The Rumaila oil field is a super-giant oil field located in southern Iraq, approximately 20 mi (32 km) from the Kuwaiti border. Discovered in 1953 by the Basrah Petroleum Company (BPC), an associate company of the Iraq Petroleum Company (IPC), the field is estimated to contain 17 billion barrels, which accounts for 12% of Iraq's oil reserves estimated at 143.1 billion barrels. Rumaila is said to be the largest oilfield ever discovered in Iraq and is considered the third largest oil field in the world.Under Abd al-Karim Qasim, the oilfield was confiscated by the Iraqi government by Public Law No. 80 of 11 December 1961. Since then, this massive oil field has remained under Iraqi control. The assets and rights of IPC were nationalised by Saddam Hussein in 1972, and those of BPC in 1975. The dispute between Iraq and Kuwait over alleged slant-drilling in the field was one of reasons for Iraq's invasion of Kuwait in 1990.The oil field requires regular investment to manage its reservoir. To maintain steady output, 200,000 barrels a day of lost production has to be replaced every year.