The impact of the metal bearing seal on rolling cutter bit performance at high rotary speeds has been dramatic. In the high-cost drilling environment of the North Sea, the metal sealed bit has proven its ability to extend rolling cutter bearing life at high rotary speed and thereby provide significant reductions in drilling costs. Thisimprovement is encouraging more widespread use of these bits with downhole motors and steerable systems.An analysis of recent run data from the Norwegian sector of the North Sea shows metal sealed rolling cutter bits can be used for a much greater number of bit revolutions than their elastomer seal counterparts and, consequently, footage per bit has more than doubled without sacrificing rate of penetration. Cost savings of up to $100,000 per well have been documented. This paper describes the design of the metal sealed bit and its performance in the Ekofisk and Eldfisk fields.

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