| 摘要 |
A drill collar string is provided for use in the drilling of a well. The string comprises a plurality of drill collars having straight tubular sections vertically spaced apart along the length of the string. Each of the sections are weight relieved along one side thereof to produce an eccentric weighting of the sections such that they act to maintain the drill collar string so that it has little, if any, rubbing contact with the sides of the borehole. Such a drill collar string is also provided with a lowermost drill collar which is likewise eccentrically weighted so that the overall combination can increase drilling rates over those afforded by standard slick drill collars and winged stabilizers.
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