GB2383062A

GB2383062A - Earth-boring bit and nozzle

Info

Publication number: GB2383062A
Application number: GB0305140A
Authority: GB
Inventors: James A Larsen; Michael Allen Siracki
Original assignee: Smith International Inc
Current assignee: Smith International Inc
Priority date: 1999-03-11
Filing date: 2000-03-10
Publication date: 2003-06-18
Anticipated expiration: 2020-03-10
Also published as: GB0305138D0; GB2384014A; GB0305140D0; GB2384014B; GB2383062B

Abstract

A nozzle and retainer assembly 40 is provided for use in a rotary cone earth boring bit 44. The rotary cone earth boring bit comprises a bit body assembly 30; at least one rotary cone (34, figure 3) rotatably mounted on the bit body assembly; a fluid bore 54 through the body; a receptacle 42 in the bit body being in communication with the fluid bore and having an interior end with a seat shoulder 50 and an open opposite end; a nozzle 46 having a passage with a first end 75 in communication with the fluid bore and an orifice end 76 opposite thereto, wherein the passage has an internal surface defining at least one flute (81, figure 7A) therein that slopes in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle; and a retainer 48 removably attached to the receptacle and nozzle to retain the nozzle in the receptacle.

Description

EARTH-BORING BIT AND NOZZLE The present invention relates to an earth-boring bit and to a nozzle. In particular, the present invention to a nozzle and retainer assembly for use in rotary cone earth boring bits.

Earth boring bits used for drilling holes in the earth are typically classified into two types: drag bits which have no moving parts and shear the formation (e. g. polycrystalline diamond compact (PDC) bits, diamond impregnated bits, etc. ) and rotary cone bits which have one or more generally conic roller cones rotatably mounted on the bit body. The roller cones have cutting teeth and/or inserts extending therefrom and rotation of the bit body rotates the cones so that the cutting teeth and/or inserts crush and gouge the formation.

Both of these types of bits use nozzles mounted on the bit body to direct drilling fluid coming down the drill string to sweep the bottom of the borehole and carry cuttings back up the hole on the outside of the drill string. This fluid flow, or"bit hydraulics", serves three primary purposes: cutting removal, relief of chip hold down pressure, and, in the case of rotary cone bits, cleaning of the cones. The location and type of the nozzles used can greatly affect these purposes.

Location of the nozzles relative to the borehole bottom is especially relevant to rotary cone bits versus drag bits. Because the face of the drag bit body is directly against the formation, the nozzles in a drag bit

are readily located near the borehole bottom by mounting of a nozzle in a receptacle in the bit body. In contrast, the bit body of a rotary cone bit is disposed above the bottom of the formation by the rotary cones and thus fluid exiting from a nozzle recessed or flush with the bit body must travel a significant distance before impinging at or near the borehole bottom. Moving the nozzle exit closer to the hole bottom can generally improve chip removal by increasing the bottom hole energy and by improving the ability of the fluid to relieve chip hold-down pressures.

One way in which the exit orifice of nozzles in rotary cone bits have been moved closer to the borehole bottom is by using steel tubes that extend from the bit body with a wear-resistant nozzle mounted in the end of the tube.

These extended nozzle tubes have the advantage of being able to closely locate the exit orifice of the nozzle close to the borehole bottom. However, the extended tubes are susceptible to breaking. A tube breaking off of the bit effectively ends the run of that particular bit and may require a costly down hole fishing (retrieving) operation to remove the tube from the bottom of the borehole.

Another way that the exit orifice has been moved

closer to the borehole bottom is by the use of"miniextended"nozzles. Conventional nozzles are generally flush or recessed from the outer surface of the receptacle in the bit body in which they are mounted. Mini-extended nozzles have a portion which extends beyond the receptacle in which it is mounted but still are retained by conventional nozzle retention means. With reference to Figure 1, a conventional mini-extended nozzle 10 is shown

mounted in receptacle 12 defined in bit body assembly 14.

Nozzle 10 defines passage 16 for the direction of drilling fluid through the nozzle. Receptacle 12 conventionally has a standard inner diameter for a given size bit. Retainer 18 threads into receptacle 12 at threaded connection 24 and retains nozzle 10 in receptacle 12 by capturing shoulder 20 of nozzle 10 by ledge 22 extending radially inward from retainer 18. Nozzle 10 seats on shoulder 26 in receptacle 12. Seal 28 seals between the outer surface of nozzle 10 and the inside of receptacle 12. Nozzle 10 is referred to as a"mini-extended"nozzle due to the fact that the nozzle has portion 11 extending beyond receptacle 12. The outer diameter of portion 11 is smaller than the outer diameter of base portion 13 of nozzle 10 in order to extend beyond ledge 22 of retainer 18. The advantage of mini-extended nozzles is their relative durability and ruggedness compared to extended tubes. However, a mini-extended nozzle does not locate the nozzle orifice as close to the borehole bottom as an extended tube.

US-A-5669459 discloses a retention body for holding a mini-extended nozzle closer to the borehole bottom. This design has the advantage of better protecting the miniextended nozzle during operation by extending a mild steel retention body along the portion of the nozzle that extends beyond the body of the bit. By better protecting the nozzle, the orifice of the nozzle can be moved closer to the borehole bottom compared to a mini-extended nozzle mounted in a conventional receptacle while at the same time avoiding the potential breakage problems associated with extended tubes.

Thus for a rotary cone bit, the mini-extended nozzle can be used in a conventional receptacle for some extension, with a retention body like that disclosed in US-A-5669459 for additional extension, or with an extended tube for even more extension but with a risk of tube breakage.

In addition to location of the nozzle in the axial direction (i. e. distance from borehole bottom), the type of nozzle used affects the goals of chip removal, relief of chip hold down pressure, and cone cleaning. More specifically, the nozzle passageway and orifice can affect bit hydraulics. US-A-5494124 (as well as related patents US-A-5632349 and US-A-5653298) discloses a type of nozzle with a passageway and orifice design that is purported to provide advantages over other nozzles when used in an earth boring bit. Figures 1,3, and 5 of US-A-5494124 show the shaped orifices (slot 16,46, and 76 respectively) while Figures 2,4, and 6 of US-A-5494124 show the corresponding internal passage 20,50, 80 respectively.

With reference to Figure 2 of the present application, an embodiment of nozzle 10'of the type disclosed in US-A-5494124 is shown in receptacle 12 with retainer 18 capturing end 21 of nozzle 10'. Nozzle 10'is recessed from the opening of receptacle 12. Passage 16'has transition zone 29 that transitions from passage 16'to orifice 31. US-A-5494124 teaches particular shapes of transition zone 29 and orifice 31 to achieve the desired fluid characteristics for the nozzle.

One disadvantage of the nozzle of US-A-5494124 is that its internal passage 16'must be much larger than that of a conventional nozzle to allow sufficient room for the desired short transition zone 29 with its high rate of inward taper to orifice 31, especially for larger sized nozzle orifices. The standard receptacle 12 in a bit together with the retention means used to hold the nozzle in the receptacle limit the maximum outer envelope of the nozzle, and this together with the minimum acceptable wall thickness of the nozzle limits the maximum size of internal passage 16'of the nozzle. Thus, for a given receptacle 12, the maximum nozzle orifice size achievable by the nozzle of US-A-5494124 will be appreciably less than that of a conventional nozzle. This is a disadvantage because standard drilling practices often require larger nozzle orifices to reduce the pressure drop across the bit. The inability to accommodate larger nozzle orifices makes the nozzles of US-A-5494124 less versatile and unable to be used in certain drilling applications that may require a pressure drop that is less than that available with the largest nozzle of US-A-5494124 for the particular receptacle in the bit.

This disadvantage of the nozzle of US-A-5494124 is compounded when it is desired to take advantage of the mini-extended nozzle concept by extending the end of the nozzle beyond the receptacle in which it is mounted.

Retainer 18 used with mini-extended nozzle 10 in Figure 1 requires a reduced outer diameter of extended portion 11.

This reduced diameter even more severely restricts the maximum size of internal passage 16'of the nozzle of US-A-5494124 as shown in Figure 2, thus further reducing

the maximum nozzle exit orifice size possible relative to a mini-extended nozzle with a conventional internal passage.

Furthermore, the nozzle of US-A-5494124 relies in part on a relatively short transition zone 29 to taper from passageway 16'to orifice 31. Passageway 16'only slightly tapers radially inward from interior end 19 to transition zone 29 and thus maintains a relatively large inner diameter compared to passageway 16 in Figure 1.

Transferring passageway 16'to a mini-extended nozzle of Figure 1 can be seen by the dashed line in Figure 1 which represents extended passageway 16"for a nozzle of the type shown in US-A-5494124. As can be seen, the inner diameter of passageway 1611 is larger than the outer diameter of extended portion 11 at a point indicated at 17. Thus, such an extension is not possible with retainer 18 of Figure 1.

While nozzles of the type shown in US-A-5494124 have been used with drag bits as shown in Figure 2, they are not directly translatable to a rotary cone bit without the disadvantages discussed above. Therefore, a need exists for a nozzle and retainer assembly that allows for an increase in the size of the internal passage of a miniextended nozzle so that the teachings of US-A-5494124 can be used in a mini-extended design for a range of nozzle orifice sizes comparable to that of conventional miniextended nozzles.

One teaching of US-A-5494124 is the generation of lower than hydrostatic pressure zones on the hole bottom.

In drilling applications, fluid is transmitted to the hole bottom via a drill string to remove cuttings from the hole

bottom and transport them back to the surface through the annular space between the drill string and the hole wall.

Weighting materials are typically added to the drilling fluid to ensure that the bore hole pressure is greater than that of the pore pressure to ensure the integrity of the bore hole. If the fluid is under-weighted, causing the bore pressure to be less than the pore pressure of the surrounding formation, the hole can cave in and stick the drill string in the hole which causes costly hole deviations. However, if the hole pressure is too high, rock bit penetration rates are significantly reduced since the chips generated by the cutters tend to be held in the formation by the pressure differential across the hole surfaces. The nozzles of US-A-5494124 are intended to generate localised low pressure zones on the hole bottom which allows cuttings to lift from the hole bottom in these localised zones in the presence of global overburden pressures. To generate the localised low pressure zones, the nozzles of US-A-5494124 are intended to generate lobes of flow which move the fluid radially outboard from the centreline of the nozzle. Because the flow from the nozzles of US-A-5494124 is not axisymmetric like that of nozzle 10 in Figure 1, a need exists to optimise the rotational position of the nozzles relative to the cones of a rotary cone bit.

Additionally, nozzles may have passages and/or asymmetric orifices that direct the fluid at an angle. As fluid flows through an angled passage, it will impart a rotational force on the nozzle. Such nozzles must be able to be readily located at a desired rotational orientation and/or locked against rotational forces from fluid flow

through the bit. Thus a need exists for a nozzle and retainer assembly that allows for an increase in the size of the internal passageway of a mini-extended nozzle and provide for rotational location and/or locking of the nozzle relative to the bit body.

According to a first aspect of the present invention, there is provided a rotary cone earth boring bit, the bit comprising: a bit body assembly ; at least one rotary cone rotatably mounted on the bit body assembly; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having an outer surface having a stepped portion extending radially outward so as to define a first nozzle shoulder spaced from and facing toward the seat shoulder and a second nozzle shoulder facing opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and a second end opposite thereto defining an orifice at the second end of the nozzle; and, a retainer concentrically disposed about the outer surface of the nozzle and removably attached to the receptacle, the retainer having a first end engaged with the second nozzle shoulder so as to retain the nozzle in the receptacle and a second end opposite thereto toward the open end of the receptacle.

An annular seal may be located between the seat shoulder of the receptacle and a gland shoulder of the rib of the nozzle.

According to a second aspect of the present invention, there is provided a rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto extending beyond the open end of the receptacle, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the passage having a first cross-sectional area at the first end, a second cross-sectional area at a point axially coextensive with the open end of the receptacle and a third cross-sectional area at the orifice end, the second crosssectional area being at least about 25% of the first crosssectional area; the passage converging from the second cross-sectional area to the third cross-sectional area; and, a retainer removably engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle, the retainer engaging the nozzle at a point that is between the seat shoulder and the open end of the receptacle.

According to a third aspect of the present invention, there is provided a nozzle, the nozzle comprising a body with a generally cylindrical outer surface having a centre axis and having a longitudinal direction from a first end to a second end opposite thereto, the body having a passage therethrough from the first end to the second end of the nozzle, the outer surface having a stepped portion located near the first end of the nozzle and extending radially outwards and having a first nozzle shoulder spaced longitudinally from the first end and facing in the longitudinal direction toward the first end and a second nozzle shoulder opposite thereto facing in the longitudinal direction toward the second end, the outer surface of the nozzle at all points other than the stepped portion being radially inward of the stepped portion.

According to a fourth aspect of the present invention, there is provided a rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a cone axis and a cone surface extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone surface having a plurality of cutting elements extending therefrom; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto extending beyond the open end of the receptacle, the nozzle having a passage therethrough having a first end in communication with the fluid bore and

an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle defining at least one flute therein that slopes in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle ; and, a retainer removably engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle, the retainer engaging the nozzle at a point that is between the seat shoulder and the open end of the receptacle.

According to a fifth aspect of the present invention, there is provided a rotary cone earth boring bit, the bit comprising: a bit body assembly ; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a rotational axis and extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone having an outer surface with a plurality of cutting elements extending therefrom ; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle having three or fewer flutes therein, each flute sloping in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle, the

flute being directed between about 700 to about 1600 or between about 2000 to about 2900 from the radially outermost point of the receptacle relative to the centre of the bit body in a clockwise direction.

According to a sixth aspect of the present invention, there is provided a rotary cone earth boring bit, the bit comprising: a bit body assembly ; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a rotational axis and extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone having an outer surface with a plurality of cutting elements extending therefrom ; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end

of the nozzle having only one flute therein, the flute 9 sloping in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle, the flute being directed between about 600 to about 3000 from the radially outermost point of the receptacle from the centre of the bit body in a clockwise direction.

An embodiment of the present invention provides a nozzle and retainer assembly that moves the engagement

point between the nozzle and retainer radially outward to allow for additional cross-sectional area of the nozzle which in turn allows for a larger internal passage.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a prior art miniextended nozzle and retainer assembly mounted in a bit; Figure 2 is a cross-section of a prior art nozzle and retainer assembly mounted in a bit; Figure 3 is a side view of an example of a bit according to the present invention; Figure 4 is a cross-section of the preferred embodiment of the nozzle and retainer assembly of the present invention mounted in a bit and shown with orientation tool; Figure 5 is a perspective view of the nozzle of Figure

4 ; Figure 6 is an overlay of the nozzle of Figure 4 with the nozzle of Figure 1 comparing the two nozzles in the same size receptacle in a bit; Figure 7A is a partial bottom view of an example of a bit according to an embodiment of the present invention;

Figure 7B is a cross-section of the nozzle of Figure 7A along line B-B; Figure 8 is a partial bottom view of the bit of Figure 7A with the nozzle in a different orientation; Figure 9A is a partial bottom view of an example of a bit according to another embodiment of the present invention; Figure 9B is a cross-section of the nozzle of Figure 9A along line B-B ; Figure 10 is a bottom view of the bit of Figure 9A with the nozzles in different orientations; Figure 11A is a partial bottom view of an example of a bit according to another embodiment of the present invention; Figure lIB is a cross-section of the nozzle of Figure 11A along line B-B; Figure 12 is a cross-section of an alternative embodiment of the nozzle and retainer assembly of the present invention mounted in a bit; Figure 13 is a perspective view of the nozzle of Figure 12; Figure 14 is a cross-section of another alternative embodiment of the nozzle and retainer assembly of the

present invention mounted in a bit and shown with an alternative orientation tool; Figure 15A is an underside perspective view of an alternative embodiment of an orientation tool that can be used with the assembly of Figure 14; Figure 15B is a top side perspective view of the orientation tool of Figure 15A ; Figure 16A is a cross-section of another alternative embodiment of the present invention mounted in a bit; Figure 16B is a perspective view of the nozzle of Figure 16A; Figure 16C is a perspective view of the nozzle of Figure 16A; Figure 17 is a cross-section of another alternative embodiment of the present invention mounted in a bit; and, Figure 18 is a cross-section of an alternative embodiment of a portion of the bit assembly of the present invention.

With reference to Figure 3-5, the preferred embodiment of the present invention is shown. Figure 3 shows bit 44 of the present invention with bit body assembly 30 having legs 32 extending downward and threaded end 33 opposite thereto for attachment to a drill string. Rotary cones 34 are rotatably mounted to bit body assembly 30 as is known

in the art for contacting borehole bottom 36. Nozzle and retainer assembly 40 is mounted in receptacle 42 of bit body assembly 30. Bit body assembly 30 also has boss 38 extending radially outward to locate receptacle 42 radially outward and axially toward borehole bottom 36. Nozzle 46 is captured in receptacle 42 by retainer 48 which is removably mounted within receptacle 42 to engage nozzle 46 at engagement point 49. As can be seen, by virtue of rotary cones 34 engaging borehole bottom 36, bit body assembly 30 is disposed above borehole bottom 36 in contrast to a drag bit where the bit body directly engages the borehole bottom.

One aspect of this embodiment of the present invention involves moving engagement point 49 between retainer 48 and nozzle 46 radially outward to allow more space for internal passage 74 as may be required by nozzles of the type disclosed in US-A-5494124, US-A-5632349 and US-A-5653298.

The disclosure of these patents are incorporated herein by reference. These types of nozzles require a larger internal passage relative to conventional nozzles to achieve comparable nozzle sizes. This aspect of the present invention provides more space for larger internal passages in the nozzle to allow them to be used with a comparable range of nozzle sizes as conventional nozzles while still allowing them to be mounted in standard nozzle receptacles in the bit body.

Receptacle 42 is located in bit body assembly 30.

Receptacle 42 can be located in bit body assembly 30 by many methods. Examples of these methods include machining receptacle 42, welding in a pre-machined sleeve such as

that disclosed in US-A-5538093 or by attaching a tube such as that disclosed in US-A-5669459 that moves receptacle 42 closer to borehole bottom 36. Any of these methods of installation would provide a nozzle receptacle 42 that by definition is considered a part of bit body assembly 30 for the purposes of this invention. Receptacle 42 extends from interior end 51 defining seat shoulder 50 to open end 52 and is in communication with fluid bore 54 of bit 44.

Receptacle 42 is generally cylindrical with inside surface 56. At least a portion of inside surface 56 defines receptacle threads 58. Inside surface 56 also defines annular seal groove 60 at interior end 51 with gland shoulder 62 facing shoulder 50.

Nozzle 46 is at least partially disposed in receptacle 42. Nozzle 46 has first end 70 abutted against shoulder 50 and second end 72 extending beyond open end 52 of receptacle 42. Nozzle 46 has internal passage 74 that extends through nozzle 46 from first end 70 to second end 72. Internal passage 74 is in communication with fluid bore 54 and exits second end 72 at orifice 76. Nozzle 46 has outer surface 78 of which a substantial or major portion is generally cylindrical. Outer surface 78 defines stepped portion 80 extending radially outward to define first nozzle shoulder 82 facing and disposed from shoulder 50 and second nozzle shoulder 84 facing generally opposite first nozzle shoulder 82. First nozzle shoulder 82 is preferably at generally the same axial location as gland shoulder 62 so that annular gland 86 is defined between shoulder 50 as one side and first nozzle shoulder 82 and gland shoulder 62 together as the other side.

Seal 90 is located in annular gland 86. Seal 90 can be either a circumferential seal, a face seal, or a combination of both. A circumferential type seal is preferred although a variety of suitable seals are known in the art. A standard o-ring seal as is known in the art is preferred.

In Figure 4, nozzle 46 is held in the receptacle 42 by retainer 48. In this embodiment, retainer 48 has first portion 88 that is removably attached to inside surface 56 of receptacle 42 and second portion 89 that positively engages second nozzle shoulder 84 to capture nozzle 46 in receptacle 42. More particularly, retainer sleeve 48 is shown as sleeve 92 that is generally cylindrical with external threads 94 that engage nozzle receptacle threads 58. Sleeve 92 has first end 96 abutting against second nozzle shoulder 84. Sleeve 92 has second end 98 opposite first end 96 that is adapted for receiving a wrench (not shown) for turning sleeve 92. Sleeve 92 has inside surface 100 that is generally cylindrical and which has a diameter sufficiently larger than outer surface 78 of nozzle 46 such that sleeve 92 can be readily rotated relative to nozzle 46.

The advantage of the present invention can be seen with reference to Figure 6 which shows nozzle 46 of Figure 4 overlaid with the conventional mini-extended nozzle 10 of Figure 1. As can be seen, stepped portion 80 provides first nozzle shoulder 82 which is positioned more radially outwards compared to shoulder 20 of conventional nozzle 10 of Figure 1. Additionally, stepped portion 80 locates first nozzle shoulder 82 under retainer 48 and stepped

portion 80 completes seal gland 86. In contrast, shoulder 20 of conventional nozzle 10 of Figure 1 is radially inward and retainer 18 is used to complete the seal gland. As can be seen, receptacles 12,42 of the two Figures overlaid in Figure 6 are the same size yet nozzle 46 accommodates a larger internal passage 74 than that of nozzle 10. It can be seen that internal passage 74 of nozzle 46 would break through the side wall of conventional nozzle 10 at the zone indicated as 119.

With reference again to Figure 4, internal passage 74 of nozzle 46 has first end 75 in communication with fluid bore 54 and second end 77 opposite thereto defining orifice 76 at second end 72 of nozzle 46. Internal passage 74 has first cross-sectional area Al at first end 75, second cross-sectional area A2 at a point axially coextensive with open end 52 of receptacle 42, and third cross-sectional area A3 at orifice 76. Internal passage 74 converges from second cross-sectional area A2 to third cross-sectional area A3 defining transition zone 79. The portion of passage 74 extending from first cross-sectional area Al to second cross-sectional area A2 may taper slightly radially inwards toward second cross-sectional area A2 and it is preferred that A2 is at least about 25% of Al. It is further preferred that A2 is at least about 60% of Al. It is preferred that A3 be less than 75% of A2. Al and A2 being relatively larger than A3 with a short transition zone 79 contributes to the hydraulic characteristics of nozzle 46. As can be seen, when transition zone 79 is kept the same length as transition zone 29 of Figure 2 in the extended nozzle 46 of Figures 4-5, the cross-sectional area of passage 74 is larger relative to passage 16 of

conventional mini-extended nozzle 10 of Figure 1. And as shown in Figures 1 and 6, extended passage 16"would break through nozzle 10. Thus, this arrangement provides additional cross-sectional area of nozzle 46 to allow for a larger cross-sectional area of internal passage 74 therethrough and particularly second cross-sectional area A2 of internal passage 74.

As an example, the outside diameter of the extended portion of nozzle 10 of Figure 1 has a minor outside diameter of 0.945 inches (approx. 24mm) and a crosssectional area of 0.701 sq. in (approx. 4. 5cm2). The nozzle of the present invention allows the outer diameter of the nozzle to expand to 1.24 inches (approx. 31.5mm) for a cross-sectional area of 1.208 sq. in (approx. 7. 8cm2). This is a 72% increase in cross sectional area of the nozzle to accommodate internal passage 74 therethrough.

With the lobed orifices of the nozzles of US-A-5494124, the rotational position of nozzle 46 in receptacle 42 has an effect on the bit hydraulics because the fluid flow exiting from the orifice 76 is non-uniform.

For example, with reference to Figures 7A and 7B, a trilobed orifice 76'is shown in nozzle 46. In this example, orifice 76'has three lobes 73a, 73b and 73c. Internal passage 74 includes transition zone 79 as discussed above.

Internal passage 74 has inside surface 71 that defines flutes 81a, 81b and 81c in transition zone 79 that correspond to lobes 73a, 73b and 73c, respectively.

Orifice 76'and transition zone 79 of this example are similar to the orifice and transition zone of Figures 3 and 4 of US-A-5494124. Each flute 81a, 81b and 81c creates

fluid flow in a direction represented by arrows 83a, 83b and 83c, respectively, in an angular direction towards centreline 85 of nozzle 46. This is similar to the slope of flute 81a which slopes toward the centre of nozzle 46 as it approaches second end 72 of nozzle 46. Arrows 83a, b, and c in Figure 7A will be used to indicate the direction of flutes 81a, 81b, and 81c respectively in Figure 7A.

The fluid flow exiting from flutes 81 is generally of a higher velocity than the surrounding fluid. If flute 81 is directed toward a portion of a cone 34, the higher velocity fluid flow from that flute 81 will pass in the proximity of the cone 34 and aid in cleaning cuttings from that portion of the cone. If cuttings are not cleaned from the cone, they may hydrate and adhere to the cone and portions of the cutting elements 37, thus preventing the full extent of the cutting elements from drilling the borehole bottom. Cleaning the cuttings from the cone prior to their hydration prevents adherence of the cuttings to the cone and improves the overall rate of penetration of the bit by allowing the full extent of cutting elements 37 to drill the borehole bottom. Furthermore, the low pressure zones created on the borehole bottom 36 that may be created by certain embodiments of nozzle 46 facilitate lifting of the cuttings in the presence of the borehole overburden pressure by reducing the pressure differential between the borehole pressure and the pore pressure.

In Figure 7A, flute 81b is directed toward the leading side of cone 34b to clean cuttings therefrom and flute 81c is directed toward the trailing side of cone 34c to clean cuttings therefrom. It is preferred that flutes 81b and

81c be directed toward the outer rows 35 of cutting elements 37 to aid in removing cuttings from around cutting elements 37. For the purpose of assigning relative rotational positions of flutes 81, reference point A is located on bit body assembly 30 at the radially outermost point of receptacle 42 with angles proceeding clockwise therefrom. Thus, in the example of Figures 7A and 7B, arrow 83a from flute 81a is directed to 00, arrow 83b from B1b is directed to 1200 and arrow 83c from flute 81c is directed to 240 . This example is a preferred rotational orientation of a tri-lobed orifice nozzle due to the dual cone cleaning by two of the flutes of the nozzle.

In an alternative of Figure 7A, it may be desired to direct flute 81b at a different angle but still directed at the leading side of cone 34b. There is approximately a 900 range C of orientations, from about 700 to about 1600, for flute 81b to still be directed to the outer rows of the leading side of cone 34b. Range C extends from plane cl through the centre line of nozzle 46 and the radially outermost point of cone 34b with respect to cone axis 27 and plane c2 through the centre line of nozzle 46 and a point on row 35c of cutting elements 37. When flute 83b is said to be directed within range C, it means that a plane bisecting flute 81b first intersects cone 34b at a point between plane cl and plane c2. Similarly, flute 81c can be directed within approximately a 900 range D of about 2000 to 2900 from reference point A in a clockwise direction to be directed to the outer rows of the trailing side of cone 34c. Range D extends similarly to range C but with respect to cone 34c. These ranges may vary somewhat for different

type bits depending on the location and orientation of receptacle 42 relative to cones 34.

Figure 8 shows an alternative embodiment of a trilobed orifice nozzle where flute 81a is directed to the centre of bit body assembly 30, or 1800 from reference point A, to clean cuttings from the centre of the bit.

Flute 81a may be within about 1600 to 2000 from reference point A in the clockwise direction to still be useful in cleaning in between cones 34b and 34c.

Figures 9A and 9B show another embodiment of nozzle 46 for use with the present invention. Nozzle 46 has round or circular orifice 76". Internal passage 74 has inside surface 71 which defines only a single flute 81 which directs fluid in the direction represented by arrow 83.

Flute 81 is preferably directed toward the outer rows 35 of inserts 37 on cone 34b or 34c, but can also be directed toward the centre of the bit to increase bottom hole chip removal for the inner rows as shown by range E.

Alternatively stated, flute 81 is preferably directed between about 600 to about 3000 with respect to reference point A in the clockwise direction.

With reference to Figure 10, a bit is shown with three nozzles 46 installed. Flute 81a is directed to the leading side of cone 34a, flute 81b directed to the centre of the bit, and flute 81c is directed to the trailing side of 34c.

Figure 10 is just one representative pattern of possible orientations of three nozzles 46 in bit body assembly 30.

With reference to Figures 11A and llB, another embodiment of nozzle 46 is shown with orifice 76'''being generally heart shaped. With this particular orifice, lobes 73a and 73b have corresponding flutes 81a and 81b defined in inside surface 71 of internal passage 74.

However, the portion of orifice 76'''outside of the lobes is of sufficient cross-section that the predominant flow is from the non-lobe area of orifice 76'''represented by arrow 87. Orifice 76'''can be located such that arrow 87 is directed at outer rows 35 of cone 34b or 34c and/or within the angle ranges discussed above with regard to the single fluted nozzle shown in Figures 9A and 9B.

In view of the variation in desired rotational orientations of nozzle 46, it is preferred that nozzle 46 be capable of being variably rotationally located and locked relative to bit assembly 44 when non-axisymmetric orifice nozzles are used. The preferred means of rotationally locating nozzle 46 with respect to bit body assembly 30 can be seen with reference to Figures 4 and 5.

Outer surface 78 of nozzle 46 is generally axisymmetric with the exception of orifice 76 (which may be nonaxisymmetric as discussed above with regard to Figures 7 to 11) and key 110 that rotationally locates and/or locks nozzle 46 relative to receptacle 42. Key 110 is shown in Figure 5 as notch 112 defined in stepped portion 80. Boss 38 of bit assembly 44 defines transverse port 114 that communicates with receptacle 42. Tool 116 is insertable into port 114 to align notch 112 with port 114. When it has been determined what the optimal orientation angle B is for a particular nozzle for a particular bit assembly, notch 112 is located relative to the shape of orifice 76

such that when notch 112 is aligned with port 114 in bit assembly 44, orifice 76 will be oriented as desired. In the preferred mode of assembly of nozzle and retainer assembly 40 of the present invention, seal 90 is inserted into seal groove 60. Nozzle 46 is placed in receptacle 42 and pushed in until first end 70 abuts against shoulder 50.

Retainer 48 is then inserted into receptacle 42 and rotated to engage retainer threads 94 with receptacle threads 58.

Nozzle 46 is rotationally located with tool 116. This is achieved by inserting tool 116 into port 114 and maintaining a slight insertion force on the tool while nozzle 46 is rotated back and forth to align notch 112 with port 114 at which time tool 116 will seat into notch 112 with a perceptible movement. While tool 116 is held seated in notch 112, retainer 48 is tightened with a wrench (not shown) that engages second end 98. Once retainer 48 is tightened, tool 116 is then removed. In this embodiment, tool 116 fixes the rotational position of nozzle 46 while retainer 48 is tightened.

It is likely that a particular nozzle 46 may have a different optimal orientation angle B for different bit types or different locations on the bit. For example, a tri-lobe orifice nozzle may be oriented in one receptacle such that a lobe is directed straight towards the side of the borehole and oriented in another receptacle such that one of the lobes is directed to clean one of the rotary cones. To accommodate the need to orient the same nozzle at different orientations, multiple keys 110 can be located about the circumference of stepped portion 80. Additional nozzle reference lines 103 can be placed on second end 72 of nozzle 46 to correspond to the circumferential location

of the multiple keys and aid in rotational location of the nozzle as desired. For example, a nozzle could have a notch 112 located every 300 around stepped portion 80. It should be understood that a variety of keys 110 can be used in addition to notch 112. However, it is preferred that key 110 not disrupt first nozzle shoulder 82 so that it will provide a uniform surface to complete seal gland 86.

With reference to Figures 12 and 13, an alternative embodiment of the nozzle and retainer assembly of the present invention is shown which rotationally locates and continually rotationally locks nozzle 46 relative to bit assembly 44. In this embodiment, key 110 is shown as indentation 120. Boss 38 of bit body assembly 30 defines

transverse port 114'which defines port shoulder 122. Pin 124 is slidably disposed within port 114'and has flange 126 that stops against port shoulder 122. Pin 124 has tip 128 that protrudes from port 114'into receptacle 42. Plug 130 is fixed at the exit of port 114'and spring 132 is disposed between plug 130 and flange 126 of pin 124 to bias pin 124 toward receptacle 42. In the preferred assembly of this embodiment, nozzle 46 is first located in receptacle 42. Pin 124, which is tapered at end 128, slides radially outboard as ledge 80 of nozzle 46 contacts pin end 128.

Nozzle 46 is then rotated back and forth until indentation 120 aligns with port 114'at which time tip 128 of pin 124 will snap into indentation 120 by the force of spring 132.

The positive engagement between tip 128 and indentation 120 rotationally locates and locks nozzle 46 while retainer 48 is then tightened. Additionally, tip 128 continues to rotationally lock nozzle 46 during operation should retainer 48 loosen or become unable to resist the

rotational forces imparted on nozzle 46 by the fluid flow.

To accommodate multiple orientation angles B, multiple indentations 120 can be circumferentially spaced about stepped portion 80.

With reference to Figure 14, another alternative embodiment of rotationally locating nozzle 46 relative to bit assembly 44 is shown. Template 140 has outer posts 142 that engage slots 144 on bit assembly 44 and inner posts 146 that engage slots 148 on nozzle 46. As an alternative, milled flats could be used in place of slots 148 on nozzle 46 or template 140 could be constructed to locate against leg 32 of bit assembly 44. Template 140 is used to hold nozzle 46 at the desired rotational position while retainer 48 is tightened. A wrench (not shown) is used to engage second end 98 of retainer 48 to tighten retainer 48 while nozzle 46 is held by template 140.

Figures 15A-B show an alternative embodiment of template 140 where inner posts 146 extend from inner disk 150 that can be rotated relative to outer disk 152 from which outer posts 142 extend. With reference to Figure 15B, inner disk 150 can have hex head 154 to be rotatable by a wrench. In this embodiment, nozzle 46 can be oriented relative to bit assembly 44 at any desired rotational position by rotating inner disk 150 relative to outer disk 150. Once the desired position is reached, inner disk 150 is held in place while retainer 48 is tightened. The same nozzle may have a different optimal orientation angle B for different bit types and this embodiment allows variable orientation.

With reference to Figures 16A-C, an alternative embodiment of the present invention is shown. In this embodiment, nozzle 160 has nozzle threads 162 that engage receptacle threads 58. By having nozzle 160 thread directly to receptacle threads 58 instead of interposing threaded sleeve 92 as described above, the maximum outer diameter of the nozzle is expanded thereby allowing a larger internal passage 164. Nozzle 160 has outer surface 166 that defines nozzle groove 168. In comparison with the embodiment described above, it can be seen that nozzle 160 has been expanded into the area formerly occupied by threaded sleeve 92 and it is in the additional portion of nozzle 160 in which nozzle groove 168 is defined. Boss 38 defines port 170 that tangentially intersects receptacle 42 to define receptacle groove 172 opposite nozzle groove 168.

Retainer 48 is shown as pin 174, which may be a nail, that can be driven into port 170 to engage nozzle groove 168 and receptacle groove 172 to rotationally locate and lock nozzle 160 relative to bit assembly 44. In the preferred assembly of this embodiment, nozzle 160 is threaded into receptacle 42. As nozzle 160 approaches shoulder 50 in receptacle 42, pin 174 is inserted into port 170 and an insertion force is maintained on pin 174 while nozzle 160 is rotated back and forth to align nozzle groove 168 with receptacle groove 172. Upon alignment, pin 174 will insert in between nozzle groove 168 and receptacle groove 172 to rotationally lock nozzle 160 relative to bit assembly 44.

This positional locking mechanism could also be practised on the embodiment of Figure 5 by machining a groove in the stepped portion 80 that would match the receptacle port 170 and receptacle groove 172.

Figure 17 shows an additional alternative embodiment where the outer diameter of nozzle 160'is increased like the nozzle of Figures 16A-C and outer surface 166'defines nozzle threads 162'to engage receptacle threads 58. Retainer 48 in this embodiment is C-shape clip 180 that is removably inserted into receptacle groove 182 defined in

receptacle 42"and nozzle groove 184 defined in outer surface 166'of nozzle 160'to retain nozzle 160'in receptacle 42". C-shape clips or snap rings are a known way of retaining nozzles in bits. By expanding the diameter of nozzle 160'to engage receptacle 42 directly, additional space is provided for nozzle groove 184 to allow for larger internal passage 164'. This allows crosssectional area A2 to be as large as needed to provide a desired range of flow rates for nozzles of the type of US-A-5494124.

With reference to Figure 18, an alternative embodiment of bit 44 of the present invention is partially shown. In this embodiment, instead of being mounted in a boss as shown in Figure 3, nozzle and retainer assembly 40 is mounted in retention body 190 of the type disclosed in US-A-5669459, which is incorporated herein by reference.

Retention body 190 is attached to bit body assembly, for example by welding, and provides a way to locate nozzle 46 closer to the borehole bottom while being robust enough to resist breakage often associated with extended nozzle tubes. Receptacle 42'''is of the same construction as receptacle 42 in boss 38 of Figure 4.

Although the present invention has been described with respect to certain embodiments, various changes,

substitutions and modifications may be suggested to one skilled in the art and it is intended that the present invention encompass such changes, substitutions and modifications as fall within the scope of the appended claims.

Claims

CLAIMS 1. A rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a cone axis and a cone surface extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone surface having a plurality of cutting elements extending therefrom; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface ; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto extending beyond the open end of the receptacle, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle defining at least one flute therein that slopes in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle; and, a retainer removably engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle, the retainer engaging the nozzle at a point that is between the seat shoulder and the open end of the receptacle.

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2. A bit according to claim 1, wherein the flute is directed toward at least one of the cones.

3. A bit according to claim 2, wherein a plane bisecting the flute and extending in the flute direction first intersects one of the cones at a point between the radially outermost point of the cone relative to the cone axis and about the midpoint of the cone surface.

4. A bit according to claim 3, wherein the cutting elements are arranged around the cone surface in rows, and wherein the plane bisecting the flute first intersects one of the cutting elements at a point within the radially outermost two rows of cutting elements.

5. A bit according to claim 1, wherein the flute is directed radially outward of the bit body assembly.

6. A bit according to claim 1, wherein the flute is directed between about 70 to about 160 or between about 220 to about 290 from the radially outermost point of the receptacle in a clockwise direction.

7. A bit according to any of claims 1 to 6, wherein the internal passage has more than one flute.

8. A bit according to any of claims 1 to 7, wherein the orifice is round.

9. A bit according to any of claims 1 to 7, wherein the orifice has at least two lobes and the internal passage has a flute corresponding to each lobe.

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10. A rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a rotational axis and extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone having an outer surface with a plurality of cutting elements extending therefrom; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle having three or fewer flutes therein, each flute sloping in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle, the flute being directed between about 70 to about 160 or between about 200 to about 2900 from the radially outermost point of the receptacle relative to the centre of the bit body in a clockwise direction.

11. A bit according to claim 10, further comprising a retainer engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle.

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12. A bit according to claim 11, wherein the retainer engages the nozzle at a point that is between the seat shoulder and the open end of the receptacle.

13. A bit according to any of claims 10 to 12, wherein the second end of the nozzle extends beyond the open end of the receptacle.

14. A rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a rotational axis and extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone having an outer surface with a plurality of cutting elements extending therefrom; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle having only one flute therein, the flute sloping in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle, the flute being directed

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between about 600 to about 300 from the radially outermost point of the receptacle from the centre of the bit body in a clockwise direction.

15. A bit according to claim 14, further comprising a retainer engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle.

16. A bit according to claim 15, wherein the retainer engages the nozzle at a point that is between the seat shoulder and the open end of the receptacle.

17. A bit according to any of claims 14 to 16, wherein the second end of the nozzle extends beyond the open end of the receptacle.

18. A bit according to any of claims 1 to 17, wherein the receptacle and the inside surface of the receptacle are generally cylindrical.

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CLAIMS OF PARENT APPLICATION AS FILED 1. A rotary cone earth boring bit, the bit comprising: a bit body assembly ; at least one rotary cone rotatably mounted on the bit body assembly; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having an outer surface having a stepped portion extending radially outward so as to define a first nozzle shoulder spaced from and facing toward the seat shoulder and a second nozzle shoulder facing opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and a second end opposite thereto defining an orifice at the second end of the nozzle ; and, a retainer concentrically disposed about the outer surface of the nozzle and removably attached to the receptacle, the retainer having a first end engaged with the second nozzle shoulder so as to retain the nozzle in the receptacle and a second end opposite thereto toward the open end of the receptacle.
2. A bit according to claim 1, wherein the second end of the nozzle extends beyond the open end of the receptacle.
3. A bit according to claim 2, wherein the passage has a first cross-sectional area at the first end, a second

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cross-sectional area at a point axially coextensive with the open end of the receptacle and a third cross-sectional area at the orifice, the second cross-sectional area being at least about 25% of the first cross-sectional area, the passage converging from the second cross-sectional area to the third cross-sectional area.
4. A bit according to claim 3, wherein the second crosssectional area is at least about 60% of the first crosssectional area.
5. A bit according to claim 3 or claim 4, wherein the third cross-sectional area is less than about 75% of the second cross-sectional area.
6. A bit according to any of claims 1 to 5, wherein the orifice is non-axisymmetric relative to the nozzle axis.
7. A bit according to any of claims 1 to 6, wherein the nozzle is keyed to allow rotational location of the nozzle relative to the bit body assembly.
8. A bit according to claim 7, wherein the nozzle is keyed by the stepped portion having at least one notch therein and the bit body assembly has a port with a first end in communication with the receptacle at the same axial extent as the notch such that the notch is locatable opposite the port.
9. A bit according to claim 8, wherein the port has a second end opposite the first end that is in communication to the exterior of the bit such that a tool can be inserted into the port to engage the notch in the stepped portion.

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10. A bit according to claim 8, further comprising a pin slidably disposed within the port and biased to extend through the first end of the port to engage the notch in the stepped portion.
11. A bit according to claim 7, wherein the second end of the nozzle has at least one locating slot and the bit body assembly has at least one reference slot such that the nozzle can be held at a desired rotational location relative to the bit body assembly during installation of the retainer sleeve in the receptacle.
12. A bit according to claim 6, wherein the stepped portion of the nozzle has an outer circumferential surface that has a nozzle groove and wherein the bit body assembly has a port with one end in communication with the receptacle at the same axial extent as the nozzle groove, and wherein a pin is disposed through the port and in engagement with the nozzle groove.
13. A bit according to claim 12, wherein the pin prevents rotational movement of the nozzle relative to the receptacle.
14. A bit according to any of claims 1 to 13, wherein the nozzle is constructed of a wear-resistant material.
15. A bit according to claim 14, wherein the wear resistant material is primarily tungsten carbide.
16. A bit according to any of claims 1 to 15, wherein the retainer is a sleeve.

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17. A rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto extending beyond the open end of the receptacle, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the passage having a first cross-sectional area at the first end, a second cross-sectional area at a point axially coextensive with the open end of the receptacle and a third cross-sectional area at the orifice end, the second crosssectional area being at least about 25% of the first crosssectional area; the passage converging from the second cross-sectional area to the third cross-sectional area; and, a retainer removably engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle, the retainer engaging the nozzle at a point that is between the seat shoulder and the open end of the receptacle.
18. A bit according to claim 17, wherein the second crosssectional area is at least about 60% of the first crosssectional area.

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19. A bit according to claim 17 or claim 18, wherein the third cross-sectional area is less than about 75% of the second cross-sectional area.
20. A bit according to any of claims 17 to 19, wherein the nozzle has an outer surface defining a circumferential stepped portion extending radially outward so as to define a first nozzle shoulder spaced from and facing toward the seat shoulder and a second nozzle shoulder facing opposite thereto.
21. A bit according to claim 20, wherein the retainer is a sleeve concentrically disposed about the outer surface of the nozzle and having an outside surface removably attached to the inside surface of the receptacle, the sleeve having a first end engaged with the second nozzle shoulder of the stepped portion so as to retain the nozzle in the receptacle and a second end opposite thereto toward the open end of the receptacle.
22. A bit according to claim 21, further comprising an annular seal located between the seat shoulder of the receptacle and the first nozzle shoulder of the stepped portion of the nozzle.
23. A bit according to any of claims 20 to 22, wherein the orifice is non-axisymmetric relative to the nozzle axis.
24. A bit according to claim 23, wherein the nozzle is keyed to allow rotational location of the nozzle relative to the bit body assembly.

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25. A bit according to claim 24, wherein the nozzle is keyed by the stepped portion having at least one notch therein and the bit body assembly has a port with a first end in communication with the receptacle at the same axial extend as the notch such that the notch is locatable opposite the port.
26. A bit according to claim 25, wherein the port has a second end opposite that is in communication to the exterior of the bit such that a tool can be inserted into the port to engage the notch in the rib.
27. A bit according to claim 25, further comprising a pin slidably disposed within the port and biased to extend through the first end of the port to engage the notch in the rib.
28. A bit according to claim 17, wherein the second end of the nozzle has at least one locating slot and the bit body assembly has at least one reference slot such that the nozzle can be held at a desired rotational location relative to the bit body assembly during installation of the retainer in the receptacle.
29. A bit according to any of claims 17 to 28, wherein the receptacle has receptacle threads and the nozzle has an outer surface that has nozzle threads threadedly engaged with the receptacle threads.
30. A bit according to claim 29, wherein the retainer is located between the nozzle threads and the seat shoulder.

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31. A bit according to claim 30, wherein the outer surface of the nozzle at a point between the nozzle threads and the first end of the nozzle has a nozzle groove and wherein the bit body assembly has a port with one end in communication with the receptacle at the same axial extent as the nozzle groove, and wherein the retainer is a pin disposed through the port and in engagement with the nozzle groove.
32. A bit according to claim 31, wherein the pin prevents rotational movement of the nozzle relative to the receptacle.
33. A bit according to claim 29, wherein the retainer is located between the receptacle threads and the open end of the receptacle.
34. A bit according to claim 33, wherein the outer surface of the nozzle has a circumferential nozzle groove and the inside surface of the receptacle has a circumferential receptacle groove at generally the same axial extent as the nozzle groove, and wherein the retainer is a C-shape clip removably disposed in the nozzle groove and the receptacle groove to retain the nozzle in the receptacle.
35. A bit according to any of claims 1 to 34, wherein the receptacle and the inside surface of the receptacle are generally cylindrical.
36. A nozzle, the nozzle comprising a body with a generally cylindrical outer surface having a centre axis and having a longitudinal direction from a first end to a second end opposite thereto, the body having a passage therethrough from the first end to the second end of the

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nozzle, the outer surface having a stepped portion located near the first end of the nozzle and extending radially outward and having a first nozzle shoulder spaced longitudinally from the first end and facing in the longitudinal direction toward the first end and a second nozzle shoulder opposite thereto facing in the longitudinal direction toward the second end, the outer surface of the nozzle at all points other than the stepped portion being radially inward of the stepped portion.
37. A nozzle according to claim 36, wherein the passage has an orifice at the second end and has a first crosssectional area at the first end that tapers radially inward to a second cross-sectional area of at least 25% of the first cross-sectional area at a point beyond the longitudinal midpoint of the nozzle, the passage transitioning from the second cross-sectional area to the orifice with the orifice having a third cross-sectional area that is less than about 75% of the second crosssectional area.
38. A bit according to claim 36 or claim 37, wherein the nozzle is constructed of a wear-resistant material.
39. A bit according to claim 38, wherein the wear resistant material is primarily tungsten carbide.
40. A rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a cone axis and a cone surface extending from a nose toward the centre of the bit

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body to a gage side opposite thereto, the cone surface having a plurality of cutting elements extending therefrom; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto extending beyond the open end of the receptacle, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle defining at least one flute therein that slopes in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle; and, a retainer removably engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle, the retainer engaging the nozzle at a point that is between the seat shoulder and the open end of the receptacle.
41. A bit according to claim 40, wherein the flute is directed toward at least one of the cones.
42. A bit according to claim 41, wherein a plane bisecting I the flute and extending in the flute direction first intersects one of the cones at a point between the radially outermost point of the cone relative to the cone axis and about the midpoint of the cone surface.

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43. A bit according to claim 42, wherein the cutting elements are arranged around the cone surface in rows, and wherein the plane bisecting the flute first intersects one of the cutting elements at a point within the radially outermost two rows of cutting elements.
44. A bit according to claim 40, wherein the flute is directed radially outward of the bit body assembly.
45. A bit according to claim 40, wherein the flute is directed between about 70 to about 160 or between about 220 to about 290 from the radially outermost point of the receptacle in a clockwise direction.
46. A bit according to any of claims 40 to 45, wherein the internal passage has more than one flute.
47. A bit according to any of claims 40 to 46, wherein the orifice is round.
48. A bit according to any of claims 40 to 46, wherein the orifice has at least two lobes and the internal passage has a flute corresponding to each lobe.
49. A rotary cone earth boring bit, the bit comprising: a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a rotational axis and extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone having an outer surface with a plurality of cutting elements extending therefrom;

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the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle having three or fewer flutes therein, each flute sloping in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle, the flute being directed between about 700 to about 160 or between about 200 to about 290 from the radially outermost point of the receptacle relative to the centre of the bit body in a clockwise direction.
50. A bit according to claim 49, further comprising a retainer engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle.
51. A bit according to claim 50, wherein the retainer engages the nozzle at a point that is between the seat shoulder and the open end of the receptacle.
52. A bit according to any of claims 48 to 51, wherein the second end of the nozzle extends beyond the open end of the receptacle.
53. A rotary cone earth boring bit, the bit comprising:

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a bit body assembly; at least one rotary cone rotatably mounted on the bit body assembly, the cone having a rotational axis and extending from a nose toward the centre of the bit body to a gage side opposite thereto, the cone having an outer surface with a plurality of cutting elements extending therefrom; the bit body assembly having at least one fluid bore therethrough and a receptacle in communication with the fluid bore, the receptacle having an interior end having a seat shoulder, an open end opposite thereto, and an inside surface; a nozzle having a first end abutted against the seat shoulder of the receptacle and a second end opposite thereto, the nozzle having a passage therethrough having a first end in communication with the fluid bore and an orifice end opposite thereto at the second end of the nozzle, the internal passage having an inside surface, the inside surface towards the second end of the nozzle having only one flute therein, the flute sloping in a flute direction toward the centre of the nozzle as it approaches the second end of the nozzle, the flute being directed between about 60 to about 300 from the radially outermost point of the receptacle from the centre of the bit body in a clockwise direction.
54. A bit according to claim 53, further comprising a retainer engaging the inside surface of the receptacle and the nozzle to retain the nozzle in the receptacle.
55. A bit according to claim 54, wherein the retainer engages the nozzle at a point that is between the seat shoulder and the open end of the receptacle.

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56. A bit according to any of claims 53 to 55, wherein the second end of the nozzle extends beyond the open end of the receptacle.
57. A bit according to any of claims 40 to 56, wherein the receptacle and the inside surface of the receptacle are generally cylindrical.
58. An earth-boring bit, substantially in accordance with any of the examples as hereinbefore described with reference to and as illustrated by Figures 3 to 18 of the accompanying drawings.
59. A nozzle for an earth-boring bit, substantially in accordance with any of the examples as hereinbefore described with reference to and as illustrated by Figures 3 to 18 of the accompanying drawings.