Claims
- 1. A method to fabricate a bi-center bit adapted to rotate about one of two axis where the bi-center bit comprises a bit body having a proximal and a distal end where the distal end defines a pilot bit and an intermediate reamer section, where each the pilot and reamer sections define a bit face including primary and secondary cutting blades and cutting elements disposed on said blades where each cutting element defines a cutting face, the method comprising the steps of:
fabricating a cutter profile for the bit about the rotational axis “A”; identifying the pass-through axis “B” of the bit; fabricating a cutter profile for the bit about the pass-through axis “B”; and situating cutting elements on the bit face of the pilot and reamer sections such that at least a portion of a cutting element is disposed about substantially all portions of said profiles when the bit is rotated about the rotational and pass-through axes.
- 2. The method of claim 1 further including the step of positioning the cutting blades so that the rotational and pass-through axes fall along a primary cutting blade.
- 3. The method of claim 1 further including the step of positioning cutting elements on the primary cutting blade between the rotational axis “A” and pass-through axis “B” such that substantially all of the cutting faces of said elements are brought into at least partial contact with the material to be drilled when the bit is rotated about said axis “B.”
- 4. The method of claim 1 further including the step of positioning cutting elements on the primary cutting blade opposite said rotational axis “A” and between said pass-through axis “B” and gauge such that the cutting faces of substantially all such elements are brought into at least partial contact with the material to be drilled when said bit is rotated about axis “A.”
- 5. The method of claim 1 where the skew angle of cutting elements of the secondary cutting blades is between 0-80°.
- 6. The method of claim 1 where the reamer section defines at least one cutting blade which extends to the pass-through gauge and including the additional step of positioning cutting elements along said cutting blade such that cutting elements proximate to the pass-through gauge at their line of contact with the material to be drilled define an angle of attack of between 5-45°.
- 7. A method to fabricate a bit which defines at least two axes of rotation, where the bit includes a bit body defining a proximal end adapted to be coupled to the drill string, a distal end, a pilot section and a reamer section, where both said pilot and reamer sections include one or more cutting blades, the method comprising:
defining a rotational axis and a pass-through axis of the bit; and positioning cutting elements on the cutting blades of the pilot and reamer sections such as to create substantially complete cutter overlap when the bit is rotated about either the rotational and pass-through axis.
- 8. The method of claim 7 further including the step of positioning one or more stabilizing elements opposite said reamer section such that the proximal most portion of said stabilizing elements do not extend beyond the most proximal cutting elements disposed on said reamer section.
- 9. The method of claim 7 where said stabilizing element includes a gauge pad.
- 10. The method of claim 7 further including the step of orienting the cutting elements which each define a cutting face such that the cutting face of most of said elements on cutting blades situated between the rotational and pass-through axes are oriented such that they are brought into contact with the material to be drilled when the bit is rotated about the pass-through axis.
- 11. The method of claim 7 further including the step of orienting the cutting elements which each define a cutting face such that the cutting face of most of said elements on cutting blades situated between the rotational and pass-through axes are oriented such that they are brought into contact with the material to be drilled when the bit is rotated about the rotational axis.
- 12. The method of claim 7 further including the step of orienting the cutting elements which each define a cutting face such that the cutting face of most of said elements on cutting blades situated between the rotational and pass-through axes are oriented such that they are brought into contact with the material to be drilled when the bit is rotated about the rotational axis or the pass-through axis.
- 13. The method of claim 7 further including the step of orienting the cutting elements which each define a cutting face and where the cutting blades include primary and secondary blades, where the rotational and pass-through axes lie substantially along the primary blade such that the cutting faces of substantially all elements disposed along the primary cutting blade not between the rotational axis and pass-through axis but between the pass-through axis and gauge are brought into at least partial contact with the formation to be drilled when said bit is rotated about the rotational axis.
- 14. The method of claim 7 where the reamer section defines one or more blades which extend to pass-through gauge further including the step of positioning cutting elements on said blades at or near the pass-through gauge so as to from an angle between the material to be drilled and the line of contact on the cutting element where said angle is between 5-45°.
- 15. The method of claim 7 further including the step of positioning the cutting elements on the secondary blades such that they define a skew angle of between 0-80°.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending application Ser. No. 09/392,043 as filed on Sep. 8, 1999 which in turn depends from and incorporates the subject matter of provisional application Serial No. 06/118,518 as filed on Feb. 3, 1999.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60118518 |
Feb 1999 |
US |
Divisions (1)
|
Number |
Date |
Country |
Parent |
09392043 |
Sep 1999 |
US |
Child |
09969444 |
Oct 2001 |
US |