US2687823A - Gun perforator port seal - Google Patents

Description

Aug. 31, 1954 R. A. WHITMORE 2,687,823 GUN PERFORATOR PORT SEAL Filed Sept. 23. 1949 therein.

Patented Aug. 31, 1954 UNITED STATES GUN PEREORATOR PORT SEAL Raymond A. Whitmore, Alhambra, to Lane-Wells Company, Los

Calif., assignor Angeles, ,Calif., a.

corporation of Delaware Application September 23, 1949, Serial No. 117,423

perforators, the sealin meansof the present invention is particularly suited to use in the firing ports in the bodies of perforators employing high explosive shaped charge-perforator units of the type, for example, disclosed in the copending application of Will H. Lindsay, Jr. and Robert A. Phillips, Serial No. 106,567.

Heretofore sealing means such as flat disc or dome shaped members have been employed to close the ports in the various types of perforator bodies to exclude fluids therefrom which are usually present in well boreholes and into which the perforators must be lowered. Such sealing means were usually forced or pressed into suitable ccunterbored recesses formed at the outer ends of the ports. In order to obtain a tight seal, free from leakage against the high fluid pressures encountered in deep well boreholes, it was necessary that the port counterbore and seal disc or dome be accurately fitted to one another. The maintenance of the required accuracy of fit after several firings of the perforator units was found to be difiicult. Furthermore, the sealing element was usually dislodged upon firing, to fall into the well bore or at times to become wedged between the perforator body and the surrounding casing.

An object of this invention is, therefore, to provide an improved portsealing device free of the disadvantages and difficulties heretofore prevalent in such means.

Another object is to provide means to, retain the port sealing parts in the gun port after the explosive has been fired, thereby avoiding the leaving of metal parts in the well.

Another object is to provide sealing apparatus for gun ports consisting of parts which are inexpensive to manufacture, easily installed and removed, and not requiring the maintenance of close dimentional tolerances.

I The objects are attained, in general, in the following manner:

Each port in the perforator is counterbored from the outer end and undercut or underreamed at the inner end of the counterbore to form an inwardly flared annular lockin recess terminating in an outwardly facing, annular sealing shoulder. A strong, relatively thick metal sealing disc 1 Claim. (01. 220--27) is provided for each port, each such disc having a diameter slightly less than the minimum inside diameter of the counterbore thereby to permit the disc to be inserted from the outside of the port and placed against the annular sealing shoulder at the inner end of the counterbore. The disc is formed with a beveled edge which conforms generally in slope to the tapered surface of the locking recess and formin therebetween an annular, outwardly flared, locking recess. ,A

. cup-shaped retainer having a deformable cylindricalportionslidably fitting the counterbore of the gun port is provided to be inserted into the portfrom the outside and to be driven against the beveled edge surface-of the disc and into the flared locking recess formed by theclearance space between the edge surface of the disc and the said adjacent inwardly flared, underreamed portion of the port, thereby to wedge and lock the sealing disc in place. A gasket, separate from or attached to the sealing disc, may be interposed between the disc and said shoulder to insure a fluid tight, sealingof the gun port.

In the accompanying drawings which show by way of illustration, a preferred embodiment of the invention, and in. which like reference characters designate the same or similar parts throughout the several views:

Figure 1 is an elevational View, partly in longitudinal section, of a perforator body assembly as it appears in condition to be lowered into a Well;

, Figure 2 is a cross-sectional view taken on line 22 of Figure 1;

Figures 3 and l are respectively an end view and a side view of the gun port gasket;

Figures 5 and 6 are respectively an end view and a side view of the thick sealing disc;

Figure 7 is an end view of the deformable retainer; and

Figure 8 is a cross-sectional view taken on line 8-43 of Figure '7.

A fully assembled perforator is illustrated in Figure 1 in condition to be lowered into a well by conductor cable 9. The perforator which may be constructed in general as disclosed in copending application of Will H. Lindsay, Jr. and Robert A. Phillips, Serial No. 106,567, comprises a body in the form of an elongated tubular member or cylinder Hi provided with a series of laterally directed firing ports H, such ports being illustrated here as arranged in a spiral pattern, al-

though other arrangements may be employed as desired. Within the axial bore of body [0, opposite each port I I, in position to discharge through the port, is mounted a shaped charge unit indicated generally at l2. By preference each charge i2 is made up of a shaped charge of high explosive enclosed in a frustro-conical casing 83 of plastic or other suitable material, having an open forward end and a closed rear end. A crosswise passage M is provided in the rearward end thereof through which a suitable firingcord 85, such as Primacord, for example, extends for detonating the charge.

Shaped charge units 12 may be supported in accurate alignment with respect to their respective firing ports ii in any suitable or desired manner such as that disclosed in the beforementioned copending application or such as by means of a sleeve liner l6 composed of fibre, plastic or other suitable material which makes a slidable fit within the interior of the gun body 18. The liner is formed with large openings l6a for supporting the forward ends of the casings of the charge units l2 and diametrally opposite small openings ilib for supporting the rearward ends thereof as shown in Figures 1 and 2. In loading the perforator, sleeve liner it together with the charges l2 assembled therein, is inserted into the axial bore of cylindrical body it through its upper end, before the same is closed by the cable head portion ii to which suspension cable 9 is attached.

Attention will now be given to the sealing of the firing ports III with which the present invention is directly concerned. Each of the before mentioned ports H, in the perforator body Hi, is formed with an outer counterbored portion 26 terminating in an intermediate, inwardly, divergingly flared, undercut or underreamed portion, forming an annular recess 22 of greater diameter than the outer counterbored portion, the said counterbored and recessed portion terminating in an outwardly facing, annular shoulder 2!, said flared recess portion 22 and said shoulder 2! providing thereby a locking recess as hereinafter more fully described. A relatively thick disc of suitable material such as soft steel, brass or the like, having a maximum diameter slightly less than that of counterbore is inserted through the latter and positioned against shoulder 2i as indicated in Figures 1 and 2. Sealing disc-24 is provided with a tapered or beveled edge 26, the slant or taper of which is substantially the same as that of the wall 23 of the undercut or locking recess 22 of the port. To insure a fluid tight seal, a gasket of rubber or other resilient material of the form shown in Figures 3 and 4 may be interposed between disc 24 and shoulder 21. Gasket 25 may be a separate part as shown or may be cemented, bonded or otherwise attached to disc 24.

In order to lock disc 24 in place, a cup-shaped or annular retainer 2? as best shown, in Figures 7 and 8, is provided having a deformable skirt or cylindrical tubular portion whose outside diameter is substantially equal to the maximum diameter of disc 25, so that the cylindrical portion may be inserted through counterbore 20 of the gun port and the inner end thereof bear against the sloping surface of the tapered or beveled edge portion of disc 24. Continued inward motion of the retainer 21 then results, by the outward wedging action of the beveled edge of the disc, in the expansion or outward deformation of the cylindrical or skirt portion of retainer 2? into the annular space between the beveled edge surface-of disc 24 and the flared wall 23 of the recess 22, so as to wedge the sealing disc 2 securely against gasket 25 and shoulder 2|.

In order to facilitate such expansion or distortion laterally of the cylindrical or tubular skirt .portion of retainer 2'5, such portion may be slotted longitudinally at a plurality of circumferentially spaced points as best shown at 28 in Figures '7 and 8, to form thereby a series of fingers 29. Retainer 2'! need not have a closed end but is preferably formed with a large central aperture 30 to give a free path therethrough to the blast or jet of the shaped charge after the latter has perforated sealing disc 24.

In sealing the gun ports H, gasket 25, if separate from disc 24, is inserted through counterbore 26 and placed in position against shoulder 2 l Disc 24 is then inserted with its tapered edge 25 facing outwardly; The cylindrical or skirted portion of retainer 21 is next inserted inwardly through counterbore 20 until the ends of fingers 29 contact the tapered edge surface of disc 24. A hammer, or hammer and punch, is then utilized to force retainer 21 inward into counterbore 20 whereupon the tapered edge 26 of the thick sealing disc 26 causes the fingers 29 to be flared outwardly into the annular space between edge 26 of the disc and tapered wall 23 of recess 22, thereby securely wedging disc 24 against gasket 223 and shoulder 25. Disc 24 is then held solidly in place against fluid as well as mechanical pressures in either direction. Hence, upon firing, the blast or jet of the shaped charge l3 merely perforates the center of disc 2d, before it perforates the well casing and adjacent formation, allowing all port sealing parts to remain in place. A pry puller (not shown) is utilized to remove retainer 2? after the erforator is raised to the surface. The puller has a lateral lip which is hooked through hole 38 in retainer 2'! and inserted between the annular bottom portion of the retainer 2i at the edge of the aperture 313, and the remaining portion of the perforated disc 24. By prying up on the retainer and down against the now perforated sealing disc 24, the retainer is removed without difliculty, whereupon, the subsequent removal of the disc 24 and gasket 25 is readily accomplished. Gasket 25, sealing disc 24 and retainer 27 are thus expendable and must be replaced after each shot.

From the above it will be apparent that the present invention has the advantage of providing for positive and efiicient sealing of the gun ports of a well perforator, that the sealing method and sealing parts of the invention may be applied to old as well as new perforator bodies by the simple expedient of undercutting the gun ports adjacent their abutment shoulders to form the locking recesses into which the retainer fingers are expanded, and that strong, thick, sealing discs may be utilized without danger of leaving them or the retainers in the well. Another advantage in the present invention is the lack of any requirement for maintaining precise fits between the ports and the port sealing means. Thus distortion or slight erosion of the port resulting from repeated firing of the perforator charges will not prevent effective sealing of the port. The useful life of the perforator body is thus extended considerably.

While the invention has been herein illustrated and described in what is now considered to be a preferred embodiment, it is to be understood that the invention is not limited to the specific details thereof but covers all changes, modifications and adaptations within the scope of the appended claims.

What is claimed is:

In a well perforator the combination comprising: a hollow body having a port extending through its walls, said port being formed with an outer counterbored portion extending inwardly from the outer end thereof and terminating in an intermediately located, undercut, annular recess of larger internal diameter than said counterbored portion and forming thereby an outwardly facing, annular shoulder and an adjacent, coaxial, inwardly facing shoulder, said shoulders being located intermediate the inner and outer ends of said port; an imperforate sealing disc having a beveled edge and positioned in port closing engagement with said outwardly facing shoulder, with said beveled edge facing convergingly outward; and an open-ended annular retainer member having an integral cylindrically tubular, inwardly extending flange portion, said flange portion having longitudinally 20 extending slots therein which extend from the inner end thereof for a portion only of the length thereof, said flange portion having an initial inside diameter substantially equal to the minimum diameter of said sealing disc, the slotted portion of said flange portion extending coaxially into said counterbored portion and being forcibly flared at its inner end over said outwardly facing beveled edge of said disc and into wedging engagement between said beveled edge of said disc and the said inwardly facing shoulder portion of said undercut recess surrounding the edge of said disc, whereby said disc is retained and locked in said position of engagement with said outwardly facing shoulder.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 381,920 Gemunden et al. May 1, 1888 929,974 McNutt Aug. 3, 1901 1,189,922 Daly July 4, 1916 1,303,175 Draper May 6, 1919 2,029,606 Bredtschneider Feb. 4, 1936 2,350,651 Taubert et al. July 6, 1944

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