US2811921A - Shaped explosive charge apparatus with adjustable charge spacing - Google Patents

Description

ca. R. HODGSON 2,811,921 SHAPED EXPLOSIVE CHARGE APPARATUS WITH ADJUSTABLE CHARGE SPACING Filed Nov. 24. 1952 Nov. 5, 1957 PEG 2 44-LEEF45 l u ll INVENTOR. GLEN R. HODGSON HIS ATTORNEYS.

Sttes SHAPED EXPLOSIVE CHARGE APPARATUS WITH ADJUSTABLE. CHARGE SPACING Glen R. Hodgson, Houston, Tex., assignor, by mesne assignments, to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Application November 24, 1952, Serial No. 322,205

4 Claims. (Cl. 102-20) plication Serial No. 209,598, filed February 6, 1951, by

Harry S. Robertson, comprises an expendable, closed, hollow tube adapted to be lowered into a well on suitable suspension means and containing a plurality of mechanically coupled, shaped explosive charge perforating devices therein uniformly spaced apart along the longitudinal axis of the tube. While a uniform spacing is ,usually desired, in some cases it may be necessary to employ a difierent spacing, as where a fewer or greater number of perforations per foot are desired. Also, in some cases, it may be desirable to skip an entire zone as for example where there is a shale streak at a given level or a piece of apparatus in the well which is not to be perforated.

It is an object of the invention, accordingly, to provide shaped explosive charge apparatus of the above character embodying means whereby the longitudinal spacing between the respective charges or certain of them may be varied.

In accordance with the invention, longitudinally extending spacer members are provided having means at the opposite ends thereof adapted to cooperate with coupling means on the shaped explosive charge devices to facilitate coupling the latter together with the required longitudinal spacing. The spacing members may be formed of rigid material such as wire and may include transverse portions adapted to engage opposite sides of the inside wall of the tube in which the devices are contained, to retain the spacing members in proper position .and also to strengthen the tube against possible collapse under hydrostatic pressure in a well. Alternatively, the spacing members may be substantially rectangular in shape and of a size to fit snugly within the tube, or they may be tubular in shape and suitably dimensioned to be snugly received within the tube.

The invention may be better understood from the following detailed description of several typical forms thereof, taken in conjunction with the accompanying drawings in which:

, Fig. 1 is aview in longitudinal section through shaped explosive charge apparatus constructed according to the invention;

Fig. 2 is a view in elevation of a modified form of spacer; and V Fig. 3 is a view in longitudinal section through a tubular form of spacing means.

.Qonsidering first Fig. -1, shaped explosive charge perfo- 2,811,921 Patented Nov. 5, 1957 ice rating apparatus 10 is shown which may comprise a hollow tube 11 made of suitable frangible material such as aluminum, for example, provided with a base plug 12 and a cable head 13. The base plug 12 has a portion 14 of reduced diameter which is adapted to be snugly received within the lower portion of the tube 11 and it is secured thereto in any conventional manner as by screws 15, for example. In order to insure a watertight joint, conventional packing means such as one or more VO-rings 16 disposed in an annular groove 17 formed in the base plug 12 may be provided.

The cable head 13 is also preferably provided with a portion 18 of reduced diameter which is adapted to be snugly received within the upper end of the tube 11. The cable head 13 is preferably made of strong material such as steel, for example, which will not be damaged by the explosive forces developed upon detonation of the explosive charges in the apparatus. Desirably, the cable head 13 is weakly secured to the tube 11 by suitable means such as one or more shear pins 19, for example, so as to facilitate separation of the tube 11 and its contents from the cable head 13 in a perforating operation.

Disposed within the container 11 are a plurality of shaped explosive charge devices 20, only two being shown in Fig. 1 for simplicity, which may be of the type disclosed in the aforementioned copending Robertson application. The shaped explosive charge devices 20 are adapted to be coupled together by later-ally extending brackets 21 and 22 formed on opposite sides thereof, the bracket 21 carrying a pin 23 and the bracket 22 having a hole 24 formed therein in which the pin 23 on an adjacent device 20 is adapted to be received. For ease in inserting a group of linked explosive charge devices into the tube, the pins 23 and holes 24 preferably lie along the longitudinal axis of the tube 11.

According to the invention, the desired longitudinal spacing between the shaped explosive charge devices 20 is determined by spacer means 25 of appropriate length having a ,pin receiving hole 26 formed at the upper end thereof adapted to receive the pin 23 on an upper explosive charge device 20, and a pointed lower end 27 which is adapted to be received within the opening 24 in the bracket 22 on the next lower explosive charge device 20.

As shown in Fig. 1, the spacer means 25 may comprise longitudinally spaced apart generally S- shaped portions 28 and 29 and a longitudinally extending intermediate portion 30. The S- shaped portions 28 and 29 may include transversely extending portions 31 and 32, respectively, the opposite ends of which are adapted to engage the opposite sides of the inner wall of the tube 11 so as to aid in positioning the spacer means 25 and also to assist in supporting the tube 11 against possible collapse under hydrostatic pressure in a well. The spacer means 25 may be formed of any suitable frangible material that can readily be shaped yet is sufficiently rigid to retain its shape under the load imposed by the explosive devices 20. Aluminum rod, for example, is suitable for the purpose.

The spacer means 25 may be inserted between each of the shaped explosive charge devices 20 within the tube 11 or only between certain explosive charge devices as requirements dictate. Further, the spacer means 25 may be made in different lengths to provide for different numbers of shots per foot.

Detonation of the assembled shaped explosive charge devices 20 in the apparatus 10 may be effected in the manner disclosed in the aforementioned Robertson application. Thus, a Primacord fuse 33 having portions disposed in close proximity to the rear ends of the explosive charge devices 20 may be mechanically connected at one end to an electrical blasting cap 34. One terminal of the blasting cap 34 may be grounded to the nose member 12 at 35 and its other terminal may be connected to a conductor 36 in the supporting cable 37. The upper end of the cable conductor 36 may be'connectedinseries with a firing switch '38, a current controllingrheostat39, and a source of electrical energy 40, the other terminal of which may be connected to ground at 41.

If desired, the spacer means may be made substantially rectangular in shape as shown in Fig. 2. In this figure, the spacer means 25a comprises a substantially rectangular strip 42 of frangible material such as aluminum, for example, having a laterally extending pin 43 at the upper end which extends perpendicularly to the plane of the strip 42 anda lug 44 at the other end in which is formed a small pin receiving hole 45. The spacer means 25a should preferably be dimensioned so that the side edges thereof will snugly engage the inside wall of the tube 11 when it is positioned therein. As stated, this construction aids in positioning the spacer means within the tube ill and it also is of assistance in providing additional support for the tube 11.

Fig. 3 shows a further modification in which the spacer means 25b comprises a tubular member 46 having an outside diameter substantially the same as the inside diameter of the tube 11, so as to fit'snugly in the latter. Secured at the upper and lower ends of the tubular member 46 are a laterally extending pin 47, and a lug 48 carrying a pin receiving hole 49 therein, respectively.

Spacer means may also be provided according to the invention, for shortening the spacing normally obtaining when the pin 23 on theupper explosive charge device 20 is inserted in the hole 24 in the lower device 20 in Fig. 1. In this case the spacer means mightcomprise a longitudinally extending member short enough to fit ,between the pin 23 on the upper explosive device 20 and the adjacent outside wall thereof with a hole at its lower end receiving the pin 23 and. a pin at its upper. end inserted in the hole 24 in the bracket 22 on the lower explosive device 20.

From the foregoing, itwill be seen that the invention provides novel means whereby the longitudinal spacing between shaped explosive charge devices in apparatus for perforating well casing and the like may be varied, as desired. Further, by utilizing spacer members having transversely extending portions, adapted to engagethe opposite sides of the inner wall of the tube containing the shaped explosive charge devices, proper positioning of the spacer means within the tube isfacilitated and some strengthening of the tube is achieved, thus rendering' it less likely to collapse underhydrostatic pressure in a well.

It will be understood that the several specific embodiments described above are'susceptible of modification in form and detail without departing from the invention. For example, thespacer means may be varied in length to meet the particular requirements in any case and they are susceptible of wide variation in shape as Willbe apparent to those skilled in the art. Accordingly, those embodiments are to be considered merely as illustrative and not as restricting the scope of the following claims.

I claim:

1. In apparatus utilizing shaped explosive charges for perforating Well casing and the like, the-combination of a hollow tube of frangible material adapted to be disintegrated bydetonation of said charges, said tube having closure members for the opposite open ends thereof, at least two longitudinally spaced apart shaped explosive charge devices disposed in said tube, each of .said devices including portions thereof disposed in engagement with oppositesides of the inner wall of said tube to strengthen the same against inward collapse, coupling means carried by said devices on the adjacent sides thereof, longitudinally extending individual spacer means disposed between said devices and having laterally extend- 7 ing portions engaging opposite sides of the inner wall of said tube to strengthen the same against inward collapse, and means mounted at the opposite ends of said spacer means linking the same in free engagement with the coupling means on said explosive charge devices to determine the spacing therebetween.

2. In apparatus utilizing shaped explosive charges for perforating well casing and the like, the combination of an elongated tube of frangible material adapted to be disintegrated by detonation of said charges, said tube having closure members for the opposite ends thereof, at least twolongitudinally spaced apart shaped explosive charge devices in said tube, each of said devices including portions thereof disposed in engagement with opposite sides of the inner wall of said tube to strengthen the same against inward collapse, coupling means mounted on the adjacent sides of said explosive devices, and individual spacing means interposed between said explosive devices, said spacing means comprising a continuous member made of rigid frangible material having linking means at the opposite ends thereof linked in free engagement with the coupling means on said explosive devices to maintain a given spacing between the latter, and having laterally extending portions engaging opposite sides of the inner Wall of said tube to strengthen the same against inward collapse.

3. In apparatus utilizing shaped explosive charges for perforating well casing and the like, the combination of a hollow tube of frangible material adapted to be disintegrated by detonation of said charges, said tube having closure membersfor the opposite open ends thereof, at least two longitudinally spaced apart shaped explosive charge devices in said tube, each of said devices including portions thereof disposed in engagement with opposite sides of the inner wall of said tube to strengthen the same against inward collapse, coupling means carried by said devices on the adjacent sides thereof, and individual spacing means interposed between said explosive devices, said spacing means comprising a longitudinally extending strip member having linking means at the opposite ends thereof linked in free engagement with the coupling means on said explosive devices to maintain a given spacing between the latter, and having side edge portions engaging opposite sides of the inner wall of said tube to strengthen the same against inward collapse.

4. In apparatus utilizing shaped explosive charges for perforating well casing and the like, the combination of a hollow tube of frangible material adapted to be disintegrated by detonation of said charges, said tube having closure members for the opposite open ends thereof, at least two longitudinally spaced apart shaped explosive charge devices disposed in said tube, each of said devices including portions thereof disposed in engagement with opposite sides of the inner wall of said tube to strengthen the same against inward collapse, coupling means carried by said devices on the adjacent sides thereof, longitudinally extending individual tubular spacer members interposed between said explosive devices and being of a size to fit snugly within said tube, and strengthen .the same against inward collapse, said tubular member having linking meansat the opposite ends thereof linked in free engagement with the coupling means on said explosive devices to maintain a given spacing between the latter.

References Cited in the file of this patent UNITED STATES PATENTS 2,543,814 Thompson et al. Mar. 6, 1951 2,616,370 Foster Nov. 4, 1952 2,649,046 Davis Aug. 18, 1953 FOREIGN PATENTS 146,615 Austria July 25, 1936 660,285 .Great Britain Nov. 7, 1951

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