Deepwater Horizon

Deepwater Horizon.jpg
Deepwater Horizon semi-submersible drilling rig.
History
Name: Deepwater Horizon
Owner: Transocean's Triton Asset Leasing GmbH [1]
Operator: Transocean
Port of registry:
Route: Gulf of Mexico
Ordered: December 1998
Builder: Hyundai Heavy Industries [3]
Cost: US$560 million [4] [5]
Way number: 89
Laid down: 21 March 2000
Completed: 2001
Acquired: 23 February 2001
Maiden voyage: Ulsan, South Korea – Freeport, Texas
Out of service: 20 April 2010
Identification:
Fate: Sank on 22 April 2010 after an explosion and fire
Notes: Located in the Gulf of Mexico at a depth of 5,000 ft (1,500 m) at 28°44′12″N 88°23′13″W / 28°44′12″N 88°23′13″W / 28.736667; -88.386944
General characteristics
Class and type: ABS +A1 DPS-3 Column Stabilized MODU
Tonnage:
  • 32,588  GT
  • 9,776  NT
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:
Propulsion: 8 × Kamewa 7,375 hp, 360° fixed propeller azimuth thrusters
Speed: 4 knots (7.4 km/h; 4.6 mph)
Capacity:
Crew: 146
Notes: [6] [7]

Deepwater Horizon was an ultra-deepwater, dynamically positioned, semi-submersible offshore drilling rig [8] owned by Transocean. Built in 2001 in South Korea by Hyundai Heavy Industries, [9] the rig was commissioned by R&B Falcon (a later asset of Transocean), [10] registered in Majuro, and leased to BP from 2001 until September 2013. [11] In September 2009, the rig drilled the deepest oil well in history at a vertical depth of 35,050 ft (10,683 m) and measured depth of 35,055 ft (10,685 m) [12] in the Tiber Oil Field at Keathley Canyon block 102, approximately 250 miles (400 km) southeast of Houston, in 4,132 feet (1,259 m) of water. [13]

On 20 April 2010, while drilling at the Macondo Prospect, an uncontrollable blowout caused an explosion on the rig that killed 11 crewmen and ignited a fireball visible from 40 miles (64 km) away. [14] The fire was inextinguishable and, two days later, on 22 April, the Horizon sank, leaving the well gushing at the seabed and causing the largest oil spill in U.S. waters. [15]

Design

The Deepwater Nautilus, sister rig to the Deepwater Horizon being transported aboard a heavy-lift ship

Deepwater Horizon was a fifth-generation, RBS-8D design (i.e. model type), deepwater, dynamically positioned, column-stabilized, [3] semi-submersible mobile offshore drilling unit, designed to drill subsea wells for oil exploration and production using an 18.75 in (476 mm), 15,000 psi (100,000 kPa) blowout preventer, and a 21 in (530 mm) outside diameter marine riser. [6]

Deepwater Horizon was the second semi-submersible rig constructed of a class of two, although Deepwater Nautilus, its 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 ft (9,100 m). [6] In 2010 it was one of approximately 200 deepwater offshore rigs capable of drilling in waters deeper than 5,000 ft (1,500 m). [16] Its American Bureau of Shipping (ABS) class notations were "A1, Column Stabilized Drilling Unit, AMS, ACCU, DPS-3". [3]

In 2002, the rig was upgraded with "e-drill", a drill monitoring system whereby technical personnel based in Houston, Texas, received real-time drilling data from the rig and transmitted maintenance and troubleshooting information. [17]

Advanced systems played a key role in the rig's operation, from pressure and drill monitoring technology, to automated shutoff systems [18] and modelling systems for cementing. The OptiCem cement modelling system, used by Halliburton in April 2010, played a crucial part in cement slurry mix and support decisions. These decisions became a focus for investigations into the explosion on the rig that month. [19]

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