Even if you include the costly effects of Hugo Chavez's shenanigans, ExxonMobil (NYSE: XOM) had a very good 2007. Not only did the company weigh in for the December period with the largest pot of quarterly earnings ever presented by any company, but it also replaced more reserves than it produced in 2007, which is a key measure of the success for any exploration and production operation.

For the year, the company managed to replace its reserves by 132%, excluding Hugo's having helped himself to its hard-earned treasures in his country. If you take account of that country's expropriation of about half a billion oil-equivalent barrels of the company's reserves last spring, Exxon replaced 101% of its production from new developments and reassessments of previous plays. During the past decade, the company has averaged a 112% reserve replacement ratio.

It also turns out that ConocoPhillips (NYSE: COP) was far harder hit than Exxon by events in Venezuela. Excluding the effects of the expropriation, its reserve replacement ratio was a heady 159%. Factor in the nearly 1.1 billion barrels of oil equivalent (BOE) skimmed from the company by Chavez and his henchmen, though, and the company's replacement plummets to 29%.

At another extreme, Hess (NYSE: HES) replaced about 167% of its production during the year. Meanwhile, investors are still awaiting the release of reserve replacement figures from Royal Dutch Shell (NYSE: RDS-A) (NYSE: RDS-B), which in 2004 was forced to restate its reserves amid an accounting scandal. Last year, the company agreed to pay out $352.6 million plus costs to a group of investors affected by the restatement.

With oil and gas being found in progressively more remote locations and with discoveries calling into play steadily more technological sophistication, reserve replacement metrics are hardly insignificant for producers. For my money, Exxon's replacement results could have been higher, but generally they enhance my belief that the company represents an appropriate way to approach the increasingly important energy sector.

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