Transocean Marianas is an Earl & Wright Sedco 700 design semi-submersible

Semi-submersible

A semi-submersible is a specialised marine vessel with good stability and seakeeping characteristics. The semi-submersible vessel design is commonly used in a number of specific offshore roles such as for offshore drilling rigs, safety vessels, oil production platforms and heavy lift cranes.The...

 drilling unit capable of operating in harsh environments and water depths up to 7000 feet (2,133.6 m) using an 18.75 in (47.6 cm), 15,000 psi blowout preventer

Blowout preventer

A blowout preventer is a large, specialized valve used to seal, control and monitor oil and gas wells. Blowout preventers were developed to cope with extreme erratic pressures and uncontrolled flow emanating from a well reservoir during drilling. Kicks can lead to a potentially catastrophic...

 (BOP), and a 21 in (53.3 cm) outside diameter (OD) marine riser.

Transocean Marianas currently operates offshore drilling

Offshore drilling

Offshore drilling refers to a mechanical process where a wellbore is drilled through the seabed. It is typically carried out in order to explore for and subsequently produce hydrocarbons which lie in rock formations beneath the seabed...

 activities in the US section of the Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

. Throughout her career, she 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

Macondo Prospect

The Macondo Prospect is an oil and gas prospect in the United States Exclusive Economic Zone of the Gulf of Mexico, off the coast of Louisiana...

 in the Gulf of Mexico. On November 9, 2009. it was damaged by Hurricane Ida. It was replaced by the Deepwater Horizon

Deepwater Horizon

Deepwater Horizon was an ultra-deepwater, dynamically positioned, semi-submersible offshore oil drilling rig owned by Transocean. Built in 2001 in South Korea by Hyundai Heavy Industries, the rig was commissioned by R&B Falcon, which later became part of Transocean, registered in Majuro, Marshall...

, which was responsible for the Deepwater Horizon oil spill

Deepwater Horizon oil spill

The Deepwater Horizon oil spill is an oil spill in the Gulf of Mexico which flowed unabated for three months in 2010, and continues to leak fresh oil. It is the largest accidental marine oil spill in the history of the petroleum industry...

 when that rig exploded on April 20, 2010.

Piper Alpha incident

In 1988, as Tharos, the vessel operated as a large firefighting

Fireboat

A fireboat is a specialized watercraft and with pumps and nozzles designed for fighting shoreline and shipboard fires. The first fireboats, dating to the late 18th century, were tugboats, retrofitted with firefighting equipment....

, construction, diving support and accommodation vessel equipped with a helicopter and a hospital ship

Hospital ship

A hospital ship is a ship designated for primary function as a floating medical treatment facility or hospital; most are operated by the military forces of various countries, as they are intended to be used in or near war zones....

 with 22 beds, that rescued survivors from the Piper Alpha

Piper Alpha

Piper Alpha was a North Sea oil production platform operated by Occidental Petroleum Ltd. The platform began production in 1976, first as an oil platform and then later converted to gas production. An explosion and resulting fire destroyed it on 6 July 1988, killing 167 men, with only 61...

oil platform

Oil platform

An oil platform, also referred to as an offshore platform or, somewhat incorrectly, oil rig, is a lаrge structure with facilities to drill wells, to extract and process oil and natural gas, and to temporarily store product until it can be brought to shore for refining and marketing...

 disaster

Disaster

A disaster is a natural or man-made hazard that has come to fruition, resulting in an event of substantial extent causing significant physical damage or destruction, loss of life, or drastic change to the environment...

. The vessel carried out firefighting on the night of the disaster and supported the fire fighting and well kill

Well kill

A well kill is the operation of placing a column of heavy fluid into a well bore in order to prevent the flow of reservoir fluids without the need for pressure control equipment at the surface. It works on the principle that the weight of the "kill fluid" or "kill mud" will be enough to suppress...

 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

Water cannon

A water cannon is a device that shoots a high-pressure stream of water. Typically, a water cannon can deliver a large volume of water, often over dozens of metres / hundreds of feet. They are used in firefighting and riot control. Most water cannon fall under the category of a fire...

 delayed their use. Divers from Tharos recovered many bodies from the seabed

Seabed

The seabed is the bottom of the ocean.- Ocean structure :Most of the oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources...

 and from the galley area of Piper Alpha.

2011 Ghana incident

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

External links

• Transocean official website
• Transocean Marianas current position at VesselTracker