Enbridge, operator of the world’s largest crude oil pipeline system, focuses on carrying petroleum from Western Canada—including the notorious tar sand fields of Alberta—to refineries in Ontario and the U.S. Midwest. It and its affiliates have other pipelines in several parts of Canada and United States and operate Canada’s largest natural gas distribution company. In July 2010 the company’s U.S. subsidiary Enbridge Energy Partners L.P.
Lukoil is Russia's largest oil company and its largest producer of oil. In 2006, it produced 95.2 million metric tons of oil. Its international upstream subsidiary is called LUKOIL Overseas Holding. Headquartered in Moscow, LUKOIL is the second largest public company (next to ExxonMobil) in terms of proven oil and gas reserves (ca. 20 bn boe by SPE standards; some 1.3% of global oil reserves).
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.
OAO Rosneft Oil Company is an integrated petroleum company owned by the Russian Government. Rosneft is headquartered in Moscow’s Balchug district near the Kremlin, across the Moskva river. Rosneft became Russia's leading extraction and refinement company after purchasing assets of former oil giant Yukos at state-run auctions that took place following the 2003 arrest and subsequent imprisonment of former owner, Russian oligarch Mikhail Khodorkovsky, on fraud and tax evasion charges.