What happened to the Deepwater Horizon?

Deepwater Horizon was a semi submersible mobile offshore drilling unit. On 20 April 2010 an explosion caused a fire that tragically resulted in the deaths of 11 workers and injured 17 others in the Macondo Prospect oil field.

What caused the Deepwater Horizon explosion and fire?

The explosion was caused by a leak of hydrocarbons due to the failure of a safety valve known as a blowout preventer. This along with a lack of monitoring procedures allowed a leak to emit for more than 40 minutes, rapidly flowing to the surface where a mix of gases moved to the rig which contained heating, ventilation and engine room facilities producing heat.

The gas mixture ignited, killing 11 people and injuring 17 of the 126 people onboard.

The explosion caused a huge oil spill which took months to stem the leak. It had a devastating effect on the shoreline, coastal areas, wetlands and wildlife.

The leak continued for 87 days, expelling an estimated 4.9m barrels (780,000m3 ) of oil. BP’s accident and emergency plan was initiated but had significant failings and was unable to address the extent of the crisis.

What can the industry learn from the Deepwater Horizon explosion and fire?

The oil slick that emanated from the site is perhaps the worst environmental disaster of its kind.

Relaxed safety procedures and generally poor industry practices are believed to have contributed to the incident. A BP report blamed a combination of "a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces".

After the explosion the rig sank along with 5,000 feet of piping - investigation identified three leaks in that pipe system. A study also confirmed the presence of a toxic chemical residue one kilometre below the surface of the Gulf of Mexico - amounting to just 0.1% of the total amount spilled.