Claims
- 1. A rotary drag bit for drilling a subterranean formation, comprising:
a bit body having a longitudinal axis and extending radially outward therefrom toward a gage, the bit body including a face to be oriented toward the subterranean formation during drilling and carrying cutting structure for cutting the subterranean formation; a plurality of circumferentially-spaced gage pads disposed about a periphery of the bit body and extending radially therefrom and longitudinally away from the bit face, at least some of the gage pads having a longitudinally leading surface comprising a generally radially outward facing portion inclined with respect to the longitudinal axis and carrying at least one chisel-shaped cutter thereon, the at least one chisel-shaped cutter including a portion exposed above the generally radially outward facing portion of the longitudinally leading surface; and at least one of the chisel-shaped cutters comprising at least one cutting surface oriented at a preselected angle with respect to a line perpendicular to the formation, taken in the direction of intended bit rotation.
- 2. The rotary drag bit of claim 1, wherein gage pads of the plurality include at least one rotationally leading surface and further include at least one radially outer bearing surface defining a radially outer extent of each of the pads, the cutters carried by the longitudinally leading surfaces of the at least some of the pads do not protrude radially substantially beyond the radially outer bearing surfaces of the pads, and the cutters do not protrude tangentially substantially beyond the at least one rotationally leading surface of the pads.
- 3. The rotary drag bit of claim 1, wherein the at least one chisel-shaped cutter comprises at least one of the group consisting of a superabrasive material disposed upon a pre-shaped substrate, a polycrystalline diamond compact mass disposed upon a pre-shaped substrate, a polycrystalline diamond compact mass disposed upon a generally cylindrically-shaped stud, a polycrystalline diamond compact mass disposed upon a chisel-shaped stud, a polycrystalline diamond compact mass disposed upon a stud comprising tungsten carbide, a polycrystalline diamond compact mass disposed upon a generally cylindrically-shaped stud comprising tungsten carbide, an uncoated chisel-shaped stud, an uncoated chisel-shaped stud comprising tungsten carbide, a diamond coated chisel-shaped stud, and a diamond coated chisel-shaped stud comprising tungsten carbide.
- 4. The rotary drag bit of claim 1, wherein the at least one cutting surface oriented at a preselected angle with respect to a line perpendicular to the formation, taken in the direction of intended bit rotation exhibits at least one of a negative backrake angle, a neutral backrake angle, and a positive backrake angle.
- 5. The rotary drag bit of claim 1, wherein the leading surface of the gage pad on which the at least one chisel-shaped cutter is carried comprises a flat.
- 6. The rotary drag bit of claim 5, wherein the at least one cutting surface is oriented substantially transversely to the flat.
- 7. The rotary drag bit of claim 5, wherein the at least one cutting surface is oriented substantially parallel to the flat.
- 8. The rotary drag bit of claim 1, wherein the at least one chisel-shaped cutter comprises a cutting edge flanked by the at least one cutting surface and oppositely flanked by at least one other cutting surface.
- 9. The rotary drag bit of claim 8, wherein the cutting edge comprises an apex flanked by the at least one cutting surface and the at least one other cutting surface and both cutting surfaces converge toward the apex to generally define a chisel shape.
- 10. The rotary drag bit of claim 9, wherein the cutting edge comprises at least one of a a polycrystalline diamond compact cutting edge, a diamond cutting edge, and a cutting edge devoid of superabrasive material.
- 11. The rotary drag bit of claim 1, wherein at least one of the plurality of gage pads includes a longitudinally trailing surface carrying at least one cutter thereon.
- 12. The rotary drag bit of claim 11, wherein the at least one cutter carried on the longitudinally trailing surface of at least one of the plurality of gage pads is selected the group consisting of a cutter comprising a polycrystalline diamond compact cutter, a tungsten carbide insert, a diamond-coated tungsten carbide insert, a volume of tungsten carbide granules, a volume of macrocrystalline tungsten carbide, a chisel-shaped cutter, and cutter devoid of superabrasive material.
- 13. The rotary drag bit of claim 12, wherein the at least one cutter on the longitudinally trailing surface of the at least one of the plurality of gage pads comprises at least one of a substantially cylindrically-shaped cutter extending generally radially with respect to the longitudinal axis of the bit body and a generally chisel-shaped cutter.
- 14. The rotary drag bit of claim 11, wherein the longitudinally trailing surface comprises a flat.
- 15. The rotary drag bit of claim 14, wherein the at least one cutting surface is oriented substantially transversely to the flat.
- 16. The rotary drag bit of claim 14, wherein the at least one cutting surface is oriented substantially parallel to the flat.
- 17. The rotary drag bit of claim 11, wherein the at least one cutter carried on the longitudinally trailing surface comprises at least one chisel-shaped cutter comprising a cutting edge flanked by the at least one cutting surface and oppositely flanked by at least one other cutting surface.
- 18. The rotary drag bit of claim 17, wherein the cutting edge comprises an apex flanked by the at least one cutting surface and the at least one other cutting surface and both cutting surfaces converging toward the apex to generally define a chisel shape.
- 19. The rotary drag bit of claim 18, wherein the cutting edge presents at least one of a polycrystalline diamond compact cutting edge, a diamond cutting edge, a cutting edge devoid of superabrasive material.
- 20. The rotary drag bit of claim 14, wherein the at least one cutter on the longitudinally trailing surface of the at least one of the plurality of gage pads comprises a substantially cylindrically-shaped body oriented at a preselected angle with respect to the flat.
- 21. The rotary drag bit of claim 14, wherein the at least one cutter on the longitudinally trailing surface of the at least one of the plurality of gage pads comprises a substantially cylindrically-shaped body oriented generally perpendicular to the flat.
- 22. The rotary drag bit of claim 14, wherein the at least one cutter on the longitudinally trailing surface of the at least one of the plurality of gage pads comprises a diamond table mounted to a supporting cylindrical substrate and is at least partially exposed above the longitudinally trailing surface, the diamond table including a chamfer at a periphery thereof defining at least part of a cutting surface having a cutting edge at a periphery thereof.
- 23. The rotary drag bit of claim 22, wherein at least a portion of the chamfer is circumferentially arcuate.
- 24. The rotary drag bit of claim 23, wherein the chamfer is annular.
- 25. The rotary drag bit of claim 24, wherein at least a portion of the chamfer comprises a flat.
- 26. A rotary drag bit for drilling a subterranean formation, comprising:
a bit body having a longitudinal axis and extending radially outward therefrom toward a gage, the bit body including a face to be oriented toward the subterranean formation during drilling and carrying cuffing structure for cutting the subterranean formation; and a plurality of circumferentially-spaced gage pads disposed about a periphery of the bit body and extending radially therefrom and longitudinally away from the bit face, at least some of the gage pads having a longitudinally leading surface carrying a cutter thereon; at least one of the cutters comprising a chisel shape defined by an apex flanked by two side surfaces.
- 27. The rotary drag bit of claim 26, wherein one of the side surfaces is substantially parallel to a longitudinally leading surface of one of the gage pads and another of the side surfaces is substantially parallel to a rotationally leading surface thereof.
- 28. The rotary drag bit of claim 27, wherein the at least one of the cutters is selected from the group consisting of cutters comprising superabrasive material, polycrystalline diamond compact cutters, tungsten carbide inserts, and diamond-coated tungsten carbide inserts.
- 29. The rotary drag bit of claim 26, wherein gage pads of the plurality include at least one rotationally leading surface and further include at least one radially outer bearing surface defining a radially outer extent of each of the pads, and the cutters carried by the longitudinally leading surfaces of the at least some of the pads do not protrude radially substantially beyond the radially outer bearing surfaces of the pads and the cutters do not protrude tangentially substantially beyond the at least one rotationally leading surface of the pads.
- 30. The rotary drag bit of claim 26, wherein the cutters comprise at least one of the group consisting of a superabrasive material disposed upon a pre-shaped substrate, a polycrystalline diamond compact mass disposed upon a pre-shaped substrate, a polycrystalline diamond compact mass disposed upon a generally cylindrically-shaped stud, a polycrystalline diamond compact mass disposed upon a chisel-shaped stud, a polycrystalline diamond compact mass disposed upon a stud comprising tungsten carbide, a polycrystalline diamond compact mass disposed upon a generally cylindrically-shaped stud comprising tungsten carbide, an uncoated chisel-shaped stud, an uncoated chisel-shaped stud comprising tungsten carbide, a diamond coated chisel-shaped stud, and a diamond coated chisel-shaped stud comprising tungsten carbide.
- 31. The rotary drag bit of claim 26, wherein at least one of the two side surfaces is oriented at a preselected angle with respect to a line perpendicular to the formation, taken in the direction of intended bit rotation exhibits at least one of a negative backrake angle, a neutral backrake angle, and a positive backrake angle.
- 32. The rotary drag bit of claim 26, wherein the leading surface of the gage pad on which the at least one chisel-shaped cutter is carried comprises a flat.
- 33. The rotary drag bit of claim 32, wherein at least one of the two side surfaces is oriented substantially transversely to the flat.
- 34. The rotary drag bit of claim 32, wherein the at least one of the two side surfaces is oriented substantially parallel to the flat.
- 35. The rotary drag bit of claim 26, wherein the cutting edge presents at least one of a superabrasive cutting edge, a polycrystalline diamond compact cutting edge, a diamond cutting edge, a cutting edge devoid of superabrasive material.
- 36. The rotary drag bit of claim 26, wherein at least one of the plurality of gage pads includes a longitudinally trailing surface carrying at least one cutter thereon.
- 37. The rotary drag bit of claim 36, wherein the at least one cutter carried on the longitudinally trailing surface of at least one of the plurality of gage pads is selected the group consisting of a cutter comprising, a polycrystalline diamond compact cutter, a tungsten carbide insert, a diamond-coated tungsten carbide insert, a volume of tungsten carbide granules, a volume of macrocrystalline tungsten carbide, a chisel-shaped cutter, and a cutter devoid of superabrasive material.
CROSS REFERENCE TO RELATED APPLICATION
1. This application is a divisional of application Ser. No. 09/129,302, filed Aug. 5, 1998, pending, which is a continuation-in-part of U.S. application Ser. No. 08/925,284, filed Sep. 8, 1997, now U.S. Pat. No. 6,006,845, issued Dec. 28, 1999.
Divisions (1)
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Number |
Date |
Country |
Parent |
09129302 |
Aug 1998 |
US |
Child |
09753096 |
Jan 2001 |
US |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
08925284 |
Sep 1997 |
US |
Child |
09129302 |
Aug 1998 |
US |