REVERSE CIRCULATION BIT ASSEMBLY

• US 20130133956A1
• Filed: 10/17/2012
• Published: 05/30/2013
• Est. Priority Date: 10/17/2011
• Status: Active Grant

• Current Assignee: Epiroc Drilling Tools LLC (Atlas Copco AB)
• Original Assignee: Newtech Drilling Products LLC (Atlas Copco AB)
• Inventors: Jones, Mark L., Curry, Kenneth M., Ross, Jeffery T., Johnson, Kyle E.
• Granted Patent: US 9,422,771 B2
• Time in Patent Office: Days
• US Class Current: 175/393
• CPC Class Codes: E21B 10/18 characterised by conduits or nozzles for drilling fluids
• CPC Class Codes: E21B 10/60 characterised by conduits or nozzles for drilling fluids for roller bits E21B10/18; for percussion drill bits E21B10/38
• CPC Class Codes: E21B 21/10 Valve arrangements in drilling-fluid circulation systems
• CPC Class Codes: Y10T 29/49716 Converting
• CPC Class Codes: Y10T 29/49826 Assembling or joining
• CPC Class Codes: Y10T 29/49881 of separate helix [e.g., screw thread]

Abstract

A drill bit assembly for boring including a drill bit and a bit sub. A front bit end has a plurality cutting elements at a forward face of the front bit end and a first fluid return passage extending through the drill bit to a rear bit end. The bit sub couples to the rear bit end. The bit sub includes a bore disposed at a front sub end sized and shaped to receive the rear bit end of the drill bit. A plurality of legs extends from a mid-sub region toward the front sub end between pairs of cutting elements. The plurality of legs has a fluid delivery passage disposed therein with the fluid delivery passage extending from the plurality of legs to a rear sub bit end. The bit sub has a second fluid return passage connecting the first fluid return passage to the rear sub bit end.

Claims

1. A drill bit assembly for earth boring, the drill bit assembly comprising:

a drill bit having a front bit end and a rear bit end, the front bit end having a plurality of cutting elements at a forward face of the drill bit, and a first fluid return passage extending through the drill bit from the front bit end to the rear bit end;

a bit sub disposed about rear bit end and coupled to the rear bit end, the bit sub comprising;

a body with a front sub end, a rear sub end, and a bore disposed at the front sub end sized and shaped to receive the rear bit end of the drill bit, the rear sub end adapted to connect to an adjacent downhole component;

a plurality of legs extending from a mid sub region toward the front sub end between pairs of cutting elements; and

a second fluid return passage connecting the first fluid return passage to the rear sub bit end.

2. The drill bit assembly of claim 1 wherein the plurality of legs have a fluid delivery passage disposed therein, the fluid delivery passage extending from the plurality of legs to the rear sub bit end, wherein the fluid delivery passage is separated from the second fluid return passage.

3. The drill bit assembly of claim 1, wherein the bit sub body is formed of a plurality of sub components.

4. The drill bit assembly of claim 2, wherein the bit sub body is comprised of a skirt component coupled to the plurality of legs, a nut component adapted to couple to the rear end of the drill bit, and a check valve component adapted to couple to the nut component.

5. The drill bit assembly of claim 1 wherein the bit sub body has a wall and an inner surface, the inner surface defining the second fluid return passage, and the fluid delivery passage is disposed in the wall.

6. The drill bit assembly of claim 4 wherein the check valve component has an first inner surface, the drill bit assembly further comprising an inner tube component disposed in the check valve section, the inner tube component having a wall, a second inner surface, and an outer surface, wherein the second inner surface forms a portion of the second fluid return passage, and the first inner surface and the outer surface form a portion of the fluid delivery passage.

7. The drill bit assembly of claim 3 wherein the rear bit end has an external thread, the nut component has an internal thread complementary to the external thread.

8. The drill bit assembly of claim 1 wherein each of the cutting elements are disposed on a bit leg having a bit leg profile and the plurality of legs extending from the mid sub region toward the front sub end between pairs of cutting elements have a skirt profile complementary to the bit leg profile.

9. The drill bit assembly of claim 8 wherein the bit leg profile has been modified from that of a standard drill bit to complement the skirt profile.

10. The drill bit assembly of claim 8 wherein the skirt profile complements a standard drill bit leg profile.

11. The drill bit assembly of claim 8 wherein the skirt profile compliments a leg profile of a standard dill bit leg that has been modified.

12. The drill bit assembly of claim 8 wherein the plurality of legs extend beyond the bit legs.

13. The drill bit assembly of claim 1 wherein the fluid delivery passage has a check valve disposed therein, the check valve being configured to restrict flow of fluid towards the rear end of the bit sub.

14. The drill bit assembly of claim 1 wherein the cutting elements are roller cones.

15. A bit sub component comprising:

a body with a front end, a rear end, and a bore disposed at the front end sized and shaped to receive a drill bit, the rear end adapted to connect to an adjacent downhole component;

a plurality of legs extending from the front end, having a forward end, adapted to complement an outer surface of the drill bit, and having a fluid delivery passage disposed therein, the fluid delivery passage extending from the forward end to the rear sub bit end; and

a fluid return passage connecting the bore sized and shaped to receive a drill bit, the fluid return passage being isolated from the fluid delivery passage within the body.

16. The bit sub component of claim 15, wherein the bit sub is formed from a plurality of components comprising:

a skirt component including the legs, the skirt component having a bore there through;

a nut component adjacent the skirt component, the nut component having an internal thread adapted to receive a drill bit;

a check valve component coupled to the nut component, the check valve component adapted to couple to an adjacent downhole component.

17. A method of fabricating a reverse circulation drill bit assembly from a standard drill bit, the method comprising:

providing a standard drill bit having a shank;

providing a bit sub component having a plurality of legs extending from a front end of the bit sub component;

inserting the shank into the bit sub component such that the plurality of legs extends past the shank to a working surface of the drill bit; and

securing the bit sub component to the standard drill bit.

18. The method of claim 17 further comprising modifying a profile of the standard drill bit to complement a profile of the plurality of legs.

19. The method of claim 17 further comprising modifying a profile of the plurality of legs to complement a profile of the standard drill bit.

20. The method of claim 17 wherein the bit sub component is comprised of a skirt having the plurality of legs and a body section, wherein the method further comprises placing the skirt over the shank such that the shank extends through the skirt and the shank is coupled to the body section through a threaded connection.

21. The method of claim 20 wherein the body section is comprised of a nut section and a check valve section, the method further comprising coupling the nut section to the check valve section.

22. The method of claim 20 wherein the body section has an inner flange sized and shaped to complement a dual wall drill string.