Jet nozzle

Nov. 19, 1963

3,111,179

G. A. ALBERS ETAL

JET NOZZLE

Filed July 26, 1960

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ATTORNEY

United States Patent Office

3,111,179

Patented Nov. 19, 1963

3,111,179 JET NOZZLE

Gus A. Albers, Houston, and Edward B. Williams, Jr., Greenvine, Tex., assignors, by mesne assignments, to A and B Metal Manufacturing Company, Inc., Houston, ^&amp;Tex., a corporation of Texas

Filed July 26,196®, Ser. No. 45,373 4 Claims. (Cl. 175—393)

This invention relates to jet nozzles, and particularly 10 those for discharging abrasive fluids such as the jet nozzles used in rotary drill bits for drilling earth formations.

For example, rotary drill bits, of this character, are equipped with downwardly and sometimes upwardly di- 15 rected nozzle-like openings for discharging powerful jets of drilling fluid downwardly between the cutter teeth and onto the bottom of the bore hole to remove cuttings rapidly and to induce upward flow of drilling fluid for carrying the cuttings to the top of the bore hole. Such 20 powerful jets have been very successful in cleaning the teeth of the bit and clearing the bottom of the hole so 'that the teeth of the bit are continuously cutting on new formation, thereby greatly increasing the efficiency of the bit. However, the drilling fluid contains abrasive mate- 25 rial, with the result that the surfaces of the nozzle-like openings are soon eroded.

This difficulty has been relieved by constructing the jet nozzles of an extremely hard and dense metal or metal alloy that is resistant to erosion by the abrasive action 30 of the high pressure drilling fluid. Because of the difficulty of machining such hard material, the jet nozzles are usually of cylindrical shape and have an outer diameter to contain a conical cavity necessary to form and direct the jets of drilling fluid. Also, due to the difficulty in 35 machining the metal, the jet nozzles are simply inserted within the open ended recesses that are provided in the body of the drill bit, and are retained by a lock-ring fitted into an annular groove that is inset within the open end of the recess. Because it is necessary to make the jet ⁴⁸nozzle cylindrical, it is obvious that they contain a substantial amount of metal and are expensive. Also, the high pressure fluid acting on the conical surface exerts such high pressure on the retaining rings that the jet nozzles are difficult to retain in the body of the bit, with ⁴⁵the result that the jet nozzles are often pushed out by the pressure into the bottom of the bore hole where they are destructive to the teeth of the bit.

It is therefore the principal object of the present invention to provide a jet nozzle of less expensive construe- 50 tion and which, if it becomes lost, is readily disintegrated by the teeth of the bit, without damaging the bit.

Another object of the invention is to provide a jet nozzle with an inner thin walled shell of wear resistant material and to provide the exterior shape by an outer 55 breakable casing of inexpensive nonmetallic material such as a synthetic plastic, whereby the jet nozzle may be produced inexpensively by premolding the shell of a tungsten carbide material and molding the plastic about the shell.

Another object of the invention is to provide a jet nozzle with a tungsten carbide shell having sufficiently high density to withstand abrasion and destruction by chemical action of the fluids.

A further object of the invention is to provide an improved jet nozzle for replacement of conventional jet nozzles.

. In accomplishing these and other objects of the invention as hereinafter pointed out, we have provided improved structure, the preferred form of which is illustrated in the accompanying drawings, wherein:

FIG. 1 is a sectional view through the bottom of a bore hole being drilled by a rotary bit equipped with jet nozzles embodying the features of the present invention.

FIG. 2 is a fragmentary section through a portion of the body of the bit and the improved jet nozzle contained therein, the section being taken on the line 2—2 of FIG. 1.

FIG. 3 is a similar section, but showing the parts in disassembled and in spaced apart relation to better illustrate the construction.

FIG. 4 is a perspective view of the shell as viewed from the outlet end thereof.

FIG. 5 is a similar view as viewed from the inlet end thereof.

Referring more in detail to the drawings:

designates a bore hole being drilled through an earth formation 2 by a drill bit 3 attached to the lower end of a drill pipe 4. The drill pipe extends to the top of the bore hole 'and is rotated in accordance with the usual practice. The drill bit 3 includes a body 5 that is attached to the lower end of the drill pipe and carries cutters 6 having cutting teeth 7 that roll upon and chip away the bottom of the bore hole. Circulated under high pressure from the top of the bore hole is a drilling fluid that discharges through the body of the bit in one or more downwardly directed jets § that discharge between the teeth of the cutters and onto the bottom of the bore hole to clean the teeth 7 and to clear the bottom of the bore hole of cuttings. The cuttings are washed upwardly of the bore hole on the exterior side of the drill pipe to the upper end thereof, in accordance with rotary drilling of bore holes. The bit body may also be provided with one or more upwardly directed jets 9 to increase the velocity of the upward flow of the drilling fluid.

_ As above described, such drilling fluid contains abrasives and is destructive to the jet orifices 10 and 11 that are provided in the body of the bit. This difficulty has been relieved by providing the body of the bit with recesses 12 for containing jet nozzles or inserts in the shape of a cylinder. The cylindrical jet nozzles are completely formed of extremely hard, highly resistant metal or metal alloy having conical cavities shaped to provide the jet orifices.

As above described, such cylindrical jet nozzles are difficult to manufacture and machine, consequently the machining to retain them is carried out on the body of the bit. The portions 13 of the body of the bit that contain the fluid passageways 14 are counterbored to provide the recesses 12 and form shoulders 15 against which the inlet ends of the jet nozzles abut, and are retained by an expansion ring 16 which is inserted in an annular groove 17 that is inset from the open end IS of the recess 12 as shown in FIG. 2. In order to prevent leakage of the drilling fluid around the exterior of the cylindrical jet nozzle, the recess 12 is encircled by an annular groove 19 containing a sealing element such as an O ring 29.

In order to provide less expensive and more satisfactory jet nozzles, the present invention contemplates a jet nozzle that replaces the present extremely expensive nozzles 60 and which may be retained in a like manner. The jet nozzles of the present invention are of composite construction in that they include a thin walled inner shell 21 of the expensive wear resistant material and an outer casing 22 of less expensive and breakable material that 65 is preferably molded about the circumference of the shell in order to make firm contact therewith and assure complete backing and support of the shell.

The wear or abrasion resistant shell 21 may be constructed by casting or by sintering, but preferably by 70 molding thereof under heat and pressure. The materials used are preferably granules of tungsten carbide or a like alloy and a suitable bonding metal such a cobalt, nickel

3,111,179 or the like, combined under heat and pressure in a mold having a cavity corresponding to the inner and outer contour of the shell. In order to reduce porosity, the grain sizes of the tungsten carbide are regulated to eliminate as much as possible voids between particles.

The shell 21 has a cylindrical neck portion 23, forming the discharge orifice of the nozzle, and a generally conical body portion 24 flaring from the neck portion 23, whereby the base 25 thereof forms the inlet 26 to the nozzle. The wall thickness of the neck and body portions need be only enough to withstand application of the casing 22. The shell is, therefore, of minimum weight and contains a minimum amount of the costly material.

In forming the casing, the shell may be placed coaxially within a cylindrical cavity of a mold (not shown) and the plastic material is extruded into the mold to flow around the shell with sufficient pressure to assure a firm contact with the surface of the shell and to form a smooth exterior cylindrical surface 27 conforming to the cylindrical surface 28 of the recess 12. After the molding operation, there is sufficient cohesion between the plastic material and the exterior surface of the shell to maintain the parts in unitary assembly and assure a solid and firm backing of the thin walled shell. While we have particularly specified a plastic material, other materials may be substituted that are capable of flowing around the shell and which are capable of taking on a set without placing the shell under undue stress. It is also essential that a casing material be selected which will maintain tightness of the shell therein under different temperature conditions to which the jet nozzles may be subjected.

In inserting a jet nozzle constructed as described, the O ring is inserted in the groove 19 and the jet nozzle is inserted in the recess until the base 25 is in abutment with the shoulder 15. After insertion of the jet nozzle, the expansion ring 16 is contracted to a diameter for movement through the open end of the recess 12 until it comes in contact with the end face of the nozzle, whereupon it is allowed to spring into the annular groove 17 to clock the jet nozzle in position.

With the jet nozzle in place, the drilling fluid contacts only the interior surface of the shell 21. The shell 21 thus resists abrasion by the abrasive elements in the drilling fluid, so that the jets may be discharged with sufficient velocity to accomplish the intended purpose. It is obvious that the casing is completely shielded from the erosive effects of the drilling fluid by the shell, and at the same time the casing provides firm and solid backing for the shell.

Should one or more of the jet nozzles become displaced and lost into the bottom of the hole, the casing being relatively soft and the shell relatively frangible are readily broken up by the bit without damaging the teeth of the cutters. Any fragments of the jet nozzle are immediately reduced as to size where they are easily washed to the top of the hole along with the cuttings.

From the foregoing, it is obvious that we have provided a jet nozzle capable of withstanding the abrasion of high pressure jets with a minimum amount of the costly tungsten carbide material. The jet nozzles may therefore be supplied at a comparatively low cost. It is also obvious that the casing portion thereof adequately backs and supports the shell portion. If one or more of the jet nozzles are displaced, it is obvious that the composite unit is readily disrupted and disposed of without damaging the teeth of the cutters.