RECESSED EXTENDED NOZZLES FOR DRILL BITS AND DRILL BITS SO EQUIPPED

Abstract

A nozzle includes a nozzle body having an extended, tubular nozzle protrusion terminating at a nozzle exit, the nozzle body having an annular shoulder surrounding a base of the nozzle protrusion. A passage extends through the nozzle body, necking down in cross-sectional area before entering the nozzle protrusion and distally terminating at a nozzle exit, where drilling mud is discharged. A nozzle configured as described is disposed in a nozzle recess of a bit body of a rotary drag bit, the nozzle recess being of sufficient depth to receive the nozzle and recess the annular shoulder of the nozzle body a substantial distance from the bit face. A snap-ring is received in an annular groove in the wall of the nozzle recess and extends inwardly over the annular shoulder of the nozzle body. The nozzle protrusion exit extends to a location proximate the bit face.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 60/841,364, filed Aug. 31, 2006, entitled “RECESSED EXTENDED NOZZLES FOR DRILL BITS AND DRILL BITS SO EQUIPPED,” the entire contents of which is hereby incorporated herein by this reference.

FIELD OF THE INVENTION

The present invention relates to rotary drag bits for drilling subterranean formations and their operation. More specifically, embodiments of the present invention relate to recessing drill bit nozzles retained by a retention element susceptible to erosion in combination with extending the nozzle outlets to remove the retention element from damaging contact with drilling fluid.

BACKGROUND

It is conventional to use threaded exteriors to secure nozzles in nozzle recesses in the face of a fixed cutter rotary bit, also termed a rotary “drag” bit. However, it is difficult to form threads on the recess walls of certain bit bodies, particularly those formed of a tungsten carbide (WC) matrix infiltrated with a copper alloy binder, or formed of another material or materials, such as a sintered carbide, in which it might be difficult to either machine threads or to form fairly precise threads in some other reasonably efficient manner.

Therefore, it would be desirable to be able to secure nozzles within the nozzle recesses of such bit bodies in some other manner. Tri-cone bits, also termed “roller cone” bits, conventionally employ nozzles which are retained in nozzle recesses by retention elements in the form of snap-rings which are circumferentially and radially compressed when placed over a nozzle body previously disposed in a nozzle recess and then released to radially expand into an annular slot in the wall of the nozzle recess. While this approach to nozzle securement would be highly convenient for use in a drag bit, there is substantial concern that a snap-ring placed in close proximity to the formation being drilled and to the nozzle mouth or “exit” may be eroded to failure and a nozzle retained in a nozzle recess thereby consequently blown out of the nozzle recess and lost, compromising bit hydraulics and placing the hard-to-drill tungsten carbide nozzle body at the bottom of the well bore, where it may severely damage polycrystalline diamond compact (PDC) cutting elements on the bit face.

There appear to be two significant sources of such potential erosion. First, there is “blow back,” also termed “splash back” of solids-laden drilling fluid or “mud” contacting the face of the formation proximate the nozzle exit and splashing back against the bit face at the nozzle location. Second, fluid currents may be generated in the drilling mud surrounding the nozzle exit, which currents may erode the snap-ring.

FIG. 1 of the drawings depicts a conventional, snap-ring-retained, nozzle 10 as conventionally used in a roller cone bit, but in this instance shown conceptually as it might be mounted to a rotary drag bit 20. Applicant expressly states that FIG. 1 and the accompanying description thereof do not constitute prior art or an admission of same, but are provided merely to enhance the reader's understanding of the present invention and the advantages provided thereby.

Nozzle 10 comprises a nozzle body 12, conventionally formed of tungsten carbide for erosion resistance to prevent “cutting out” of the nozzle 10 by the solids-laden drilling mud, nozzle body 12 having a passage 14 therethrough constricting toward a nozzle mouth or exit 16 on the face 18 of nozzle body 12. Rotary drag bit 20, comprising bit body 22, includes at least one passage (and typically a plurality of passages) 24 extending from the trailing end (not shown) of the bit body 22 where drilling mud is received from a drill string to which rotary drag bit 20 is secured in a conventional manner, to bit face 26. At the outlet of passage 24, a radially enlarged portion of passage 24 might comprise nozzle recess 28, nozzle recess 28 terminating at annular seat 30 at its inner end. In this arrangement, an annular seal in the form of an O-ring 32 would be disposed substantially within a first, inner annular groove 34 in the wall 36 of nozzle recess 28 and compressed against nozzle body 12 to provide a fluid seal between nozzle body 12 and the wall 36 of nozzle recess 28. A snap-ring 38 would be disposed partially in a second, outer annular groove 38, a radially outer portion of snap-ring 38 being received in second, outer annular groove 40 and an inner portion extending radially inwardly over the face 18 of nozzle body 12. As shown, the face 18 and nozzle exit 16 of nozzle 10 are in close proximity to formation F being drilled, resulting in splash back of drilling mud M as shown by arrows depicting contact of drilling mud M with formation F and reflection therefrom and subsequent contact with snap-ring 38. In addition, fluid currents C generated in the drilling mud in close proximity to nozzle exit 16 may also contact and erode snap-ring 38.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, the invention comprises a nozzle including a nozzle body having an extended, tubular nozzle protrusion at one end thereof terminating at a nozzle exit, the nozzle body further comprising an annular shoulder surrounding a base of the nozzle protrusion. A passage extends through the nozzle body, the passage having a proximal end comprising an entry bore of larger cross-sectional area through which drilling mud may be received and necking down to a smaller cross-sectional area before entering an exit bore extending through the nozzle protrusion and distally terminating at the nozzle exit, where drilling mud may be discharged.

In another embodiment, a nozzle configured as described in the preceding paragraph is disposed in a nozzle recess of a bit body of a rotary drag bit. The nozzle recess is of sufficient depth, terminating at an annular seat, to receive the nozzle and recess the annular shoulder of the nozzle body a substantial distance from the bit face. A snap-ring is disposed partially in an annular groove in the wall of the nozzle recess, a radially outer portion of the snap-ring being received in the annular groove and a radially inner portion extending inwardly over the annular shoulder of the nozzle body to retain the nozzle body against the annular seat. The nozzle exit at the distal end of the nozzle protrusion extends to a location proximate the bit face, while the snap-ring is substantially removed from exposure to splash back and currents of drilling mud which might erode the snap-ring and cause loss of the nozzle and is additionally protected by a volume of non-circulating drilling mud comprising a “dead space” and resident in the annular recess defined between the exterior of the nozzle protrusion and the nozzle recess wall.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 comprises a schematic depiction of a conventional roller cone bit nozzle at it might be retained in a conventional nozzle recess of a bit body of a rotary drag bit; and

FIG. 2 comprises a schematic depiction of a nozzle according to an embodiment of the invention disposed in an elongated nozzle recess of a bit body of a rotary drag bit configured according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 of the drawings depicts a snap-ring-retained nozzle 110 according to an embodiment of the present invention. As shown, nozzle 110 is mounted to a rotary drag bit 120, configured to receive nozzle 110 according to an embodiment of the invention. Nozzle 110 comprises a substantially cylindrical nozzle body 112, which may, but is not required to be, conventionally formed of tungsten carbide for erosion resistance to prevent “cutting out” of the nozzle by the solids-laden drilling mud. Nozzle body 112 includes a longitudinal passage 114 therethrough, comprising an enlarged entry bore 114a and constricting at 114b toward an exit bore 114c terminating at nozzle mouth or exit 116. Exit bore 114c extends through a tubular nozzle protrusion 150 at one end of nozzle body 112, nozzle protrusion 150 being surrounded at its base by annular shoulder 152. As shown in FIG. 2, exit bore 114c may commence proximate the base of nozzle protrusion 150, or more proximally within cylindrical nozzle body 112.

Rotary drag bit 120, comprising bit body 122, includes at least one passage (and typically a plurality of passages) 124 extending from the trailing end of the bit body 122 (not shown) or from a plenum (not shown) within the bit body 122 where drilling mud is received from a drill string to which rotary drag bit 120 is secured in a conventional manner, to bit face 126. At the outlet of a passage 124, a radially enlarged portion of passage 124 comprises elongated nozzle recess 128 extending inwardly from bit face 126, nozzle recess 128 terminating at annular seat 130 at its inner end. In this arrangement, annular seal in the form of an O-ring 132 is disposed substantially within a first, inner annular groove 134 in the wall 136 of nozzle recess 128 and compressed against nozzle body 112 to provide a fluid seal between nozzle body 112 and the wall 136 of nozzle recess 128. A snap-ring 138 is disposed partially in a second, outer annular groove 140, a radially outer portion of snap-ring 138 being received in second, outer annular groove 140 and a radially inner portion extending radially inwardly over the annular shoulder 152 of nozzle body 112, retaining nozzle 110 within nozzle recess 128 against annular seat 130 in communication with passage 124. Thus, the flow of drilling fluid from the interior of bit body 122 through passage 124 is prevented from dislodging nozzle 110 from nozzle recess 128.

As shown, the distal end of nozzle protrusion 150 including exit 116 of nozzle 110 are in close proximity to formation F being drilled, either flush with bit face 126 or protruding slightly past the mouth of nozzle recess 128 above the bit face. On the other hand, second, outer annular groove 140 in the wall 136 of nozzle recess 128, and snap-ring 138 engaged therewith, are positioned deeply within nozzle recess 128, substantially removed from bit face 126. A suitable, non-limiting position for second, outer annular groove within nozzle recess 128 is at least about one-half inch (½″) or greater, with an associated length of nozzle protrusion 150 being selected to place nozzle exit 116 at a desired location proximate bit face 126. As a result of such positioning of snap-ring 138, and further due to a “dead space” volume of non-circulating drilling mud DS, erosive splash back on snap-ring 138 of drilling mud M emanating from nozzle exit 116 as shown by arrows depicting contact of drilling mud M with formation F and subsequent reflection from formation F toward bit face 126 is eliminated. In addition, potentially erosive fluid currents C generated in close proximity to nozzle exit 116 are similarly removed from snap-ring 138 and separated therefrom by the dead space volume of non-circulating drilling mud DS.

While the invention has been described in terms of an illustrated embodiment, those of ordinary skill in the art will recognize and appreciate that it is not so limited, the invention being limited only by the claims appended hereto.

Claims

1. A nozzle for a drill bit for drilling subterranean formations, the nozzle comprising:

a substantially cylindrical nozzle body comprising a tubular protrusion extending from one end thereof, the tubular protrusion surrounded at a base thereof by an annular shoulder; and

a passage extending longitudinally through the nozzle body from an end thereof opposite the one end to a nozzle exit at a distal end of the protrusion.

2. The nozzle of claim 1, wherein the passage extends from an entry bore at an end of the nozzle body opposite the one end and reduces in cross-sectional area to an exit bore extending through the tubular protrusion to the nozzle exit.

3. The nozzle of claim 1, wherein the nozzle body comprises tungsten carbide.

4. A rotary drill bit for drilling subterranean formations, comprising:

a bit body having a face and including at least one nozzle recess opening onto the face, the nozzle recess having an annular groove in a wall thereof;

a nozzle disposed in the at least one nozzle recess, the nozzle comprising: a substantially cylindrical nozzle body comprising a tubular protrusion extending from one end thereof, the tubular protrusion surrounded at a base thereof by an annular shoulder; and a passage extending longitudinally through the nozzle body from an end thereof opposite the one end to a nozzle exit at a distal end of the protrusion; and

a retention element disposed partially within the annular groove and extending over at least a portion of the annular shoulder.

5. The rotary drill bit of claim 4, wherein the retention element comprises a snap-ring.

6. The rotary drill bit of claim 4, further including:

another annular groove in the wall of the nozzle recess located inwardly of the annular groove; and

a resilient annular seal disposed substantially within the another annular groove and compressed against an outer surface of the nozzle body.

7. The rotary drill bit of claim 4, wherein the passage extends from an entry bore at an end of the nozzle body opposite the one end and reduces in cross-sectional area to an exit bore extending through the tubular protrusion to the nozzle exit.

8. The rotary drill bit of claim 4, wherein the nozzle exit is located proximate the bit body face.

9. The rotary drill bit of claim 4, wherein the nozzle body comprises tungsten carbide.

10. The rotary drill bit of claim 4, wherein the rotary drill bit is configured as a drag bit.

11. The rotary drill bit of claim 4, wherein the annular groove is located at least about one-half inch from the bit body face.

12. The rotary drill bit of claim 14, wherein the nozzle recess comprises an annular seat at an inner end thereof, and the nozzle body is secured between the annular seat and the retention element.

13. A rotary drag bit for drilling subterranean formations, comprising:

a bit body having a face and including at least one nozzle recess opening onto the face;

a nozzle disposed in the at least one nozzle recess, the nozzle comprising: a substantially cylindrical nozzle body comprising a tubular protrusion extending from one end thereof and terminating distally at a nozzle exit, the tubular protrusion surrounded at a base thereof by an annular shoulder;

wherein the annular shoulder is located within the nozzle recess at least about one-half inch from a surface of the bit face surrounding the nozzle recess; and

wherein the nozzle exit is located immediately proximate the surface.

14. The rotary drag bit of claim 13, wherein the nozzle recess includes an annular groove therein proximate the annular shoulder, and further comprising a retention element disposed partially within the annular groove and extending over at least a portion of the annular shoulder.

15. The rotary drill bit of claim 14, wherein the nozzle recess comprises an annular seat at an inner end thereof, and the nozzle body is secured between the annular seat and the retention element.