US2764937A

US2764937A - Apparatus for perforating well casings by means of shaped charges

Info

Publication number: US2764937A
Application number: US128950A
Authority: US
Inventors: Schlumberger Marcel
Original assignee: Borg Warner Corp
Current assignee: Borg Warner Corp
Priority date: 1949-01-22
Filing date: 1949-11-23
Publication date: 1956-10-02
Anticipated expiration: 1973-10-02

Description

Oct. 2, 1956 M. SCHLUMBERGER APPARATUS FOR P R ORATING WELL cAsINGs BY ME S SHAPED CH R ES F" d NOV. 23, 19

lNvENToR.- MARCEL SCHLUMBERGER H IS ATTORNEYS.

United States Patent APPARATUS FOR PERFORATINGWELL CASINGS .BY 0F rSHAPED CHARGES Marcel Schlumberger, Paris, France, assignor, by .mesne assignments, to Borg-Warner Corporation, Chicago, lll., a corporation of Illinois Application November 23, 1949, Serial No. 128,950 Claims priority, application `France January ,22, 1949 1 Claim. (Cl. 102-20) The .present inventionrelates to shaped charge well casing per'forating apparatus and more particularly to new and .improved perforating apparatusv of this character which incorporates a noveland highly effective assemIbly of shaped charges in a pressure-resistant container adapted to be lowered into a well.

Devices embodying sofcalled shaped or hollow charges have been employed heretofore lfor perforating -well casingsand-the like. fIn one lform of apparatus used previously for .this purpose, a plurality of shapedcha-rges 4are mounted in an elongated tubular support inserted in an elongated, enclosed pressure-resistant housing, the charges Ibeing :disposed in substantial alignment with closed ports formed in the side wall of the housing. Apparatus of this type is not entirely satisfactory because the -charge support tends .to rotate with respect to the housing while the .latter is being positioned in .a well. This may cause misaalignment between the charges and their housing ports, resulting in severe damage to the housing `and `partly or wholly ineffective perforating operations when the charges are detonated i-n a well.

`It is an object of the invention, accordingly, to provide new and 'improved shaped charge well casing perforating apparatus in which the charges are x'edly secured in a pressure-resistant housing and are at all times maintained in accurate alignment with ports formed in the side wall of the housing..

Another object of the invention is to provide new and improved perforating apparatus of the above character which comprises a small number of parts that can be quickly and easily assembled.

A further object of the invention is to provide new and improved perforating apparatus of the above character which is designed to insure the formation of an explosive jet of maximum effectiveness.

These and other objects of the invention are attained by providing perforating apparatus comprising a hollow, elongated enclosed housing having ports therein adapted to be tightly closed by suitable cap means. Shaped charges with liners are mounted in containers which are adapted to be inserted through the ports. Means are provided on the inside wall of the housing opposite each of Vthe ports for supporting the rear ends of the charge containers, and the forward ends of the latter are supported in the housing ports and are retained therein by the cap means. Each of the charge containers has an outwardly open slot at the rear end thereof to facilitate the placement of a detonating fuse at the time the containers are inserted in the housing. With this construction, assembly of 4the perforator can 'be accomplished quickly and easily and the charges are always maintained in accurate alignment with the ports in the housing.

The invention may be better understood from the lfollowing det-ailed description of a preferred embodiment thereof, taken in conjunction with the accompanying draw-ings, in which:

Fig. l is a view in longitudinal section of shaped charge 2,764,937 Patented (9ct. y 2v, 1956 Tice lIn kthe .preferred form of the invention shown in l, the perforating apparatus comprises a hollow, cylindrical pressure-resistant.housing '10 closed at top and bottom by tightly -tting caps y11 .and 12 and having a plurality of ports 13 formed in the side wall gthereo'f. Preferably, lthe ports '16 are longitudinally spaced apart along the housing lli) and angular-1y disposed :about the longitudinal axis thereof, and they .are .closed 'by conventional threaded or plug-in caps 14, lgasketsor washers.:1l5 'being provided to insure tightness. The housing '10p-may be secured to 4a supporting cable '27 'by means of which it may be positioned ina cased well (not shown).

vMount-ed i-n the housing 10 are a plurality of shaped charge assemblies 16 each comprising a vcontainer' 17, a shaped explosive charge 118 and `a lliner 19, Apreferably of metal. The charge assemblies *16 are preferably designed `according to the `disclosure vin copending application of Andre Blanchard, Serial No. v1'2"3,003,fled October Z2, 1949 for Shaped 'Charge Perforating Appara-tus, so `that undirected forces developedupondetonation .will ibe relatively reduced. Thus, each charge is mounted in a pressure-resistant container 17 `vmade Aof a suitable dense materia-l vsuch `as lead or ,a plastic compound 'containing a iiller, 'for example; the inner wall portion of the container 17 which surrounds the liner ,19 converges rearwardly; and the "apex aing'leyof the liner 19 is lgreater than .the apex angle of 'thecharge receiving chamber inthe container 17, these 4angles preferably being 55'and 30, respectively. Y

According tothe invention, 'eachk container 417. is provided with a cylindrical forward portion 20' extending beyond the liner19 and the charge/18, which forward portion 20 isadapted to 'be closely 'littedQin one ofthe ports :13. Also, each container "has .a rear portion 21 which may be seated Iin a recess 22 formed in the interior wall of the housing 10 opposite a port 1B. The rear portion 21 and the recess ZZmay be tapered as shown in Figs. l and 2 to facilitate entry of the former into the latter during the assembly operation as described below. Each container 17 is retained in position by the cap 14 iitted in the corresponding port .13.

`In order to facilitate the placement of a detonating fuse in operative relation to the explosive charges 118, each container 17 is provided with a rearwardly op'en slot 23 communicating with a tubular passage 24 within which -a Primacord fuse -25 is vadapted to be inserted. The fuse 25, when in posit-ion, is preferably separated from the explosive charge 18 by a relatively thin wall 2:6.

Detonation of the fuse 2'5 may be accomplished in any suitable manner from the surface of the earth. For example, detonation may be etfected rby an electric blasting cap 2S ignited by a source of electrical energy 29 at the surface of the earth. `One terminal of the source 29 may be grounded at 30, and its other terminal may be connected in series with a switch `31 and a conjductor 32 in the cable 27 to the blasting cap 28, the circuit being completed through the ground.

To assemble the perforator, the cap 11 is removed and the blasting cap 2S and the Primacord fuse 25 are inserted in the housing 10. With the caps 14 removed, the charge containers 17 are inserted through the ports 13 until they are properly supported in the recesses 22 and by the ports 13. During this operation, the Primacord fuse 25 passes through the slots Z3 in the rear ends of the containers 17 to the tubular passages 24. The ports 13 are then closed by the caps 14 with the washers 15 in place to insure tightness, thus completing the assembly.

In operation, the housing is moved to a desired level in a bore hole (not shown) by means of the cable 27 and the switch 31 is then closed. This sets off the blasting cap 28 and detonates the charges 18 simultaneously. The explosive jetsthus formed pass through the caps 14 and penetrate the 'adjacent Well casing. Since the charge assemblies 16 are maintained in accurate alignment with the ports 13, highly eiective jet formation is achieved without material damage to the housing 10 by the explosive jets. Further, since the charge assemblies 16 are designed according to the disclosure in the aforementioned copending application Serial No. 123,003, undi-rected forces developed around the charges upon detonation thereof iare Asubstantially reduced, so that no appreciable deformation of the housing 10 occurs.

For effective jet formation, it is important that symmetry of the charge, its liner, and the charge receiving opening in the container be accurately maintained. It has been found that even threads formed on the outside of the container may disturb the symmetry of the assembly to such an extent as to 'affect adversely the formation of the jet. For this reason, it is preferable to use only partial threads wherever threads are employed to secure parts together as in the case of the caps 14. Preferably, conventionalplug-in caps should be used instead of screw-in caps for this purpose.

The invention .thus provides a novel and highly eective shaped charge apparatus for perforating well casings or the'like. By virtue'of the construction described above, assembly of the perforator can be accomplished simply and quickly, and laccurate alignment between the shaped charge assemblies and the housing ports is maintained at all times. The specific embodiment described above is intended to be merely illustrative and it is obviously susceptible of modification Withinthe spirit of the invention. That embodiment, therefore, is not to be regarded 'as limiting in any way the scope of the following claim.

In well casing perforating apparatus, the combination of an enclosed, hollow, pressure-resistant housing adapted to be lowered into la well and having at least one port Cil formed in the side wall thereof, means forming a recess in the inner Wall of said housing opposite said port, an explosive charge container so constructed and arranged that it can be inserted into the housing through said port and positioned with a forward portion thereof snugly fitted in said port and a rear portion thereof seated in said recess, closure means for the port 'and for fixedly retaining said charge container in assembled position in the housing, means forming a substantially conical chamber in said container diverging to a coaxial, Asubstantially cylindrical opening facing said port, means forming a longitudinally extending passage near'the apex of said conical chamber and separated therefrom by 'a relatively thin Wall, means forming a rearwardly 'and sidewardly open longitudinal slot at the rear end of said container and communicating with said passage to facilitate placement of detonator means in said passage, detonator means disposed within the housing and mounted in said passage, an explosive charge in said conical chamber and having n holloWed-out portion facing said port, a liner :fitted to said hollowed-out portion, and vmeans for tiring lsaid detonator means from the surface of the earth.

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES Article entitled Casing Perforating With Shaped Explosive Charges, by R. H. McLernore, published in the Oil and Gas Journal, December 28, 1946, 4 pages.