History
Name
  • Transocean Marianas
  • P. Portia (1996–1998)
  • Polyportia (1994–1996)
  • Tharos (1979–1994)
OwnerTransocean
OperatorTransocean
Port of registry
BuilderMitsubishi Heavy Industries
Laid down13 August 1978
Acquired1 September 1979
Identification
FateScrapped September 2018
Notes[1][2]
General characteristics
Class and typeAmerican Bureau of Shipping: A1 column stabilized MODU; AMS; ACCU; DP S2
Tonnage20,461 GT; 6,138 NT; 10,100 DWT
Length91.44 m (300.0 ft)
Beam75.8952 m (249.000 ft)
Draught
  • Operating: 25 m (82 ft)
  • Transit: 9 m (30 ft)
Depth34.7472 m (114.000 ft)
Deck clearance12,352 mm (40.525 ft)
Propulsion6 x Electro-Motive Diesel MD-20 3,600hp
Speed2.0 kts
Capacity
Crew150
Notes[1]

Transocean Marianas was an Earl & Wright Sedco 700 design semi-submersible platform drilling unit capable of operating in harsh environments and water depths up to 7,000 feet (2,100 m) using an 47.6 cm (18.75 in), 15,000 psi blowout preventer (BOP), and a 53 cm (21 in) outside diameter (OD) marine riser.[3]

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 in the Gulf of Mexico. On November 9, 2009. it was damaged by Hurricane Ida. It was subsequently replaced by the Deepwater Horizon, which was responsible for the Deepwater Horizon oil spill when that rig exploded on April 20, 2010.[4]

Piper Alpha incident

In 1988, as Tharos, the vessel operated by Occidental Consortium as a large firefighting, construction, diving support and accommodation vessel equipped with a helicopter and a hospital ship with 22 beds, that rescued survivors from the Piper Alpha oil platform disaster.[5] The vessel carried out firefighting on the night of the disaster and supported the fire fighting and well kill 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 delayed their use. Divers from Tharos recovered many bodies from the seabed and from the galley area of Piper Alpha. Tharos's role in the early hours of the disaster was shown in the 1990 Scottish Television series Rescue.

2011 Ghana incident

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

Disposal

In September 2017 Transocean announced that Transocean Marianas, along with five other laid up rigs, would be retired and disposed of for recycling.[7]

References

  1. 1 2 "ABS Record: Transocean Marianas". American Bureau of Shipping. 19 October 2009. Retrieved 4 June 2010.
  2. ↑ "Vessel Info: Transocean Marianas". DNV Exchange. Det Norske Veritas. 2010. Archived from the original on 10 July 2011. Retrieved 4 June 2010.
  3. ↑ "Transocean Marianas". Transocean. 2010. Archived from the original on 9 July 2011. Retrieved 7 June 2010.
  4. ↑ "Letter from Henry Waxman to Tony Hayward - June 14, 2010" (PDF). nergycommerce.house.gov. 2010-06-14. Archived from the original (press release) on December 7, 2010. Retrieved 2010-06-14.
  5. ↑ Lancaster, John Frederick (2000). Engineering Catastrophes: Causes and Effects of Major Accidents. Cambridge: Woodhead Publishing. pp. 121–122. ISBN 1-85573-505-9. Retrieved 11 June 2010.
  6. ↑ Dezember, Ryan (7 July 2011). "Transocean Ghana rig stable after taking on water". MarketWatch. New York: Dow Jones & Co. Retrieved 12 January 2019.
  7. ↑ "Transocean Ltd. Announces Retirement of Six Floaters". Transocean Ltd. 22 September 2017. Retrieved 12 January 2019.

Further reading

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