Patent ID: 6062325
Filing Date: 2000-05-16
Classification: E21B

Abstract:
A rotary drill bit for use in drilling holes in subsurface formations, comprising a bit body having a leading face and a gauge region, a plurality of blades formed on the leading face of the bit and extending outwardly away from the axis of the bit so as to define between the blades a plurality of fluid channels leading towards the gauge region, a plurality of cutting elements mounted along each blade, and a plurality of nozzles in the bit body for supplying drilling fluid to the leading face of the bit for cleaning and cooling the cutting elements, at least some of said blades each having a leading edge at least a portion of which is which is convexly curved in the normal direction of rotation of the bit during drilling, and others of said blades each having a leading edge at least a portion of which is concavely curved in the normal direction of rotation of the bit during drilling.