Importance

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Abstract

The flow of drilling fluid across the face of a rotating bit can be improved by disposition of jet nozzles in the middle of pads defined on the rotating bit rather than in or directly communicating with water courses in the bit. Drilling fluid is therefore ejected by the nozzle and flows in a plurality of directions across the face of the pad with a maximal velocity. Drilling fluid arriving in the proximity of the nozzle and provided from other sources in the bit is thus entrained within the drilling fluid which is ejected from the nozzle. This serves then to suction drilling fluid from these other sources. In particular, in a rotating bit having a pilot bit and main reamer bit, drilling fluid supplied to the pilot bit is directed toward a pilot bit junk slot in the immediate proximity of a nozzle disposed in the middle of a reamer lobe. Drilling fluid flowing down the pilot bit junk slot is entrained within drilling fluid ejected by the reamer nozzle. The combined fluid flows spread across the face of the reamer toward the main bit junk slots and gage broaches. Therefore, fluid is suctioned or drawn from and across the pilot bit by the reamer nozzles.

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First Claim