Patent ID: 6834733
Filing Date: 2004-12-28
Classification: E21B

Abstract:
A drag-type drill bit for bore hole drilling in earth formations, comprising:a bit body having a threaded pin on one end for coupling to a drill string; a substantially dome-shaped cutter head formed integral with the bit body opposite from the threaded pin; a plurality of circumferentially spaced first blades formed integral with and extending from the cutter head, the first blades extending from substantially the center of and around the cutter head to the gage area; a plurality of second blades being positioned alternatively between the first blades, the second blades extending from respective positions offset from the center of the cutter head and extending toward the gauge area; a plurality of generally cylindrical cutting elements embedded in each of the first blades; a plurality of nozzles positioned around the cutter head to direct drilling fluid passing through the bit body against the wave-shaped blades to the annulus surrounding the bit body in the bore hole; and wherein the first blades comprise a variable pitch bi-directional pattern having a succession of concave and convex segments.