Deepwater Horizon

Technically, the Deepwater Horizon was a ship. Nevertheless, it was also a drilling rig capable of drilling at great depths under the ocean. At the time of the Gulf of Mexico oil spill (20 April 2010) it was owned by Transocean and leased by British Petroleum.

The Deepwater Horizon was built in Korea in 2001. In his book, Drowning in Oil, Loren C. Steffy describes the craft:

[She had] engines that could propel her at about four knots and eight under water thrusters that kept her positioned over the wellhead when she was at rest. The platform was bigger than a football field, capped by a drilling derrick that towered 20 stories above the main deck. Her owner, Transocean Ltd., had spend a half-billion dollars building her, and she could float in as much as 10,000 feet of water and still drill some 30,000 feet below the earth's surface--deeper than Mount Everest is tall. She was part city and part drilling machine, and she was about to become a flaming tomb.

The incident which made the Deepwater Horizon famous occurred at the Macondo well. It was in an area leased by British Petroleum in conjunction with some junior corporate investors (including Anadarko). What caused the blast is still in some dispute. What is known is that the mechanism designed to sever the rig from the well in an emergency did not operate properly. The BOP or blow out preventer did not cut the pipe when an excessive flow of hydrocarbons was detected. Subsequent viewing of the BOP showed that there were as many as three pieces of pipe stuck in the preventer, a combination far to thick for the BOP to do its job. It may have been that insufficient pressure on the outside of the pipe allowed a gas bubble to form. It is believed that malfunction of the BOP allowed this critical situation to become lethal. When the gas bubble hit the deck of the Deepwater Horizon an explosion occurred which killed 11 workers and spewed oil in the Gulf of Mexico until 15 July 2010.

Prior to the incident at the Macondo well, the Deepwater Horizon had drilled some of the deepest oil wells in the ocean. The ship/rig now lies on the bottom of the Gulf of Mexico.