summerland Oil Field|Summerland field]] extending under the [[Santa Barbara Channel]] in [[California]]. The wells were drilled from piers extending from land out into the channel.<ref>[http://www.gomr.mms.gov/homepg/regulate/environ/louisiana_coast.html History of the Offshore Oil and Gas Development in Louisiana] at the Mineral Management Services, Dept of the Interior</ref><ref>[http://www.noia.org/website/article.asp?id=123 National Ocean Industries Association]</ref>
Around 1896, the first submerged oil wells in salt water were drilled in the portion of the [[Summerland Oil Field|Summerland field]] extending under the [[Santa Barbara Channel]] in [[California]]. The wells were drilled from piers extending from land out into the channel.<ref>[http://www.gomr.mms.gov/homepg/regulate/environ/louisiana_coast.html History of the Offshore Oil and Gas Development in Louisiana] at the Mineral Management Services, Dept of the Interior</ref><ref>{{Cite web |url=http://www.noia.org/website/article.asp?id=123 |title=National Ocean Industries Association |access-date=2010-06-14 |archive-url=https://web.archive.org/web/20100806100254/http://www.noia.org/website/article.asp?id=123 |archive-date=2010-08-06 |url-status=dead }}</ref>


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 of the United States|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]].
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 of the United States|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]].<ref>{{Cite web|title=About Offshore Drilling|publisher=Engenya GmbH|url=http://www.engenya.com/aboout-offshore-drilling/|access-date=2020-08-24|website=www.engenya.com}}</ref>


One of the oldest subsea wells is the [[Bibiheybət|Bibi Eibat]] well, which came on stream in 1923 in [[Azerbaijan]].<ref>[http://www.members.tripod.com/azmsa/oil.html AzerMAR History Page]</ref>{{dubious|date=June 2010}} The well was located on an artificial island in a shallow portion of the [[Caspian Sea]]. In the early 1930s, the Texas Co., later Texaco (now [[Chevron Corporation|Chevron]]) developed the first mobile steel barges for drilling in the brackish coastal areas of the Gulf of Mexico.
One of the oldest subsea wells is the [[Bibiheybət|Bibi Eibat]] well, which came on stream in 1923 in [[Azerbaijan]].<ref>{{cite web|url=http://www.members.tripod.com/azmsa/oil.html|title=Oil in Azerbaijan|access-date=20 April 2015}}</ref>{{dubious|date=June 2010}} The well was located on an artificial island in a shallow portion of the [[Caspian Sea]]. In the early 1930s, the [[Texaco|Texas Company]] developed the first mobile steel barges for drilling in the [[Brackish water|brackish]] coastal areas of the [[Gulf of Mexico]].


In 1937, Pure Oil (now [[Chevron Corporation|Chevron]]) and its partner Superior Oil (now [[ExxonMobil]]) used a fixed platform to develop a field {{convert|1|mi|km}} offshore of [[Calcasieu Parish, Louisiana]] in {{convert|14|ft|m}} of water.
In 1937, [[Pure Oil]] and its partner [[Superior Oil]] used a fixed platform to develop a field {{convert|1|mi|km}} offshore of [[Calcasieu Parish, Louisiana]] in {{convert|14|ft|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.<ref>{{cite journal|last1=Morton|first1=Michael Quentin|title=Beyond Sight of Land: A History of Oil Exploration in the Gulf of Mexico|journal=GeoExpro|date=June 2016|volume=30|issue=3|pages=60–63|url=https://www.academia.edu/25960555|access-date=8 November 2016}}</ref>
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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.
[[File:HD.11B.173 (13388371804).jpg|thumb|Worker on an offshore drilling rig.]]
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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.<ref>{{Cite web|title=Overview– Convention & Related Agreements|url=https://www.un.org/depts/los/convention_agreements/convention_historical_perspective.htm|access-date=2020-08-20|website=www.un.org}}</ref>


In 1946, Magnolia Petroleum (now [[ExxonMobil]]) drilled at a site {{convert|18|mi|km}} off the coast, erecting a platform in {{convert|18|ft|m}} of water off [[St. Mary Parish, Louisiana]].
In 1946, [[Magnolia Petroleum Company|Magnolia]] drilled at a site {{convert|18|mi|km}} off the coast, erecting a platform in {{convert|18|ft|m}} of water off [[St. Mary Parish, Louisiana]].<ref>{{Cite web|date=2010-06-25|title=Offshore Drilling: History and Overview|url=https://www.offshore-energy.biz/offshore-drilling-history-and-overview/|access-date=2020-08-24|website=Offshore Energy|language=en-US}}</ref>


In early 1947, [[Superior Oil]] erected a drilling and production platform in {{convert|20|ft|m}} of water some {{convert|18|mi|km}} off Vermilion Parish, La. But it was Kerr-McGee Oil Industries (now [[Anadarko Petroleum]]), as operator for partners Phillips Petroleum ([[ConocoPhillips]]) and Stanolind Oil & Gas ([[BP]]) 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.<ref>[http://www.google.com/search?q=history+of+offshore+oil+wells&hl=en&tbs=tl:1&tbo=u&ei=K2QWTKKsGoOBlAfl-IysDA&sa=X&oi=timeline_result&ct=title&resnum=11&ved=0CE8Q5wIwCg History of Offshore Oil Wells (1840-2010)]</ref>
In early 1947, [[Superior Oil]] erected a drilling and production platform in {{convert|20|ft|m}} of water some {{convert|18|mi|km}} off Vermilion Parish, La. But it was [[Kerr-McGee Oil Industries|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.<ref>{{cite web|url=https://www.google.com/search?q=history+of+offshore+oil+wells&hl=en|title=history of offshore oil wells – Google Search|access-date=20 April 2015}}</ref>


When offshore drilling moved into deeper waters of up to {{convert|30|m|ft}}, fixed platform rigs were built, until demands for drilling equipment was needed in the {{convert|100|ft|m}} to {{convert|120|m|ft}} depth of the Gulf of Mexico, the first [[Jackup rig|jack-up rigs]] began appearing from specialized offshore drilling contractors such as forerunners of ENSCO International.
When offshore drilling moved into deeper waters of up to {{convert|30|m|ft}}, fixed platform rigs were built, until demands for drilling [[equipment]] was needed in the {{convert|100|ft|m}} to {{convert|120|m|ft}} depth of the Gulf of Mexico, the first [[Jackup rig|jack-up rigs]] began appearing from specialized offshore drilling contractors.<ref>{{Cite web|title=About Offshore Drilling|url=http://www.engenya.com/about-offshore-drilling/|access-date=2020-08-24|website=www.engenya.com}}</ref>
[[File:HD.11B.159 (12366079125).jpg|thumb|Offshore drilling rig, c. 1968.]]
The first [[Semi-submersible platform|semi-submersible]] resulted from an unexpected observation in 1961.<ref>{{Cite web|author=Tyler Priest|title=''Offshore at 60: The Blue Water Breakthrough''|url=https://www.offshore-mag.com/home/article/16804652/offshore-at-60-the-blue-water-breakthrough/|date=October 17, 2014|publisher=[[PennWell]]|access-date=October 16, 2021}}</ref> 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.


The first [[semi-submersible]] resulted from an unexpected observation in 1961. [[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 mid-way 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. Since then, many semi-submersibles have been purpose-designed for the drilling industry mobile offshore fleet.
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 platform|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.
[[File:Deepwater drilling systems 2.png|thumb|Comparison of deepwater [[Semi-submersible platform|semi-submersible]] and [[drillship]].]]
The first offshore [[drillship]] was the ''CUSS 1'' developed for the [[Mohole]] project to drill into the Earth's crust.<ref>{{Cite web|title=Géosciences Montpellier – The project Mohole in 1961|url=http://www.gm.univ-montp2.fr/spip/spip.php?article2163&lang=fr|access-date=2020-08-20|website=www.gm.univ-montp2.fr|language=fr}}</ref>


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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.<ref>{{cite web|url=http://www.rigzone.com/data/|title=RIGZONE – Offshore Rig Data, Onshore Fleet Analysis |access-date=20 April 2015 |archive-url=https://web.archive.org/web/20150408021427/http://www.rigzone.com/data/ |archive-date=8 April 2015 |url-status=dead}}</ref>
The first offshore [[drillship]] was the ''CUSS 1'' developed for the [[Mohole]] project to drill into the Earth's crust.


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One of the world's deepest hubs is currently the [[Perdido oil platform|Perdido]] in the Gulf of Mexico, floating in {{convert|2438|meters|feet}} of water. It is operated by [[Royal Dutch Shell]] and was built at a cost of $3 billion.<ref>{{cite news |url=https://www.reuters.com/article/idUSN3123683920100331 |title=UPDATE 1-Shell starts production at Perdido |work=[[Reuters]] |access-date=20 April 2015 |last=Hays |first=Kristen|date=31 March 2010 }}</ref> The deepest operational platform is the Petrobras America Cascade FPSO in the Walker Ridge 249 field in {{convert|2600|meters|ft}} of water.<ref>{{Cite web|title=Off-Shore Drilling|url=https://issolarenergyavailable.com/what-is/off-shore-drilling/|website=IssolareEnergy Available?}}</ref>
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As of June, 2010, there were over 620 mobile offshore drilling rigs (Jackups, semisubs, drillships, barges) available for service in the competitive rig fleet.<ref>[http://www.rigzone.com/data/ Worldwide Offshore Rig Utilization]</ref>


==Drilling platforms==
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One of the world's deepest hubs is currently the [[Perdido oil platform|Perdido]] in the Gulf of Mexico, floating in 2,438 meters of water. It is operated by [[Royal Dutch Shell]] and was built at a cost of $3 billion.<ref>[http://www.reuters.com/article/idUSN3123683920100331 Shell starts production at Perdido]</ref> The deepest operational platform is the Petrobras America Cascade FPSO in the Walker Ridge 249 field in 2,600 meters of water.
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{{Main|Oil platform}}
{{expand section|More on types of drilling platform and summary descriptions of each|date=June 2023}}
[[File:Types of offshore oil and gas structures.jpg|300px|thumb|Types of offshore oil and gas structures.]]
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:
* [[Jackup rig]]
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* [[Submersible drilling rig]]
* [[Semi-submersible platform]]
* [[Drillship]]


==Main offshore fields==
==Main offshore fields==

Notable offshore fields include:
Notable offshore fields include:
[[File:Northstar Offshore Island Beaufort Sea.jpg|thumb|[[Northstar Island]], an artificial island in the Beaufort Sea north of Alaska, is a site of oil and gas drilling.]]
* the [[North Sea]]
* the [[North Sea]]
* the [[Offshore oil and gas in the US Gulf of Mexico|Gulf of Mexico]] (offshore [[Texas]], [[Louisiana]], [[Mississippi]], and [[Alabama]])
* the [[Offshore oil and gas in the US Gulf of Mexico|Gulf of Mexico]] (offshore [[Texas]], [[Louisiana]], [[Mississippi]], and [[Alabama]])
* [[California]] (in the [[Los Angeles Basin]] and [[Santa Barbara Channel]], part of the Ventura Basin)
* [[Offshore oil and gas in California|California]] (in the [[Los Angeles Basin]] and [[Santa Barbara Channel]], part of the Ventura Basin)
* the Caspian Sea (notably some major fields offshore [[Azerbaijan]])
* the Caspian Sea (notably some major fields offshore [[Azerbaijan]])
* the [[Campos Basin|Campos]] and [[Santos Basin]]s off the coasts of [[Brazil]]
* the [[Campos Basin|Campos]] and [[Santos Basin]]s off the coasts of [[Brazil]]
Line 44: Line 60:
* several fields off [[West Africa]] most notably west of [[Nigeria]] and [[Angola]]
* several fields off [[West Africa]] most notably west of [[Nigeria]] and [[Angola]]
* offshore fields in [[South East Asia]] and [[Sakhalin]], Russia
* offshore fields in [[South East Asia]] and [[Sakhalin]], Russia
* major offshore oil fields are located in the [[Persian Gulf]] such as Safaniya, Manifa and Marjan which belong to Saudi Arabia and are developed by Saudi Aramco.<ref>http://www.highbeam.com/doc/1G1-12308981.html</ref>
* major offshore oil fields are located in the [[Persian Gulf]] such as Safaniya, Manifa and Marjan which belong to Saudi Arabia and are developed by [[Saudi Aramco]].<ref>{{cite web|url=http://www.highbeam.com/doc/1G1-12308981.html |title=Contracts let for Marjan oil field development. (Saudi Arabian Oil Co. Bids out offshore development contracts) (Saudi Arabia) – MEED Middle East Economic Digest |access-date=2011-02-26 |url-status=dead |archive-url=https://web.archive.org/web/20121105163103/http://www.highbeam.com/doc/1G1-12308981.html |archive-date=2012-11-05 }}</ref>
* fields in [[India]] (Mumbai High, K G Basin-East Coast Of India, Tapti Field Gujrat, India)
* fields in [[India]] (Mumbai High, K G Basin-East Coast Of India, Tapti Field, [[Gujarat]], India)
* the [[Taranaki Basin]] in [[New Zealand]]
* the [[East-Prinovozemelsky field|Kara Sea]] north of Siberia<ref>{{cite news|url=https://www.platts.com/latest-news/oil/moscow/russian-rosneft-announces-major-oil-gas-discovery-21300064 |title=Russian Rosneft announces major oil, gas discovery in Arctic Kara Sea |access-date=2017-08-18 | publisher = Platts }}</ref>
* the [[Arctic Ocean]] off the coasts of [[Alaska]] and Canada's [[Northwest Territories]]<ref>{{cite web|url = https://www.boem.gov/uploadedFiles/BOEM/Oil_and_Gas_Energy_Program/Resource_Evaluation/Resource_Assessment/2006AlaskaUndiscoveredOilandGasResources.pdf |title=Year 2006 National Assessment – Alaska Outer Continental Shelf |access-date=2017-08-18 | publisher = Dept Interior BEOM | url-status=dead | archive-url=https://web.archive.org/web/20120916165734/https://www.boem.gov/uploadedFiles/BOEM/Oil_and_Gas_Energy_Program/Resource_Evaluation/Resource_Assessment/2006AlaskaUndiscoveredOilandGasResources.pdf | archive-date=2012-09-16 }}</ref>


==Challenges==
==Challenges==
[[File:Oil Platform Crew Transfer.jpg|thumb|Being far from land can create many challenges, from logistics to safety concerns.]]
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.
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 {{convert|300|meters|ft}}.<ref>{{Cite book|last=Speight|first=James G.|url=https://books.google.com/books?id=xPTDBAAAQBAJ&q=Offshore+oil+and+gas+production+is+more+challenging+than+land-based+installations+due+to+the+remote+and+harsher+environment&pg=PA151|title=Handbook of Offshore Oil and Gas Operations|date=2014|publisher=Elsevier|isbn=978-0-08-087819-5|language=en}}</ref>


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.
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 hundred 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 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 ice|seabed gouging by drifting ice features]] (means of protecting offshore installations against ice action includes burial in the seabed).
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 ice|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.
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==
==Effects on the environment==
{{see also |Oil platform#Ecological effects| label 1= Ecological effects of oil platforms}}


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Offshore oil production involves environmental risks, most notably [[oil spill]]s 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]]).<ref>{{cite video | title = Debate Over Offshore Drilling | medium = internet video | publisher = [[CBS News]] | date = 2008 | url = http://www.webcastr.com/videos/news/debate-over-offshore-drilling.html | access-date = 2008-09-27 | archive-url = https://web.archive.org/web/20080824002817/http://www.webcastr.com/videos/news/debate-over-offshore-drilling.html | archive-date = 2008-08-24 | url-status = dead }}</ref> [[Produced water]] is also generated, which is water brought to the surface along with the oil and gas; it is usually highly [[Saline water|saline]] and may include dissolved or unseparated hydrocarbons.
''See also [[Oil_platform#Ecological_effects|ecological effects of oil platforms]].''

⚫
Offshore oil production involves environmental risks, most notably [[oil spill]]s from oil tankers or pipelines transporting oil from the platform to onshore facilities, and from leaks and accidents on the platform.<ref>{{cite video | title = Debate Over Offshore Drilling | medium = internet video | publisher = ''[[CBS News]]'' |date= 2008 | url = http://www.webcastr.com/videos/news/debate-over-offshore-drilling.html|accessdate=2008-09-27}}</ref> [[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==
==See also==
{{portal|Energy|Oceans}}
*[[Deep sea mining]]
{{div col|colwidth=30em}}
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*[[Deepwater drilling]]
*[[Drillship]]
* [[Deep sea mining]]
*[[Jackup barge]]
* [[Deepwater drilling]]
* [[Drillship]]
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*[[Offshore geotechnical engineering]]
* [[Jackup rig]]
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*[[Offshore oil and gas in the United States]]
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* [[Offshore geotechnical engineering]]
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*[[Oil drilling]]
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* [[Offshore oil and gas in the United States]]
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*[[Oil platform]]
*[[Semi-submersible]]
* [[Oil platform]]
*[[Shallow water drilling]]
* [[Oil well]]
* [[Semi-submersible platform]]
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*[[Submarine pipeline]]
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* [[Shallow water drilling]]
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*[[Subsea]]
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* [[Submarine pipeline]]
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* [[Subsea]]
* [[Vertebrae bend restrictor]]
{{div col end}}


==References==
==References==
Line 84: Line 107:
* [http://publicservice.evendon.com/CenterBioDiv_v_DOIM.htm Center for Biological Diversity v Dept of the Interior] 17Apr2009 DC Appellate Decision stopping offshore Alaska Oil Leases.
* [http://publicservice.evendon.com/CenterBioDiv_v_DOIM.htm Center for Biological Diversity v Dept of the Interior] 17Apr2009 DC Appellate Decision stopping offshore Alaska Oil Leases.
* [http://iodp.tamu.edu/publications/proceedings.html IODP-USIO: Publications: Proceedings of the Integrated Ocean Drilling Program]
* [http://iodp.tamu.edu/publications/proceedings.html IODP-USIO: Publications: Proceedings of the Integrated Ocean Drilling Program]
* [http://books.google.com/books?id=LQEAAAAAMBAJ&pg=PA106&dq=popular+science+1930&hl=en&sa=X&ei=zOkDT4znGcrZgQev-ZywAg&ved=0CE8Q6AEwBzhu#v=onepage&q&f=true "New Oil from the Deep Ocean Floor."] ''Popular Science'', October 1975, pp.&nbsp;106–108.
* [https://books.google.com/books?id=LQEAAAAAMBAJ&dq=popular+science+1930&pg=PA106 "New Oil from the Deep Ocean Floor."] ''Popular Science'', October 1975, pp.&nbsp;106–108.



{{DEFAULTSORT:Offshore Drilling}}
{{DEFAULTSORT:Offshore Drilling}}

[[Category:Petroleum production]]
[[Category:Petroleum production]]
[[Category:Drilling technology]]
[[Category:Drilling technology]]

Latest revision as of 03:53, 12 November 2024

Holstein, an oil drilling platform at Green Canyon in the Gulf of Mexico, approximately 100 miles from land.

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.

Offshore drilling presents all 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

[edit]
Offshore oil well drilling platform, Continental Oil Co., Gulf of Mexico, 1955.

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]

Worker on an offshore drilling rig.

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]

Offshore drilling rig, c. 1968.

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.

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

[edit]
Main article: Oil platform
Types of offshore oil and gas structures.

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

[edit]

Notable offshore fields include:

Northstar Island, an artificial island in the Beaufort Sea north of Alaska, is a site of oil and gas drilling.

Challenges

[edit]
Being far from land can create many challenges, from logistics to safety concerns.

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

[edit]
See also: Ecological effects of oil platforms

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

[edit]

References

[edit]
  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". www.engenya.com. Engenya GmbH. 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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