Importance

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Abstract

A rotary drill bit for drilling a well bore comprising a bit body adapted to be detachably secured to a drill string and receive drilling fluid under pressure therefrom and having a plurality of depending legs and a nozzle system for exit of drilling fluid from the bit body. The drill bit further comprises a plurality of roller cutters, each cutter having a generally conical roller cutter body rotatably mounted on one of the legs and a plurality of cutting elements on the cutter body. The nozzle system directs a plurality of streams of drilling fluid from the bit body, each stream being so directed as to flow generally toward the cutter body of a roller cutter, with the stream impinging at least one cutting element on the roller cutter body, and thereafter impinging the well bore bottom at least in part at a generally pie shaped portion of the bottom which is within the vertical projection of the roller cutter on the well bore bottom and forward, with respect to the direction of rotation of the drill bit, of the points of engagement of the cutting elements of this latter roller cutter with the well bore bottom for improved cleaning action.

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First Claim