US2960008A

US2960008A - Perforating gun

Info

Publication number: US2960008A
Application number: US642271A
Authority: US
Inventors: Otis J Mccullough
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-02-25
Filing date: 1957-02-25
Publication date: 1960-11-15
Anticipated expiration: 1977-11-15

Description

Ufli t 1 This invention relates to guns for firing projectiles, and more particularly to the type of gun employed for perforating the wall of a Well, such as a casing lining a Well bore, to establish fluid communication between the interior of the casing and the surrounding earth formations. Conventional bullet-firing perforating guns employ relatively intricate and expensive, mechanical, electrical, and gasor flame-employing firing systems for propelling the projectiles or bullets to make the perforations. These are subject to numerous difliculties well-known to those familiar with this art, which it is a principal object of this invention to overcome.

The most common arrangement employed in conventional gun perforators comprises a plurality of gun barrels, each of which carries a bullet and a charge of propellant explosive. The explosive charges for the several bullets are set off from a common firing charge located in a firing chamber relatively remote from the individual barrels, the individual explosive charges being fired by hot gases or flame propagated from the firing chamber through passageways leading to the several bullet barrels. Such an arrangement is subject to many sources of interference with the effective propagation of the gas or flame depended upon for firing the individual bullet-propelling charges and result in frequent mis-firing or ineffective action by the bullets.

The present invention is directed to a new arrangement by which the difiiculties occurring in the operation of more conventional bullet guns, as mentioned above, may be overcome by introducing between the main firing charge and an individual propellant charge, a hydraulic force-transmitting medium. In this way the force of the main firing charge is transmitted through the hydraulic transmitting medium in the form of a powerful compression wave, which is directed against the individual charges of propellant explosive to set them off and propel the bullets through the barrels. In this system, the hydraulic force-transmitting medium may be likened to the firing pin of a percussion-fired gun or the like, and may be exemplified by the term hydraulic firing pin. The force transmitted through the hydraulic fluid to the propellant charges no doubt also supplements the force produced by the explosion of the charge and thus supplements the latter in its propelling action upon the bullet.

It is a primary object, therefore, of this invention to provide a perforating gun of the general character described which employs a hydraulic fluid as a force-transmitting medium from the firing charge of the gun to the individual propellant charges for the several bullets or projectiles fired from the gun.

The terms hydraulic fluid, hydraulic force-transmitting medium, and the like, as used herein, contemplate substantially non-compressible fluids, such as water, oil, grease, materials of plastic character capable of flowing, and mixtures having these characteristics.

It is an important object of this invention to provide a Well perforating gun having one or more barrels in which projectiles are supported, each projectile being propelled States Pa Y 2 from its barrel by the explosion of a powder charge disposed in the projectile-propelling relation thereto, the powder charge being set ofi by force transmitted from a common firing charge acting through a substantially noncompressible substance of fluid character.

A further object is to provide a well perforating gun having one or more barrels in which projectiles are supported and propelled by the explosion of individual powder charges mounted in propelling relation thereto in the barrels, the individual charges being set off by force transmitted from a main firing charge through a confined passage in which is disposed a body of a hydraulic fluid, which acts to transmit the force from the firing charge to the individual propellant charges to cause their ignition.

An additional object is to provide in a bullet firing gun of the general character described, a hydraulic forcetransmitting medium interposed between the main firing charge and the individual bullet propellant charges and to further interpose between the hydraulic medium and the main firing charge an air space which may function as a shock absorber for reaction or recoil from the hydraulic medium.

A further object of the invention is to provide a perforating gun in which the individual propellant charges for the projectiles are fired by force transmitted through a hydraulic medium from a common firing charge.

An additional object is to provide a well perforating gun having one or more barrels in which projectiles are supported, each projectile being propelled from its barrel by the explosion of an individual explosive charge, and having a firing chamber to receive a main firing charge, the firing chamber being connected to the inner ends of each of the barrels by a passageway, there being confined in said passageway a body of a substantially non-compressible fluid for transmitting force from the firing chamber to all of the individual propellant charges, at least a portion of said passage between the firing chamber and the non-compressible fluid being left unfilled with fluid to provide an air-space therein.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing, which illustrates a useful embodiment in accordance with this invention.

In the drawing:

Fig.1 is a longitudinal sectional view of a gun embodying the present invention, the section being taken generally along line 1-1 of Fig. 2;

Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. l; and

Fig. 3 is a cross-sectional view taken along line 3--3 of Fig. 1.

In the illustrative form of the invention, there is provided a body 10 having a threaded pin 11 at its lower end adapted to receive cap or closure 12 and having at its upper end an internally threaded counterbore 13 to receive the threaded plug 15 of a firing head 16 which, at its upper end, has a threaded counterbore 17 for connection thereto of a conventional cable socket 18, from which the suspension means for the gun, shown as a cable 19, extends upwardly.

Body 10 is provided with a plurality of longitudinally spaced, inwardly extending, internally threaded recesses 20, for receiving externally threaded gun barrels 21, alternate ones of which may face in opposite directions, as shown, but which, it will be understood, may face in one direction, if desired. Each of the gun barrels has a bore 22 for receiving a bullet .or projectile 23, which is secured to a shear disk 24 which bears against the inner end of the barrel and forms a closure between the inner end of the barrel, and a chamber 25 which forms an inward extension of recess 21 and is adapted to receive the propellant explosive charge 26, which may be of any conventional character. It will be understood that the gun barrel arrangement and the form of the projectile, the shear disk, and the projectile charges may be of any known and generally conventional construction and arrangement, the .present invention not being limited to the details of these elements.

v A passage 28 .of restricted cross-sectional area leads downwardly from the bottom of counterbore 13 through body to one side of the longitudinal axis of the body, and lateral passages 29 connect passage 28 to propellant chambers 25, as illustrated. In the illustrative example two of the passages 28 are employed, each comrnunicating with one set of the gun barrels-facing in one direction. While a single passage may be employed to connect to all of the propellant chambers, it is generally simpler, mechanically, to provide a separate passage for each set of oppositely facing gun barrels, although if all of the gun barrels face in the same direction, a single passage 28 will be sufficient to connect to all of the propellant chambers of such barrels.

The lower ends of passages 28 are closed, in any suitable manner, as illustrated, by means of the abutting end face 30 of closure cap 12, suitable seals 31 being provided between the end of body 10 and cap 30 to assure a fluid-tight seal between these members.

A fluid 3-2 is contained in passages 28, the fluid 32 having the properties previously mentioned, namely, a substantially non-compressible material of flowable character. In most instances it is preferable that the fluid 32 should not fill passages 28 completely, but that a section, designated 28a, in the upper portions of passages 28 should be left unfilled with the hydraulic fluid. Sections 28a will, of course, contain atmospheric air. The sections 28a perform an important shock-absorbing function, as will be described more fully hereinafter. The body of fluid 32 will preferably be in direct contact with the propellant charges 26.

The threaded plug 15 of a firing head 16 has a bore or recess 35, which defines a firing chamber which is adapted to receive a charge of powder 36, which constitutes a main firing charge, or so-called primer, for the gun. At its inner end, recess 35 is counterbored and internally threaded to receive a choke bushing 37 which communicates at one end with firing chamber 35 and at the other end with a reduced diameter bore 33, in which is seated a conventional explosive ignition cap 40 adapted to be electrically fired in the conventional manner by current provided through a conductor 41, which extends through cable 19 to the surface in accordance with conventional practices for electrically firing fuses or initiating charges in guns of the general character herein described.

In operation of the gun, the parts may be assembled, as in the drawing, with the projectiles 23 in the respective barrel bores 22, and with a body of suitable hydraulic fluid 32, which preferably is water, contained in passages 28 filling the same to a point below or spaced from the upper ends of the passages which communicate with firing chamber 35, the upper sections 28a of the passages 28, above the level of fluid 32 therein, being filled with air. 1e propellant charges 26, firing charge 36, and initiating charge 40 will, of course, be properly installed and the parts otherwise suitably assembled and arranged. Then the gun is lowered into the well by means of cable 19 to a point in the well at which the perforations are to be made, whereupon the initiating charge 40 may be fired and this, in turn, will set off the main firing charge or primer 36. The explosion of the latter will be transmitted through passages 28 to the body of fluid 32 and the forceof that explosion will be transmitted by the hydraulic fluid to the individual propellant charges 26, which will be set off by the impact-ive or compressiveforces thus exerted thereon by the hy- .draulic fluid, and will drive bullets-23 from barrels 22,

the force of the propellant explosive being built up by resistance of shear disk 24, in the well-known manner, to increase the propelling force applied to the bullets.

Since fluid 32 is substantially non-compressible, it will be understood that the force transmitted thereby will be exerted in all directions; hence, it is found in most cases that some relief for forces directed against the surrounding portions of the gun body is desirable and to this end it is usually preferable to provide some type of shock absorbing medium which will afford such relief. An effective shock absorbing arrangement for this purpose is that provided by leaving an air space between the column of fluid 32 and firing chamber 35, this space being filled with air, Will act to absorb recoil forces and prevent shattering of the gun body by the forces applied to fluid 32 by the explosion of the priming charge 36 and propellant charges 26.

By the arrangement described, the force of the explosion from charge 36 will be transmitted substantially simultaneously by means of fluid 32 to all of the several propellant charges 26, so that all of the bullets fire simultaneously and with maximum efliciency.

It will be understood that various changes and modifications may be made in the details of the illustrative embodiment within the scope of the appended claims, but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A perforating gun comprising a gun barrel having a projectile therein, a firing chamber spaced from the gun barrel to receive a firing charge, a passage connecting the firing chamber to the gun barrel, an explosive propellant charge in the gun barrel disposed in propelling relation to the projectile therein, and a body of a substantially non-compressible material of hydraulic force transmitting character confined in said passage and in contact with said propellant charge, said non-compressible material 'being operable upon ignition of a firing charge in said firing chamber to hydraulically transmit the force thereof to the propellant charge, whereby to set-off the propellant charge and to increase the propelling force on said projectile.

2. A perforating gun comprising a gun barrel having a projectile therein, a firing chamber spaced from the gun barrel to receive a firing charge, a passage connecting the firing chamber to the gun barrel, an explosive propellant charge in the gun barrel disposed in propelling relation to the projectile therein, and a body of a substantially non-compressible material of hydraulic forcetransmitting character confined in said passage and in contact with said propellant charge, said passage having an air space between said firing chamber and said body of material, said non-compressible material being operable upon ignition of a firing charge in said firing chamber to hydraulically transmit the force thereof to the propellant charge, whereby to set-off the propellant charge and to increase the propelling force on said projectile.

3. A perforating gun comprising a gun barrel having a projectile therein, a firing chamber spaced from the gun barrel to receive a firing charge, a passage connecting the firing chamber to the gun barrel, an explosive propellant charge in the gun barrel disposed in propelling relation to the projectile therein, and a body of water confined in said passage and in contact with said propellant charge, said body of water being operable upon ignition of a firing charge in said firing chamber to hydraulically transmit the force thereof to the propellant charge, whereby to set-off the propellant charge and to increase the propelling force on said projectile.

4. A perforating gun comprising a gun barrel having a projectile therein, a firing chamber spaced from the gun barrel to receive a firing charge, a passage connecting the firing chamber to the gun barrel, an explosive propellant charge in the gun barrel disposed in propelling relation to the projectile therein, a body of water confined in said passageand in contact with said propellant charge,

and an air space in said passage between said firing chamber and said body of Water, said body of water being operable upon ignition of a firing charge in said firing chamber to hydraulically transmit the force thereof to the propellant charge, whereby to set-off the propellant charge and to increase the propelling force on said a projectile.

5. A perforating gun comprising a plurality of spaced apart gun barrels each having a projectile therein, a firing chamber spaced from the several gun barrels to receive a firing charge, passage means connecting the firing chamber to the several gun barrels, an explosive propellant charge in each of the gun barrels disposed in propelling relation to the projectile therein, and a continuous body of a substantially non-compressible material of flowable character confined in said passage means and in contact with each of said propellant charges, said non-compressible material'being operable upon ignition of a firing charge in said firing chamber to hydraulically transmit the force thereof to the propellant charges, whereby to set off the propellant charges and to increase the propelling forces on said projectiles.

6. The improvement in a perforating gun as defined in claim 5 wherein said substantially non-compressible material is water.

l 7. A perforating gun comprising a plurality of spaced apart gun barrels each having a projectile therein, a firing chamber spaced from the several gun barrels to receive a firing charge, passage means connecting the firing chamber to the several gun barrels, an explosive propellant charge in each of the gun barrels disposed in propelling relation to the propectile therein, and a continuous body of a substantially non-compressible material of flowable character confined in said passage and'in contact with each of said propellant charges, the volume of said material being less than that of'said passage to thereby define an air-filled space portion in said passage between said chamber and said body of non-compressible material.

'8. A perforating gun comprising a plurality of spaced apart gun barrels each having a proj chamber spaced from the several gun barrels to receive a firing charge, passage means connecting the firing chamber to the several gun barrels, an explosive propellant charge in each of the gun barrels disposed in propelling ectile therein, a firing I relation to the projectile therein, and a continuous body of water confined in said passage means and in contact with each of said propellant charges.

9. A perforating gun comprising a plurality of spaced apart gun barrels each having a projectile therein, a firing chamber spaced from the several gun barrels to receive a firing charge, passage means connecting the firing chamber to the several gun barrels, an explosive propellant charge in each of the gun barrels disposed in propelling relation to the projectile therein, a continuous body of a substantially non-compressible material of fiowable character confined in said passage and in contact with each of said propellant charges, and shockabsorbing means comprising an air-filled space in said passage between said firing chamber and said body of non-compressible material.

10. A perforating gun, comprising, a body having a plurality of spaced apart inwardly extending gun barrels each having a projectile therein, a firing chamber spaced from the inner ends of the several gun barrels to receive a firing charge, restricted diameter passage means connecting the firing chamber to the inner ends of the several gun barrels, an explosive propellant charge in the inner end of each of the gun barrels disposed in propelling relation to the projectile therein, and a continuous body of a substantially non-compressible material of tlowable character confined in said passage and in contact with each of said propellant charges, said noncompressible material being operable upon ignition of a firing charge in said firing chamber to hydraulically transmit the force thereof to the propellant charges, whereby to set ofi the propellant charges and to increase the propelling forces on said projectiles.

11. A perforating gun as defined by claim 10 wherein said substantially non-compressible material is water.

References Cited in the file of this patent UNITED STATES PATENTS 2,265,982 Bolton Dec. 16, 1941 2,414,900 Schiavon Jan. 28, 1947 2,456,977 McCullough Dec. 21, 1948 2,457,277 Schlumberger Dec. 28, 1948 2,726,602 Davis et Dec. 13, 19