Importance

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Abstract

A fixed cutter, or rotary drag, bit for drilling subterranean formations, exhibiting an enhanced resistance to bit balling and an improved rate of penetration. The bit includes an auger-like blade configuration, wherein positively raked, relatively tall blades lean rotationally forward to provide increased clearance and volume between the bit face and the formation to facilitate removal of cuttings coming off the tops of the cutters from the bit face. The blades are each substantially contiguous with an elongated, helical gage pad raked rotationally forwardly in the manner of the blades, the longitudinal lengths of the gage pads and the radially outer edges of the blades in combination with their slope providing a stabilizing structure which substantially completely circumferentially encompasses the bit body. The slope or pitch of the helix angle of the blade edges and gage pads may be varied as desired to optimize hydraulic efficiency, cutter requirements of directional drilling, and stability needs. The bit also includes nozzles positioned on the bit face and aimed toward the face of a blade following each respective nozzle to improve cleaning of the blades and to improve the hydraulic energy and fluid velocities along the gage. The bit also preferably includes aggressively raked superabrasive cutters having a ground relief on the substrate supporting the diamond table rotationally behind the table to minimize contact of the substrate material with the formation.

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First Claim