Deepwater Horizon Rig Explosion (2010)

Deepwater Horizon was an ultra-deepwater, dynamically positioned, semi-submersible drilling rig owned by Transocean and operated under lease by BP in the Gulf of Mexico. On the evening of 20 April 2010, at 7:45 p.m. CDT, while the rig was completing an exploratory well at the Macondo Prospect (Mississippi Canyon Block 252), about 41 miles off the coast of Louisiana, a blowout at the wellhead sent a geyser of seawater, and then a mixture of drilling mud, methane gas, and water, erupting onto the rig. The gas ignited into a series of explosions and a fire visible from 40 miles away. Crew attempted to activate the blowout preventer and, as a final safeguard, a device known as a blind shear ram, but both failed to seal the well.

Eleven rig workers were killed. Ten men — Jason Anderson, 35, of Midfield, Texas; Donald Clark, 49, of Newellton, Louisiana; Stephen Ray Curtis, 40, of Georgetown, Louisiana; Gordon Jones, 28, of Baton Rouge, Louisiana; Roy Wyatt Kemp, 27, of Jonesville, Louisiana; Karl Kleppinger Jr., 38, of Natchez, Mississippi; Keith Blair Manuel, 56, of Gonzales, Louisiana; Dewey Revette, 48, of State Line, Mississippi; Shane Roshto, 22, of Liberty, Mississippi; and Adam Weise, 24, of Yorktown, Texas — were presumed killed by the initial explosion. An eleventh worker, crane operator Aaron Dale Burkeen, 37, of Philadelphia, Mississippi, died in the fire that followed. Of 115 survivors, 17 were injured; the rig was evacuated and injured workers were airlifted to medical care.

The fire could not be extinguished. After burning for roughly 36 hours, Deepwater Horizon sank on 22 April 2010, coming to rest on the seafloor about 1,500 metres deep and roughly 400 metres northwest of the well. With the rig gone, the well continued releasing oil at the seabed, producing what has been recorded as the largest marine oil spill in history and 40 miles of coastal pollution. The spill was not closed by a cap until 15 July 2010, and the well was declared "effectively dead" on 19 September 2010 after relief wells permanently sealed it. NOAA subsequently established the Gulf Spill Restoration project to help restore the affected coastline.

Investigations into the explosion focused in part on decisions about cementing the well's final casing, including the OptiCem cement-modelling system Halliburton used in April 2010. In January 2013, Transocean agreed to pay US$1.4 billion for violations of the U.S. Clean Water Act; BP separately agreed to pay $2.4 billion, with additional potential penalties estimated at $5 billion to $20 billion. In September 2014, Halliburton agreed to pay $1.1 billion into a trust to settle a large share of the legal claims against it. On 4 September 2014, U.S. District Judge Carl Barbier ruled that BP was guilty of gross negligence and willful misconduct under the Clean Water Act, calling BP's conduct "reckless" and Transocean's and Halliburton's conduct "negligent"; he apportioned 67 percent of the blame for the spill to BP, 30 percent to Transocean, and 3 percent to Halliburton. BP said it would appeal. On 8 December 2014, the U.S. Supreme Court rejected BP's challenge to the compensation settlement for spill victims, initially estimated by BP at about $7.8 billion; by 2018, roughly 390,000 claims had been filed, with about $65 billion paid in settlements and further claims still outstanding. The spill has since been cited by lawyers, academics, and journalists as an example of ecocide.