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50. Exxon Mobil
2006 rank: 51
For ExxonMobil, the need to replace exhausted reservoirs of oil and gas with new finds is the mother of invention. The company copes with potentially hostile environments both above and below ground in such places as Angola, Congo, and Kazakhstan. By 2010, Exxon expects about 40% of its production, up from 25% in 2005, to come from “challenging environments” such as deep ocean waters or unconventional sources such as tar-like “heavy oil.”
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