US2639770A - Small gun for perforating casing in oil wells - Google Patents

Description

May 26, 1953 r. A. HUBER SMALL GUN FOR PERFORMING cAsING 1N oIL WELLS Filed sept. 11, 195o lll. $11114ltrrflflllllalllll,Iliff/116711 n Zrlllllll/lllrflllllllllli l rlllllllu/III 2 Shets-Sheet l .444514 rnvfrf .furl

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ATTORNEY May 26, 1953 T. A.- HUBR SMALL GUN FOR PERFORATING CASING IN OIL WELLS Filed sept. 11 195o 2 Sheets-Sheet 2 A INVENTOR Theodore A. Huben, BY

, ATTORNEY.

Patented May 26, 1953 SMALL GUN FOR PRORAT'ING CASING IN OIL WELLS Theodore A. Huber, Houston, Tex., assigner, by

me'sne assignments, to Standard Oil Development Company, Elizabeth, N. Jr., a. corporation of Delaware Application September 11, 1950, `Serial No. 1'84-,161

2 Claims. l

This invention relates to guns for perf'orating pipe `in oil wells or the like and more particularly to guns which are small enough to run through tubing in `a well for perforating casing beneath the tubing.

Guns vand Iearplc'isives have long been used for pericia-ting casing in oil wells and the art is well developed. As commonly constructed the barrels of guns used for such purposes are fixed hori- 'zontally in a carriage and these barrels approach in length, as far 'as is practical, the diameter of the 'casing -so as to obtain the maximum fire poweri If 'shaped charges of explosives are used instead of guns which fire bullets, these also have been fixed in a carriage `or gun body. Even under' the best conditions, effective perforation of oil well casing, and the cement which usually surrounds it, is difficult to accomplish, and since the `size of the gun 'or explosive is important, casing perforators used heretofore have not been run into the well through tubing or other pipe smaller 4in diameter than the casing.

It has recently been proposed to perform certain operations including the perforating of casing in an foil Well while tubing is in it; See for example application of Theodore A. 'Huber Serial No. 133,025, led December 15, 1949, for Method of Completing and Repairing Oil Wells where the use of a casing perforating gun capable of being ruin through tubing is required. Large l savings in time and cost can be effected in this way if eirective perforation can be accomplished.

Small guns are, of course, old in the art and eve'n iff they were not, no invention would be n- 4volved in merely changing the dimensions of known guns. But from experience it has been round that, in order to solve the problem of perforating casing beneath tubing in the well, more must be `done 'than merely provide a' small diamete'r gun and gun carriage, for small guns have barrels too short to provide adecua-te ring power unless they are placed in a position close to their targets when they are iired.

In accordance with the present invention, it is proposed to solve the problem of providing effective firing power to perforate casing with an assembly which is run into and out of the well `through tubing by arranging the guns in their vcarriage on trunnions and by providing means `for rotating them from the vertical positions which they occupy while being lowered into the well, into horizontal iring positions. Inasmuch 'ae the guns may be 'iire'd by electricity, it iis convenient to employ an electric motor to rotate them exactly the right amount. It is also 2 venient to employ limit switches to cause the ring to occur when the barrels are horizontal and to return the guns .to vertical position so that they 'can be retrieved from the well if they are not destroyed upon lirng.

The objects 'of the invention will be apparent from the following description, taken in connection with the accompanying drawings, in which:

Fig. 1 is a view in vertical ycrosshseetion `of a portion of an yoil well with a Ygun being lowered through tubing therein` Fig. 2 isa similar view of a lower portion of the 'well 'of Fig. l with the gun thereof in firing position.

Fig. 3 is a similar view of the portion of the well of 2 showing how bullets are red from the gun into the earth formations.

Fig. 4 is a similar view of the portion of the well of Fig. 3 showing the Igun being retrieved through the casing.

Fig. 5 is asimilar view of the lower portion of an oil well lshowing how shaped charge explosives may be employed to carry out the principles 'of the invention instead of a bullet gun.

Fig. 6 is a similar View showing how a gun using shaped charges may be retrieved through tubing in the well.

Fig. 7 is an enlarged fragmentary view, partly in orossseetion of a gun somewhat Ysimilar to that illustrated in Figs. 1 to 4 and illustrating one system for rotating the gun barrels and 4for firing the guns when they are in the desired po- Sition.

Fig. 8 is a transverse cross-sectional view of the gun of Fig. '7 showing a detail of the driving mechanism for rotating the guns, the View being taken on the line 8-1-8 thereof.

Fig. 9 is a transverse cross-sectional view of the gun of Fig. 7 showing a detail of the limit switch employed, the view beiner taken on the line 3d-9 thereof.

Fig. 10 is a transverse cross-sectional view of the gun of Fig. '7 showing a detail of the trunnions and driving mechanism, the view being taken on the line Illl0 thereof.

Fig. 1l is a `circuit diagram of the gun of Fig. 7.

Referring to the drawings in detail and first to Figs. 1 to i which illustrate a sequence of operation of a gun constructed in accordance with the principles of the invention, it will be seen that the casing ef an oil well is there shown at l2. A tubing i3 is positioned in the well with its 'lower end above the portion of the 'casing which is to be perforated, as shown in Figs. 2, 3, and 4.

Within the tubing i3., as shown in rig. l and of steel and it is of cylindrical shape with anumber of slots I6 provided transversely to accommodate gun barrels I1 which are mounted for rotation in the slots I6 by trunnions I8.

The gun barrels I1 are of a length greater than the diameter of the tubing I3 and only slightly less than the diameter of the casing I2. In order for them to be lowered into the well through the tubing, it is necessary that they be held in a vertical position as shown in Fig. 1. After the carriage has passed out of the bottom of the tubing, the barrels I1 may be rotated to the horizontal position as shown in Fig. 2. The carriage I4 can then be raised and lowered by the cable I5 and the guns red individually at different depths, or all of the guns may be red at the same time, or nearly so, in accordance -with well'known perforating technique.

If the guns are of the type which shoot bullets,

each barrel I1 may be loaded at both ends with -crease the effective gun barrel length and secure greater penetration, as described hereinafter and 'shown in Fig. 7.

After the bullets have been red, the barrels I1 may be rotated back into the vertical position as shown inFig. 4, so that they can be pulled bac-k up through the tubing I3 from the well.

Mechanism including areversing screw like the to remove them -level-Winder on a fishing reel may readily be provided by those skilled in the art for causing the barrels to reverse their direction of rotation after firing. Provision of such means for reversing direction enables the use of a stronger gun body or carriage, because the slots I6 there- 'in may then be reenforced along one side at the top and one side at the bottom. However, in the arrangement described hereinafter and shown in Figs. 7 to 10, the barrels rotate a total of 180 degrees and do not reverse their direction of rotation. In any event the guns are red after they are rotated 90 degrees, or approximately so.

If shaped charges of explosive are used to perforate the casing, or 'if the gun or explosive is otherwise designed to concentrate the force of the explosion upon points opposite the ends of the gun, as taught in the Mims Patent 1,582,184, it may be convenient to have the barrels blow up as shown in Fig. 5. Fragments of the barrels Aare there shown at 22 and holes in the casing -and earth formation are shown at 23.

The gun carriage I4 then comes back out of the well empty, as shown in Fig. 6. y

Figs. 7 to 10 of the drawing show one way of rotating the barrels I1 on their trunnions I8. In Fig. 7, the barrels I1 are shown as bullet guns with one bulletl 24 in each barrel. It will be observed that the mouth of upper barrel I1 shown in Fig. 7 is at the top while the mouth of the lower barrel I1 is at the bottom when the barrels are in their running-in (full line in Fig. 7) position. The barrels may be thus alternately positioned. Since all the barrelsrotate @Gunterclockwise, as viewed in Fig. 7, when they take their horizontal positions, as shown in dotted lines, the upper barrel I1 will re bo the left while the lower one Will re to the right. The same staggering of the perforations, that is, one to the right and one tothe left could be obtained by loading all the barrels alike, say with their muzzles pointing upwardly, in the full line position of Fig. 7 and by causing alternate ones to rotate in opposite directions, that is, half clockwise and half counter-clockwise.

For rotating the barrels, one trunnion I8 of each barrel may be provided with ka gear 25 driven by a Worm 26 on a shaft 21 which extends downwardly through the carriage I4 from a chamber at the top. Alternate worms 26. may be right and left hand screws, if desired, to cause half of the barrels to rotate in opposite directions. Within the chamber is `an electric motor 28, connected to the shaft 21 by suitable gears 29 and 30.

Also within the chamber in the top of the carriage I4 are two limit switches, the blades 3I and 32 of which are insulated and mounted on a rider 33 which is threaded upon a screw 34 connected to the shaft of the motor 28. The blade 3| engages a ground bar 35 over most of the path of travel of the rider 33. This blade is in the circuit for the motor and the length of the ground bar 35 is such, and the pitch of the screw 34 is such that the barrels I1 rotate 180 degrees from the position shown in full lines in Fig. 7 before the blade 3| leaves the lower end of the ground bar 35. `When it does leave, the circuit of the motor 28 is broken and the rotation of the barrels I1 cease.

The blade 32 is designed to strike an insulated contact 36 at a time when the rider 33 has traveled half way from the position shown to the point where blade 31 leaves the ground bar 35. The contact 3G is connected to the ring fuses of the guns, so that they re automaticallyvwhen the barrels I1 have rotated 90 degrees from their vertical position.

Electric current is supplied to the motor 28 and vthe fuses of the guns through a conductor in the cable I5. The circuit may be like that shown in Fig. 11. As there shown, the conductor 31 of the' cable has a switch 38 at the surface of the ground in series with the source of current 39. One pole of the source 39 is grounded as shown at 40 so that if one terminal of thevmotor 23 is grounded in the well bore, the motor is energized. This grounding occurs so long as blade 3l is engaging ground bar 35, which may be connected to the carriage I4 which is located in the mud or other fluid in the well bore or in contact with the casing of the well. Until the switch 38 is closed at the surface of the ground, no current can pass down the cable however so the barrels I1 are not rotated until the carriage is in the desired position in the well bore. The conductor 31 of the cable I5 is also connected to the blade 32. Hence when blade 32 engages contact 36, the fuses 4I of the guns are energized vby thesource 39, assuming the switch 38 remains closed.

While only a few embodiments of the invention have been shown and describedv herein, it is obvious that changes may be made Without departing from the spirit of the invention or the scope of the annexed claims.

What I desire to claim is:

1. In an arrangement for perforating casing in oil wells or the like, an elongated carriage small enough in diameter to enable it to be run into the Well through tubing inside the casing to be perforated, a plurality of guns mounted individually for rotation in said carriage, each of said guns having a diameter less than the diameter of the tubing and a length greaterL than the diameter of the tubing but less than the diameter of the casingI and means for rotating said guns simultaneously from their vertical position longitudinal of the carriage into a position transverse the'reof, each of said guns being loaded with only one bullet, alternate guns being positioned with their muzzles at opposite ends so that when the guns are rotated in the same direction of rotation to their horizontal positions, adjacent gunswill be facing in opposite directions, thereby being in a position to perforate the casing with staggered holes when said guns are fired.

2. In an arrangement for perforating casing in oil Wells or the like, an elongated carriage small enough in diameter to enable it to be run into the well through tubing inside the casing to be perforated, a plurality of guns mounted individually for rotation in said carriage, each of said guns having a diameter less than the diameter of the tubing and a length greater than the di- 4ameter of the tubing but less than the diameter of the casing to be perforated, means for rotating said guns simultaneously from vertical positions longitudinal of the carriage through arcs of 180 to second vertical positions longitudinal of the carriage, and means for firing the guns at a time when they have traversed approximately one-half of their 180 arcs of travel, each of said guns being loaded with one bullet, alternate guns being positioned with their muzzles at opposite ends so that when the guns are rotated in the same direction of rotation over their arcs and fired, they will be facing in opposite directions, thereby perforating the casing with staggered holes.

THEODORE A. HUBER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,582,184 Mims Apr. 27, 1926 2,013,457 Burt Sept. 3, 1935 2,198,821 Jessup Apr. 30, 1940 2,334,428 Miller Nov. 16, 1943 2,543,814 Thompson Mar. 6, 1951

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