An offshore oil spill is the release of liquid petroleum hydrocarbon into the ocean or coastal waters. The spills occur due to accidental release of crude oil from tankers, offshore platforms, drilling rigs and wells. The oil spill disasters have a huge negative impact on the marine species. Besides, the recovery work related to oil spills involves billions of dollars.
Here is the list of biggest offshore oil spill in the world:
Deepwater Horizon oil spill: Occurred in April 2010 in BP’s Macondo oil and gas prospect in the Gulf of Mexico, the Deepwater Horizon oil spill disaster led to the release of 4.9 million barrels of oil into the water. It is regarded as the largest marine oil spill in the history of the petroleum industry. On 20 April 2010, a massive explosion occurred on the Deepwater Horizon semi-submersible offshore oil rig that was working on a Macondo exploration well. The explosion resulted in the ignition of hydrocarbons that were released to the surface.
Due to failure of the blowout preventer (BOP) device to seal the well, the oil and gas flow was not controllable. Burning continuously for 36 hours, the rig finally sank on 22 April 2010. To prevent the oil leakage, a sealing cap was finally bolted on top of the blowout preventer on 15 July 2010. The disaster resulted in the death of 11 people.
Sedco 135F – IXTOC I oil spill: Also known as the IXTOC I oil spill, the Sedco 135F disaster led to the release of 3.5 million barrels of oil into the sea. The disaster occurred in June 1979 in the Bahia de Campeche (Bay of Campeche), an inlet of the Gulf of Mexico. The Sedco 135F offshore oil rig was drilling the IXTOC I well for Mexican company PEMEX when the disaster took place. The main cause that led to the oil spill was the loss of circulation of heavy fluid, which acted as a lubricant for the drill. The fluid also offered a column of hydrostatic pressure to restrict the circulation of oil and gas to the surface. Due to lack of mud column’s hydrostatic pressure, following the drilling of the well to 3.65km, there was uncontrolled release of oil and gas to the surface, resulting in the ignition of the rig. On 23 March 1980, the well was completed sealed.
Atlantic Empress oil spill: The disaster occurred on 19 July 1979 following the collision of two fully loaded large crude oil carriers nearly 16km off the coast of Tobago. The oil carriers were the Atlantic Empress and the Aegean Captain. The collision led to the release of 2.1 million barrels of oil into the Caribbean Sea. While the Atlantic Empress was carrying 276,000t of crude oil from Saudi Arabia to Beaumont, Texas, the Aegean Captain was transporting 200,000t of crude oil to Singapore from the southern Caribbean Sea island Aruba. The accident caused the death of 26 people and burnt the entire body of the Atlantic Empress.
Nowruz oil spills: Releasing 1.9 million barrels of oil into water, the two oil spills occurred in Nowruz oil field located in the Persian Gulf, Iran, in 1983. On 24 January 1983, a supply ship collided with a rig at Nowruz field, resulting in the rupture of the riser at one wellhead. The collision led to the spill of oil at a rate of 240m3 per day. On 18 September 1983, the well was finally capping to prevent the leakage. During the capping operation, 11 people were killed. The second oil spill at the field happened when a rig was hit by Iraqi bombers in April 1983. The attack led to a well blowout that released oil at a rate of 795m3 per day.
ABT Summer oil spill: The disaster occurred when the ABT Summer oil cargo vessel carrying 260,000t of Iranian heavy crude oil from the Gulf terminal at Kharg Island in Iran to Rotterdam caught fire on the 28 May 1991. Taking place about 1,448km off the coast of Angola, the disaster released 1.9 million barrels of oil into the ocean. Before sinking into the ocean, the tanker burnt for three days.
Castillo de Bellver oil spill: Spilling about 1.88 million barrels of oil, the disaster occurred in August 1983 when a Spanish oil tanker Castillo de Bellver carrying 250,000t of Arabian light crude oil caught fire in the Table Bay near Cape Town, South Africa. The tanker was about 112km northwest of Cape Town when the accident happened. Spilling oil into the bay, the tanker broke into two pieces when it was about 36km away from the coast.