DRILL BIT

Abstract

A drill bit comprises a bit body having a body face and a plurality of blades each extending from the bit body from a root portion adjacent the body face to a tip portion defining a cutting region, each blade having a leading face and a trailing face. The drill bit further comprises at least one outlet port disposed adjacent the leading face of at least one blade at a location between the root and tip portions of said at least one blade, the at least one outlet port for directing drilling fluid towards the cutting region of the at least one blade.

Claims

1. A drill bit, comprising: a bit body having a body face; a plurality of blades each extending from the bit body from a root portion adjacent the body face to a tip portion defining a cutting region, each blade having a leading face and a trailing face; and at least one outlet port disposed adjacent the leading face of at least one blade at a location between the root and tip portions of said at least one blade, the at least one outlet port for directing drilling fluid towards the cutting region of the at least one blade.

2. The drill bit according to claim 1, wherein the location of the at least one outlet port between the root and tip portions of the at least one blade is such that the at least one outlet port is elevated relative to the body face.

3. The drill bit according to claim 1, wherein the at least one outlet port is located closer to the tip portion of the at least one blade than the root portion.

4. The drill bit according to claim 1, wherein the at least one outlet port is disposed on the leading face of the at least one blade.

5. The drill bit according to claim 1, wherein the at least one outlet port is disposed on a projection extending outwardly from the leading face of at least one blade.

6. The drill bit according to claim 5, wherein the projection extends outwardly from the leading face of the at least one blade in a direction towards the trailing face of an adjacent blade.

7. The drill bit according to claim 5, wherein the projection defines a ledge, wherein the at least one outlet port is formed in or on the ledge.

8. The drill bit according to claim 7, wherein the ledge defines a profile along its length, said profile following a profile of the tip portion of the at least one blade.

9. The drill bit according to claim 7, wherein the ledge defines a flow guide surface to guide flow from a separate flow source towards the cutting region of the at least one blade.

10. The drill bit according to claim 5, wherein the projection is a discrete projection located between the root and tip portions of the at least one blade.

11. The drill bit according to claim 5, wherein the projection extends from the body face of the bit body in the same direction as at least a portion of the at least one blade.

12. The drill bit according to claim 5, wherein the projection extends from a projection root adjacent the body face to a projection tip intermediate the root and tip portions of the at least one blade.

13. The drill bit according to claim 5, wherein the projection is integrally formed with the at least one blade.

14. The drill bit according to claim 1, wherein the at least one outlet port is elongate in a direction generally parallel with the leading face of the at least one blade.

15. The drill bit according to claim 1, comprising at least one outlet port disposed adjacent the leading face of two or more blades.

16. The drill bit according to claim 1, wherein the cutting region of each blade comprises at least one cutting element.

17. The drill bit according to claim 16, wherein at least one cutting element projects from the leading face of a blade and at least partially over the at least one port.

18. The drill bit according to claim 1, comprising a plurality of nozzles disposed on the body face of the drill bit to allow the flow of drilling fluid out of the bit body.

19. A method for drilling a bore, comprising: engaging a drill bit against a formation to be drilled, the drill bit comprising a bit body having a body face and a plurality of blades each extending from the bit body from a root portion adjacent the body face to a tip portion defining a cutting region, each blade having a leading face and a trailing face; rotating the drill bit to cause the cutting region of each blade to remove material from the formation to produce drill cuttings; and flowing drilling fluid from at least one outlet port which is disposed adjacent the leading face of at least one blade at a location between the root and tip portions of said at least one blade, the drilling fluid being directed towards the cutting region of the at least one blade.

20. The method according to claim 19, comprising directing drilling fluid from the at least one outlet at a location between the cutting region and drill cuttings being removed.

21. The method according to claim 19, comprising additionally flowing drilling fluid from a plurality of nozzles disposed on the body face of the bit body.

22. A drill bit, comprising: a bit body having a body face; a plurality of blades each extending from the bit body from a root portion adjacent the body face to a tip portion defining a cutting region, each blade having a leading face and a trailing face; a plurality of nozzles disposed on the body face to flow drilling fluid out of the bit body; and at least one outlet port disposed adjacent the leading face of at least one blade at a location between the root and tip portions of said at least one blade, the at least one outlet port for directing drilling fluid towards the cutting region of the at least one blade.

23. The drill bit according to claim 22, comprising a flow guide disposed on the leading face of at least one blade, the flow guide for directing a portion of drilling fluid from at least one nozzle away from the bit body towards the cutting region of the at least one blade.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0061] FIG. 1 is an end elevation view of a drill bit;

[0062] FIG. 2 is a perspective view of a portion of the drill bit of FIG. 1;

[0063] FIG. 3 graphically illustrates the relationship between jet force from a nozzle as distance increases from the nozzle;

[0064] FIG. 4 is a diagrammatic illustration of the flow of drilling fluid from an outlet port of the drill bit of FIG. 1 interacting with a drill cutting when in use;

[0065] FIG. 5 is a diagrammatic illustration of the flow of drilling fluid from a nozzle typically provided on a drill bit interacting with a drill cutting;

[0066] FIG. 6 is an enlarged perspective view of the drill bit of FIG. 1, in the region of cutting elements of a blade; and

[0067] FIGS. 7 to 9 are perspective views of portions of alternative drill bits illustrating example forms of outlet port;

DETAILED DESCRIPTION OF THE DRAWINGS

[0068] An end elevation view of a drill bit, generally identified by reference numeral 10, is provided in FIG. 1, with a perspective view of a portion of the drill bit 10 shown in FIG. 2. The drill bit 10 may be used in multiple different drilling applications. For example, the drill bit 10 may be used in the drilling of wellbores into the earth.

[0069] The drill bit 10 includes a bit body 12 having a body face 14 and a plurality of blades 16 extending from the body face 14. There are six blades 16 provided in the present example and formed of a first set of three long blades 16a which connect at a central hub 17, and a second set of three shorter blades 16b each interposed between adjacent long blades 16a. In this case the terms longer and shorter are with respect to a general radial length of the blades 16 with respect to a central axis of the drill bit 10. In other examples more or less blades may be provided, and they may be arranged in any suitable form. Unless explicitly mentioned otherwise it is not intended that the blades 16 are limited to the specific form or geometry illustrated. The profiles defined between the blades 16 and body surface 14 may be defined as waterways.

[0070] The blades 16 extend from the bit body 12 from a root portion 18 adjacent the body face 14 to a tip portion 20 which defines a cutting region 22. During operation, the drill bit 10 is engaged with a formation with suitable weight applied and is rotated via a connected drill string and/or motor (not shown) such that the cutting region 22 of each blade 16 removes material from the formation to produce drill cuttings. Certain features of the present disclosure relate to enabling efficient use of a drilling fluid to improve bit hydraulics aimed in particular at drill cuttings management and bit cooling. In particular, and as will be described in further detail below, the provision of one or more elevated drilling fluid outlet ports on the blades 16 can provide significant advantages.

[0071] Each blade 16 defines a leading face 24 and a trailing face 26. The designation of leading and trailing is made with reference to the intended direction of rotation to cause cutting, which in the present example is an anti-clockwise direction as viewed in FIG. 1. Respective junk slots 28 are formed between the leading face 24 of one blade 16 and the trailing face 26 of an adjacent blade 16. Each blade 16 includes a plurality of cutting elements 30 provided in each cutting region 22. More specifically, a plurality of cutting elements 30 are provided, side-by-side, on a shoulder region defined between the leading face 24 and tip region 20 of each blade 16, with the cutting elements 30 projecting from the leading faces 24 (i.e., towards or into the adjacent junk slot 28). The cutting elements 30 may be provided in a known form, for example in terms of geometry, material composition, attachment mechanism, manufacturing technique etc. Some or all of the cutting elements 30 may be integrally formed with the respective blades. Some or all of the cutting elements 30 may be provided in insert form.

[0072] The drill bit 10 comprises a plurality of nozzles 32 disposed on the body face 14 of the bit body 12 within the waterways to allow the flow of drilling fluid out of the bit body 12. The nozzles 32 are in communication with an internal feed bore (not shown) of the drill bit 10 which delivers drilling fluid from a remote location, such as a surface location in earth drilling operations. In the present example each nozzle 32 is associated with a respective junk slot 28 and delivers drilling fluid to assist in the clearing of drill cuttings from the drilled bore while also cooling the drill bit 10, particularly the cutting elements 30.

[0073] One or more outlet ports 34 are disposed on the leading face 24 of each blade 16, at a location partway between the root and tip portions 18, 20 and function to direct drilling fluid towards the cutting elements 30 in the cutting region 22 of each blade 16. In this respect, the outlet ports 34 may be considered to be elevated ports, relative to the body surface 14 of the bit body 12 and nozzles 32. This elevated position provides significant benefits, as will be described in detail below.

[0074] In the present example the blades 16 include different numbers of outlet ports 34, with the longer blades 16a each including two ports 34, and the shorter blades 16b each including a single port. Such an arrangement may be dictated by the length of the associated cutting region 22. However, different arrangements are possible, including a single outlet port provided on each blade, multiple outlet ports provided on each blade etc.

[0075] A projection 36 extends from the leading face 24 of each blade 16, into an associated junk slot 28, wherein each projection 36 defines a ledge 38, with the outlet ports 34 being formed on or in the ledges 38. As such, the outlet ports 34 are positioned below and directed towards the respective cutting regions 22 and associated cutting elements 30. The projections 36 may be integrally formed with the blades 16. Alternatively, the projections 36 may be separately formed and subsequently secured to a blade 16. In the present example the projections 36 each extend from the body face 14 of the bit body 12 to a location partway between the root and tip portions 18, 20 of each blade 16. However, in other examples one or more of the projections 36 may be considered to be discrete projections in that they may not extend from the body face 14. Rather, the projections may be provided as discrete components on the leading face of an associated blade 16.

[0076] In the present example the projections 36 and associated ledges 38 may define flow guides for use in directing a portion of drilling fluid from the nozzles 32 away from the bit body 12 and generally towards the cutting regions 22 of the blades 16.

[0077] As noted above, the presence of the elevated outlet ports 34 provides significant advantages or improvements to the bit hydraulics. For example, and as illustrated diagrammatically in FIG. 3 (the data for which was provided via CFD simulation), the jet force of drilling fluid from a nozzle or outlet reduces as the distance from the nozzle or outlet increases. Thus, the jet force from the nozzles 32 in the waterways will have diminished to a certain degree by the time the drilling fluid reaches the cutting regions 22. Providing the outlet ports 34 in a position closer to the cutting regions 22 is such that drilling fluid may reach the cutting regions 24 with higher energy and force, increasing the ability for the drilling fluid to shear drill cuttings, to remove or flush drill cuttings from the cutting region, and increase the applied cooling effect to the drill bit 10.

[0078] Furthermore, the closer proximity of the outlet ports 34 to the cutting regions 22 may permit improved focussing or targeting of the drilling fluid at the cutting region 22. This may in particular improve the ability for the drilling fluid to impinge at a location between the cutting region and drill cuttings in the process of being removed from the borehole. That is, and as diagrammatically illustrated in FIG. 4, a jet or stream of drilling fluid 40 from an outlet port 34 may be directed more accurately beneath a drill cutting 42 being sheared from the bottom of the bore hole by a cutting insert 30, effectively assisting to lift the drill cutting 42 away from the cutting edge. This precise targeting combined with the above described higher velocity fluid jet and shear force may assist to separate or sever the drill cutting 42, preventing a long ribbon from being formed and reducing the risk of bit balling (or other binding phenomenon) occurring. Such focussed directing of the drilling fluid may contrast with a jet of drilling fluid from a typical waterway nozzle provided without the benefit of the present disclosure, as diagrammatically illustrated in FIG. 5, in which a wider and less targeted fluid jet 44 with reduced energy or force may impinge on the outside of a drill cutting 42 being removed.

[0079] Furthermore, the dual function of the ledges 38 (see FIGS. 1 and 2) in positioning the outlet ports 34 in their elevated position and guiding flow from the nozzles 32 towards the cutting regions 22 provides a synergy towards significantly improving bit hydraulics.

[0080] Referring again to FIGS. 1 and 2, in the present example the outlet ports 34 are generally elongate in a direction generally parallel with the leading face 24 of an associated blade 16. Such elongation may permit a required flow area to be achieved while minimising the extent to which an associated projection 36 extends from the leading face 24 of the blade (i.e., the extent of extension into a junk slot 28). Furthermore, an elongated outlet port may permit a wider fan profile to be achieved, thus providing a wider coverage along the cutting region 22 from a single outlet port.

[0081] The elongate shape of the outlet ports 34 may also mitigate against blockage from drill cuttings. That is, the elongate shape may promote a degree of self-cleaning. For example, as illustrated in FIG. 6, should any drill cutting 42 transfer into an outlet port 34 it is less likely to entirely block the elongate port 34. With a partial blockage or restriction the remaining flow space would be reduced which would result in a higher flow speed and therefore increase the shear forces on the drill cutting in the port. The increased shear force may translate to an increased force to clear the blockage.

[0082] Furthermore, the closer proximity of the outlet ports 34 to the cutting region 22 may be such that the drill cuttings 42 are of a smaller size by the time they encroach towards or enter the outlet ports 34, providing further assurances against blockages. Also, the elongation of the outlet ports 34 may allow these to have a greater length than the individual cutting width of the cutting elements 30 such that the outlet ports 34 may be larger than the width of drill cuttings 42 generated.

[0083] In the present example the outlet ports 34 are generally rectangular with rounded ends (e.g., stadium shaped), and multiple ports may be provided to cover a desired length. However, other forms of outlet port may be provided. For example, FIG. 7 is a perspective view of an alternative drill bit 110 in the region of a blade 116 which includes an outlet port 134 on a ledge 138 of a projection 136 extending from a leading face 124 of the blade 116. In this example a single outlet port 134 is provided with an extended length to provide the desired extent of drilling fluid delivery below cutting elements 130.

[0084] FIG. 8 provides a further example form of an outlet port 234 which is elongate and generally tear shaped, which may provide a desired outlet flow profile and may contribute to the promotion of self-cleaning.

[0085] FIG. 9 provides another example form of an outlet port 334, again having an elongate profile but provided by a sequence of connected different profile sections, in this case circular and rectangular profile sections. This may provide for different flow profiles to be achieved along the length of the at least one outlet port.

[0086] It should be recognised that any suitable form of outlet port may be provided, which may be elongate as noted above, albeit with any desired profile, or indeed may be non-elongate, for example circular, square etc.

[0087] It should be recognised that the examples provided herein are merely exemplary and that various modifications may be made thereto.