The petroleum industry in Kuwait is the largest industry in the country, accounting nearly half of the country's GDP. Kuwait has a proven crude oil reserves of 104 billion barrels (15 km³), estimated to be 9% of the world's reserves. Kuwait's oil reserves are the fourth largest in the world and the Burgan Field is the second largest oil field. Kuwait is the world's eleventh largest oil producer and seventh largest exporter. Kuwait's oil production accounts for 7% of world-wide oil production.
Since the government of Kuwait owns the oil industry, it controls a lot of the country's economy; in all, about 43 percent of the GDP. Kuwait’s oil exports vary depending on internal needs – almost all of Kuwait’s energy is derived from oil – and on international demand and prices and production quotas fixed by the OPEC, of which Kuwait is a member. OPEC’s quotas, however, are difficult to enforce, and Kuwait and other countries have been accused of violating them. In 2005, oil production was 2.418 million bbl/day (2005 est).
Kuwait's chief oil companies are: