Some American oil companies are ExxonMobil, Chevron Corp., ConocoPhillips and Shell Oil Company. ExxonMobil is the sixth-largest company in the world and was the second-most profitable in 2014. It formed when Exxon and Mobil merged in 1999; both companies began as part of John D. Rockefeller’s Standard Oil Company. ExxonMobil’s holdings include oil and natural gas reserves. The company’s estimated reserves are approximately 25.2 billion barrels of oil equivalent, as of November 2015.
Chevron is another descendant of Standard Oil, and it has oil, natural gas, geothermal energy and hydrocarbon exploration activities, as well as refining, transporting, manufacturing and retail operations. The company merged with Texaco in 2000 and employs over 65,000 people, with annual revenue exceeding $200 billion, as of 2014. Chevron claims to be the world’s largest producer of geothermal energy and is leading the industry’s exploration of renewable sources such as solar and wind.
ConocoPhillips formed out of the merger of Conoco Inc. and Phillips Petroleum Co. in 2002. The company's operations extend to oil, natural gas and petroleum. It had an annual revenue of $65 billion in 2012 and assets in excess of $117 billion.
Shell Oil Company is a U.S. subsidiary of Royal Dutch Shell, with 22,000 employees based in the United States and 82,000 worldwide. Shell maintains an independent chain of approximately 25,000 gas stations, and it had an annual revenue of $2.15 billion in 2014.