US2607417A - Gun perforator - Google Patents

Description

J. H. CASTEL GUN PERFORATOR Aug. 19, 1952 Filed Aug. l2, 1948 JNVENTOR few Hmm CMM BY 1./ Huf/m7 ATTORNEY Patented Aug. 19, 1952 GUN PER-FORATOR Jacques Honor Castel, Houston, Tex., vassigner to Perforating Guns Atlas Corporation, Houston, Tex., a corporation ofY Delaware Application August 12, 1948, vSerial No. 43,917

This invention relates to a gun periorator.

The invention has been designed primarily to be used to shoot Vbullets through the casing of a well for the purpose of bringing the inside of vthe casing Vinto communication with the porous earth formation around it from which it is desired to produce a iiuid.

Frequently at the time the casing is perforated with the gun the well is lled with fluid, such as water, mud, oil and the like. In a deep well the hydrostatic pressure developed byrthis fluid becomes very great, attaining, currently, ten thousand pounds per square inch. It is the object oi this invention to provide a gun perforator which is simple in construction and which will prevent the fluid of the well from entering the gun perforator, and specifically, the powder chamber where it vwould wet the powder and cause the gun to misfire.

It isanother object of the invention to provide a novel typeof bullet holder that will maintain the bullet in the desired position with respect to the barrel and the powder chamber irrespective of the hydrostatic pressure created by the iluid outside ofthe gun.

.Itis still another object Iof the invention to increase the penetration power of the bullet, for a given length of barrel, by holding the rear part of the bullet inside of the powder chamber, thus artificially lengthening the travel rof the A'bullet while the propelling power of the gases is applied behind it( It is a further object of the invention ,to increase the penetration power of the bullet by providing, between the powder chamber and the gun bore, a section of progressively decreasing diameter which guides `progressively the gases from the powder chamber to the much smaller diameter bore thus avoiding any turbulence of the gases and loss of power.

It isa further object of the invention to provide a combination of bullet and bullet holder that will resist avery high hydrostatic pressure of thewell, which at the same time will not offer any undue resistance to the motion of the bullet when the ignition. of the powder begins, thus eliminating the possibility of the powder detonating and, as a consequence, damaging or destroying the gun.

A still further object of the invention is to provide a gun perforator in which the ignition of the main powder load is caused by a powerful auxiliary ignition charge, or boo-ster, Vwith the result vthat the main charge is ignited more quickly and more uniformly than by the regular fuse embedded in powder. Y

claims. (Crisi-0.55

Other objectsandadvantages will be apparent from the following specification which is illustrated by the accompanying drawings wherein:

Figure l is a side elevation of a preferred form of gun periorator.

Figure 2 is a cross-sectional view taken on the line 2 2 of Figure 1.

Figure 3 is a side elevation of a bullet employed.

Figure 4 is a cross-sectional view of a bullet holder, and Y Figure 5 is a side elevational view of the bullet and holder assembled, the holder being shown in section.

Referring now more particularly to the drawings wherein like numerals of reference designate the same parts in each of the figures, the numeral I designates the main body ofthe gun perforator whose upperend is screw threaded into the adjacent end of a bell housing 2. There is a cable 3 which has its metallic armor clamped in the rope socket 4 to support the gun and said cable has an inner insulated core 5 to lead theelectric current to the various ignition chambers.l v This core 5 extends through the channel 5 in the body I and it then follows the'groove l, cut in the periphery of the gun body, to connect in parallel all the resistance plugs in the body, such as 8. The resistance plugs carry resistances 9 which are in serieswith the leads I0 that carry the current to the ignition plugs II. Generally the resistance value of resistances 9 changes from plug to plug or from series of plugs, according to the sequence of firing desired.

lThe gun body carries a number of gun chambers, each one having one powder chamber I2', a 'threaded igniter socket I2a, one barrel I3, one bullet holder It, one seal ordinarily made of a resilient compound I5, one gasket I6, and a load of powder I'I. In the igniter socket |211, shown in more detail in Figure 2, is the screw-threaded igniter body I8.

The igniter body, made of heat treated'steel; carries a center bore into which is inserted the firing pin IS, insulated by a tough insulation material 20. A short fuse ZI is soldered one end to the firing pin I9, and the other end to the mass of the igniter body. There is a cup 22 which is lled with loose powder and is inserted at the inner end of the igniter. There is a washer 23 under the igniter flange and a washer 24 under the nut 25 which keep the uid of the well from entering the gun. The leads In are connected to the resistance plugs 3.

Referring to Figure 2, the powder chamber I2 carries a counterbore 26 on the side adjacent the cartridge and into which seats rather loosely the bullet holder I4. The bullet holder rests on the shoulder 21 around the powder chamber `and keeps both the bullet and the bullet holder in position in the chamber, no matter how great is The bullet holder is generally made of mild steel. Its diameter is only a few thousandths of an inch smaller than the counterbore 26 of the powder chamber. The shape of the inner surface of the counterbore 26 is such that it allows ample strength to the bullet assembly and at the same time leads progressively the gases from the burning powder in the chamber to the much smaller diameter of the barrel bore, thus reducing to a minimum the losses of power through turbulence of the gases. Ihe top of the holder which comes into contact with the barrel I3 is preferably tapered not only to keep the explosion gases from leaking between itself and the barrel, butmainly to make the holder resistant to much higher pressures than would a flat holder of the same thickness.

To'assemble thebullet and the bullet holder the point of the bullet is forced through the holder until the tapered groove 28 receives the rim 29 of the holder. Since the bore through rim 29 is smaller than the diameter of the bullet, the bullet is held in the holder.

With this type of bullet assembly, the greater the hydrostatic pressure on seal I5, the higher the pressure of the bullet on the rim 29 of the holder I4. But as this pressure on the ri-m '29 increases, the grip on the bullet increases at the same time. The bullet cannot enlarge the bore through rim 29 because the latter is held in the counterbore and cannot expand. Tests have repeatedly shown that bullet holders having a rim thickness of no more than elf to /Gl and a tapered groove of no more than .015 deep, hold pressure in excess of 35,000 pounds per square inch, which is very ample for the actual conditions encountered in the wells to be perforated. It is absolutely indispensable, from a safety point of view, that the bullet and its holder stand very great pressures. If one holder were to fail under the pressure of the well, the bullet would be projected at great speed toward the chamber and would ignite the powder by the impact developed. This would result in one bullet perforating the casing at the wrong place, necessitating very expensive repair work to the well, and possibly even the loss of the well.

It seems simple at first sight to make the bullet holder hold higher pressure by just increasing the thickness of the metal. But this will have several objections. First, it will increase the price of the holder. Second, it will take up that much more space of the powder chamber, with the consequence of a loss of power. Third, and more important, it will make it much more diicult for the bullet to leave the holder when the powder is red. As a consequence, the pressure will have to become very great inside of the vchamber before the bullet will start moving and such pressure may become high enough to cause the powder to detonate instead of burning normally, and cause the explosion of the gun.

The type of bullet holder described holds very high pressure from the outside, but on the contrary, when the pressure is from inside the chamber, such as happens when the gun is red, the bullet will leave its holder very easily, on account of the smallness of the taper of the groove 28. 'I'his means that the pressure at the inside of the chamber will not become excessive before the bullet starts moving inside the barrel bore, thus eliminating the possibility of damage to the gun. as mentioned above.

Loading the gun preparatory to the gun perforation consists in inserting one igniter in each one of the igniter sockets I2a, one powder load I1 in chamber I2, one bullet holder assembly I 4 in each counterbore 26, one gasket I6, and one sea1 I5 in each barrel I3 and screwing every barrel in the corresponding threaded socket in the gun body. The gun is then ready to be lowered into the well to the desired depth by means of the cable 3 which is spooled on a cable drum at the surface. When this depth is reached, a current is sent through the conductor 5 of the cable. This current ,goes to the variousigniters I8 with `an intensity apportioned to the value of the resistances 9. When the current in one igniter is high enough to make the fuse 2l red hot, the powder in cup 22 is ignited, which in turn ignites suddenly the main powder charge I'I which then drives the bullet with a high muzzle velocity.

When al1 the chambers have been red, the gun is brought to the surface to be reloaded and used again.

What I claim is:

l. In a gun perforator, a'gun body having a powder chamber therein, a barrel in the body having a bore in communication with the powder chamber, a bullet fitted into the inner end of the bore, said bullet having an external, annular. groove which tapers' toward the point of the bullet and a perpendicular shoulder in said bullet groove to prevent backward movement, anannular bullet holder clamped between the barrel and body and having an outwardly converging rim which interlocks in said groove.

2. In a gun perforator, a gun body having a powder chamber therein, a barrel in the body having a lengthwise bore of smaller transverse diameter than the powder chamber and whose inner end is adjacent said chambenran annular bullet holder removably clamped between the barrel and the body, the inner side of thebullet holder forming a wall of the main powder chamber and which is of a progressively decreasing diameter towards the barrel.

3. In a gun perforator, a body having a main powder chamber therein and an ignition charge chamber in communication with the main powder chamber, a barrel in the body having a bore of smaller transverse 'diameter than the main powder chamber and whose inner end is adjacent said main powder chamber, a bullet ltted into the inner end of the bore and having an external annular groove, an annular bullet holder clamped between the barrel and the body and having an outwardly converging rim which interlocks with said groove, the innerside of said bullet holder forming a wall rof the main powder chamber and which is of a progressively decreasing diameter toward the barrel. y

4. In a gun perforator, a body having a main powder chamber therein, a barrel in the body having a bore of smaller transverse diameter than the main powder chamber and whose inner end is adjacent said main powder chamber, a bullet tted into the end of the bore and having an external annular groove tapering toward the point of the bullet and a perpendicular shoulder in said bullet groove to prevent backward movement, an annular bullet holder clamped between the barrel and. the body and having an outwardly converging rim which interlocks with said groove, said bullet holder having a wall coextensive with the Wall of said chamber and of progressively decreasing diameter toward said barrel.

5. In a gun perforator, a body having a powder chamber therein, a barrel in the body having a bore of smaller diameter than the chamber and whose inner end is adjacent said chamber, said body having a counterbore about said chamber adjacent said barrel, a bullet fitted into the end of the bore and having an external annular groove tapering toward the point of the bullet and a perpendicular shoulder in said bullet groove to prevent backward movement, an annular bullet holder in said counterbore clamped between the barrel and the body and having an outwardly 6 converging rim which interlocks with said groove, said bullet holder having a tapered outer face in engagement with said barrel and an inner surface coextensive with the wall of said chamber, said inner face being of progressively decreasing diameter toward said barrel.

JACQUES HONOR CASTEL.

REFERENCES CITED The following references are of record in the :die of this patent:

UNITED STATES PATENTS Number Name Date 1,376,530 Greener May 3, 1921 2,257,276 Reynolds Sept. 30, 1941 2,276,544 Miller Mar. 17, 1942 2,407,081 Johnson Sept. 3, 1946

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