oil

South African-based Sasol (South African Coal, Oil and Gas Corporation) is an integrated energy and chemicals company in the business of mining, oil, gas, and chemical production. It uses a proprietary process to convert coal and gas into liquid fuels and chemicals.

Premier Oil is a relatively small company devoted entirely to the "upstream" sector of the industry, the exploitation of oil and gas, as opposed to the "downstream'" refining and retail sector. Premier Oil has license interests in eight countries: Albania, Denmark, Germany, Indonesia, Myanmar, Netherlands, Pakistan and the UK.

Valero Energy Corporation is a Fortune 500 company based in San Antonio, Texas, with 21,836 employees and annual revenue of more than US$90 billion. The company owns and operates 17 refineries throughout the United States, Canada and the Caribbean with a combined throughput capacity of approximately 3.3 million barrels per day, making it the largest refiner in North America.

Marathon, founded as the Ohio Oil Company, has gone through several incarnations over the decades. For a while it was taken over by the Standard Oil Trust, later it was acquired by U.S. Steel, and still later its refining and marketing operations were for a time part of a joint venture with Ashland Oil. Today Marathon is independent and is among the mid-sized oil majors based in the United States. The company has faced controversy in connection with the air pollution caused by its U.S.

Occidental Petroleum Corporation's principal activity is sell crude oil and natural gas. The company's operations are carried out through many subsidiaries and affiliates. Two major subsidiaries are Occidental Chemical Corporation and Occidental Oil and Gas Corporation. The company also owns 76% of OxyVinyls, the primary maker of PVC in North America.

ExxonMobil (NYSE: XOM) is the largest publicly traded integrated petroleum and natural gas company in the world, and the world's largest company measured by revenues ($404.5 billion in 2007) and market capitalization ($517.92 billion on July 20, 2007).

With operations in more than 100 countries, Royal Dutch Shell is one of the handful of massive companies that dominate the global petroleum industry. In 2008 it was the largest corporation on earth, based on its nearly half a trillion dollars in revenue. Formerly an unusual Dutch-British hybrid with two boards of directors, the company was reorganized in the wake of a scandal involving inflated reporting of its oil reserves.

Since its privatization in the 1990s, Spain’s Repsol YPF has become one of the world’s largest integrated oil companies. While retaining its dominant position in its home country, Repsol made a major push into South America, becoming the largest foreign energy player on that continent. The YPF part of its name reflects a major acquisition in Argentina.

Noble Energy is an independent oil and gas exploration and production company with operations in the western United States, the Gulf of Mexico, the Middle East, the North Sea and West Africa. Some of its most significant (and most controversial) activity is off the coast of Equatorial Guinea, whose dictator Teodoro Obiang has been accused of using little of the revenue from foreign energy companies to help his own people.