Rolling cone bit with gage and off-gage cutter elements positioned to separate sidewall and bottom hole cutting duty

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;
• wherein the gage diameter of the bit is greater than 7 inches and less than or equal to 10 inches and D is within the range of 0.020-0.150 inch.

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;
• wherein the gage diameter of the bit is greater than 10 inches and less than or equal to 15 inches and D is within the range of 0.025-0.200 inches.

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;
• wherein the gage diameter of the bit is greater than 15 inches and D is within the range of 0.030-0.250 inch.

A drill bit having a bit axis for drilling through formation material and forming a borehole of a predetermined gage having a borehole wall and a hole bottom and a borehole corner, the bit comprising:

• a bit body;
• at least one rolling cone cutter mounted on said bit body and rotatable about a cone axis of rotation, said cutter comprising:
• a first frustoconical surface proximal to said borehole sidewall as said cutter rotates about said cone axis;
• a second surface joining said first surface in a circumferential shoulder, said second surface proximal to the hole bottom as said cutter rotates about said cone axis;
• a plurality of gage inserts secured to said cone cutter adjacent to said shoulder in a circumferential gage row, said plurality of gage inserts having a generally cylindrical base portion of a first diameter and a cutting portion attached to said base portion and extending to full gage;
• a plurality of off-gage cutter elements secured to said cone cutter on said second surface in a circumferential first inner row of cutter elements and having cutting surfaces that are off-gage by distance D;
• and
• wherein the ratio of distance D to said first diameter is less than 0.3.

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, said heel surface and said conical surface converging to form a circumferential shoulder therebetween;
• a plurality of gage inserts positioned on said cone cutter adjacent to said shoulder in a circumferential gage row, said plurality of gage inserts having generally cylindrical base portions of a first diameter and cutting portions 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 on said conical surface 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 the cutting profiles of said plurality of gage inserts and said plurality of off-gage cutter elements overlap by a predetermined distance of overlap when viewed in rotated profile;
• and
• wherein the ratio of said predetermined distance of overlap to said first diameter is greater than 0.4.

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 three rolling cone cutters rotatably mounted on said bit body, each of said cone cutters comprising:
• a generally conical surface and an adjacent heel surface that converge to form a circumferential shoulder therebetween;
• a plurality of gage cutter elements positioned adjacent to said shoulder in a circumferential gage row, said plurality of gage cutter elements having cutting surfaces that extend to full gage;
• a plurality of off-gage cutter elements positioned on said conical surface 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 are off-gage by a predetermined 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.

An earth-boring b it 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 first plurality of cutter elements positioned on said heel surface in a first circumferential row and having cutting surfaces that cut to full gage diameter along a first cutting path having a most radially distant point P1 as measured from said bit axis;
• a second plurality of cutter elements positioned on said cone cutter in a second circumferential row, said second plurality of cutter elements having cutting surfaces that are off-gage a first predetermined distance and that cut along a second cutting path having a most radially distant point P2 as measured from said bit axis;
• a third plurality of cutter elements positioned on said cone cutter in a third circumferential row that is spaced apart from said second row, said third plurality of cutter elements having cutting surfaces that cut along a third cutting path having a most radially distance point P3 as measured from said bit axis, the radial distance from said bit axis to P2 exceeding the radial distance from said bit axis to P3 by a second predetermined distance;
• wherein said first and second predetermined distances are selected such that said second plurality of cutter elements and said third plurality of cutter elements cooperatively cut the corner of the borehole and such that said second plurality of cutter elements primarily cut the borehole sidewall and said third plurality of cutter elements primarily cut the borehole bottom.