Deepwater Horizon Oil Spill

Deepwater Horizon oil spill of 2010, which is also called the Gulf of Mexico oil spill of 2010, is the largest marine oil spill in history. It was caused by an explosion on the Deepwater Horizon oil rig on April 20, 2010, which was owned and operated by Transocean and drilling for BP in the Macondo Prospect oil field in the Gulf of Mexico, approximately 66 km southeast off the coast of Louisiana and its consequent sinking on April 22. The same blowout that caused the explosion also led to a massive offshore oil spill in the Gulf of Mexico, which is considered as the largest accidental marine oil spill in the world, and the largest environmental disaster in U.S. history.11 workers were killed and 17 injured by the explosion. About 2,100 km of the U.S. Gulf Coast covered in oil. Massive harm was done to wildlife in and around the Gulf of Mexico, including the deaths of an estimated 800,000 birds and 65,000 turtles. Oil company BP had to pay a sum of $65 billion in compensation to people impacted by the spill. The spill released of an estimated 134 million to 206 million gallons of oil into the Gulf of Mexico.

Deepwater Horizon prior to explosion.
Oil from the Deepwater Horizon oil spill approaches the coast of Mobile, Alabama

The oil well over which the rig was positioned was situated on the seabed 4,993 feet (1,522 metres) below the surface and stretched approximately 18,000 feet (5,486 metres) into the rock. On the night of April 20, a surge of natural gas blasted through a concrete core which was recently installed in order to cover the well for later use. It was later revealed that a similar incident had occurred on a BP-owned rig in the Caspian Sea in September 2008. Both cores were likely too weak to withstand the pressure because they were composed of a concrete mixture that used nitrogen gas to accelerate curing. The natural gas, which was released by the fracture of the core, travelled up the Deepwater rig’s riser to the platform, where it ignited, killing 11 workers and injuring 17. The rig capsized and sank on the dawn of April 22, shattering the riser, through which drilling mud had been injected in order to counter the upward pressure of oil and natural gas. Without any opposing force, oil began to discharge into the gulf. The volume of oil escaping the damaged well was originally estimated by BP to be about 1,000 barrels per day.

According to BP’s internal investigation, a bubble of methane gas escaped from the well and shot up the drill column, expanding swiftly as it burst through several seals and barriers before exploding. Survivors described the incident as an abrupt explosion that gave them less than five minutes to escape as the alarm went off. The explosion led to a fire that engulfed the platform. After burning for more than a day, Deepwater Horizon sank on April 22. BP published a report that suggested that the ignition source was the released gas entering the air intakes of the diesel generators and engulfing the deck area where the exhaust outlets for the main generators were emitting hot exhaust gas.

An oil-covered pelican struggles in the surf on the coast of the Gulf of Mexico after BP’s Deepwater Horizon oil rig exploded, leaking millions of litres of oil in 2010

The Deepwater Horizon accident was a result of failures in multiple barriers related to human, organizational, and technical barrier elements. Barriers which were planned and included in design often degraded over time. Root causes are complex and rarely due to deliberate intent or risk-taking. Serious blowouts are rarely occurring events, and the rationale for many safeguards may be lost over time and the continuous activities to keep them functional may not occur. The reassessment of the risks should include indicators for measuring and evaluating the risk level over time.

Much of the Deepwater Horizon oil spill has disappeared now as a result of the bacteria. Oil-eating microbes developed by the scientists have consumed a considerable portion of the Deepwater Horizon oil spill. Chemicals that were used to disperse the oil kept it underwater, making it more available to the microbes that live in the deeper portions of the ocean.