Roller Cone Drill Bit With Debris Flow Paths Through Associated Support Arms

Abstract

A roller cone drill bit having a bit body with at least one support arm extending therefrom. Each support arm may have an interior surface and an exterior surface with an associated spindle extending inwardly from the interior surface. A respective cone assembly may be rotatably disposed on each spindle. A gap may be formed between interior portions of each cone assembly and exterior portions of the associated spindle with a fluid seal disposed in the gap to block fluid flow therethrough. Each cone assembly may include a generally circular backface disposed adjacent to the interior surface of the associated support arm. At least one fluid passageway may extend through each support arm to allow communication of fluid from the interior surface to an exterior surface of the support arm. A debris diverter insert having a generally hollow bore may be disposed within each fluid passageway.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

FIG. 1A is a schematic drawing in section and in elevation with portions broken away showing examples of wellbores which may be formed by a roller cone drill bit incorporating teachings of the present disclosure;

FIG. 1B is a schematic drawing in section and in elevation with portions broken away showing the drill string and attached roller cone drill bit of FIG. 1A adjacent to the bottom of a wellbore;

FIG. 2 is a schematic drawing in elevation showing a roller cone drill bit incorporating teachings of the present disclosure;

FIG. 3 is a schematic drawing partially in section and partially in elevation with portions broken away showing a support arm and cone assembly incorporating teachings of the present disclosure;

FIG. 4 is schematic drawing showing an isometric view in section and in elevation with portions broken away of a support arm incorporating teachings of the present disclosure;

FIG. 5A is a schematic drawing showing an isometric view with portions broken away of the support arm of FIG. 4 with a debris relief hole and insert disposed in a first location in accordance with teachings of the present disclosure;

FIG. 5B is a schematic drawing showing an isometric view with portions broken away of the support arm of FIG. 4 with the debris relief hole and debris insert disposed in a second location in accordance with teachings of the present disclosure;

FIG. 5C is a schematic drawing showing an isometric view with portions broken away of the support arm of FIG. 4 with a first debris insert, second debris insert and associated debris relief holes disposed at respective locations in accordance with teachings of the present disclosure;

FIG. 6A is a schematic drawing in section showing portions of a debris insert and associated fluid flow path extending through a support arm;

FIG. 6B is a schematic drawing in section a debris insert and associated fluid flow path having an alternative configuration in accordance with teachings of the present disclosure;

FIG. 7A-7F are schematic drawings showing isometric views of various configurations of debris inserts which may be installed in a fluid flow path extending through a support arm in accordance with teachings of the present disclosure;

FIG. 8A is a schematic drawing in section with portions broken away showing an alternative arrangement for debris insert and associated fluid flow path extending through a support arm;

FIG. 8B is a schematic drawing in section with portions broken away taken along lines 8B-8B of FIG. 8A;

FIG. 9A is a schematic drawing with portions broken away showing an isometric view of a support arm with a debris relief hole extending through the support arm in accordance with teachings of the present disclosure; and

FIG. 9B is a schematic drawing with portions broken away showing an exterior surface of the support arm of FIG. 9A with an exit for the relief hole formed in the exterior surface in accordance with teachings of the present disclosure.

Claims

1. A roller cone drill bit comprising: a bit body having at least one support arm extending therefrom;each support arm having an interior surface and an exterior surface with a spindle extending from the interior surface;a respective cone assembly rotatably mounted on each spindle with a bearing structure disposed therebetween;an internal cavity formed in each cone assembly to receive the associated spindle;a first gap formed between interior portions of each cone assembly and exterior portions of the associated spindle;a second gap formed between portions of each cone assembly and adjacent portions of the interior surface of the associated support arm;the second gap extending radially outward from an intersection between the spindle and the interior surface of the associated support arm;at least one fluid seal disposed within the first gap to form a fluid barrier between interior portions of the associated cone assembly and exterior portions of the associated spindle;each support arm having at least a first fluid flow path extending from the interior surface through the support arm to the exterior surface;each fluid flow path disposed in the associated support arm in fluid communication with the second gap; andeach fluid flow path operable to direct fluid containing downhole debris from the interior surface to the exterior of the associated support arm.

2. The drill bit of claim 1 further comprising a respective cutting structure disposed on each cone assembly for engagement with a subterranean formation to form a wellbore.

3. The drill bit of claim 1 further comprising each cone assembly having a respective axis of rotation corresponding generally with a longitudinal axis of the respective spindle.

4. The drill bit of claim 1 further comprising: a debris diverter insert disposed in each fluid flow path; andthe diverter insert having a bore extending therethrough to allow fluid flow from the interior surface to the exterior surface of the associated support arm.

5. The drill bit of claim 4 further comprising: each debris diverter insert having a first length; andthe associated fluid flow path having a second length which is greater than the first length of the associated debris diverter insert.

6. The drill bit of claim 4 further comprising; each fluid flow path having a first diameter portion and a second diameter portion;the first diameter portion of each fluid flow passageway sized to receive the debris diverter insert therein; andthe second diameter portion of each fluid flow path having a diameter approximately equal to the bore in the debris diverter insert.

7. The drill bit of claim 4 further comprising; each fluid flow path having a first diameter portion and a second diameter portion;the first diameter portion of the fluid flow path sized to receive the debris diverter insert therein; andthe second diameter portion of the fluid flow having a diameter greater than the bore in the debris diverter insert.

8. The drill bit of claim 4 further comprising; each fluid flow path having a first diameter portion and a second diameter portion;the first diameter portion of the fluid flow passageway sized to receive the diverter insert therein; andthe second diameter portion of the fluid flow path having a diameter less than the bore in the debris diverter insert.

9. The drill bit of claim 4 further comprising: each support arm having a leading edge and a trailing edge;the leading edge and the trailing edge of the support arm spaced from each other;a first fluid flow path disposed in the support arm proximate the leading edge and a second fluid flow path disposed in the support arm proximate the trailing edge; andthe first fluid flow path and the second fluid flow path operable to direct fluid flow containing downhole debris from the interior surface to the exterior surface of the associated support arm.

10. The drill bit of claim 9 further comprising: a first debris diverter insert disposed in the first fluid flow path;a second debris diverter insert disposed in the second fluid flow path; andthe first diverter insert and the second diverter insert having a respective bore extending therethrough to allow fluid flow from the interior surface of the associated support arm to the exterior surface of the associated support arm.

11. The drill bit of claim 4 further comprising at least one debris diverter insert having a cross-section selected from the group consisting of circular, oval, elliptical, triangular, square, rectangular, and hexagonal.

12. The drill bit of claim 4 further comprising at least one debris diverter insert having a generally conical configuration.

13. The drill bit of claim 4 further comprising: each debris diverter insert having a first end and a second end;the second end of each debris diverter insert disposed within the associated fluid flow path;the first end of each diverter plug disposed adjacent to the interior surface of the support arm; andthe first end of the diverter plug having a cut-out portion operable to direct fluid flow into the respective bore.

14. The drill bit of claim 13 further comprising the first end of at least one debris diverter insert having a cap with a gap formed adjacent to the cap.

15. The drill bit of claim 14 further comprising the cap having a shape selected from the group consisting of flat and dome shaped.

16. The drill bit of claim 1 further comprising a debris diverter insert disposed in the interior surface of at least one support arm with at least a portion of the debris diverter insert offset from the fluid flow path.

17. A method of designing a roller cone drill bit having at least one support arm comprising forming a fluid flow path extending through each support arm whereby rotation of an associated cone assembly relative to the support arm results in directing fluid containing downhole debris to flow through the fluid flow path to improve the downhole drilling life of an associated fluid seal by reducing the amount of debris which contacts the fluid seal.

18. The method of claim 17 further comprising forming at least a first fluid flow path extending from an interior surface of at least one support arm to an exterior surface of the at least one support arm whereby rotation of the associated cone assembly relative to the interior surface of the at least one support arm halts in directing the fluid containing downhole debris to flow from the interior surface to the exterior surface of the at least one support arm through the first fluid flow path.

19. The method of claim 18 further comprising placing a diverter insert having a bore extending therethrough in the first fluid flow path adjacent to the interior surface.

20. The method of claim 18 further comprising forming the first fluid flow path in the interior surface adjacent to a leading edge of the associated support arm; forming a second fluid flow path extending from the interior surface through the support arm to the exterior surface; andforming the second fluid flow path proximate the trailing edge of the support arm.

21. The method of claim 20 further comprising: installing a first debris diverter insert in the first fluid flow path; andinstalling a second debris diverter having a bore extending therethrough in the second fluid flow path.

22. A method to enhance protection of fluid seals and bearing structures associated with a roller cone drill bit while drilling a wellbore using the roller cone drill bit comprising: rotating a cone assembly relative to a spindle and an associated support arm of the drill bit; anddirecting fluid containing downhole debris from a gap extending radially outward from an intersection between the spindle and the interior surface of the associated support arm through a first fluid flow path extending from the interior surface of the support arm to an exterior surface of the support arm.

23. The method of claim 22 further comprising directing fluid containing downhole debris through the first fluid flow path adjacent to a leading edge of the associated support arm.

24. The method of claim 22 further comprising: directing fluid containing downhole debris through the first fluid flow path adjacent to a leading edge of the associated support arm; anddirecting fluid containing downhole debris through a second fluid flow path extending from an interior surface of the support arm to the exterior surface, the second fluid flow path proximate a trailing edge of the support arm.

25. The method of claim 22 further comprising diverting debris from the first fluid flow path with a first debris diverter installed in the first fluid flow path.

26. The method of claim 24 further comprising diverting debris from each fluid flow path with a respective debris diverter having a bore extending therethrough to allow fluid flow from the interior surface to the exterior surface of the associated support arm.