Exxon Mobil, the largest U.S. oil company, said it added 3.5 billion barrels of oil equivalent to its 2010 reserve total, bringing the company's reserves of oil and natural gas to 24.8 billion barrels. The addition of 3.5 billion barrels is twice what the company produced last year and represents the highest total since the 1999 merger with Mobil.
The 2010 number includes expansions of existing fields as well as acquisitions of other petroleum-rich fields around the world including Russia, Canada, the United States, Nigeria, Norway and Abu Dhabi, according to the Associated Press. Most of the reserves added by Exxon Mobil (XOM) were natural gas.
Of the reserves added in 2010, 2.8 billion barrels were gained through the company's purchase of XTO Energy. Exxon and other oil majors have struggled to gain access to new oil reserves around the world as state-run companies have been reluctant to part ways with their oil assets.
Separately, ConocoPhillips (COP) the third-largest U.S. oil company, said added net proved reserves of 920 million barrels of oil equivalent last year, a total that equals 138% of the company's production for the year.