Deepwater Horizon

For Information on the oil spill, see Deepwater Horizon oil spill. For the oil rig explosion, see Deepwater Horizon explosion.

Deepwater Horizon prior to destruction. Parts of the structure providing buoyancy are invisible below the waterline in this image.
History
Name	Deepwater Horizon
Owner	Transocean's Triton Asset Leasing GmbH
Operator	Transocean
Port of registry	Majuro, Marshall Islands
Route	Gulf of Mexico
Ordered	December 1998
Builder	Hyundai Heavy Industries
Cost	US$560 million
Way number	89
Laid down	March 21, 2000
Completed	2001
Acquired	February 23, 2001
Maiden voyage	Ulsan, South Korea – Freeport, Texas
Out of service	April 21, 2010 (exploded)
Identification	ABS class no.: 0139290 Call sign: V7HC9 IMO number: 8764597 MMSI no.: 538002213
Fate	Destroyed
Status	Sunk at 28.736667°N 88.386944°W / 28.736667; -88.386944
General characteristics
Class and type	ABS +A1 DPS-3 Column Stabilized MODU
Tonnage	32,588 t (32,073 long tons; 35,922 short tons)
Displacement	52,587 t (51,756 long tons; 57,967 short tons)
Length	112 m (367 ft)
Beam	78 m (256 ft)
Height	97.4 m (320 ft)
Draught	23 m (75 ft)
Depth	41.5 m (136 ft)
Deck clearance	34.010 m (111.58 ft)
Installed power	7,000 kW 11,000 volts 6 x Wartsila 18V32 9775 hp diesel engines 6 x ABB AMG 0900xU10 AC generators
Propulsion	8 x Kamewa 7,375 hp, 360° fixed propeller azimuth thrusters
Speed	4 kts
Capacity	Liquid mud: 705 m3 (24,900 cu ft) Drill water: 2,078 m3 (73,400 cu ft) Potable water: 1,185 m3 (41,800 cu ft) Fuel oil: 4,426 m3 (156,300 cu ft) Bulk mud: 386 m3 (13,600 cu ft) Bulk cement: 231 m3 (8,200 cu ft)
Crew	146
Notes

Deepwater Horizon was an ultra-deepwater, dynamically positioned, semi-submersible offshore drilling rig. Built in 2001 in South Korea, it was owned by Transocean, registered in Majuro, Marshall Islands, and leased to BP plc until 2013.

In September 2009, the rig drilled the deepest oil well in history at a vertical depth of 35,050 ft (10,680 m) and measured depth of 35,055 ft (10,685 m). On April 20, 2010, an explosion on the rig killed eleven crewmen. The resulting fire could not be extinguished and, on April 22, 2010, Deepwater Horizon sank, leaving its well gushing and causing the largest offshore oil spill in United States history.

Design

Deepwater Nautilus, sister ship to the Horizon, in transit, showing the full design (including underwater section).

Deepwater Horizon was a fifth-generation, RBS-8D design, ultra-deepwater, dynamically positioned, column-stabilized, semi-submersible mobile offshore drilling unit (MODU), designed to drill subsea wells for oil exploration and production using an 18.75 in (47.6 cm), 15,000 psi blowout preventer (BOP), and a 21 in (53 cm) outside diameter (OD) marine riser. Deepwater Horizon was the second semi-submersible rig constructed of a class of two, although Deepwater Nautilus, her predecessor, is not dynamically positioned. The rig was 396 by 256 ft (121 by 78 m) and capable of operating in waters up to 8,000 feet (2,400 m) deep, to a maximum drill depth of 30,000 feet (9,100 m), and in 2010 was one of approximately two hundred deepwater offshore rigs capable of drilling in waters more than 5,000 ft (1,500 m).

In 2002, the rig was upgraded with "e-drill," a drill monitoring system whereby technicians based in Houston, Texas, received real-time drilling data from the rig and transmitted maintenance and troubleshooting information.

History

Construction

Designed originally for R&B Falcon, Deepwater Horizon was built by Hyundai Heavy Industries in Ulsan, South Korea. Construction started in December 1998 and the rig was delivered in February 2001 after the acquisition of R&B Falcon by Transocean.

According to R&B Falcon's SEC filings for 2001, the transfer document between R&B Falcon to Transocean was dated 17 August 2001, and the rig was specified as "official registration number of 29273-PEXT-1, IMO No. 8764597, with Gross Tonnage of 32,588 and with Net Tonnage of 9,778" and the transfer value as US $340 million. As at 2010, the rig was insured for US $560 million, the sum covering its replacement cost and wreckage removal.

Ownership and lease

Transocean, the rig owner, operated the rig under the Marshalese flag of convenience. Beginning in 2008, BP Exploration leased Deepwater Horizon from Transocean Ltd. In October 2009, the contract was extended until 2013. The lease contract was worth $544 million, a rate of $496,800 per day.

Drilling operations

Deepwater Horizon worked on wells in the Atlantis (BP 56%, BHP Billiton 44%) and Thunder Horse (BP 75%, ExxonMobil 25%) oil fields. In 2006 it discovered oil in the Kaskida field, and in 2009 the "giant" Tiber field. The well in the Tiber field has a vertical depth of 35,050 ft (10,683 m) and a measured depth of 35,055 ft (10,685 m), of which 4,132 ft (1,259 m) was water. The well was the deepest oil well in the world, and more than 5,000 feet (1,500 m) deeper than the design specification on the company's fleet list.

In February 2010, Deepwater Horizon commenced drilling an exploratory well at the Macondo Prospect (Mississippi Canyon Block 252), about 41 miles (66 km) off the southeast coast of Louisiana, at a water depth of approximately 5,000 feet (1,500 m). The Macondo prospect exploration rights were acquired by BP in 2009, with the prospect jointly owned by BP (65%), Anadarko (25%) and MOEX Offshore 2007 (10%). Deepwater Horizon was still working on the Macondo site on 20 April 2010, when a violent explosion occurred leading to destruction of the rig and resulting oil spill. The well was in the final stages of drilling at the time; the cement casing for the well was injected and hardening, and the rig was due to move shortly to its next role as a semi-permanent production platform.

Explosion and oil spill

Main articles: Deepwater Horizon explosion and Deepwater Horizon oil spill

Deepwater Horizon on fire after the explosion.

At 09:45 p.m. CDT April 20, 2010, during the final phases of drilling the exploratory well at Macondo, a geyser of seawater erupted from the marine riser onto the rig, shooting 240 ft (73 m) into the air. This was soon followed by the eruption of a slushy combination of mud, methane gas, and water. The gas component of the slushy material quickly transitioned into a fully gaseous state and then ignited into a series of explosions and then a firestorm. Workers immediately attempted to activate the blowout preventer, but it failed.

At the time of the explosion, there were 126 crew on board; seven were employees of BP, 79 of Transocean, there were also employees of various other companies involved in the operation of the rig, including Anadarko, Halliburton and M-I Swaco. Eleven workers were presumed killed in the initial explosion. The rig was evacuated, with numerous injured workers airlifted to medical facilities. Support ships sprayed the rig with water in an ultimately unsuccessful bid to cool it and prevent it from capsizing. This was an attempt to buy time while attempts were made to stop the oil and gas that were feeding the flames from coming up the riser pipe. If it had been successful, it would have reduced the flames and allowed special teams of firefighters to board the stricken rig and extinguish the remaining fire.

After burning for approximately 36 hours, Deepwater Horizon sank on April 22, 2010, in water approximately 5,000 ft (1,500 m) deep, and has been located resting on the seafloor approximately 1,300 ft (400 m) (about a quarter of a mile) northwest of the well.

The oil from the ruptured well continues to flow as of June 2010. A number of attempts to staunch the flow were either unsuccessful or have met with only limited success, and relief wells to allow termination of the flow are unlikely to be completed for some time. BP has said that measures to fully curtail the flow are unlikely to succeed until at least August 2010, the estimated completion date for the relief wells. The spill threatens fisheries, tourism, and the habitat of hundreds of bird species. The oil spill also can cause massive damage to the fragile ecosystem of the gulf coast and waters. Some estimates of the spill make this the largest oil spill ever in the Gulf of Mexico and US history.

Aftermath

Transocean received an early partial settlement for total loss of the Deepwater Horizon of US $401 million around May 5 2010. Financial analysts note that the insurance recovery is likely to outweigh the value of the rig (although not necessarily its replacement value) and any liabilities - the latter estimated at up to US $200 million.

Litigation, ultimate roll call of damage, and the scope of final insurance recovery, are all unknown at present.

See also

• Atlantis PQ
• Ocean Ranger
• Piper Alpha
• Thunder Horse PDQ
• Transocean John Shaw
• Ixtoc I oil spill
• Kola Superdeep Borehole

External links

• Transocean official website
• Deepwater Horizon detail at Transocean's website and at RigZone.com
• Photograph of Deepwater Horizon in 2004 at Geographic.org
• Griffitt, Michelle. "Initial Exploration Plan Mississippi Canyon Block 252 OCS-G 32306" (PDF). BP Exploration and Production. New Orleans, Louisiana: Minerals Management Service.
• Washburn, Mark (2010-05-14). "A huff and boom ended Deepwater Horizon's good luck". The McClatchy Company. Retrieved 2010-06-18. {{cite news}}: Italic or bold markup not allowed in: |newspaper= (help) - detailed media description of the events of the day of the Deepwater Horizon explosion (yahoo news mirror)