Directable nozzle for rock drilling bits

Abstract

A directable nozzle assembly 100 for a rotary drill bit 10 is disclosed, having a nozzle 110 comprising a generally spherical body 112, and having an extension 114 extending from the body 112. A passage 116 extends through the body 112 and extension 114 portions. A seal 130 is provided for sealing the nozzle 110 to the nozzle boss area 14 of the rotary drill bit 10. A removable retainer 140 is provided having a hollow interior, an angle limiter surface 146, and an interior compression surface 150. In another embodiment is a wear resistant sleeve 160, having a collar 162 with a nozzle seat 164 and a body 170, inserted into a flow port 12 of rotary drill bit 10.

Description

CROSS REFERENCE TO RELATED APPLICATION

None.

BACKGROUND OF THE INVENTION

1. TECHNICAL FIELD

The present invention relates generally to drilling bits used for drilling earth formations. More specifically, the present invention relates to a novel design for a directable jet nozzle for rock bits, which works in combination with a retaining system which defines limits of angular orientation.

2. DESCRIPTION OF RELATED ART

In the exploration of oil, gas, and geothermal energy, drilling operations are used to create boreholes, or wells, in the earth. These operations normally employ rotary and percussion drilling techniques. In rotary drilling, the borehole is created by rotating a tubular drill string with a drill bit secured to its lower end. As the drill bit deepens the hole, tubular segments are added to the top of the drill string. While drilling, a drilling fluid is continually pumped into the drilling string from surface pumping equipment. The drilling fluid is transported through the center of the hollow drill string and into the drill bit. The drilling fluid exits the drill bit at an increased velocity through one or more nozzles in the drill bit. The drilling fluid then returns to the surface by traveling up the annular space between the borehole and the drill string. The drilling fluid carries rock cuttings out of the borehole and also serves to cool and lubricate the drill bit.

One type of rotary rock drill is a drag bit. Early designs for drag bits included hard facing applied to steel cutting edges. Modern designs for drag bits have extremely hard cutting elements, such as natural or synthetic diamonds, mounted to a bit body. As the drag bit is rotated, the hard cutting elements scrape against the bottom and sides of the borehole to cut away rock.

Another type of rotary rock drill is the roller cone bit. These drill bits have rotatable cones mounted on bearings on the body of the drill bit, which rotate as the drill bit is rotated. Cutting elements, or teeth, protrude from the cones. The angles of the cones and bearing pins on which they are mounted are aligned so that the cones roll on the bottom of the hole with a controlled amount of slippage. One type of roller cone cutter is an integral body of hardened steel with teeth formed on its periphery. Another type has a steel body with a plurality of tungsten carbide or similar inserts of high hardness that protrude from the surface of the body. As the roller cone cutters roll on the bottom of the hole being drilled, the teeth or carbide inserts apply a high compressive load to the rock and fracture it. The cutting action of roller cone cutters is typically a combination of crushing, chipping and scraping. The cuttings from a roller cone cutter are typically a mixture of moderately large chips and fine particles.

When drilling rock with a roller cone cutter, it is imperative to remove the cuttings from the bottom of the hole. Failure to remove the cuttings from the hole-face will result in redrilling the cuttings. Redrilling rock cuttings substantially reduces the rate of penetration and causes premature failure of the roller cone drill bit. Roller cone drill bit cutting structures and bearing systems are both susceptible to premature failure when cuttings are not promptly removed from the hole-face when drilling. As an example, cutting structures may begin to track in a pattern that prevents normal progressive drilling. Build-up of cuttings or grindings of rock may quickly erode the metal surrounding the inserts, reducing the area of retention. This may allow inserts to be released in a catastrophic failure of the drill bit. Similarly, cuttings and grinds may build-up behind journal shirttail sections causing erosion and exposure of ball-plugs and seals, also resulting in catastrophic failure of the drill bit.

The importance of optimizing drilling hydraulics in oil and gas exploration has long been known. Drill bit manufacturers provided plastic slide rules to operators and contractors for many years, allowing them to calculate the various hydraulic components. In the late 1970's, Field Engineers used programmable calculators for the same purpose. In 1980, Reed Rock Bit® introduced an interactive microcomputer program for Field Engineers planning well drilling and hydraulics programs. A goal of these calculations, however made, was the proper selection of nozzles for the drill bits.

Various theories of hydraulics optimization have been advanced in oil and gas exploration. One popular theory relies upon maximization of a calculated numeric known as Hydraulic Horsepower. Another popular theory relies upon maximization of a calculated numeric known as Jet Impact Force. Both theories depend upon calculation of the pressure losses in the drilling system and allocating the optimum amount of remaining available pressure loss through the nozzles. Utilization of the theoretical optimum available pressure loss is achieved, in part, by increasing or decreasing the velocity through the nozzles. The velocity is adjusted by changing the cross-sectional area of the nozzle through which the fluid flows. Since nozzles in conventional drilling bits are interchangeable, this is easily accomplished.

Coincident to the practice of optimizing jet nozzle selection, it is known that the distance between the nozzle exit and the hole-face is an important factor in optimizing drilling hydraulics, and thus rate-of penetration. The closer the nozzle exit to the hole-face, the better the bottom hole cleaning properties. As the nozzle exit approaches the hole-face, there is less intervening turbulent flowing drilling fluid to interfere with the cleaning action of the fluid flowing from the nozzle. Conventional drill bits are limited by manufacturing practices as to how far up nozzle bosses can be manufactured, and still allow journals to be turned on machine centers. There is also a counterbalancing constraint requirement to provide sufficient return area across the drill bit for drilling fluid and cuttings to navigate the drill bit geometry in transit to the annulus of the well bore.

In addition to proximity to the hole-face, it has been determined that the angularity with which the fluid strikes the bottom of the hole can have a substantial impact on the hydraulic cleaning of the hole-face, and thus rate-of penetration. Drill bits and formations have different physical characteristics, leaving the optimum angle of nozzle direction relegated somewhat to experimentation between drill bits and formations. Additionally, the practice of high-speed drilling in which drill bits are rotated in excess of 100 rpm can change the optimum angle of nozzle direction. There is a counterbalancing constraint in which excessive angular disposition of the nozzle may contribute to cone erosion or seal exposure.

Numerous attempts have been made to provide a commercially practical directable nozzle design, as well as extended nozzle designs. U.S. Pat. No. 6,585,063 issued to Larsen discloses a multi-stage diffuser nozzle for rolling-cutter bits. The nozzle may comprise two or more portions, including a diffuser upstream of the nozzle outlet and a multi-outlet nozzle. The nozzle must be oriented as it is inserted and fixed in a given orientation.

U.S. Pat. No. 6,571,887 issued to Nguyen et al. discloses a nozzle retention body welded to the bit body between adjacent bit legs. The nozzle retention body may be of differing configuration and orientation, but it retains a generally conventional nozzle.

U.S. Pat. No. 6,390,211 issued to Tibbitts discloses a ball-mounted nozzle for a fixed-cutter bit or a rolling-cutter bit. The nozzle body is spherical and seats in a spherical receptacle. A retainer ring is used to secure the nozzle against rotation in the seat. U.S. Pat. No. 6,186,251 issued to Butcher discloses modifying the nozzle size or orientation with the intention of modifying the force balance.

U.S. Pat. No. 5,992,763 issued to Smith et al. discloses a nozzle having an indentation adjacent the nozzle opening or exit to enhance the flow of drilling fluid entrained near the face of the nozzle. U.S. Pat. No. 5,967,244 issued to Arfele discloses an “indexed” nozzle for fixed-cutter bits. The nozzle has a grooved exterior with corresponding grooves in a lock ring.

A primary disadvantage of several of the known art designs is that they are difficult and expensive to manufacture. Several of the designs are not compatible with the nozzle boss on standard rock bits having interchangeable nozzles. When modifications to the bit itself are required, the several costs associated with non-standard designs, such as tooling and machine set-ups, further increase the cost.

Another disadvantage of several of the known art designs is the time required for assembly of the drill bits. In the drilling industry, drill bit selection decisions are often made while drilling, in response to the drilling rate achieved and the condition of the dull bit removed from the hole. Several of the known art designs require welding operations which have proven to be an impediment to their acceptance in the drilling industry.

Another disadvantage of several of the known art designs is that they are not reusable. Sintered tungsten carbide nozzles are expensive, and operators expect to be able to reuse them. When dull drill bits are removed from the well, nozzles are removed and reused or recycled.

A significant disadvantage of the known art directable nozzle designs is that they are capable of being aligned in a manner that creates excessive turbulence around the nozzle boss and seal areas, resulting in hydraulic erosion of the steel around the nozzle boss, known-as “wash-outs,” and premature failure of the drill bit.

Another significant disadvantage of the known art directable nozzles is that they are capable of being aligned in a manner detrimental to the hydraulic performance of the drill bit. Still another significant disadvantage of the known art directable nozzles is that they are capable of being aligned in a manner which can result in improper alignment and premature bit failure from erosion of cones and/or exposure of journal bearing seals.

Thus it can be seen that, collectively, the known art fails to resolve the issue of a need for a directable nozzle that is inexpensive to manufacture, that is cost effective, that is easy to install, that is reusable, that has a restricted range of disposition, that avoids wash-outs, and that avoids poor hydraulic performance from misalignment.

SUMMARY OF THE INVENTION

The present invention is a significant improvement over that described in the above enumerated known directable nozzle designs. References to the present invention are intended to refer to one of more of the various embodiments disclosed of which can be inferred from the disclosure contained herein.

A principal advantage of the present invention is that it provides a nozzle system that has a designed restricted directability. As a result of this feature, rig floor assemblies by untrained personnel can be completed without risk of various problems associated with known directable nozzle designs. A benefit of this feature is that the present invention prevents excessive nozzle angularity resulting in internal turbulence around the nozzle boss and seal areas, hydraulic erosion and premature failure of the drill bit. Another benefit of this feature is that the present invention prevents excessive nozzle angularity resulting in inefficient hydraulic performance of the drill bit. Another benefit of this feature is that the present invention prevents excessive nozzle angularity resulting in improper alignment and premature bit failure from erosion of cones and/or erosion of shirttail regions and exposure of journal bearing seals.

Another advantage of the preferred embodiment of the present invention is that it is inexpensive and easier to manufacture than conventional designs. The design is compatible with the nozzle boss on standard rock bits having interchangeable nozzles. Another advantage of the present invention is the time required for assembly of the drill bits. No welding is required, and nozzle size selections can be made at the rig floor, immediately prior to connecting the drill bit to the drill string. This is critical as optimization of the nozzle selection requires knowledge of the drilling fluid and hydraulic system parameters at the time and depth the previous drill bit is removed from the wellbore.

Another advantage of the present invention is that it is reusable. Other advantages of the present invention will become apparent from the following descriptions, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a directable nozzle assembly for a rotary drill bit is disclosed, having a nozzle comprising a generally spherical body, and having an extension extending from the body. A passage extends through the body and extension portions. A seal is provided for sealing the nozzle to the nozzle boss area of the rotary drill bit. A removable retainer is provided having a hollow interior, a threaded external surface, an angle limiter surface, and an interior compression surface.

In another preferred embodiment, the angle limiter surface is frustum shaped. In another preferred embodiment, the interior compression surface is spherically shaped. In another preferred embodiment, the retainer has a wrench receptacle on a first end. In still another preferred embodiment, the retainer has a second end seal surface which restricts expansion of a packing seal. In the preferred embodiment, the limiter surface of the retainer prevents misalignment between a first portal of the nozzle body and the flow port of a rotary drill bit.

In an alternative preferred embodiment, the nozzle has a first portal on the spherical body and a second portal on the extension portion. An erosion resistant hollow sleeve is provided, having a collar portion with a spherical seat for receiving the nozzle body. The sleeve also has a hollow cylindrical body portion. A seal is provided for sealing the sleeve to the nozzle boss area of the rotary drill bit. In a more preferred embodiment, the body has a tapered end. In the preferred embodiment, the angle limiter surface of the retainer prevents misalignment between the first portal of the nozzle body with the hollow center of the sleeve. Additional features are presented in detail herein below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a rotary drill bit having a directable nozzle assembly installed in accordance with a preferred embodiment of the present invention.

FIG. 2 is a top view of the rotary drill bit of FIG. 1, illustrating multiple directable nozzle assemblies installed in accordance with a preferred embodiment of the present invention.

FIG. 3 is a side-sectional view of a known art interchangeable nozzle assembly installed in a rotary drill bit.

FIG. 4 is an exploded side-sectional view of the components of a directable nozzle assembly in accordance with a preferred embodiment of the present invention, as shown in reference to a rotary drill bit.

FIG. 5 is a side-sectional view of the preferred embodiment disclosed in FIG. 4, illustrating the nozzle directed in an axis parallel to the axis of the flow port of the rotary drill bit.

FIG. 6 is a side-sectional view of the preferred embodiment disclosed in FIGS. 4 and 5, illustrating the nozzle directed in an axis of maximum angular relation to the axis of the flow port of the rotary drill bit.

FIG. 7 is a side-sectional view of a directable nozzle assembly, installed in a rotary drill bit, and utilizing an erosion resistant sleeve in accordance with another preferred embodiment of the present invention.

FIG. 8 is a side-sectional view of an extended directable nozzle assembly, installed in a rotary drill bit, utilizing an erosion resistant sleeve in accordance with another preferred embodiment of the present invention.

FIG. 9 is a side-sectional view of a directable nozzle assembly, installed in a rotary drill bit, utilizing an erosion resistant sleeve, and having a seal disposed within the sleeve, in accordance with another preferred embodiment of the present invention

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an isometric view of a rotary drill bit 10 having a directable nozzle assembly 100 installed in accordance with a preferred embodiment of the present invention. FIG. 2 is a top view of rotary drill bit 10 of FIG. 1, illustrating multiple directable nozzle assemblies 100 installed in accordance with a preferred embodiment of the present invention.

FIG. 3 is a side-sectional view of a known art interchangeable nozzle assembly 200 installed in a nozzle boss 14 of rotary drill bit 10. In the view, it is seen that a nozzle 210 is non-directable. Nozzle 210 is secured in fixed alignment with a flow port 12 in rotary drill bit 10. A seal 130 is located in a groove 16 to prevent drilling fluid from bypassing nozzle 210. Drilling fluid passes through flow port 12 of rotary drill bit 10 and then through a nozzle passage 216 of nozzle 210. The drilling fluid enters a first portal 218 and exits a second portal 220, which is significantly smaller in diameter than first portal 218. Nozzle 210 is secured in position by a retainer 240. Retainer 240 has a nozzle boss connection means for securing retainer 240 to rotary drill bit 10. Most conventional nozzle boss connection means incorporate threaded external surfaces 244 which is thread connectable to a threaded portion 22 of nozzle boss 14 to hold nozzle assembly 200 in place.

FIG. 4 is an exploded side-sectional view of the components of directable nozzle assembly 100 in accordance with a preferred embodiment of the present invention, as shown in reference to rotary drill bit 10. A nozzle 110 is provided, having a spherical body portion 112. An extension portion 114 extends from body 112. A nozzle passage 116 extends throughout body 112 and extension 114. Nozzle passage 116 has a first portal 118 located on body 112. A second portal 120 is located on extension 114.

A retainer 140 is provided, having a functionally unique structure. Retainer 140 has a nozzle boss connection means 144. In the preferred embodiment, nozzle boss connection means 144 is a threaded external surface 144. Retainer 140 may have a wrench receptacle 142 on its top surface, and a limiter surface 146 extends downward and inward from the top of retainer 140. In the preferred embodiment, limiter 146 is contoured for complementary engagement with extension 114. In a more preferred embodiment, limiter 146 forms a frustum, or conic section, for engagement with a generally cylindrical extension 114.

A contoured compression surface 150 extends downward from limiter 146. In a preferred embodiment, compression surface 150 is contoured for complementary engagement with nozzle body 112. In a more preferred embodiment, compression surface 150 forms a spherical segment. Also in a preferred embodiment, a small chamfer 148 is located between limiter 146 and compression surface 150.

As with conventional rotary drill bits previously described, rotary drill bit 10 has a flow port 12. A nozzle boss 14 is formed on rotary drill bit 10 for receiving nozzle assembly 100. In the preferred embodiment, nozzle boss 14 has a retainer connection means 22. In the preferred embodiment, retainer connection means is a threaded portion 22 for threaded coupling to retainer 140. A groove 16 is receivable of a seal 130. A bore relief 20 may separate threaded portion 22 from groove 16. A base 18 is formed at the bottom of groove 16. A nozzle seat 24 is formed below base 18. In the preferred embodiment, seat 24 is contoured for complementary engagement with nozzle body 112. In a more preferred embodiment, seat 24 forms a spherical segment.

FIG. 5 is a side-sectional view of nozzle assembly 100 installed in rotary drill bit 10, illustrating nozzle 110 directed in an axis coincident to the central axis of flow port 12, in a manner similar to the orientation of conventional nozzle assemblies, as illustrated in FIG. 3. FIG. 6 is a side-sectional view of nozzle assembly 100 installed in rotary drill bit 10, illustrating nozzle 110 directed in an axis of maximum angular relation to the central axis of flow port 12.

FIG. 7 is a side-sectional view of an alternative preferred embodiment of directable nozzle assembly 100, shown installed in rotary drill bit 10. In this embodiment, nozzle assembly 100 further includes an erosion resistant sleeve 160. As seen in FIG. 7, sleeve 160 is insertable into nozzle boss 14 below nozzle 110. Sleeve 160 has a collar 162. Collar 162 engages base 18 of nozzle boss 14, and resides in groove 16 in place of, or in conjunction with, seal 130. A nozzle seat 164 is formed on collar 162. In the preferred embodiment, seat 164 is contoured for complementary engagement with nozzle body 112. In a more preferred embodiment, seat 164 forms a spherical segment.

Sleeve 160 has a body portion 170 that extends into flow port 12 beyond first portal 118 of nozzle 110. In a more preferred embodiment, a taper 172 is inscribed on the inside diameter of body 170. In this embodiment, a seal 180 is located in bore relief 20 of nozzle boss 14 to prevent drilling fluid from bypassing nozzle 110. In a more preferred embodiment, seal 180 is a packing seal.

FIG. 8 is a side-sectional of an alternative preferred embodiment of directable nozzle assembly 100, shown installed in rotary drill bit 10. In this embodiment, extension 114 of nozzle 110 is significantly extended. The significant extension of extension 114 is compatible with all embodiments of the present invention.

FIG. 9 is a side-sectional view of another preferred embodiment of directable nozzle assembly 100, shown installed in rotary drill bit 10. In this embodiment, sleeve 160 further includes a seal groove 168 for accommodation of a seal 190. In the preferred embodiment, seal 190 is an o-ring seal. As shown in FIG. 9, another o-ring seal 130 can be located in groove 16 to seal with collar 162 of sleeve 160. However, the use of seal 190 is also compatible with the embodiments disclosed in FIGS. 7 and 8, in which seal 180 is located in bore relief 20.

The foregoing detailed description is to be clearly understood as being given by way of illustration and example, the spirit and scope of the present invention being limited solely by the appended claims. In particular, and by way of example and not limitation, it is well known to use alternative nozzle boss connection means to retain nozzles in rotary drill bits other than retainers with threaded connections. Conventional nozzle assemblies alternatively include nozzles having circumferential grooves and nozzle bosses with holes. In these assemblies, a “nail” is driven into the hole in the nozzle boss, for intersection with the circumferential groove to retain the nozzle. It would be readily apparent to anyone of ordinary skill in the art that the presently disclosed inventive embodiments can be incorporated into such assemblies. For example, the top to nozzle boss 14 can be modified to function as limiter surface 146, and multiple grooves can be formed on the surface of nozzle body 112 to accept the nail at various positions.

OPERATION OF THE INVENTION

FIG. 2 is a top view of rotary drill bit 10, illustrating multiple directable nozzle assemblies 100 installed in accordance with a preferred embodiment of the present invention. In this view, it can be seen that second portals 120 are angled toward the leading surface of the cutting structures of rotary drill bit 10. This capability is a principal objective of the present invention. However, excessive angularity may subject the cutting structure and bearing system to erosion resulting in premature failure. Likewise, excessive angular orientation can result in misalignment of flow ports 12 and first portals 118, generating turbulence and erosion inside rotary drill bit 10, resulting in premature failure. For these reasons and others, another principal objective of the present invention is to provide a predetermined, restricted range of angular orientation of directable nozzle assemblies 100.

FIG. 4 is an exploded side-sectional view of the components of directable nozzle assembly 100 in accordance with a preferred embodiment of the present invention, as shown in reference to rotary drill bit 10. As seen in the preferred embodiment illustrated, nozzle 110 has a spherical body portion 112 that enables multidirectional rotation of nozzle 110. This capability is best seen in reference to FIG. 5 and FIG. 6.

Still referring to FIG. 4, extension 114 of nozzle 110 serves a dual purpose. First, extension 114 positions second portal 120 closer to the object of delivery of the drilling fluid. This is well known and documented to improve hydraulic cleaning of the bottom of the hole. Secondly, extension 114 provides an index for engaging limiter 146 of retainer 140 to provide a predetermined, restricted range of angular orientation of directable nozzles 110. This is best seen in FIG. 6.

In the preferred embodiment, retainer 140 may have wrench receptacle 142 on its top surface and threaded external surface 144 for threaded and removable assembly in conventional rotary drill bits 10. Unique to the present invention, limiter surface 146 extends downward and inward from the top of retainer 140. In the preferred embodiment, limiter 146 is contoured for complementary engagement with extension 114. In a more preferred embodiment, limiter 146 forms a frustum, or conic section, for engagement with a generally cylindrical extension 114. The engagement with extension 114 with limiter 146 defines the maximum obtainable angular orientation of directable nozzles 110. This relationship is illustrated in FIG. 6.

Nozzle passage 116 extends throughout body 112 and extension 114, with first portal 118 located on body 112 for entrance of the drilling fluid, and second portal 120 located on extension 114 for exit of the drilling fluid. Second portal 120 is generally smaller in diameter than first portal 118. The flow of the drilling fluid is thereby accelerated through nozzle passage 116, obtaining the desired high-velocity necessary to improve the performance of the rotary drill bit 10.

Referring again to FIG. 4, retainer 140 has a contoured compression surface 150 extending downward from limiter 146. In a preferred embodiment, compression surface 150 is contoured for complementary engagement with nozzle body 112. In a more preferred embodiment, compression surface 150 forms a spherical segment.

Similarly, in the preferred embodiment, rotary drill bit 10 has a nozzle seat 24 formed in nozzle boss 14 below base 18. In the preferred embodiment, seat 24 is contoured for complementary engagement with nozzle body 112. In a more preferred embodiment, seat 24 forms a spherical segment.

The geometric orientation of seat 24 is inverse to that of compression surface 150. In this configuration, as retainer 140 is progressively threaded into nozzle boss 14 of rotary drill bit 10, nozzle body 112 is compressed between compression surface 150 of retainer 140 and seat 24 of rotary drill bit 10. The compressive force on nozzle body 112 maintains nozzle 110 in place, while resisting the high outward force generated in nozzle passage 116 by the flow of the drilling fluid. The force against nozzle 110 is distributed in the threaded engagement between external threads 144 of retainer 140 and threaded portion 22 of nozzle boss 14.

As with conventional rotary drill bits previously described, nozzle boss 14 has a threaded portion 22 for threaded coupling to retainer 140, and a groove 16 for location of a seal 130, such as an o-ring seal. This advantageously allows convenient interchangeability between directable nozzle assembly 100 and conventional nozzle assembly 200 in rotary drill bit 10.

FIG. 5 illustrates nozzle 110 directed in an axis coincident to the central axis of flow port 12, in a manner similar to the orientation of conventional nozzle assemblies, as illustrated in FIG. 3. FIG. 6 illustrates nozzle 110 directed in an axis of maximum angular relation to the central axis of flow port 12. As seen in this view, the maximum angular relation is predefined by interference between limiter 146 and extension 114.

A principal advantage of the present invention is that by predefining the range of angular orientation of directable nozzles 110, catastrophic failure of rotary drill bit 10 can be avoided. This is particularly important because nozzles 110 can be easily assembled on the floor of the drilling rig by persons unfamiliar with the risk of improper orientation. Another advantage of this relationship is that retainers 140 can be provided which have different limiter 146 settings, and whereas retainers 140 are identified by the angle obtained with extension 114 engaging limiter 146. This can be used to obtain the specific angular orientation desired. The desired angle may be determined by drilling parameters and experimentation. Personnel can then select a retainer 140 identified to provide the angle, without the need for special alignment tools and gauges and training on their use.

As seen in the preferred embodiment disclosed in FIG. 6, limiter 146 restricts angular orientation of nozzle 110, and contains first portal 118 within alignment of flow port 12. Additional angularity would position first portal 118 of nozzle 110 substantially out of alignment with flow port 12, with flow port 12 substantially blocked by nozzle body 112. This causes at least three significant problems. First, the turbulence generated would subject nozzle boss 14 to rapid erosion from the flow of the drilling fluid. Seals 130 would fail, resulting in retainer 140 erosion, and premature failure of rotary drill bit 10. Retainers 140 are traditionally made of steel, and are quickly eroded if exposed directly to the drilling fluid flow stream inside rotary drill bits 10. Second, this configuration effectively reduces the orifice size of first portal 118, disrupting the designed fluid dynamics of nozzle 110's design, and causing an increase in the pressure loss in the system. Third, additional turbulence is generated by the misalignment of first portal 118 and flow port 12, causing an increase in the pressure loss in the system. These second and third affects result in a possible requirement to reduce the pump speed at the drilling rig floor to manage the pressure in the system, reducing the system flow rate, and resulting in poor performance of rotary drill bit 10.

FIG. 7 is a side-sectional view of an alternative preferred embodiment of directable nozzle assembly 100. In this embodiment, nozzle assembly 100 further includes an erosion resistant sleeve 160, designed to prevent erosion from turbulence inside flow port 12 that is unique to directable nozzle assembly 100. Sleeve 160 is insertable into conventional nozzle boss 14 below nozzle 110.

As with conventional rotary drill bits previously described, nozzle boss 14 has a threaded portion 22 for threaded coupling to retainer 140, and a groove 16 for location of a seal 130, such as an o-ring seal. This advantageously allows convenient interchangeability between directable nozzle assembly 100 and conventional nozzle assembly 200 in rotary drill bit 10.

As seen in FIG. 6, as nozzle 110 is directably positioned, first portal 118 increases in proximity to one side of flow port 12, and decreases in proximity to the opposite side of flow port 12. Where first portal 118 is in close alignment with flow port 12, flow is efficient and turbulence is minimized. Where first portal 118 is not in alignment with flow port 12, a discontinuity in the flow path exists, and turbulence is generated where drilling fluid engages nozzle body 112, instead of entering first portal 118. This results in erosion of flow port 12.

The above described turbulence will occur even though portal 118 is maintained within flow port 12 by engagement of limiter 146 with extension 114. Over time, the turbulence will subject nozzle boss 14 to erosion. Seals 130 are therefore at increased risk of failure, as are retainer 140 and rotary drill bit 10. Sleeve 160 provides an erosion resistant channel that will tolerate the turbulence generated within flow port 12.

Referring again to FIG. 7, sleeve 160 has a body portion 170 that extends into flow port 12 beyond first portal 118 of nozzle 110. The outside diameter of body 170 of sleeve 160 fits in close tolerance or slight interference fit with the inside diameter of flow port 12. In a more preferred embodiment, a taper 172 is inscribed on the inside diameter of body 170. Taper 172 permits a smooth transition for drilling fluid in flow port 12 entering sleeve 160.

Sleeve 160 has a collar 162 that engages base 18 of nozzle boss 14, and resides in groove 16 in place of, or in conjunction with, o-ring seal 130. As rotary drill bits 10 are normally inverted for nozzle installation, this configuration allows collar 162 to suspend sleeve 160 in position while nozzle 110 is fitted into place.

A nozzle seat 164 is provided on collar 162, providing the function and benefit of nozzle seat 24 inside nozzle boss 14. In the preferred embodiment, seat 164 is contoured for complementary engagement with nozzle body 112. In a more preferred embodiment, seat 164 forms a spherical segment.

The geometric orientation of nozzle seat 164 is inverse to that of compression surface 150. In this configuration, as retainer 140 is progressively threaded into nozzle boss 14 of rotary drill bit 10, nozzle body 112 is compressed between compression surface 150 of retainer 140 and nozzle seat 164 of sleeve 160. The compressive force on nozzle body 112 maintains nozzle 110 in place, while resisting the high outward force generated in nozzle passage 116 by the flow of the drilling fluid. The compressive force on nozzle body 112 further secures sleeve 160 in place, compressed between nozzle 110 and base 18.

In the preferred embodiment, nozzles 100 and sleeves 160 are made of a hard metal, such as tungsten carbide, or titanium carbide. The hardness of the hard metal nozzles provides wear resistance to the abrasive forces associated with the high-velocity flow of the drilling fluid through the constricted diameter of nozzles 100, and the turbulence generated in the vicinity of sleeves 160.

In the preferred embodiment disclosed in FIG. 7, an alternative seal configuration is also disclosed. In this embodiment, a seal 180 is located in bore relief 20 of nozzle boss 14 to prevent drilling fluid from bypassing nozzle 110. In a more preferred embodiment, seal 180 is a packing seal.

FIG. 9 discloses another seal configuration for use with this embodiment. In this embodiment, sleeve 160 further includes a seal groove 168 for accommodation of a seal 190. In the preferred embodiment, seal 190 is an o-ring seal. As shown in FIG. 9, another o-ring seal 130 can be located in groove 16 to seal with collar 162 of sleeve 160. However, the use of seal 190 is also compatible with the embodiments disclosed in FIGS. 7 and 8, in which seal 180 is located in bore relief 20.

FIG. 8 is a side-sectional view of directable nozzle assembly 100, in which extension 114 of nozzle 110 is significantly extended. The significant extension of extension 114 is compatible with all of the disclosed embodiments of the present invention.

The foregoing detailed description is to be clearly understood as being given by way of illustration and example, the spirit and scope of the present invention being limited solely by the appended claims.

Claims

1. A directable nozzle assembly for a rotary drill bit, comprising:

a nozzle comprising: a generally spherical body; an extension extending from the body; and, a passage extending through the body and extension;

a seal; and,

a removable retainer comprising: a hollow interior; a nozzle boss connection means; a limiter surface; and, an interior compression surface.

2. The directable nozzle assembly of claim 1, further comprising:

wherein interference between the limiter surface and the extension limits the angular disposition of the nozzle passage relative to the retainer.

3. The directable nozzle assembly of claim 1, the nozzle further comprising:

a first portal formed at the intersection of the passage and the body; and,

a second portal formed at the intersection of the passage and the extension.

4. The directable nozzle assembly of claim 2, further comprising:

the limiter surface preventing location of the first portal beyond a flow port in a rotary drill bit.

5. The directable nozzle assembly of claim 1, wherein the nozzle boss connection means further comprises a threaded external surface.

6. The directable nozzle assembly of claim 1, the retainer further comprising:

the limiter surface being frustum shaped.

7. The directable nozzle assembly of claim 1, the retainer further comprising:

the interior compression surface being spherically shaped.

8. The directable nozzle assembly of claim 1, the retainer further comprising:

a wrench receptacle on a first end.

9. The directable nozzle assembly of claim 1, the retainer further comprising:

a second end seal surface; and,

wherein the seal surface restricts expansion of a packing seal.

10. A directable nozzle assembly for a rotary drill bit, comprising:

a nozzle comprising: a generally spherical body; an extension extending from the body; a passage extending through the body and extension; a first portal formed at the intersection of the passage and the body; a second portal formed at the intersection of the passage and the extension; and,

a hollow sleeve comprising: a collar having a seat receivable of the nozzle body; a body insertable into a flow port of a rotary drill bit; and,

a seal; and,

a removable retainer comprising: a hollow interior; a nozzle boss connection means; a limiter surface; and, an interior compression surface.

11. The directable nozzle assembly of claim 10, the sleeve further comprising:

wherein the collar of the sleeve is receivable in a seal groove of a rotary drill bit.

12. The directable nozzle assembly of claim 10, further comprising:

wherein the outside diameter of the body is receivable in close tolerance fit within a flow port of a drill bit.

13. The directable nozzle assembly of claim 10, further comprising:

wherein the outside diameter of the body is receivable in interference fit within a flow port of a drill bit.

14. The directable nozzle assembly of claim 10, the sleeve further comprising:

a taper at the end of the body opposite to the collar.

15. The directable nozzle assembly of claim 10, the sleeve further comprising:

a seal slot located in the collar.

16. The directable nozzle assembly of claim 10, further comprising:

wherein interference between the limiter surface and the extension limits the angular disposition of the nozzle passage relative to the retainer.

17. The directable nozzle assembly of claim 10, further comprising:

the limiter surface preventing location of the first portal beyond a inside diameter of the sleeve body.

18. The directable nozzle assembly of claim 1, wherein the nozzle boss connection means further comprises a threaded external surface.

19. The directable nozzle assembly of claim 10, further comprising:

wherein the sleeve is made of a material having a hardness greater than the hardness of a flow port of a rotary drill bit in which the sleeve is installed.

20. The directable nozzle assembly of claim 10, further comprising:

wherein the sleeve is made of tungsten carbide or titanium carbide.

21. A rotary drill bit, adapted for use with a directable nozzle assembly, comprising:

a flow port;

a nozzle boss connected to the flow port;

a retainer connection means;

a groove for receiving a seal; and,

a spherical segment shaped nozzle seat adapted for complementary engagement with a spherical nozzle body.

22. The rotary drill bit of claim 22, further comprising:

the nozzle seat being in the shape of a spherical section.

23. The rotary drill bit of claim 22, the retainer connection means further comprising:

an internally threaded portion.

24. The rotary drill bit of claim 22, further comprising:

a bore relief; and,

a packing seal located in the bore relief.

25. A rotary drill bit, comprising:

a flow port;

a nozzle boss connected to the flow port;

a retainer connection means;

a groove for receiving a seal;

a spherical segment shaped nozzle seat;

a seal located in the groove;

a nozzle comprising: a spherical body complementarily engaged with the nozzle seat; an extension extending from the body; and, a passage extending through the body and extension; and

a removable retainer comprising: a hollow interior; a nozzle boss connection means connected to the retainer connection means; a limiter surface through which the extension of the nozzle extends; and, a spherical segment interior compression surface complementarily engaged with the nozzle body.

26. A rotary drill bit, comprising:

a flow port;

a nozzle boss connected to the flow port;

a retainer connection means;

a bore relief;

a groove;

a seal located in the bore relief;

a nozzle comprising: a generally spherical body; an extension extending from the body; a passage extending through the body and extension;

a hollow sleeve made of wear resistant material, comprising: a collar located in the groove of the nozzle boss; a spherical segment shaped nozzle seat on the collar; a body located in the flow port; and, a hollow interior; a nozzle boss connection means connected to the retainer connection means; a limiter surface through which the extension of the nozzle extends; and, a spherical segment interior compression surface complementarily engaged with the nozzle body.