Government-controlled companies dominate the ranks of the world's largest energy producers. In fact, based on revenues for 2017, the top three biggest energy-producing companies are state-owned enterprises controlled by national governments.

Many of the biggest state-owned oil companies operate in the Middle East, a region long synonymous with state control of energy resources. Other state-owned oil giants are in Russia and China, as well as Latin America and Africa.

Saudi Aramco

The Saudi Arabian Oil Company, also known as Saudi Aramco, is the world's largest oil company, generating $455.5 billion in revenue last year. In 2017, it produced 10.2 million barrels of oil per day. Saudi Aramco is controlled by Saudi Arabia's Ministry of Petroleum and Mineral Resources and the Supreme Council for Petroleum and Minerals.

Rosneft

Rosneft is Russia's biggest integrated oil and gas company, generating $91.7 billion in revenue during 2017. As of Sept. 2018, it was producing 11.35 million barrels of oil per day. The majority of its oil production takes place in Russia, but the company also has ongoing exploration and production activities in the United States, Canada, Vietnam, Norway and Brazil, among other countries. Prior to its initial public offering (IPO) in 2006, all of Rosneft's shares were owned by the Russian government through its holding company JSC Rosneftegaz, and as of 2018, the government maintains control of 50% of the company's stock.

National Iranian Oil Company

The National Iranian Oil Company is responsible for all upstream operations in the oil and natural gas sectors and all downstream activities in the oil sector in Iran. The company is wholly owned by the state and operates under the direction of Iran's Supreme Leadership Council. It has the capacity to produce 4 million barrels of oil per day. It's seen depressed production caused primarily by international economic sanctions related to Iran's nuclear weapons program.

China National Petroleum Corporation

China National Petroleum Corporation (CNPC) is a state-owned oil and gas company with operations around the world. The company was producing 1.9 million barrels of oil per day as of July 2018, generating $428.6 million in revenue last year. Much of CNPC's oil operations are organized under its subsidiary, PetroChina.

Kuwait Petroleum Corporation

The state-owned Kuwait Petroleum Corporation (KPC) is responsible for carrying out Kuwait's oil policy as set by the country's Ministry of Petroleum and Supreme Petroleum Council. KPC and its network of subsidiary companies control all upstream and downstream oil operations in the country. The company generated $252 billion in revenue for 2017. Its production stands at around 3.15 million barrels of oil per day as of Jan. 2018.

Petroleos de Venezuela

Petróleos de Venezuela S.A. (PDVSA) has dominated oil and gas production in Venezuela since the industry was nationalized in 1976. It controls some of the world's largest proven reserves of oil. In 2016, the company was producing about 2.5 million barrels per day. More than a dozen international oil and gas companies maintain exploration and production operations in Venezuela under investment agreements with PDVSA.

Nigerian National Petroleum Corporation

The Nigerian National Petroleum Corporation (NNPC) is the biggest oil operator in Africa, reporting production of about 2.0 million barrels per day in 2017. The state-owned company and its subsidiaries regulate the Nigerian oil and natural gas industries and oversee upstream and downstream operational development. International oil companies work with NNPC under joint venture agreements and production-sharing contracts.