Deepwater Horizon - Design

Design

Deepwater Horizon was a fifth-generation, RBS-8D design (i.e. model type), deepwater, dynamically positioned, column-stabilized, 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.

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), and in 2010 was one of approximately 200 deepwater offshore rigs capable of drilling in waters more than 5,000 ft (1,500 m). Its American Bureau of Shipping (ABS) class notations were "A1, Column Stabilized Drilling Unit, AMS, ACCU, DPS-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.

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