Claims
- 1. A two stage bit enabling enhanced penetration rates comprising:a body defining a proximal end adapted for connection to a drilling string and a distal end, where said distal end defines a pilot and an intermediate reamer section; where said pilot includes a first cutter face defining a given diameter D; where said reamer section includes a second cutter face defining a given diameter R where R>D; where the first cutter face includes upsets where each upset defines an upper and a lower portion where said upper portion is provided with a series of cutting elements and said lower portion is provided with a surface adapted to extend to gauge into substantially non-cutting contact with the formation; where the second cutter face includes upsets which extend substantially to gauge and which extend over 180° of the rotational circumference of said reamer where said upsets define an upper and a lower portion where said upper portion is provided with a series of cutting elements; and where the upsets formed on the pilot section are misaligned relative to the upsets formed on the reamer section.
- 2. The two stage bit of claim 1 where said lower portion includes a gauge pad which extends to gauge.
- 3. The two stage bit of claim 1 where said cutting elements are formed of polycrystalline diamond.
- 4. An anti-whirl two stage bit comprising:a body defining a proximal end adapted to be connected to a drilling string and a distal end, where said distal end defines a pilot and a reamer section; where said pilot includes a cutting face having a first diameter where said cutting face is comprised of two or more cutting blades defining proximal and distal surfaces; where said reamer includes a cutting face having a second diameter where said cutting face is comprised of two or more cutting blades defining proximal and distal surfaces where said blades extend over at least 180° of the rotational circumference of the reamer and extend substantially to gauge; where the first diameter is less than said second diameter; where cutting elements are disposed on the distal surfaces of said cutting blades and where said proximal surfaces are adapted to slidably engage the formation during rotation of the bit; and where the cutting blades on the pilot are misaligned relative to the cutting blades on the reamer.
- 5. The bit of claim 4 where the proximal surfaces extend to gauge.
- 6. The bit of claim 5 where the proximal surfaces define at least one gauge pad.
- 7. A two stage bit comprising:a body defining an upper end adapted for connection to a drilling string and a lower end where said lower end defines a first and a second stage; said first stage comprised of two or more cutting blades adapted to accommodate a series of cutting elements, said first section further defining a maximum diameter P; said second stage defining a second cutting face comprised of a series of cutting blades about at least 180° of the rotational circumference of said face, where at least a portion of said blades extend substantially to gauge in to substantially non-cutting contact with the formation, where said second section further defines a maximum diameter R; said first and second stages being vertically segregated by a zone having no cutting blades and which defines a smaller diameter than either said first or second stage.
- 8. The two stage bit of claim 7 further including gauge pads disposed about the first and second stages.
- 9. The two stage bit of claim 7 where the rotational circumference of the cutting blades on both the first and second stages is at least 240°.
- 10. The two stage bit of claim 7 where the upsets of one or both of the first and second stages is angled with resect to the direction of rotation.
- 11. The two stage bit of claim 7 where R>P.
- 12. The two stage bit of claim 11 where the diameter of the first stage is at least 50% of the diameter of the second stage.
REFERENCE TO PROVISIONAL APPLICATION
Pursuant to 35 U.S.C. § 119(e), this application derives from a provisional application for the same invention filed on May 28, 1998, Provisional Ser. No. 60/088,010.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
5992547 |
Caraway et al. |
Nov 1999 |
A |
5992548 |
Silva et al. |
Nov 1999 |
A |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/088010 |
May 1998 |
US |