BP state. The "Deepwater Horizon" oil spill was a major industrial accident on the Gulf of Mexico, which killed 11 people and injured 16 others, leaked about of oil with plus or minus 10% uncertainty, which makes it the largest accidental marine oil spill in the history of the petroleum industry, and cost to the company more than $65 billion of cleanup costs, charges and penalties. On 20 April 2010, the semi-submersible exploratory offshore drilling rig "Deepwater Horizon" located in the Macondo Prospect in the Gulf of Mexico exploded after a blowout. After burning for two days, the rig sank. The
Montara oil spill 1 November. The West Triton jackup drilling rig arrived at the Montara Field in an attempt to plug the oil leak on 11 September 2009. Oil and gas producer, Woodside Petroleum Ltd offered to assist PTTEPAA in cleaning up the oil spill with the use of a rig closer to the spill site. However, PTTEPAA rejected the Woodside offer on the basis of "safety reasons". The Woodside rig was a semisubmersible drilling rig and, as it floats on the sea surface, was not deemed as a suitable platform for the relief well. A jackup rig was required because it could