''Transocean Marianas'' was an Earl & Wright Sedco 700 design

semi-submersible platform 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 dr ...

drilling unit capable of operating in harsh environments and water depths up to using an , 15,000 psi

blowout preventer A blowout preventer (BOP) (pronounced B-O-P, not "bop") is a specialized valve or similar mechanical device, used to seal, control and monitor oil and gas wells to prevent blowouts, the uncontrolled release of crude oil or natural gas from a w ...

(BOP), and a outside diameter (OD)

marine riser Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military ...

. ''Transocean Marianas'' has operated under several names: ''Tharos'' from 1979 to 1994, ''Polyportia'' from 1994 to 1996, and ''P. Portia'' from 1996 to 1998. On October 7, 2009, it began drilling on the

Macondo well The Macondo Prospect (Mississippi Canyon Block 252, abbreviated MC252) is an oil and gas prospect in the United States Exclusive Economic Zone of the Gulf of Mexico, off the coast of Louisiana. The prospect was the site of the ''Deepwater Horiz ...

in the Gulf of Mexico. On November 9, 2009. it was damaged by

Hurricane Ida Hurricane Ida was a deadly and extremely destructive Category 4 Atlantic hurricane in 2021 that became the second-most damaging and intense hurricane to make landfall in the U.S. state of Louisiana on record, behind Hurricane Katrina in 200 ...

. It was subsequently replaced by the ''

Deepwater Horizon ''Deepwater Horizon'' was an ultra-deepwater, dynamically positioned, semi-submersible offshore drilling rig owned by Transocean and operated by BP. On 20 April 2010, while drilling at the Macondo Prospect, a blowout caused an explosion on ...

'', which was responsible for the

Deepwater Horizon oil spill The ''Deepwater Horizon'' oil spill (also referred to as the "BP oil spill") was an industrial disaster that began on 20 April 2010 off of the coast of the United States in the Gulf of Mexico on the BP-operated Macondo Prospect, considered ...

when that rig exploded on April 20, 2010.

''Piper Alpha'' incident

In 1988, as ''Tharos'', the vessel operated by Occidental Consortium as a large

firefighting Firefighting is the act of extinguishing or preventing the spread of unwanted fires from threatening human lives and destroying property and the environment. A person who engages in firefighting is known as a firefighter. Firefighters typically ...

, construction, diving support and accommodation vessel equipped with a helicopter and a

hospital ship A hospital ship is a ship designated for primary function as a floating medical treatment facility or hospital. Most are operated by the military forces (mostly navies) of various countries, as they are intended to be used in or near war zones. ...

with 22 beds, that rescued survivors from the ''

Piper Alpha Piper Alpha was an oil platform located in the North Sea approximately north-east of Aberdeen, Scotland. It was operated by Occidental Petroleum (Caledonia) Limited (OPCAL) and began production in 1976, initially as an oil-only platform but la ...

oil platform An oil platform (or oil rig, offshore platform, oil production platform, and similar terms) is a large structure with facilities to extract and process petroleum and natural gas that lie in rock formations beneath the seabed. Many oil platfor ...

disaster A disaster is a serious problem occurring over a short or long period of time that causes widespread human, material, economic or environmental loss which exceeds the ability of the affected community or society to cope using its own resources ...

. The vessel carried out firefighting on the night of the disaster and supported the fire fighting and

well kill A well kill is the operation of placing a column of heavy fluid into a well bore in order to prevent the flow of reservoir fluids without the need for pressure control equipment at the surface. It works on the principle that the hydrostatic head ...

operations that led to the extinguishing of the blaze. However, flaws in the design of the vessel's extensible rescue arm prevented it from rescuing crew from the platform, while errors in the operation of the

water cannon A water cannon is a device that shoots a high-velocity stream of water. Typically, a water cannon can deliver a large volume of water, often over dozens of meters. They are used in firefighting, large vehicle washing, riot control, and mining ...

delayed their use. Divers from ''Tharos'' recovered many bodies from the

seabed The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'. The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...

and from the

galley A galley is a type of ship that is propelled mainly by oars. The galley is characterized by its long, slender hull, shallow draft, and low freeboard (clearance between sea and gunwale). Virtually all types of galleys had sails that could be used ...

area of ''Piper Alpha''. ''Thaross role in the early hours of the disaster was shown in the 1990

Scottish Television Scottish Television (now, legally, known as STV Central Limited) is the ITV network franchisee for Central Scotland. The channel — the largest of the three ITV franchises in Scotland — has been in operation since 31 August 1957 and is the ...

series ''

Rescue Rescue comprises responsive operations that usually involve the saving of life, or the urgent treatment of injuries after an accident or a dangerous situation. Tools used might include search and rescue dogs, mounted search and rescue ho ...

''.

2011 Ghana incident

On July 6, 2011, the ''Transocean Marianas'' was evacuated due to it taking on water off the coast of Ghana.

Disposal

In September 2017 Transocean announced that ''Transocean Marianas'', along with five other laid up rigs, would be retired and disposed of for recycling.

References

External links

Transocean official website

at ''VesselTracker'' 1979 ships Drilling rigs Semi-submersibles Ships built by Mitsubishi Heavy Industries Ships built in Singapore Transocean

''Piper Alpha'' incident

2011 Ghana incident

Disposal

References

Further reading

External links