Patent ID: 6510909
Filing Date: 2003-01-28
Classification: E21B

Abstract:
An earth-boring bit having a predetermined gage diameter for drilling a borehole, the bit comprising:a bit body having a bit axis; at least one rolling cone cutter rotatably mounted on said bit body and having a generally conical surface and an adjacent heel surface; a plurality of gage cutter elements positioned on said cone cutter in a circumferential gage row, said plurality of gage cutter elements having cutting surfaces that cut along a first cutting path having a most radially distant point P1 as measured from said bit axis; a plurality of off-gage cutter elements positioned on said cone cutter in a circumferential first inner row that is spaced apart from said gage row, said plurality of off-gage cutter elements having cutting surfaces that cut along a second cutting path having a most radially distance point P2 as measured from said bit axis, the radial distance from said bit axis to P1 exceeding the radial distance from said bit axis to P2 by a distance D that is selected such that said plurality of gage cutter elements and said plurality of off-gage cutter elements cooperatively cut the corner of the borehole and such that said plurality of gage cutter elements primarily cut the borehole sidewall and said plurality of off-gage cutter elements primarily cut the borehole bottom when the bit is new; wherein the gage diameter of the bit is less than or equal to seven inches and D is within the range of 0.015-0.100 inch.