US2691459A

US2691459A - Disintegrable sealing member

Info

Publication number: US2691459A
Authority: US
Inventors: Raymond A Whitmore
Original assignee: Lane Wells Co
Current assignee: Lane Wells Co
Priority date: 1950-12-14
Filing date: 1950-12-14
Publication date: 1954-10-12
Anticipated expiration: 1971-10-12

Description

Oct. `12, 19754 R. A. WHITMORE 0m N wl. n. M W 0 e ings.

Patented Oct. 12, 1954 UN IT'E'D STATES I'P- if l,-oFf-rica pIsINTEcR-ABLE sEALING MEMBER Raymond A. Whitmore, Alhambra, Calif., assigner toi LanelWells' Company, LosAngeles, Calif.,1 a

corporation of Delaware Application December 14, 1950,.Serial No; 200,824

(CLZZIi-ZW 2 claims. 1

This inventionv relates to gun perforators and ymore specically to uid seals ofthe type .used

located either gun units including'suitable pro-fwk .pulsive charge chambers and barrels adapted t re' bullets through the openings, vor explosive shaped charges which project jets of highkvelocity gases to pierce the casing or formation. Inorder vtotadaptV such tools to being loweredinto fluid filled Well boreholes and'casings, it `is of course desirable to seal the discharge openings in the gun perforator bodies to prevent the ingress of well fluid which would damage lor otherwise be detrimental to the perforating action of the charges. The present invention is particularly concerned with new and improved iiuid sealing means for such purposes.

Heretofore the discharge openings of well perforating gun units or bodies have been-sealed byl various types 4of sealing elements 'which were adapted to be vdislodged by the explosive force or bythe impact of the perforator bullet, and to fall from. the gun vmuzzle or Adischarge opening'into the well casing. Frequently such dislodged seals i hamper subsequentv operations in such ways as by becoming jammed between the gun body and surrounding well Wall or casing, or by becoming entrained in the upward flow of well fluid and blocking or clogging the flow therefrom or by interfering with the action of valves or the like mechanisms. The presence ofsuch sealing elements in the well bore or casing is therefore objectionable.

In an effort to overcome or eliminate some of the before-mentioned objectionable features attendant upon the presence of dislodged fluid sealing bodies in the well or casing, frangible sealing members, usually in the form of discs of cup shaped members made of brass, copper, steel and the like, have been applied to the discharge open- Such seals are fractured, torn-and broken by the bullet or explosive force, and leave as a residue seal fragments which are materially less of a threat to subsequent well-operations. Never-f" tireless, such fragmntsare frequenuy'objecncnable in size, and 'in some `instances Ythe seal-may onlybe pierced, leaving atorn body? in place in v`the gun body, theserrated edgesof which maybe of greater operational hazard than lthe. presence of an Vundamagedbutv dislodged seal.

Sealing devices, heretofore employed, were usually either substantially flat or slightly dished metal discs having integrally formed skirtedperipheries constituting annular sealingy Wallsengag'eable with the inside surfaceof the walls of the discharge openings. AThis form of sealing device requires considerable tensilestrength inthe sea-l l material to withstand the bending stresses set up Within the device by thefiuidpressures encountered within the well borehole, and `the thickness and type of material chosen for use with such forms of sealing devices'nn1st-necessarilyha-ve considerable .ductility and tensile strength. Sealing` devices of this kind are not destroyed b-y the firing of the perforator gun or shaped charge but usually are only perforatedtorn, or merely dislodgedas a result of which they offer the disadvantages and hazards hereinbefore mentioned.

It is, therefore, an object ofthis invention to provide` asealing device of they.: character described in which many of the undesirable and limiting features heretofore prevalent .in such uid seals have been eliminated. y

It is also an object to provide a friable or disintegrable fluid sealing device which, upon impact of a bul-letor an explosive force thereon, will be substantially completely destroyed and thus Will leave substantially'no debris or pieces of appreciable size in the well, as contrasted with the .frangible or ductile seals heretofore employed,

which are only fractured, torn, orbroken into .fragments of substantial size, or of seals which are dislodged intact from the discharge opening.

Another object of the invention is to provide a fluid seal member of uniform conguration free from depending edges or skirts which may be retained in the kdischarge opening or b e discharged therefrom as a Whole ring or. as fragments of' a ring. The present seal body is of such'character that the entire seal is subjected to substantially l uniform disintegrating' force sor that disintegration is complete and distinctfromy rupture or fragmentation commonfin the use of soz-called frangible seals.

Affurther object-of the invention -is to prove y a seal, the configuration andcurvature of which is such as yto, provide a distribution of. the. compressive forces whereby the resultant forces will .act against the'walls of the discharge opening to which it is tted in such manner to withstand great pressures without requiring proportionate strength of material, and whereby such forces will act to aid in the sea-ling of the discharge aperture, the sealing pressure being effectively increased as the pressure to be sealed against increases.

The objects of the invention are accomplished, in general, by composing the fluid seal device of a friable, brittle material such as cast iron, glass, micalex or ceramics and the like, as distinct from ductile material such as copper, brass, steel or rubber, by reason of which such material tears and shears rather than disintegrates.7 The objects are also accomplished by the use of a dome or hemispherical shape for the seal body, the edges of which thrust perpendicularly against an annular seating surface formed in the body of the gun in such manner as to transfer the cornpressive forces from the sealing member as substantially pure compression forces to the said seating surface by virtue of which the tensile strength of the material of which the sealing device is composed may be substantially less than otherwise would be required.

These and other objects, advantages and features of novelty will be evident hereinafter.

The 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 a fragmentary longitudinal sectional view of one form of periorating gun equipped with the seal of the present invention.

Figure 2 is an enlarged detail transverse section taken on line 2-2 of Figure 1.

The perforating apparatus, here shown by way of example as one of the many types of such apparatus to which the seals of the present invention may be employed, is one utilizing shaped charges as distinct from a gun-type perforator using cartridges and bullets. However, it is to be understood that the present seal is advantageously applicable to either type of perforator.

The perforator apparatus, here shown by way of example and to which the seals of the present invention are applied, comprises a hollow, substantially cylindrical body or shell I@ closed at its lower end by a suitable formed tapered bull plug II. The relatively thick wall of the cylindrical body I has a series of longitudinallyspaced radially-directed ports or discharge openings I2 extending therethrough to the inside of the central bore or chamber I3, each opening being enlarged on the outside by a relatively short counterbore I4 of slightly increased inside diameter. An outwardly facing inclined shoulder I5, having a surface of frusto-conical form, interconnects the inner portion of the discharge opening I2 with its outer counterbore IA. A series of a plurality of discharge openings such as that shown at I2, I (only two of which are shown in Figure l for convenience of illustration, duplicate ones thereof having been omitted) may be arranged in any desired pattern. One suitable pattern which is frequently used is that rformed by spacing the discharge openings in a spiral arrangement along the length of the body.

A perforating unit such as shown at It is located opposite and in alignment with each discharge opening. Such units are here disclosed in outline only, and may be either shaped charge units or gun type units including cartridges and perforating bullets as desired. In either case,

the perforating unit is so mounted that the bullet or the jet-shaped blast from the shaped charge unit will be directed outward in a radial direction through the center of the discharge opening i2. In the form of gun here shown, the inner wall of the body IB opposite each of the discharge openings l2 is provided with a radially directed recess I7, the adjacent rear end I8 of each of the shaped charge units IS being cooperatively shaped to fit within and be retained by the recess. As indicated at 2li, the charge unit may include a front retainer sleeve having the approximate shape of a truncated cone and which extends forwardly from the front edge of the body of the unit I5 to engage the inner end of the discharge opening I2, serving thereby to support and to center the adjacent forward end of the charge i3 in accurate axial alignment relative to the center of the discharge opening I2.

For further details of the particular gun herein illustrated, reference may be had to the copending application of Will H. Lindsay and Robert A. Phillips, Serial No. 106,567, led July 25, 1949,

In the form of perforating devices here illustrated, the upper end of the body i0 is closed by a disc 2i, through the center of which extends a fuse 22 leading to the shaped charge perforating units I6. An electric detonator cap 23 is mounted upon the disc 2i and is connected to and controlled by an insulated electrical conductor 24. For closing the upper end of the body lll and securing the disc 2| in place, a threaded sleeve 2d is provided, into which is secured a subconnection or casing 25 which may contain the detonating control mechanism (not shown), and a conductor cable 26 is anchored in a cable socket 25 integral with the top of the casing 25. by means of which the gun may be lowered into and removed from the well. It will be understood that the present invention is not concerned with such structure of the firing control mechanism, electrical connections and other details thereof, and that any equivalent or suitable structure and arrangement of such parts may be employed as desired.

Prior to the time of detonation of the charge or cartridge I, it is essential that the discharge openings I2 be provided with a fluid-tight closure against the admission of well fluid or other substance which might damage the cartridge or propellant charge or in any way interfere with the full, complete and eiiicient firing or detonation thereof. For example, in the case of the shaped charge as illustrated, the shaped cavity and the space ahead of it must be kept free of liquid which would interfere with the proper jet action thereof. Accordingly, a fluid tight, pressure-resistant seal for the opening I2 is provided in the form of a friable, dome-shaped cap 30. The shape or structure of the cap 30 is preferably that of a segment of a spherical shell, having inner and outer spherical surfaces of uniform radius ci curvature and positioned with its convex surface racing outwardly. Since, as before noted, it is desirable not only to remove or pierce the seal upon detonation of the charge or cartridge, but to completely destroy or disintegrate the material thereof, the cap is preferably formed of a friable material which will readily disintegrate into ne particles upon impact of a bullet or explosive blast, as distinct from merely frangible material of considerable relative tensile strength and ductility such as brass, copper, steel or the like. Materials found to have the shattering and disintegrating qualities here desired are those such as glass, castY iron, 'micalex and porcelain and other ceramics of various kinds. Suchr materials have been.,found successful forthe purpose and are here referred to as'suitable for use in the manufacture of the present seal.

Preferably, the dome-like body of the present sealing member 30 is provided with an edge 3l having a ,surface which constitutes a frustum of a cone, the apex of which coincides approximately withvthefcenter of curvature of the spherical inner `and outer surfaces of the body itself. With the hereinbefore mentioned materials, a l 1A, thickness of dome material has been found `suitable for a seal of this shape having a diameter of approximately 1%f diameter.y While expedients offmanufacture may vdictate various departures fromthe uniform internal and external curvatures` and thus a variation from La uniform thickness of the body of the seal as here specied and may vsimilarly dictate variations in the exact angularity of the frusto-conical edge surface, it will be understood that such formation is now deemed advantageous and desirable. However, it will be understood that the invention is in no way limited to the exact configuration referred to except as hereinafter indicated in the claims. Thus, the invention may be practiced, utilizing various curvatures, thicknesses and edge dispositions for the sealing member 30 as determined by one skilled in the art.

By further reference to Figure 2 of the drawings, it will be noted that the surface of the shoulder I5 at the juncture of the opening I2 and its outer counterbore I4 also takes the form of a frustum of a cone, the apex and axis of which coincide with the axis of the opening I2 and the counterbore I4'. As here shown, and as preferred in the practice of the invention, the apex angle included between opposite sides of the frusto-conical surface of the shoulder I4 approximates the angle included between opposite sides of the frusto-conical edge surface of the body of the seal. An included angle of 140 degrees, taken from approximately the center of curvature of the dome, is preferred. If desired, these apex angles may vary, as for instance, such variation as is necessary to make allowance for the thickness of sealing material therebetween after the seal is located and secured, thus providing as accurate conformity as possible between the surface of the seal edge 3I and the shoulder surface I5. However, for most cases, and bearing in mind the size of the parts and the diiiculties of manufacture, a substantial equality of included apex angle will suffice. The invention is, of course, not limited to such specified angularty, but these may be varied somewhat without sacrifice of thinness of the seal member.

In assembling the seal member 30 within the counterbore I4 of the discharge opening I2, a gasket ring 32 of rubber or like flexible or resilient packing material is employed. The ring is preferably formed with a U-shaped, annular channel 33 to receive the edges 3I of the seal member 30 and to surround and cover a marginal portion of such edges in self-sealing engagement. The gasket ring is provided with an outer fillet shaped or meniscus like leg portion 34 of increasing thickness toward its outer periphery 35 to conform with the outward divergence of the surface of the seal with respect to the inside cylindrical surface of the walls of the counterbore I4. The outwardly facing surface of the thickened extremity of the packing ring is preferably curved inwardly to. provide an annular. fillet-like body making a feather edge engagement with both the outside surface of the seal member and withk the inner cylindrical surface-of the counterbore wall. Such arrangement provides for -the pressingof such edgesagainst such surfaces upon the application of uid pressure thereto, thereby providing a self-sealing action to the packing ring.

In the form of the invention herein illustrated, the angle of -inclination of the `frusto-conical edges of the seal member 30 and of the shoulder I5 is substantially equal and is shown as substantially 20 degrees with respect to the-diametrical plane of the opening I2. While `the angularity-of the shoulder I5 and that of the edge surface 3| of the seal member 30 are not necessarily identical, the arrangement, as disclosed, has been found well suited to the functions requiredand the conditions encountered -in- -a uid filled borehole. In considering the effect ofthe shape and angularity of the seal member as hereinbefore described, it will be'noted that uponl being subjected to outside fluid pressures, the dome-like configuration will result in the setting up of circumferential compressional forces through 'the body of the seal member, which forces are directed to the edges thereof, where the angularity of the edge 3I in conjunction with the angularity of the shoulder I5 will result in the transfer of such forces, in the form of substantially pure compression, to the surface of the shoulder I5 of the discharge opening. Thus, the material of the seal member, not being subjected to bending stresses, may have a minimum of tensile strength while still withstanding the required compression stress without breakage. While the angles herein suggested are believed preferable in most instances, circumstances and choice of material may dictate slight variations therefrom. In any event, it is to be noted that a seal member formed as a segment of a spherical shell, as hereinbefore described, will be subjected to compressional stresses only, thereby permitting its formation of a brittle and disintegrable material as herein set forth.

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

What is claimed is:

1. The combination with the discharge opening of an explosive well perforator body having a coaxial counterbore for said opening adjacent the outer end thereof and an outwardly facing, outwardly diverging frusto-conical shoulder surface at the juncture of the said discharge opening and the said outer counterbore, of a sealing member having substantially the shape of a segment of a spherical shell composed of material disintegrable upon impact, said member being bounded by a circular, frusto-conical edge surface, having an apex substantially coinciding with the center of curvature of said shell, and said frusto-conical shoulder surface being formed to substantially conform to the said edge surface; and an encircling, U-shaped seating and packing ring of flexible material interengaging said shoulder and said edge surfaces, the outer leg of the U of said ring being of greater thickness toward its periphery and extending outwardly to lie over a marginal portion of the outer face of the member and make sealing contact with a portion of the inside cylindrical surface of said counterbore.

2. The combination with the discharge opening of an explosive Well perforator body having a coaxial counterbore for said opening adjacent the outer end thereof and an outwardly facing, outwardly dverging frusto-conical shoulder surface at the juncture of the said discharge opening and the said outer counterbore, the angularity of the surface of which is approximately 20 degrees to a plane perpendicular to the axis of said discharge opening, of a sealing member having substantially the shape of a segment of a spherical shell composed of material disintegrable upon impact, said member being bounded by a circular, frusta-conical edge surface, substantially conforming to the said surface of said :truste-conical shoulder; and an encircling, U-shaped seating and packing ring of flexible material interengaging said shoulder and said edge surfaces, the outer leg of the U of said ring being of greater thickness toward its periphery and extending outwardly to lie over a marginal portion of the outer face of the member and make sealing Contact with a portion of the inside cylindrical surface of said counterbore.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 663,879 Gallup Dec. 18, 1900 1,684,292 Turnquist Sept. 11, 1928 1,669,685 Weber May 15, 1928 2,142,572 Metzner Jan. 3, 1939 2,146,586 Evans Feb. 7, 1939 2,216,144 Turechek Oct. 1, 1940 2,250,056 Alexander July 22, 1941 2,258,724 Wagner et al. Oct. 14, 1941 2,261,035 Miller Oct. 28, 1941 2,280,183 Bennett Apr. 21, 1942 2,311,077 Oldham Feb. 16, 1943 2,328,247 Alexander Aug. 31, 1943 2,408,774 Goddard et a1. Oct. 8, 1946 2,426,521 Parker Aug. 26, 1947