With the price of oil hovering near $70 a barrel, oil companies cannot pump the stuff fast enough. But in order to keep pumping in the long run, they also need to keep finding it. Unfortunately, most big Western oil firms are getting worse at exploration. Neil McMahon, an analyst at Sanford Bernstein, calculates that such companies had an average reserve-replacement ratio of 129% over the past five years-meaning that they found 29% more oil and gas than they pumped. But last year the ratio fell to 114%.
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