Rotary drill bit with a reduced tendency for bit whirl

• Main Authors: ANDREW MURDOCK, DANIEL J SARIK, ALEX NEWTON, JOHN FULLER
• Format: Patent
• Language: English
• Published: 17.04.1996
• Edition: 6
• Subjects: EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS

A rotary drill bit, eg drag or roller cone bit, comprises a bit body 10, a shank 11 for connection to a drill string, cutters 14 and a gauge structure 20 around the bit body which engages the sides 19 of the borehole being drilled; at least a section of the gauge structure 20 is rotatably mounted on bearings 23 on the bit body so that the gauge section may remain substantially non-rotating in engagement with the formation while the bit body rotates relative to it. The gauge section may be provided with means to restrain it against rotation in the form of projections (26 fig 2). The external surface of the gauge section 20 may be formed with longitudinal grooves (25 fig 2) to permit drilling fluid past the gauge section to the annulus between the drill string and the borehole. Alternatively the outer surface of the gauge section may be generally cylindrical, in which case internal passages 9 are provided through the gauge section and/or the bit body for the flow of the drilling fluid.