US2785631A - Shaped explosive-charge perforating apparatus - Google Patents

Description

SHAPED EXPLOSIVE-CHARGE FERFORATING APPARATUS Filed Oct. 5, 1950 FIGJ.

INVENTOR. ANDRE BLANCHARD BY r m i 4: mm v a .m v w 3 a V mg Qua M i'mpfi HIS ATTORNEYS.

nited States Patent SHAPED EXPLOSIVE-CHARGE PERFORATING APPARATUS Application October 5, .1950, Serial No. 188,534 4 Claims. (Cl. 102-20) The present invention relates to perforating apparatus utilizing one or more shaped explosive charges mounted in a reusable enclosed housing which may serve as an expansion chamber for absorbing part of the concussion produced when the charges are exploded. More specifically, it has to do with novel means for minimizing damage to the housing from effects accompanying the detonation of the charges.

Metallic bore hole casings are currently being perforated by shaped explosive charges in containers lowered into the casing in a hollow cylindrical housing. The applicants. copending application Serial No. 123,003, filed October 22, 1949, discloses apparatus of this character embodying greatly improved charge containers which are designed so as to increase the depth of penetration by the explosive jets and to reduce the damaging effect of. the exploding charges on the housing in which they are mounted. By virtueof the latter feature, the housing .for the charges may be reused a number of times. Each perforating operation, however, causes some expansion of the housin and the impact of the charge container fragments upon the interior wall thereof causes erosion so that eventually, after many opera tions, the housing becomes unserviceable.

It is an object of the invention, accordingly, to provide new and improved shaped charge perforating apparatus of the above character wherein the detonation of the charges results in negligible damage to the gun housing.

Another object of the invention is to provide new and improved shaped charge perforating apparatus of the above character in which the detonation of the charges in a hollow housing causes substantially no expansion of said housing.

A further object of the invention is to provide new and improved shaped charge perforating apparatus in which the detonation of the charges within a hollow housing causes substantially no erosion on the interior of said housing.

These and. other objects of the invention are attained by placing about the containers for the individual shaped charges a flexible resilient material, such as rubber, for example. Preferably, a cover or sleeve of flexible resilient material is inserted over, or manufactured around, the metallic or plastic container in which a shaped charge is mounted. 'The flexible resilient material apparently cushions the impact of the container particles on the interior wall of the housing in which the charges are mounted. Hence, expansion and erosion of "the hous-.

ing are reduced to a minimum and the'useful life of the .65

housingis materially increased. p

, Additional objects and advantages of the invention will be apparent from the following detailed description of several typical embodiments thereof, taken in conjunction with the accompanying drawing, in which:

Fig. 1 is a view in longitudinal section of a shaped charge 'perforator showing several illustrative forms of 2 cushioning means constructed according to the present invention;

Fig. 2 is a view partly in transverse section taken along the line 2-2 of Fig. 1 showing one form of cushioning means according to the invention;

Fig. 3 is a view partly in transverse section taken along line 33' of Fig. 1 showing another form of the invention; and V Fig. 4 is a view in longitudinal section of the cushioning means used in Fig. 2.

In Fig. 1 the invention is shown as embodied in shaped charge casing perforating assembly of the type disclosed in the aforementioned copending patent application, comprising a hollow housing 10 adapted to be lowered on a cable 9 into a bore hole 11, which may contain a conductive liquid 12. The bore hole 11 is lined with a metallic casing 13 which is to be perforated by the perforating apparatus described herein.

The housing 10 may comprise, for example, a hollow cylindrical section 14 of strong material such as steel, for example, the ends of which are closed by pressure resistant cap members 15 and 16, also of steel. Circumferentially and axially spaced along the wall of the cylindrical section 14 are a plurality of ports 17, 18 and 19, which may be sealed in any suitable manner as by threaded caps 20, 21 and 22, respectively.

A plurality of shaped explosive charge units 23, 24 and 25 are mounted in the housing 10 with their hollowed portions opposite the caps 20, 21 and 22, respectively. The charges in the units 23, 24 and 25 are adapted to be detonated from the rear by any suitable means such as a Prim'acord fuse 26, for example. The fuse 26 may be detonated at one end by an electric blasting cap 27 having an electrical igniter 28. One terminal of the igniter 28 may be grounded to the housing 10 'at a junction 29, the other terminal being connected in a circuit including an insulated conductor 30, a switch 31, and an electrical energy source 32 connected to a ground 33, at the surface of the earth.

The shaped explosive charge unit 23 is preferably of the type disclosed in the aforementioned copending application and it comprises a container 35 made of lead or other suitable material in which is disposed the charge 34, the cavity 36 in the charge being lined with a conical liner 36 made of suitable material such as metal or a plastic, for example. An outwardly open longitudinally extending slot 50 (Fig. 2) is formed at the rear end of the container35, in which the Primacord fuse 26 is adapted to be received. I

.As indicated above, when the .charge 23'is detonated, that portion of the housing 10 in the immediate vicinity thereof will experience some minute expansion and the 10 in the subsequent reuse thereof eventually will dam-' age the housing 10 and render it wholly unserviceable.

In accordance with the invention, expansion of the housing 10 and erosion of the interior wall thereofare reduced to 'a negligible minimum by disposing a flexible and resilient material such as soft rubber, for example,

around the housing container 35. Thus the charge 24 (Fig. 2) may be the same as the charge 23 except that a rubber sleeve 37 is snugly fitted around the container 35 essentially in the manner shown. If desired, longitudinal slots (not shown) may be formed in the sleeve 37 to facilitate its insertion over the container 35. While the reasons for these phenomena are not completely understood, tests have proved that the presence of the sleeve 37 will reduce appreciably the amount of erosion and expansion produced in the casing when the charge is detonated.

In the modification shown in Fig. 3, the charge unit may comprise a container 38 including a substantially cylindrical forward portion 41 and a portion 42 tapering rearwardly to an opening 43. A closure member 44 of relatively light material may be provided for the opening 43 and it may be provided with detent portions 40 adapted to be received in recesses 45 formed in the 7 those skilled in the art.

outer wall of the container 38 to retain the closure member 44 to the container 38. The closure member 44 may be provided with an arcuate wall 46 adjacent which the Primacord fuse 26 is adapted to be positioned.

Surrounding the container 38 is a sleeve-like member 39 made of rubber, or other suitable material, the rear portion 47 of which is shaped similarly to the rear portion of the container 35 in Fig. 2 so that it will fit into the retaining recesses 48 (Fig. 1) formed in the interior wall of the housing 10. The rear portion 47 of the sleeve member 39 is also provided with an outwardly open longitudinally extending slot 49 through which the Primacord fuse 26 may be inserted and positioned against the closure member 44.

It will be noted that the container 33 has less metal around the rear portion of the charge than does the container 35 in Fig. 2 and that the rear portion 47 of the flexible resilient sleeve member 39 completely surrounds the explosive charge in the container 38. This form of the invention, therefore, gives added protection to those portions of the housing which lie on each side and somewhat to the rear of the charge where erosion due to the impact of container fragments is likely to be greatest.

about the charges, preferably in the form of sleeve members over the charge containers,erosion and expansion of the housing are substantially reduced. As a result, the housing may be reused a considerable number of times before becoming so damaged as to be unserviceable.

It will be understood that the several illustrative embodiments disclosed herein are susceptible of numerous modifications in form and detail within the scope of the invention. 0f course, the protective cover or coating may take many forms and shapes as will be obvious to The embodiments described and shown in the drawings, therefore, are not to be regarded as limiting the scope of the following claims.

I claim:

l. A shaped charge perforating apparatus for use in a borehole including, in combination, an elongated housing to be lowered repeatedly into a borehole and including pressure resistant walls defining a closed air filled chamber, at least one shaped explosive charge containing unit detachably mounted in the chamber transversely on the walls thereof to direct its explosive jet outwardly toward the Wall of the borehole, said unit including a container having a relatively hard frangible shell portion encircling said charge, said charge being adapted to fracture the shell portion and to scatter its fragments forcefully against the inner Walls of the chamher, a sleeve portion of relatively soft, resilient material attached to and surrounding the major portion of the shell of the container over the length of the charge therein to shield the inner Walls of the chamber from the lateral effects of the explosion, and means to detonate The dimensions of the sleeve-like member are not Thus, the invention provides a novel and highly ef fective shaped explosive charge. assembly which can be detonated in a hollow housing as in well casing perforating apparatus, for example, with minimum damage to p the housing. By disposing resilient flexible material References Cited in the file of this patent UNITED STATES PATENTS Elliott June 18, 1946 2,415,814' Davis et a1. Feb. 18, 1947 2,494,256 I Muskat et al. Jan. 10,1950 2,499,440 Wood Mar. 7, 1950 2,543,057 Porter Feb. 27, 1951 2,629,325 Sweetman Feb. 24, .1953 2,630,182 Klotz Mar/3, 1953

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