There is a nationalized oil company that is working very well, too well. From wiki:
Saudi Arabian Oil Company, is the state-owned national oil company of Saudi Arabia. It is the world's most valuable company, estimated at 781 billion US$ in 2006, while more recent estimates of 2010 put its value in the range 2.2 trillion USD to 7 trillion USD. It is also the oil corporation with the largest proven crude oil reserves and production. Headquartered in Dhahran, Saudi Arabia, Saudi Aramco also operates the world's largest single hydrocarbon network, the Master Gas System. It was known as just Aramco between the years of 1933-1988, an acronym for Arabian American Oil Company.
Its yearly production is 3.4 billion barrels and it managed over 100 oil and gas fields in Saudi Arabia totaling at least 264 billion barrels of oil reserves and 253 trillion scf of gas reserves.
Among those fields fully owned by the company is the Ghawar Field, the world's largest oil field; the Safaniya Field, the world's largest offshore field; and the Shaybah Field, one of the world's largest of its kind.