![]() Deepwater Horizon, on fire after the explosion
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History | |
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Name | Deepwater Horizon |
Owner | Transocean |
Operator | Transocean |
Port of registry | Majuro, Marshall Islands |
Route | Gulf of Mexico |
Ordered | December 1998 |
Builder | Hyundai Heavy Industries |
Cost | US$560 million [2][3] |
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) [1] |
Identification | list error: <br /> list (help) ABS class no.: 0139290 Call sign: V7HC9 IMO number: 8764597 |
Fate | Destroyed [1] |
Status | list error: <br /> list (help) Sunk 28°44′12″N 88°23′13″W / 28.736667°N 88.386944°W |
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) |
Installed power | 42 MW |
Propulsion | Diesel electric |
Speed | 4 kts |
Crew | 146 |
Notes | 8202 tonne Variable Deck Load, DP Class 3, 8 thrusters, 10,000 ft drilling water depth |
Deepwater Horizon was an ultra-deepwater, dynamically positioned, semi-submersible offshore drilling rig. The rig was built in 2001 in South Korea, is owned by Transocean and was leased to BP plc until September 2013.[4] Deepwater Horizon was registered in Majuro, Marshall Islands. 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).[5]
On April 20, 2010, an explosion on the rig left eleven crewmen dead. The resulting fire could not be extinguished, and on April 22, 2010, the rig sank, leaving the well gushing, causing the largest offshore oil spill in the United States history.[6]
Deepwater Horizon was a fifth-generation, RBS-8D design, ultra-deepwater, dynamically positioned, column-stabilized, semi-submersible drilling rig[7] (Mobile Offshore Drilling Unit), designed to drill subsea wells for oil exploration and production purposes. Deepwater Horizon was the second semi-submersible rig constructed of a class of two, although the Deepwater Nautilus, her predecessor, is not dynamically positioned. The rig was 396 by 256 ft (121 by 78 m),[7], could operate in waters up to 8,000 feet (2,400 m) deep, to a maximum drill depth of 30,000 feet (9,100 m),[8] 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).[9]
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.[10]
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, and was insured for $560 million.[11]
Transocean, the rig owner, operated the rig under the Marshalese flag of convenience.[12] Beginning in 2008, BP Exploration leased the Deepwater Horizon from Transocean Ltd.[12] In October 2009, the contract was extended until 2013.[4][12] The lease contract was worth $544 million, a rate of $496,800 per day.[13]
The Deepwater Horizon worked on wells in the Atlantis and Thunder Horse Oil Fields, a 2006 discovery in the Kaskida field, and the 2009 Tiber oilfield.[14][15] On September 2, 2009, Deepwater Horizon drilled on the Tiber oilfield with a vertical depth of 35,050 ft (10,683 m) and measured depth of 35,055 ft (10,685 m), of which 4,132 ft (1,259 m) was water, which was at the time the deepest oil well in the world.[15][16][17][18] The well was more than 5,000 feet deeper than the design specification on the company's fleet list.[19]
In March 2008, at the Minerals Management Service's lease sale,[20] BP purchased the mineral rights to drill for oil on Mississippi Canyon Block 252, referred to as the Macondo Prospect, in the United States sector of the Gulf of Mexico, about 41 miles (66 km) off the southeast coast of Louisiana.
The Deepwater Horizon commenced drilling in the Macondo Prospect in February 2010 at a water depth of approximately 5,000 feet (1,500 m).[21] As of April 20, 2010, the Deepwater Horizon was still working on the site.[22][23][14][24]
On April 20, 2010, the rig was in the final phases of drilling an exploratory oil well in which casing was being cemented in place as a reinforcement by Halliburton.[22] The planned well was to be drilled to 18,000 feet (5,500 m) below sea level, and was then to be plugged and suspended for subsequent completion as a subsea producer.[21] At 9:45 p.m. CDT,[25] 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.[26]
Eleven workers were presumed killed in the initial explosion. The rig was evacuated, with numerous injured workers airlifted to medical facilities.[1] 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.[27]
After burning for approximately 36 hours, the 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.[22][28][29]
The oil was not stopped before the Deepwater Horizon sank. As of the beginning of June, 2010, the oil was still flowing. Some estimates of the spill make this the largest oil spill ever in the Gulf of Mexico, threatening fisheries, tourism, and the habitat of hundreds of bird species.[30]
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