US 2883931 A
Description (OCR text may contain errors)
c; A. HOUCK ET AL A ril as, 1959 DETONATOR Filed Dec. 18, 1953 2 Sheets-Sheet 1 INVENTORS United S ates Patent i DETONATOR Application December 18, 1953, Serial No. 399,032
4- Claims. (Cl. 102-20) This invention relates to apparatus employed in perforating well casings by explosive means, and more particularly to a novel means for detonating a detonable fuse of the type employed to detonate one or more explosive units which in turn, when detonated, perform a function in casing perforation.
It is customary, in perforating well casings in situ to employ one or the other of two principal perforating modes, the first of which involves firing hard projectiles through the casing and into the surrounding cement and rock, and the second of which utilizes the unique piercing characteristics of so-called shaped charges of high explosive material. A variety of means are employed in both modes for detonating or firing the charges that propel the projectiles, or that by a sort of jet-like action pierce an obstacle. One common means of thus firing or detonating the charges is a length of relatively insensitive detonable fuse. The fuse may extend to one or more explosive units, and when detonated serves in turn to fire or detonate substantially simultaneously or in rapid succession the several charges to which it extends. Fuse employed for this purpose is, due to the environment of its use and for general reasons of safety to personnel and equipment, chosen from a variety of types, all of which are insensitive to ordinary, severe handling shocks of both mechanical and thermal nature; and for that reason must be detonated by an extremely severe concussive shock. Heretofore detonation of such fuse material has usually been effected by conventional electrical blasting caps containing a detonable material such as fulminate of mercury. It is well known that caps of the type mentioned are apt to be accidentally detonated by relatively light shock and are susceptible to detonation by static electricity, abrasion with hard materials such as are employed for holding the cap, with tools, and with other caps; and that, therefore, considerable care must be exercised in handling such caps. As a consequence of the danger involved in assembling apparatus of the nature of that hereinbefore mentioned and employing blasting caps as a fuse detonating means, field assembly and field renewal of the apparatus has been precluded, and such operations have been carried out in specially prepared places and only by skilled personnel.
The present invention provides means for detonating fuses of the type aforementioned without use of blasting caps or any other means or materials sensitive to ordinary handling shock, whereby assembly of the fuse and apparatus in its container or supports may be safely effected without undue care in regard to the explosives employed. Additionally the invention provides an apparatus for per forating well casings that is readily and quickly and safely assemblable by ordinary workmen, and which is such that those expendable items of the apparatus that are destroyed or consumed in the casing-perforating operation are easily renewed withan extreme measure of safety for adjacent personnel and equipment, permitting repersonnel. I
, 2,883,931 Patented Apr. '28, 1.9.59
Generally, the invention provides a novel detonator means which may be used in a string of interconnected perforating unit sections interconnected at easily assembled and disassambled joints including short substitute joints or subs," the detonator means using the sections and subs as support means and employing an electrically ignited charge of defiagrable material or powder not sensitive to ordinary handling shock, to create pressure to disrupt or shear apart a piece of hard material and propel, preferably, a portion or piece or fragment of the latter along a preferably restricted path into detonating impingement with a portion, preferably an end, of a detonable fuse held and positioned in the path by a part of the means, whereby the fuse is detonated without use of any means sensitive to ordinary handling shock. The means for detonating the fuse are preferably but not necessarily formed as a principal bored and chambered plug snugly fitting in an end of a sub, into the chamber of which plug an electrically heated igniter is removably fitted, the chamber containing adjacent the igniter a defiagrable charge which in turn is restrained from exit from the chamber by a disruptable element, preferably in the form of a shear disc, which serves to tightly close the chamber, the shear disc being tightly held in posiiton by a bored member, readily yet tightly fitting in the bore of the plug as by being threaded thereinto, the bore of the member being completely covered at one end by the shear disc and preferably being arranged to provide a restricted path for a projectile formed of a fragment of the shear disc upon disruption of the latter by pressure created by defiagration of the deflagrable charge; the means also including a fuse holding and positioning device arranged to hold and position a portion, preferably an end, of a detonable fuse either in the bore of the member or outside but in axial alignment therewith, so that the fragment of the shear disc will, with a high degree of certainty, be propelled at high speed into detonating impingement or impact with the fuse and detonate the latter. The plug is preferably of a shoulderedcylinder form adapted to easily but snugly slide into position in one end of a sub with the shoulder abutting the end of the sub, and the bored member providing the restricted path for a fragment of the disc preferably such as to screw readily but tightly into the internally threaded bore of the plug to thereby tightly press the disc in place over the powder chamber of the plug; and the fuse holding means is preferably in the form of a readily removable means including a pin arranged transversely across the axis of the perforator sections, with a hole in the pin arranged in substantially axial alignment with the bore of the plug and member so that a portion, preferably an end, of a detonable fuse, either with or without an auxiliary charge, can be positioned either in the bore of the member or outside but in substantially axial alignment with said bore and in the direct path of the propelled fragment. The pin, the fuse, the shear disc, the deflagrable charge, and the igniter may all be expendable items of the apparatus, are all quite readily assembled and replaced or renewed, and are, with all other parts of the apparatus, very insensitive to ordinary handling shocks.
With the aforementioned and other obvious disadvantages and dangers of the prior art devices and apparatus in view, it is accordingly, a principal object of the present invention to provide a detonator for a detonable fuse which is effective to detonate such a fuse without means or materials sensitive to ordinary handling shock.
A further object of the invention is the provision of a readily and safely renewable detonator for a detonable fuse, the detonator being simple in construction and highly effective to detonate the fuse in the complete absence of means sensitive to ordinary handling shock.
An additional object of the invention is the provision of a fuse detonator comprising a disruptable element, shock insensitive means to disrupt the element and propel at least a portion of the element along a path, and means to hold a detonable fuse with a portion thereof in the path so the propelled portion of the element will make detonating impingement with the portion 'of the fuse disposed in its path.
Another object of the invention is to provide in a well casing perforator apparatus using explosive charges in the perforating operation and a detonable fuses to detonate the charges, a simple and safe detonator for detonating the fuse, the apparatus including the detonator comprising only parts and materials not sensitive to ordi- 4 frusto-conical end of a charge-aligner 21 forming part of an explosive-containing shaped-charge unit 22, or a means hereinafter described in detail. Diametrically opposite each aperture 18 is a respective recess 23 formed in the interior wall of the perforator section, and the recess being adapted to alternatively receive a pin, hereinafter described, or the cylindrical base 24 of a shapedcharge unit 22. Units 22 are of conventional commercial form and may be such as are disclosed in the application for patent of Lindsay et 211., Serial No. 106,567, filed July 25, 1949, now US. Patent No. 2,707,917, issued May 10, 1955.
A length of detonable fuse 25 such as Primacord 5O grain 'PETN, manufactured by Ensign-Bickford Company, for example, is arranged in each perforator section 12 for detonating the shaped charge units 22 in the reponents of the invention and indicating the general relathere indicated by the bracketed portion A, and showing certain details pertinent to the subject matter of the invention; A
Fig. 2B is a longitudinal sectional view similar to Fig. 2A and showing details of structure included in that bracketed at B in Fig. 1;
Fig. 3A is a fragmentary detail view on a plane indicated by line 3-3 of Fig. 2B, principally in section, and illustrating the means for holding and positioning a portion of one kind of detonable fuse in the path of a propelled fragment; and
Fig. 3B is a view similar to Fig. 3A but depicting the holding means positioning another kind of detonable fuse in the path of a propelled fragment.
' -Referring to 'the drawings, and to Fig. 1 thereof in particular, a well casing perforating apparatus assembly is indicated generally by ordinal 10, the apparatus comprising an upper cylindrical body section 11, a series of interconnected perforator sections indicated generally at 12, the lowermost one of which is terminated by a bull plug 13. While but two sections 12 are shown, it will be understood that only one such section may be employed, or two or more, as conditions and requirements of the perforating operation dictate. Each of sections 12 above the lowermost thereof includes a substitute joint or sub 14 at its lower end, the bull plug 13 serving in lieu of a sub for the lowermost of the sections. The upper part of body section 11 is provided with an upstanding cable head 15 in which is secured and sealed in conventional manner a suspending cable 16 which comprises an insulated electrical conductor 17 whose purpose is to supply the suspended apparatus with electric current, the grounded exterior of the metallic body of the apparatus and the earth serving as a return path for the current.
Each perforator section 12 is provided with a plurality .of threaded apertures 18 (see Fig. 2A), each equipped spective section, the fuse extending through holes formed in the bases 24 of units 22, one hole 'to each of the units, and extending downwardly below the lowermost unit 22 in the section. This downwardly extending end portion 26 of fuse 25 is preferably but not necessarily encased in a stifi tubular case 27 (see Fig. 3A) formed of fiber or other stiff material, or may be provided with a closedend case 27a (see Fig. 3B), formed of fiber or metal and partly filled with detonable material28 of the same composition as that employed in fuse 25, selection of the type of case depending upon the relative insensitivity to shock of the type of detonable fuse employed. For types of fuses extremely difficult to detonate, and with other considerations set out hereinafter in mind, the.closedend case is preferred; whereas for other types of detonable fuses a tubular case, as case 27, or no case at all, is sufficient. Detonable material 28, being of the same type or composition as that employed in fuse 25, is not sensitive to ordinary handling shocks, hence either arrangement of fuse end may readily be assembled in the apparatus of the invention by unskilled personnel with out danger of accidental detonation.
A portion of the fuse, such as end 26, is held in position for detonation by means including a pin 30 suitably shaped as indicated from metal, thermo-setting resin or other suitable material, the pin being formed at one end to snugly fit in one of the recesses 23 and at its other end with an exterior taper complementary to the taper of a plug 19 and further with an internal bore 31 arranged to'receive a compression spring 32 adapted to be compressed by plug 19 when the latter is screwed home in recess 18. Pin 30 is provided with a transverse hole or bore 33 through which the end 26 of the fuse 25 is threaded, the fuse being held therein by suitable means such as the force of gravity, a friction fit, wedge means, or, preferably and as illustrated, by an elastic grommet 34 applied over the end of the fuse and forced into position along the fuse and into contact with pin 30. A suitable length of the fuse is left protruding from the lower side or face of the grommet, as will hereinafter be explained in more detail.
Situated below each pin 30, and supported by the sub 14 (or bull nose 13) secured to the lower end of a section 12 is a detonator indicated generally in Fig. 1 by ordinal 36 and comprising a chamber-forming means preferably in the form of a bored plug 36a (Fig. 2B) dimensioned to fit snugly in the upper cylindrical part of the respective sub 14 or nose 13, as indicated. Plug 36a is preferably formed with an internally threaded bore 37, a smaller step-bore 38 and a still smaller and preferably slightly tapered chamber-forming bore 39 having a generally conical base 40 terminating in an igniter-pin receiving aperture or bore 41, which in turn is provided with a flared lower opening 42. Plug 36a also is provided with a circumferentially disposed series of longitudinally extending bores 43, two of which are shown in Fig. 2B, each positioned close to the outside of the plug as indicated and serving to pass electric conductors Also comprised in the detonator 36 is a means in the form of a preferably bored plug member 44 formed to be mounted tightly and securely in bore 37, as by means of complementary threads as illustrated, for example; the plug having a preferably straight bore or passage 45 so dimensioned and positioned that when plug 44 is tightly engaged with the bottom of bore 37, bore or passage 45 is in substantially axial alignment with both hole 33 of pin 30 and chamber-forming bore 39 of plug 36a, and such that the diameter or principal dimension of bore or passage 45 is somewhat less than that of bore 38 and of bore 39. Bore or passage 45 is preferably terminated at its upper or outer end by a conical recess 46 which is adapted to guide and receive the end 26 of a fuse 25 when the apparatus is assembled. Also, the length of the straight part of bore 45 is preferably of the order of one inch, although considerable variation in this dimension is permissible, depending upon other design factors. 7 V
Tightly pressed into place in short step-bore 38 by plug member 44 is a preferably recessed disruptable element 47 preferably of the character of a shear-disc of mild cold-rolled steel or similar material. Element 47 retains in place in slightly tapered bore 39 a cylinder 49 of fiber or similar suitable material, which rests on the conical base 40 and in turn serves to aid in sealing in bore 39 a deflagrable charge 50 of a common propellant powder and an electrically operable igniter 51 having an electrically insulated pin 52 extending through a conical sealing plug 53 and insulating washer 54 as indicated, the pin being threaded at its end to receive suitable nuts 55 to secure the igniter in position and to receive a suitable electric conductor as will hereinafter be ex lained. Charge 50 is insensitive to ordinary handling shock and may, by way of example, be a pellet containing 30 grains of Hercules H.E.S. 5002.180 propellant powder; and igniter 51 may be of a type using a fusible electric filament embedded in black powder, or such as is fully disclosed in the patent to Phillips, No. 2,649,736 issued August 25, 1953. The arrangement and proportions of the structures just described are such that when electric current is supplied to igniter pin 52 and returned through the interconnected metallic bodies of the several structures to the source, deflagrable charge 50 is ignited or defiagrated and produces a high pressure in the chamber formed by bore 39. As this pressure increases to near its peak value, a fragment or portion of disruptable element 47 is broken or sheared out, usually in the form of a round slug or fragment, the latter is propelled at high speed along a more or less confined path provided in bore or passage 45, and into detonating impingement with that portion of fuse 25 which is disposed in its path. While bore or passage 45 is illustrated as a cylindrical bore since that shape is perhaps easiest and simplest to form, the passage could well be of other shape, and could be of dimensions different from those of the end portion of fuse 25. Also, while element 47 has been illustrated as a simply coined disc, it could :be of frangible material of other type and shape, it being necessary for the purposes of the invention only that the pressure provided in chamber or bore 39 be sufiicient to disrupt and propel a portion, either all or a part, of element 47 into detonating impingement with or upon a portion of fuse 25. Further, while for the sake of simplicity and ease of assembly the end face of the fuse, in the disclosed embodiment of the apparatus, forms a target for the propelled portion of element 47, it is evident that a loop of fuse 25 could also be used at the target. Thus, for example, the chamber could be of spherical shape with the fuse arrayed on the interior wall with a disruptable element in the form of a frangible sphere inside and containing the igniter at its center surrounded by the defiagrable charge, whereby at least one portion of the frangible sphere would be propelled into detonating impingement with the detonable fuse.
Plug 36a is formed with means to hold it in position against undue downward descent in the bore of a sub or nose 13, the means preferably being in the form of an annular shoulder resting on the end of the sub or nose, as indicated; and the plug is held from upward dislodgement in the assembled apparatus by a transversely notched internally-threaded sleeve 36b which is attached to the upper end of plug 36a as by means of a threaded joint as illustrated, the sleeve having opposed holding notches 36c complementary to pin 30 as indicated in Fig 23.
Referring now to Fig. 2A, body section 11 is provided with a bore 56 having internal threads for a threaded joint 57, and an internal upper shoulder 58 An adapter plug 59, provided with an external upwardly facing shoulder 60 and a threaded upper central periphery is screwed into the lower end of bore 56. This plug is provided with a circumferentially arranged series of longitudinally extending through-holes 61 for reception of a plurality of connector bolts such as 62, 62a, which latter are each encircled by a respective tubular insulator sleeve 63 and a pair of end insulating washers 64, 64, the insulator devices serving the obvious function of electrically isolating the through-bolts from the metal of adapter plug 59. Nuts, as shown, are provided to retain the bolts in place.
Positioned in bore 56 immediately above the connector bolts and plug 59 is a terminal block 65 having sockets in its lower end and making contact with respective connector bolts, and having conductors such as 65b, 65c, one for each socket, leading upwardly through the block, the latter being properly oriented in bore 56 with respect to the several bolts by any suitable means, as, for example, a pin 66 mounted in plug 59' and engaging in a complementary hole in the terminal block. Positioned above terminal block 65 in body section 11 is a circuit controller 65a (see Fig. 1) which may be of any suitable type and, for example, may be like or similar to that fully described in the patent to Johnston, No. 2,048,451. The purpose of controller 65a, to which the conductors such as 65b, 65c lead, is to provide electric current to each of the conductors in a prearranged sequence, as is explained in the patent.
The connector bolts such as 62, 62a, have secured to their lower ends, as by soldering, respective insulated conductors such as 67, 68 which are provided in excess length and which extend loosely downwardly past 22 and through one or another of bores 43 in plug 36a, from which one conductor, such as 67, extends to and terminates at, an igniter pin 52 as shown in Fig. 2B. Others of the conductors, such as 68, extend downwardly and are secured to respective ones of connector bolts such as 6211, similar to bolts 62, 62a. Connector bolts such as 62b are arranged in an adapter plug 69 which in all material respects may be similar to plug 59 and which is secured in place in similar fashion, in the lower end of the bore of sub 14. Conductors such as 70 are secured to respective connector bolts such as 62b and extend downwardly therefrom to other of igniter pins such as 52, there being an igniter pin in a detonator for each of the peiforator unit sections such as 12. Conductor 70 may, for example, lead to the lowermost detonator 36, which is located in the upper end of bull nose 13 and the lower end of the lowermost perforator section 12, as indicated in Fig. 1.
As employed herein, the term deflagrable charge is intended to denote a charge of combustible material capable when ignited of burning rapidly or deflagrating with release of. considerable energy, but yet insensitive to ordinary handling shock. Typical of such charge is a charge of Hercules H.E.S. 5002.180 powder; and in contrast thereto is a charge of fulminate of mercury, which is normally a detonable substance sensitive to ordinary thermal and mechanical shocks such as slight abrasion, and which violently explodes when ignited or subjected to mechanical shock. By detonating is usually meant combustion at such a rapid rate that a sudden and violent explosion results. By the expression ordi.
nary handling shock is meant that type of shock, whether thermal or mechanical or of other nature, to which the Combustible or detonable materials or devices of the nature of those disclosed are in any way likely to be subjected in normal handling, assembly, and usage procedures and that type of shock being of such characteristics that subjection thereto of such sensitive devices as blasting caps would at least occasionally result in ex plosion of the sensitive device. Further, as employed herein, the term detonating impingement is intended to mean the engagement of a moving body or element with a detonable material with such speed and energy of impact that the detonable material detonates. By the expression sensitive to ordinary handling shock is meant lsuch sensitivity to thermal or mechanical shock or static electricity that explosion of the substance is likely to at least occasionally occur when the material or portions thereof are subjected to such shocks as could normally be encountered in ordinary handling of the material, such as occur, for example, in handling, assembling, dropping, and the like.
While wide variations in design, loading, and assembly of'apparatus according to the invention are possible, one commercially acceptable design will be characterized as an example. Using the aforementioned Primacord 50 'grain PETN fuse, the end being arranged as shown in Fig. 2B of the drawings and spaced one and one-sixteenth inches from the nearest face of a shear disc or element '47 of mild cold-rolled steel one-tenth inch thick at the bore, a bore 45 of seven thirty-seconds of an inch in diameter, a propellant charge loading density of 260 grains per cubic inch of free space in chamber or bore 39 (26 grains in a chamber free space of approximately one-tenth cubic inch volume), the propellant being Hercules H.E.S. 5002.180, and plug member 44 and plug 36a being of hardened steel, commercially acceptable detonation of the fuse is effected upon ignition of deflagrable charge 50 by igniter 51.
Several possible modes of assembly of the illustrated apparatus are apparent. With respect to the detonator proper, a cylinder 49 and an igniter are dropped into the chamber of plug 36a, seal plug 53, washer 54 and a 'nut 55 applied and tightened, a defiagrable charge 50 'dropped in the chamber and an element 47 set in place pin 52 with a nut 55, plug 36a dropped into sub 14 and the latter screwed onto section 12 (the excess of wire such as 67, 68 permitting any necessary or accidental twisting); wires such as 68 then being secured to bolts such as 62b, plug 69 screwed into sub 14 (with excess wire again permitting twisting), and the procedure con tinued until the perforator string is completed. Wires and electric conductors are preferably suitably coded to facilitate termination of the correct wire at each igniter .pin. Disassembly is obvious and is simpler and easier due to the destructionin use of the expendable items such as igniter, deflagrating charge, shear disc, fuse, grommet, and wires.
From the above description of a preferred embodiment of the invention it will be noted that there is provided a simple detonator for a detonable fuse, comprising only means which are quite insensitive to ordinary handling shock; the detonator and associated apparatus being easily and quickly assemblable without danger of accidental detonation or explosion, and the apparatus being readily disassemblable after usage whereby the expendable parts .may be easily and quickly replaced. The invention thus permits safe and rapid assembly of well casing perforators and like equipment by relatively inexperienced or unskilled workmen, and in the field, accordingly, greatly reducing the cost and danger of such work and the time required for equipment servicing.
It is apparent to those skilled in the art to which the invention pertains that many modifications of the apparatus and its components may readily be effected; hence to be limited to the specific details of the described preferred embodiment of the invention is not desired, but what is claimed is:
l. A readily and safely renewable detonator for a detonable fuse comprising: readily demountable cylindrical upper and lower support members in substantially axial alignment; an axially bored and chambered plug snugly mounted in the upper end of said lower support member; a deflagrating charge and an igniter therefor slidably insertable into the chamber of said plug; a disruptable element closing said chamber; a bored member removably secured in the bore of said plug, with the bore thereof covered at one end by said disruptable element; and readily assembled means for holding said plug in said supports and serving to hold and position an end of a detonable fuse insensitive to ordinary handling shock in substantially axial alignment with said bore; whereby upon ignition of said charge by said igniter said disruptable element is disrupted and at least a portion thereof propelled along said bore and into detonating impingement with said end of said fuse, and whereby the fuse is detonated without any material sensitive to ordinary handling shock. 4 2. A readily and safely renewable detonator for a ,detonable fuse comprising: readily demountable cylindri- ;cal upper and lower support members in substantially axial alignment; an axially bored and chambered plug position an end of a detonable fuse insensitive to ordinary handling shock in substantially axial alignment with said bore; whereby upon ignition of said charge by said igniter said disruptable element is disrupted and at least a portion thereof propelled along said bore and into detonating impingement with said end of said fuse, and whereby the fuse is detonated without any material sensitive to ordinary handling shock.
3. In a well casing perforating apparatus in which a series of detonable charges of material insensitive to ordinary handling shock are arranged to be detonated in rapid succession by a detonable cord fuse likewise insensitive to ordinary handling shock and extending to said detonable charges, a detonator arranged to detonate said fuse and comprising: readily demountable cylindrical upper and lower housing members for said charges, in substantially axial alignment, said housing members providing respectively upper and lower support members; an axially bored and chambered plug snugly mounted in the upper end of said lower support member; a deflagrating charge and an igniter therefor slidably insertable into the chamber of said plug; a disruptable element closing said chamber; a bored member removably secured in the bore of said plug, with the bore thereof covered at one end by said disruptable element; and readily assembled means for holding said plug in said supports and serving to hold and position an end of a detonable fuse insensitive to ordinary handling shock in substantially axial alignment with said bore; whereby upon ignition of said charge by said igniter said disruptable element is disrupted and at least a portion thereof propelled along said bore and into detonating impingement with said end of said fuse, and whereby the fuse is detonated without any material sensitive to ordinary handling shock. '4. In well perforating apparatus including a sealed carrier providing an elongated hollow spaced therein, shaped charge perforating units mounted in the hollow space of said carrier and adapted to fire outwardly through the walls of said carrier, and a detonable cord fuse insensitive to ordinary handlingshock extending in detonating relation to said shaped charge perforating units, the combination therewith of adetonator for said fuse comprising: an axially bored and chambered plug readily removably mounted in the hollow space of said carrier; a deflagrating charge and an igniter therefor slidably insertable into the chamber of said plug; a disruptable element closing said chamber; a bored member removably secured in the bore of said plug, withthe bore thereof covered at one end by said disruptable element; readily assembled means for holding said plug in the hollow space of said carrier and serving to hold andposition an end of said fuse in substantially axial alignment with the bore of said bored member; whereby upon iginition of said charge by said igniter said disruptable element is disrupted and at least 10 a portion thereof propelled along said bore and into detonating impingement with said end of said fuse, and whereby the fuse is detonated without any material sensitive to ordinary handling shock.
References Cited in the file of this patent UNITED STATES PATENTS 120,963 Gomez Nov. 14, 1871 839,194 Du Pont Dec. 25, 1906 1,322,083 Barlow Nov. 18, 1919 2,265,982 Bolton Dec. 16, 1941 2,604,044 Sevold July 22, 1952 2,617,326 Morris Nov. 11, 1952 2,627,160 MacDonald Feb. 3, 1953 2,629,325 Sweetman Feb. 24, 1953 2,649,736 Phillips Aug. 25, 1953 2,662,474 Turechek et a1 Dec. 15, 1953 2,705,920 Kanady Apr, 12, 1955