US2765739A - Jet carrier sealing plug - Google Patents

Description

Oct. 9, 1956 H. H. Mo HAUPT ET AL JET CARRIER SEALING PLUG 2 Sheets-Sheet 1 Filed Jan. 26, 1951 Haves H. Ma/mupr sews 6746697 INVENTORS fii'faefi/'i Oct 1956 H. H. MOHAUPT ETAL JET CARRIER SEALING PLUG 2 Sheets-Sheet 2 Filed Jan. 26, 1951 m M Z 5 we w nited ttes JET CARRIER SEALING PLUG Application January 26, 1951, Serial No. 207,924

Claims. Cl. 102-20 This invention relates to improvements in means for perforating casing in wells and for perforating and fracturing earth formations around well bores.

Of late years a new and novel method for perforating in wells and particularly in oil and gas wells has been developed in the oil industry. Such method has largely replaced the older method of perforating through the use of bullets and involves instead the use of explosive charges provided with surface cavities which are preferably lined with an inert material such as metal. A multiplicity of such charges, which are generally 'known as shaped charges, are lowered into the well to be perforated and the charges are detonated with their lined cavities directed more or less laterally in the well bore to direct the principal energy of explosion as a jet through the well casing and on into the formation surrounding the well bore. For the purpose of lowering the charges into the wells, it is necessary to provide a carrier for said charges, and an assembly comprising a multiplicity of such charges and a carrier or gun body therefor is generally disclosed and claimed in United States Letters Patent No. 2,494,256, issued January 10, 1950 to Morris Muskat, Floyd W. Parker and William L. Kehl. It will be seen that a gun body disclosed in such patent consists of a tubular body having closed sealed ends and being hollow to receive a multiplicity of the aforesaid charges. The charges in the patent are shown having their lined cavities directed laterally, said charges extending into the gun body which provides an expansion chamber to take up the non-working energy of the detonated charge and thus prevent damage to the casing and the well. Hollow tubular guns of this type have proven to be substantially the only successful means for elfecting the perforation of well casing in wells by the use of shaped charges. Inasmuch as such tubular gun bodies must not only be sealed at top and bottom, but must also be sealed at the gun port for each charge to prevent the ingress of well fluid, each such gun port must be provided with a sealing plug, and it is with such sealing plugs that the instant invention is particularly concerned.

In the devising of such a proper sealing plug several considerations must be dealt with. First, there must, of course, be a complete seal at each gun port, such seal to be eflective under the frequently high hydrostatic heads encountered in the deeper fluid filled wells. Second, it is required that the plug be of such nature that vupon detonation of the charge, debris and the like will not be lodged in the well and expensive bailing out operations made necessary. Third, unless the gun port be exceedingly small, the plug must be of such nature as to choke and restrict the pressures of the detonating gases of the charge which follow the principal energy-containing, laterally directed jet formed by the detonation of the charge, so that such gases will not split the well casing and otherwise damage the well. Fourth, the plug, particularly if of such structure as not to disintegrate upon the detonation of the charge, must be of such nature as under no circumstances to be expelled from the gun port, whereby it becomes penetrates.

2,7557% Patented Get. 9, 1956 debris in the well and may even jam the gun body within the well. Fifth, since the tubular sealed gun body is not intended to be expendable, it is necessary that repeated shooting of the gun not render the gun port unsealable. Since repeated detonation of charges through a gun port will tend to-elongate and enlarge the port, it is necessary therefore that either the plug be adaptable to seal enlarged gun ports or protect the gun ports from such damage.

In an effort to provide a thoroughly satisfactory sealing plug for gun portsin the aforedescribed type of gun body, two principal expedients have been resorted to. The first of these comprises a flat, disk-like, expendable plug which seats in an annular seat at the outer extremity of the gun port over a resilient O-ring placed in such seat, the disk being retained in place by hammering a ductile metal, or the like, about the edges of the disk to wedge said disk into its close fit in the seat. Inasmuch as the hydrostatic pressure head of fluid is directed inwardly, such a sealing means provides an excellent seal. However, since the O'ring is not ordinarily disintegrated by the detonation of the charge, but rather is blown out into the well, an O-ring is ordinarily deposited in the well from each gun port fired through. Since hundreds of shaped charges may be used in the perforating of a single Well, there is thus deposited a considerable amount of debris in the well. The foregoing sealing means is used ordinarily with a reduced size gun port, and thus no gas pressure expulsion problem is presented. Since the plug itself is destroyed by the detonation, there is likewise no problem of expelling the plug into the Well. The plug, of course, afiords no protection to the gun port and thus the gun port is expanded with each use of a shaped charge therewith. To a large extent the plug is adaptable to an expanded gun port but eventually, of course, its adaptive limit is reached. Thus, the disk-like expendable plug, while proven commercially useful and having been used in considerable amount throughout the industry, has the principal disadvantage of providing O-ring debris in the well and the additional disadvantage of failing to provide an entirely satisfactory solution to the problem of expanding gun ports.

The second principal expedient used has been a solid, threaded, non-expendable metal plug adapted to be threaded into the gun port and having a flange seating inan annular recess about the outer extremity of the gun port, a resilient O-ring or equivalent washer being interposed between the seat and the flange. Such a plug is provided with a bore extending from its inner extremity but not penetrating through its outer extremity, a thin wall of metal being left through which the jet from the charge Again, this charge provides an excellent seal for the gun body. Since the plug is intended to be retained in the port after detonation of the charge the O-ring is not ejected into the well. The relatively heavy metal plug restricts the gun port orifice in such fashion as to choke the gas pressure of the detonating charge from damaging the well, and the plug likewise affords protection to the sides of the gun port bore. On the other hand, the plug is retained in the gun body only by its threads and is for this reason subject to accidental expulsion into the well. This condition is particularly aggravated after several reuses of the gun body, after which the sides of the threaded gun port bore have expanded to a certain degree, even though protected by the plug. Such expulsion of the plug into the well has presented a serious problem to the use of this type plug, inasmuch as not only does the occasional expulsion of such a plug provide a serious debris problem but such expulsion may cause, and has caused, actual jamming of the gun body in .the well.

Consequently, it is the particular object of this inveni tion to provide a sealing plug for guns of the above-described type which are so constructed as to be impossible f expulsion from the gun. body on detonation of the shaped charge.

It is a further object of the invention to provide such a gun plug wherein no debris whatsoever is expelled into the well.

Another of the objects of this invention is to provide a sealing plug, which is so constructed as to choke and restrict any gas pressure built up within the gun after detonation of the charge.

A still further obiect of the invention is to provide a plug which effectively protects the sides of the gun port bore in enhanced manner.

Yet another object of the invention is to provide a sealing plug incorporating the above-enumerated advantages and providing the additional function of supporting the shaped charge itself in its proper position within the gun body.

Further objects of the invention will appear hereinafter.

In the drawings:

Figure 1 shows a gun body incorporating the invention lowered in a cased well and ready for the perforating operation.

Figure 2 shows a side elevational view of such gun body, partly cut away, to show the sealing plug and shaped charge positioned therein,

Figure 3 shows a cross-sectional view of the assembly shown in Figure 2, taken along the line 33 thereof.

Figure 4 shows a cross-sectional view of the assembly shown in Figure 2 taken along the line 44 thereof.

Figure 5 shows a perspective view of the principal component of the sealing plug.

Figure 6 shows a modification of the sealing means of the plug.

Figure 7 shows another modification of the sealing means of the plug.

Referring to the drawings and particularly to Figures 1 through 5, the invention in its general aspect shows a plug member 10, having a flange l2 and an extension 14, the extension 14 having outer threads 16. Such plug 19 is threaded into the threaded gun port 29 of the gun body 22, so that the flange 12 seats on the inner surface of the gun body 22. A seal is effected by the use of a resilient sealing means 26 between the flange 12 and the gun body 22. A bore 30 is provided in the plug 20 and sealed by a closure comprising a small flat disk 32 composed of brass or slightly ductile metal which is pressed or hammered in tight fit into the seat 323 of the plug 10. In operation, the shaped charge 4t) detonates and expels a jet through the bore 39, through the disk 32, destroying the same in passage, and through the casing 42 into the formation 4-4. The plug It which is retained within the gun body 22 by its flange 12 cannot, of course, be

expelled into the well, nor can any debris, the sealing means 26' being trapped in the assembly and the disk 32 being destroyed. The restricted orifice provided by the plug chokes off any gas pressure that might damage the well, and the plug and flange l2 protect the wall of the gun port 29 from the excessive effects of detonation. A tube 46 may extend from the bore 30 of the plug to retain the shaped charge 40 in position, but such tube will be destroyed by the jet.

Referring now to the more particular aspects of the invention and its environment, there is shown in the well 48, the gun body 22, which is preferably of heavy steel and has a hollow tubular form. The gun body is provided with a round closure 59 on its lower end and a conical cap 52, such conical cap enclosing a detonating mechanism for the shaped charges 49, and providing for attaching the gun body to the lower end of an electrically wired cable 54 by which the gun body is lowered in the well, and which connects to the detonating mechanism v46, after which the disks 32 are hammered home.

which in turn fires a detonating fuse 56 which sets off the'shaped charges 40.

Each shaped charge 46 includes a housing 58, which housing comprises a conical case having a cylindrical discharge end and a smaller cylindrical detonation initiating end 60, such end being provided with a bore 62 which receives the detonating fuse 56, which fuse passes adjacent a booster-charge, not shown, which detonates the explosive 64 within the housing 58. Extending from the end 60 of the housing 58 is a smallcylindrical end 66 adapted to be received within a recess 68 in thegun body 22. The explosive 64 is provided withta cavity 70, which cavity has a metal liner 72 directed laterally through the gun port 29. Forwardly of the metal liner 72, an annular shoulder 74 is provided in the housing 58 to receive an alignment disk 76, which alignment disk is orificed to receive an extremity of the tube 46 in a manner to be hereinafter described.

Each shaped charge 40 registers with a gun port 20, which gun port threadably receives from inwardly of the gun body the plug element 10. The flange 12 of such plug element, as particularly shown in Figure 4, seats upon an annular seat 78 on the inner surface-of the gun body and compresses an O-ring or equivalent resilient sealing means 26. A keyway 80 is provided on the inner surface of the bore 30 of the plug element 10, so that a keyed rotating tool, not shown, may be thrust through the gun port 20 to thread the plug element 10 into the said gun port. As hereinbefore described, a bore 30 is provided through the plug element 10, and such bore issealed by the disk 32 which is pressed into tight fit into the seat 38 of the said plug.

The shaped charge may be supported in registration with the gun port 20 by auxiliary means, so that the laterally directed jet formed upon detonation of the charge will pass through the bore 30, disk 32, casing 42 and into the formation 44. However, an additional feature of the invention is that it is adapted to the extension of a tube 46 from the inner extremity of the bore 30 to abut by the shoulder 82 of such tube the alignment disk 76 of the charge 40, thereby, positioning in lateral registration with the gun port the said charge 40. An inner threading 84 is provided in the bore 30, and a threaded lock sleeve 86 threads into such bore to urge the said tube 46 against the alignment disk 76.

Assembly of the gun unit in loaded condition is ac complished by removing the closure 50 or conical cap 52, threading the plug elements 10 by the aforementioned keyed tool into the gun ports 20 and threading the charges 40 with the detonating fuse 56, and inserting the same through one end of the gun body, positioning each charge ,so that its cylindrical end 66 projects into one of the recesses 68. Thertubes 46 may thenbe inserted through the bores 30 of the aforesaid plug elements to register the shouldered extremities of such tubes with the orifices ,of the alignment disks76 of the charges 40. The lock sleeve is then threaded into the bore 30 to abut the tube The closure 50 or cap,52, as the case may be, is then replaced,

the. detonating fuse 56, of course, being connected to the detonating mechanism in the cap 52, and the. gun unit is ,-ready for lowering into the well and firing.

It will, of course, be evident that inasmuch as the principal seal of the aforesaid sealing plug is effected by means of the O-ring or equivalent resilient means 26, it is desirable that the plug element 10 be screwed down hard against such means. Figures 6 and 7 show modifications of such sealing means whereby the seal may be enhanced. Figure 6 shows a form of plug element 10 whereby the sealing face of the flange 12 iscut away to provide edge contact with the annular seat 78 of the gun body 22, whereby the sealing means 26 is confined by the edge 38 of the said flange 12. Figure 7 shows the use of a ductile, deformable ring 90 of, soft metal, .such as ,copper or lead, in the seat 78, whereby suchvmetal is deformed upon threading in of the plug element to provide additional sealing means and to assist in confining the sealing means 26.

It will be apparent that the use of the aforedescri-bed invention will provide an efiective sealing plug for shaped charge gun bodies of the type described and will have those attributes outlined which are necessary for optimum performance of the gun. The instant plug seals; it pro vides no debris to be spilled into the well; it chokes gas pressures, which if released might damage the well; it cannot be blown out of the gun port; and it protects the wall of the gun port from excessive damage and distortion due to detonation of the charge. Further, as shown, the sealing plug readily forms part of the structure supporting and aligning the shaped charge with the gun port.

While there has been described what is at present considered preferred embodiments of the present invention, it will be apparent to those skilled in the art that various modifications and changes may be made without departing from the essence of the invention, and it is intended to cover herein all such modifications and changes as come within the true scope and spirit of the appended claims.

We claim:

1. A jet carrier assembly comprising: a gun body having a wall defining a shaped charge enclosing chamber; a threaded port in said gun body wall; a plug removably threaded in said port, said plug being interiorly mounted directly on said gun body wall; a bore through said plug; tool-engaging means in said bore engageable by a plugturning tool; a removable closure on said plug sealing said bore and covering said tool-engaging means; an interior flange on said plug engageable with the inner surface of said gun body wall to prevent outward movement of said plug through said wall upon the firing of a shaped charge; a shaped charge in said chamber held therein by said plug in position to fire a jet through said bore; and deformable sealing means interposed between said inner surface of said gun body wall and said flange.

2. A jet carrier assembly comprising: a gun body having a wall defining a shaped charge enclosing chamber; a threaded port in said gun body wall; a plug removably threaded in said port, said plug being interiorly mounted directly on said gun body wall; a bore through said plug; a removable closure on said plug sealing said bore; a tube supported within said bore and extending inwardly from said bore; a shaped charge being laterally disposed in said gun body and supported by said tube and a portion of said gun body wall opposite said port; an interior flange on said plug engageable with the inner surface of said gun body wall to prevent outward movement of said plug through said wall upon the firing of said shaped charge; and deformable sealing means interposed between said inner surface of said gun body wall and said flange.

3. A jet carrier assembly comprising: a gun body having a wall defining a shaped charge enclosing chamber; a shaped charge being housed and laterally disposed in said chamber; a threaded port in said gun body wall; a plug threaded in said port, said plug being interiorly mounted directly on said gun body wall; a bore through said plug; a closure sealing said bore; a tube extending inwardly from said bore; an alignment disk carried by said shaped charge housing and engageable with said tube to support said charge; a lock sleeve threadable into said bore and abuttable against said tube to urge said tube against said disk; an interior flange on said plug engageable with the inner surface of said gun body wall to prevent outward movement of said plug through said wall upon the firing of said shaped charge; and a sealing means interposed between said inner wall and said flange.

4. A jet carrier assembly comprising: a gun body having a wall definnig a shaped charge enclosing chamber; a shaped charge laterally disposed in said chamber; a threaded port in said gun body wall; a recess in the inner surface of said gun body wall opposite said port, said recess seatably receiving an extremity of said shaped charge; a plug threaded in said port, said plug being interiorly mounted directly on said gun body wall; a here through said plug; a removable closure on said plug sealing said bore; a tube supported within said bore for axial movement therein extending inwardly from said bore; an alignment disk carried by said shaped charge and engageable with said tube to support said charge; means cooperating with said plug for moving said tube inwardly of said bore to firmly seat and hold said shaped charge in said recess; an interior flange on said plug engageable with the inner surface of said gun body wall to prevent outward movement of said plug through said wall upon the firing of said shaped charge; and a deformable sealing means interposed between said inner wall and said flange.

5. A jet carrier assembly comprising: a gun body having a wall defining a shaped charge enclosing chamber; a housed shaped charge laterally disposed in said chamber; a threaded port in said gun body wall; a plug threaded in said port, said plug being interiorly mounted directly on said gun body wall; a cylindrical bore through said plug, the outer end of said plug having a seat comprising an annular recess concentric with said bore and communicating therewith; a closure sealing said bore, said closure comprising a relatively thin metallic disk seated in said annular recess; a tube extending inwardly into said chamber from a point intermediate the ends of said bore; an alignment disk carried by said shaped charge housing and engageable with said tube to support said charge; a lock sleeve threadable into said bore and abuttable against said tube to urge said tube against said disk; an interior flange on said plug engageable with the inner surface of said gun body wall to prevent outward movement of said plug through said wall upon the firing of said shaped charge; and a sealing means interposed between said inner wall and said flange.

References Cited in the file of this patent UNITED STATES PATENTS 2,351,179 Aloi June 13, 1944 2,494,256 Muskat et al. Jan. 10, 1950 2,500,119 Cooper Mar. 7, 1950 2,530,966 Huber Nov. 21, 1950 2,565,788 Tow Aug. 10, 1951 2,680,406 Austin June 8, 1954 OTHER REFERENCES Article by W. T. Box and R. F. Meiklejohn published in World Oils; vol. 130, No. 4; March 1950, pages 112, 116, 118, 121, 122.

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