US2252270A

US2252270A - Perforating device

Info

Publication number: US2252270A
Application number: US239015A
Authority: US
Inventors: Leonidas C Miller
Original assignee: AMERICAN OIL TOOL Co
Current assignee: AMERICAN OIL TOOL Co
Priority date: 1938-11-05
Filing date: 1938-11-05
Publication date: 1941-08-12
Anticipated expiration: 1958-08-12

Description

Aug. 12, 1941- cgMlLLE PERFORATING DEVICE F11-ed Nov. 5, 1938 5 Sheets-Sheet l Aug. 12, 1941. "L, c. MILLER PERFORMING DEVICE Filed NOV. 5, 1938 5 Sheets-Sheet 2 gmc/M30@ All@ 12, 1941- c. MILLER PERFORATING DEVICE Filed Nov. 5, 1938 5 Sheets-Sheet 3 Z D l '0040* e2 Z0 @www l////// |401/ Z D Aug. l12, 1941. L c. MILLER 2,252,270

PERFORATING DEVICE Filed Nov. 5. 1938 5 sheets-sheet 4r gramma/oo@ Leon/'das C. /W/V/ev" Aug. 12, 1941. L, WLLER 2,252,270

PERFORATING DEVICE Filed Nov. 5, 1958 5 Sheets-Sheet 5 Patented Aug. 12, 1941 PERFORMING DEVICE Leonidas C. Miller, Dallas, Tex., assignor to Amex'-L ican Oil Tool Company, Dallas, Tex., a corpo.

ration of Texas Application November, 1938, Serial No, 239,015

` y19 Claims; (Cll ici-csi' 'I'his invention relates to newfand useful improvements in perforating devices.

In the drilling of `oil wells andy the production of flowing wells, it has become common practice to perforate the well casing alongits portion which extends through oil bearing sands and it is oney object of this invention to provide an improved perforating device for this purpose.

An important object of the invention is' to provide an improved perforating device which is adapted to be lowered into a well casing on a wire line or cable and which includes a dry cell orv other battery for supplying the electrical current forfiring the gun cartridges, of the device, whereby the necessity of conducting electrical current from the surface for firing purposes, is eliminated and the running of the tool into the casing, as well as the removalo'f the same therefrom,is eliminated.

A particular object of the invention is to provide a casing perforator having improved control means for controlling the firing of the cartridges or projections, said vcontrol means being so constructed that it may be setat the surface vprior to the lowering ofthe device into the casing and being arranged so that it will auto-y matically fire the cartridges after a predeter?k mined time lapseand in a desired order, in ac,-

cordance with the setting'or adjustment made at thesurface.

' Another object of the'invention is to provide an improved casing perforatorrincluding a plu'-v rality o f gun cartridges for perforating fthe casving and having means for preventingunintentional or accidental firing of the cartridges during the lowering orraising ofthe devicel through the well casing, whereby saidl cartridges cannot be fired until the device is properly positioned in the desired location.

A further object of the invention is toprovide an improved perforator, yof the character described', which provides a double switch through which the current must flow 4to the gun cartridges to fire the same; one of said lswitchesl being associated witha 'mechanical latchingv means which is arranged to positivelyprevent closing of.- said switch during raising or lowering of the device through the well casing.

rStill another object of the invention is to provide a time'mechanism carried by the device for controlling the firing of the cartridges, whereby said switch may be set at theA surface Ato automatically nre the cartridges at `any, predetermined time, thereby eliminating the necessity of manually controlling the rlring from the surface,

A still further object of theinvention is to provide an improved casing perforator which is a self-contained unit and which has its source of electrical power and control switches mounted therein, whereby no connecting or lead-in wires for current or control are necessary, which greatly facilitates handling of the device.

A construction designed tov carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following speciilcationy and' by reference to the accompanying drawings, in which an example of the invention is shown, and wherein: l v

Figure l isa transverse; vertical, sectional view of the upper portionof an improved casing perforating device, constructed in accordance with the invention,

Figure 2 is a continuation of the parts shown in Figure 1, showing the intermediate portion of ther device and illustratingthesafety switch and other" vparts in the position shown as the device is being lowered into the well casing,

Figure' 3 is a continuation of the parts shown in Figure 2 and illustrating the lower portion ofthe device,

Figure 4 is an enlarged, transverse, vertical,l sectional of the intermediate portion ofthe de-l vice and showing thesafety switch'in a' closed] position after said device has been' properly po'f sitioned vin the well casing,

Figure 5 is a continuation of the 'partsshown in Figure 4, with the mechanical latching in its outward position,

Figure 6 is a' transverse, vertical, sectional means view, taken Aon the line 6 6 of Figure 1,

Figure 7 is a transverse, vertical, sectional view, taken` on the linel-l of Figure 1,

Figure 8 isV a horizontal, cross-sectional view,

taken on'the line 8 8 of Figure 2,

Figure 9 isa horizontal, cross-sectional view,

takenon the line 9`9 of Figure 2,

Figure 10 is a horizontal, cross-sectionalview, taken on the line lli- I0 of Figure 2,

Figure 11 is a horizontal, cross-sectional vie'w,f

taken on the line Il-`-"l lof Figure 2,.,

-Figure 12 is a transverse, vertical; vsectional A View showing the latch member in positionfduringthe raising of the f ievice'throughV the Awell casing,

Figure i3 is yawning diagram iuustratmg thev switch and'control means for tiring the "gun car'- tridges, l

Figure 14 is a view similar to Figure 1 and of the device, illustrated in Figures 14 to 17,.

with the said upper end connected to ground by means of a removable sleeve.

In the drawings, the numeral IIJ designates an elongate tubular section or sleeve which has its upper end provided with internal screw threads. A plug II closes the upper end of the sleeve or section I and the upper end ofv this plug has an annular retaining member or cap I2 ,threaded thereon. opening I2' formed in the cap andan annular shoulder I4, which is formed on the lower end of the pin I3, is conned beneath said cap. The pin I3 is rotatable with relation to the retaining. cap I2. and these parts form a 'swivel connection. The upper end of the pin I3 has the coupling I5 at the lower end of a cable or wire line I5 connected thereto and, with this arrangement, the elongat'etubular sleeve or section I0 issuspended from the cable. I

The lower end of the section I 0 is `formed with external screw threads and is connected by means of a coupling collar I6 with a second or lower elongate tubular sectionvH. A transverse plate or disk I8 is confined between the ends oi" the sections IU and I1 (Figure 2), being clamped therebetween and this disk separates theinterior of the section III from the interior of the section I1. Rotation of the disk I8 is prevented by means of dowel pins I9 which Vengage in recesses formed in said disk and inthe upper end of the lower section I1. The extreme lower end of the lower section I1 is formed withexternal screw threads which are threaded into the upper end of a housing 20. cartridges 2| which are adapted to lbe red to perforate the well casing A, as will be explained.

The details of the housing 20, together with the particular construction of the gun cartridges,

forms no part of the ApresentV invention and so long as said cartridges are adapted to be fired by means of an electrical current, the purposes of the invention will be carried out. Also, it is pointed out that any desired number of cartridges may be employed.

The sections I0 and I1 formfan elongate tubular housing or casing which is separated by the transverse disk or partition J8. is suspended from the cable I5 and since its lower end is attached to the cartridge housingV 20, it will be manifest that the latter housing is carried thereby. The cable I5 may thus be utilized to lower the device within the well casing A to' a desired position therein.

The upper sectionv I0 is adapted to house a` socket 22 is mounted on the transverse disk'` or A pin I3 projects through' an yaxial This housing carries the.

This housing partition IB which separates the bore of the upper section I0 from the bore of the lower section I1. This socket is clearly shown in Figure 4 and includes an outer annular, elastic shell 23 which rests upon said disk. Rotation of the shell with relation to the disk is prevented by dowel pins 24, which engage recesses in the lower end of said shell and the top of said disk. The shell is constructed of soft rubber or other elastic, electrical non-conducting material and a socket body 25 is mounted within the upper end of the shell, being molded or otherwise secured therein. The socket body is preferably constructed of Bakelite or similar material and a recess B is formed in the top of said body. A metallic contact sleeve B is mounted in said recess and serves to conduct an electrical current downwardly through the socket, as will be hereinafter explained. An axial recess C having a contact sleeve vC 'therein is located in the body and electrical current :is also conducted through this sleeve. A plurality of other recesses D are also formedin the body 25 and each recess has a contact sleeve D similar to the sleeves B' and C. It is pointed out that the number of recesses D depends upon the number of cartridges contained in the'cartridge housing `2|), as one of these recesses is provided for each cartridge. The recesses B and C do not lead directly to, or are not directly, connected with, a cartridge but lead through a safetyswitch, which will be hereinafter explained.

A tubulancasing 26 is insertable within the upper section I0 and the lower end of this casing is closed by a plug 21, which is threaded onto its lower end. Theplug. 21 is hollowed out and has its bottomclosed by. a disk 28 which is constructed of. Bakelite or similar material and which is suitably fastened in the plug. The disk carries a contact prong B2 which is adapted to engage within the contact sleeve B 'in the recess B whenthe casing 26 is in position within the section IIL A similar contact prong .C2 is located axially of the disk 28 and is arranged to engage within thecontact sleeve C' of the recess C. fA, plurality of additional contact prongs D2 `are also mounted in the disk 28 and are adapted to engage` within4 the contact sleeves DT within the recesses D. With this arrangement, it will be obvious that when the tubular casing`26 is in position within the section I0, the contact prongs B2, ,C2 and D2 are engaged within their respective contact sleeves so that an electrical connection is set up between said prongs and said sleeves.

The casing 26jextends upwardly substantially throughout the length of the section I0 and said casing is preferably formed in two sections which are connected together by means of a coupling plug 23, said plug being threaded to the two sections of said casing. A switch assembly S, which carries-the control mechanism` fory controlling the firing of the cartridges', as will be hereinafter explained, is mounted within the tubularv casing 26 between the plug 29 andthe lowerniost plug 21. This switch assembly `is clearly shown in Figures 1, 6 and 7 and includes apairof side plates 30 and 3tlgI which are 4spaced from each other and which extendbetween the

plugs

21 and 29. As is clearly shown 'in Figure 1, the upper plug 29 is formed with a depending angular lug 3| and the extreme upper ends oi' the side plates 3U and 30 are suitably fastenedto this'lug. The lower ends of the

plates

30 and 30 aresimilarly fastened to an upstanding collar or lug 32 which is preferably formed integral with the plug 21. In this manner, the side plates 30 and 30' are rigidly mounted Within the tubu-y lar casing 26.

Mounted between the side plates 30 and 30' near the upper ends thereof ls a timer mechanism T. This mechanism is of standard construction, being actuated by means of a flat spring 33, which spring has one end secured to a shaft 34. The shaft extends through andy is journaled within the side plate 30 andy has a winding key 35 located on the outer side of the plate 30. A suitable opening 36 is formed in the tubular casing 26, whereby access to the key 35 may be had. The opposite end of the at spring 33 is fastened by means of a rivet 31 to the inner wall of the side plate 30. A gear train or mechanism is driven by the shaft 34 and this mechanism is such as is used in a Watch. 'Ihe details ofthe mechanism are not shown since it is of ordinary construction, the mechanism yserving to require a predetermined length of time for the shaft to complete one revolution. The mechanism includes a pinion 38 and an enlarged gear 39, which is fastened on a stub shaft 40 which is journaled in the plates 38 and 30' below the spring 33. One end of the shaft 40 extends outwardly through the side plate 30' and has a cam 4| secured thereto. This cam has a recess 42 (Figure 13) formed in its periphery. Obviously, when the spring 33 is wound it is placed under a tension and, as said spring unwinds to return to a normal position, the shaft 34 is rotated to rotate the pinion 38. Rotation of the pinion imparts a rotation to the cam shaft 4|) through the medium of the gear train 38 and, therefore,

the cam 4| is rotated. The timerT may be constructed so that it will take any given length of time for the cam 4| to complete one revolution, lthat is, it may take thirty minutes or it may take sixty minutes, depending on howv long it takes the gear train to impart suflicient rotation to the shaft 34 to cause the cam shaft 40 to make a 1 complete revolution.

An elongate operating arm or lever is pivoted on a pin 44 on the outer side of the side plate 30'. The upper end of this lever extends contiguous to theperiphery of the cam 4| and a lug 45 on said lever is arranged to ride on the surface of said cam, being held -in engagement with said cam periphery by a coiled spring 46 (Figure 7). The upper4 end of the lever 43 is offset and is provided with a roller 41. This roller is arranged to engage a spring switch blade 48, which blade is mounted on an angular bracket 49 secured to the outer surface of the plate 30. The switch blade 48 is movable between an electrical contact 50 mounted on a bracket 5| secured to the plate, and a second contact 52 which is secured rto a second bracket 53. When the lug 45 on the operating lever 43 is riding on the periphery of the cam wheel 4| the switch blade 48 is in engagement with a contact 50. However, when the cam 4| has'rotated a complete revolution to move the recess 42 opposite the lug 45, said lug enters the recess, whereby the operating lever 43 is swung on the pivot 44. Such swinging of the lever 43 causes the upper end of said lever to move the switch blade 48 out of engagement with the contact 50 and to engage said blade with the contact 52. The electrical circuits which are closed and opened by the engagement of the blade 48 with the

contacts

50 and 52 will be hereinafter described.

The lower end of the operating lever 43 isbent upon itself at substantially a right angle to form a projecting lug 54. When the lug 45 .at the upper vportion of the lever 43 is riding on the periphery of the cam 4|, the lever 43 is in a position, with the lug 54 at its lower end engaging within a recess 55 provided in the periphery of a circular cam disk 56, whereby rotation of the cam disk 56 is prevented. Whenever the lug 45 drops into the recess 42 on the cam 4|, the lever 43 is swung, which swinging disengages the lug 54 from-the recess 55 in the cam 56 and, when this occurs, the cam 56 is capable of-rotation. The cam 56 is mounted on a shaft 51 which is journaled in the side plates 38 and 30', as clearly shown in Figure 1. The cam 56 is located on the outer side of the plate 38', while a gear 58 is fastened on the shaft 51 adjacent the inner side of said plates. The gear 58 is in constant mesh with a gear 59, Which latter gear meshes with an operating pinion 60. The pinion 60 is mounted on la shaft 6| which is journaled in the

plates

30 and 30 and the outer end of the shaft 6| is provided with a winding key 62 which is located within an opening\l63 formed in the outer tubular casing 26. A flat spring 64 has one end secured to the shaft 6| with its opposite end fastened by meansof a rivet 65 to the inside of the plate 30. 'I'he winding key 62 is utilized to rotate the shaft in a direction to wind the spring 64 and place the same under a tension. The shaft 6| is connected with the cam 56 through the

gears

58 and 59 and the pinion 68 vand when the spring 64 is placed under a tension, the recess 55 in the cam 56 is opposite the lug 54 on the operating lever 43, whereby said lug may engage within said recess to prevent rotation of said cam. When rotation of the cam is prevented, rotation of the shaft 6| is also prevented and, therefore the spring 64 cannot unwind until the lug 54 is disengaged from the recess 55 permit rotation of the cam 56.

Since the cam 56 is mounted on the shaft 51, it will be manifest that said shaft is rotated when the cam disk 56 is rotated. The shaft 51 exf tends through the

plates

30 and 30 and has a switch arm 66 keyed or otherwise secured thereto, whereby when the shaft51 is rotated the switch arm 66 is also rotated. A contact 61 is secured to the outer endof the arm 66 and is arranged to travel over a plurality of contacts 68 which are mounted in a commutator disk 69 which is suitably mounted within the side -plate 30.` With this arrangement, it will be manifest that when the switch arm is rotated it will successively engage vth-e contacts 68 on the commutator disk as it completes one revolution. The contacts 68 are connected-k to the cartridges 2| located in the cartridge housing 20 and when engaged by the switch arm contact 61 close an elec-l trical circuit to said cartridges tofire the same,

set to rotate the cam 4| at a desired speed, whereby a predetermined lapse of time will be necessary for the cam to complete one revolution or a portion of a revolution and move the recess 42 thereof opposite the lug 45 of the operating lever 43. The cam may, of course, be'adjusted to so locate the recess 42 that one revolution, or any portion thereof, is necessary to move said'recess opposite the lug. During the timethat the cam 4| is rotating, the lug 54 at the lower end of the lever 43 is engaged within the recess 55 of the cam disk 56, whereby rotation of the shaft 51 and spring 84unwinds to rotate the shaft 51 throughV the medium of the

gears

58 and 59 and the pinion 8|).4 'Ihe rotation of the'shaft 51 causes the switch arm 86 on said shaft to rotate, whereby the contact 81 on the outer endV of said `arm passes over and engages the various contacts 88 on the commutator disk |59.v As the switch arm completes its revolution, the engagement of the contact 81 with the contacts 68 completes an electrical circuit to the various cartridges 2| so as to re the same. Inthis manner,` the. disk 58 acts as'a locking means which prevents operation of the switch arm 68 until such time as the cam disk 4| of the timing mechanism T completes its revolution. Thus, it is possible to accurately control the exact time at which the cartridges 2| are red.

For supplying the electrical current necessary to fire the cartridges, a dry cell battery 10 of any desired construction is mounted inthe upper end of the casing 26 above the plug 29 (Figure 1)`. This battery is cylindrical in cross-section and is located within an elongated sleeve 1| which has its lower end secured-by screw threads to the upper portion of the plug29. An annular insulating jacket 12 is interposed between the battery 10 and the sleeve 1| and serves to insulate said battery from the sleeve.` The lower end of the battery -is supported on a coiled spring 13 which is conned within the jacket 12 and the contact 10 at the lower end of said battery engages the spring. A contact screw 14 extends through an axial bore formed in the plug 29 and the upper end of this screw carries a plate 15 which is engaged by the spring 13. With this arrangement, the current may flow from the contact 10' oi the battery through the spring and to the elongate contact screw 14. The screw is suitably insulated from the plug 29 by means of an insulating sleeve 16. The lower end of the contact screw is connected by means of a wire 14a with the Contact 52 which is mounted side of the side plate 30'.

The upper end of the sleeve 1| wherein the battery 10 is mounted, is closed by'a cap 11, which cap has an annular insulating collar 18 mounted therein. A contact pin 19 is mounted axially of the insulating collar 18 and has itsV lower end engaging the contact 10a at the upper end of the battery 1D, whereby an electrical connection is established therebetween. The upper end of the contact screw 19 is engaged by a spring pressed plunger 80 which is mounted axially in the lower portion of the plug I, which closes the upper end of the section I0. The plunger 80 is metallic and, of course, contacts the metallic plug, whereby the same is grounded and, thus, the contact 18a at the upper end of the battery 10 is connected to ground through the screw 19 and the plunger 80. The upper portion of the sleeve 1i which carries the battery 18 is axially alined within the upper endof the casing 28 by means of a spacing collar 8| which is threadedV into said casing. A suitable ilanged cap 82 surrounds the extended or projecting portion of the sleeve 1| and overlies thespacing collar 8| and the upper end of the ca-sing'26. The cap is constructed of rubber, or other shock absorbing matermi and the outer surface of thefianged cap at one contacts the bore of the section I8, whereby the casing 26 is held in axial alinement at its upper end within said section. v

From the above, it will be seen that the battery 10 is carried in the upper portion of the casing 26, while the control mechanism for flring the cartridges 2| is carried inthe lower portion of the casing. The upper contact 18a of the battery 18 is connected to ground through the screw 19 and the plunger 80, while the lower contact 10 of the battery is connected through the screw 14 and the wire 14a to the contact 52 which is located on the side plate 30'. As has been explained, the operating lever 43 controls the movement or swinging of the switch blade 48 and, normally, said switch blade is riding onthe periphery of the cam 4|, whereby said switch blade is out of engagement with the contact 52 and in engagement with the contact 58. When engaging the contact 50, it is obvious that the switch blade 48 has opened the circuit from the battery 10 and therefore no current is ilowing from said battery. When the timing mechanism T has rotated the cam disk 4| sufficiently to move the recess 42 opposite the lug 45 of the operating lever, said operating lever swings to the position shown in Figure 7, whereby the switch bladeA is engaged with the contact 52. When -this occurs, the current from the battery 10 mayA ow to the switch blade 48. From the switch blade the current'fiows through awire 48a downwardly to the contact prong B2 which is engaged with the contact sleeve B' in the recess B, which is located in the contact socket body 25 at the lower end of the section I8. In this manner, the current from the battery is conducted to the sleeve B' when the Switch blade 48 is engaging the contact 52. The current is conducted from the sleeve B' by a wire 48b which has its upper end electrically connected to said sleeve. This wire extends downwardly through an opening 84 which is formed in the transverse partition |8`and has its lower end connected to the flexible switch blade 85 of a safety switch assembly E.

'Ihe safety switch assembly E includes an annular body 86 which is suitably fastened within the section |1 near the upper portion thereof. 'Ihe body 88 has an axial bore 81 which has its upper end closed by an insulating disk 88 which is suitably fastened within the upper portion thereof. The lower end of the bore of ".he body is closed by :a disk 89 which is threaded thereinto.v The resilient switch blade A88 has its upper end bolted to the insulating member 88 and the lower end of the lead wire 48h is electrically connected to this upper end. Diametrically opposite the switch blade 85 is a second switch blade 85', similar in construction to the `blade 85. The upper portion of the blade 85' is also secured to the disk 88 and a lead wire 85a has its lower end electrically connected with said blade. The upper end of the wire 85a extends through an opening 84 `which is located axially in the partition or plate |8 .and the extreme upper end of the wire 85a is electrically connected with the sleeve C' which is located in the recess C of the electrical socket 25. In this manner, the switch blade 85 is electrically connected with the prong C2 which engages the sleeve C' and a wire 85b leads from said prongto the switch arm 88 which travels over the commutator disk 89.

With the abovearrangement, it will be seen that the electrical current is conducted from the battery through the contact 52 and the switch blade 48, then through the wire 48a downwardly through the prong B2 and the sleeve B', then through the wire 48h to the switchblade 85. When an electrical connection is established between the switch blade 85 and the other switch 5 blade 85, as will be explained, the current flows upwardly through the wire 85a, contact sleeve C', prong C2 and wire 85h to the switch arm 66.- Thus, the current is conducted to the contact member G1 on said switch arm andas said arm engages the contact 68 of the 4commutator disk 69, the current is carriedto the latter contact 68. A wire 68a leads from each contact 68 and extends downwardly to one of the contact prongs D2 which is in engagement with one of the sleeves D' located in each recess D in the connecting socket 25. Each contact sleeve D has the upper end of a lead wire 68b'connected thereto and this Wire extends kdownwardly through an opening 84a in the partition I8. The lower end of the wire 68h is connected to one of the gun cartridges 2|. Thus, when the switch arm 66 engages the contact 68 on the commutator disk, the current flows from the contact 68 downwardly through the wire 68a, contact prong D2, contact sleeve D' and wire 68h to the cartridge connected with said wire 68h. For housing the wires leading from the contact sleeves D', a suitable conduit 90 is located'at one side of the section I1 within the interior thereof (Figures 3 and 4). For packing off around the

wires

48h, 85a and 68b, which extend through the partition I8, a suitable packing member 9| may be secured to the underside of said partition, being held in place by a retaining ring 92. The packing member 9| has upwardly extending sleeves 9 I which extend into the openings in the partition and surround the wires'so as to assure a seal around said wires. The provision of the packing element 9| prevents any fluid which might be in the section I1 from entering the connecting socket 25.

From the above, it will be seen that when the timing mechanism T has rotatedl the cam disk 4| suiliciently to swing the lever 43 so as to close the circuit between the switch blade 48 and the contact 52, electrical current is conducted downwardly from the battery to the blade 85 of the safety switch E. When said switch blade 85 has electrical connection with the switch blade 85, the current is then conducted to the switch arm 66 which travels over the commutator disk 69. At the same time that the lever 43 has moved the switch blade 48 into engagement with the contact 52, the lug 54 at the lower end of said lever has been disengaged from the cam disk 56, which permits the switch arm 66 to rotate around the commutator 69, as has been explained. 'I'herefore, when the current is conducted to the switch blade 85, the switch arm 66 is rotated around the commutator disk to engage the various contacts 68 for firing cartridges. Of course, if there is no electrical connection between the switch .blade 85 and the switch blade 85 of the safety switch E, it is impossible for the cartridgeto be fired for, obviously, no current can be conducted to the switch arm 66 of the commutator.

For controlling themaking and breaking of an electrical connection between the

switch blades

85 and 85 an elongate operating rod 93 is disposed axially within the lower section I1 of the housing.- The upper portion of this stem extends through an axial opening 89 in the plug which closes the bore of Ithe body 86 of the safety switch E, while the extreme upper end of said stem projects through an opening 88' in the insulating disk 88 which closesthe upper end of said body. An insulating sleeve 94 surrounds the upper portion of the rod 93 and insulates the rod from the metallic body of the switch. The extreme upper end of the rod 93 is movable within a guide sleeve 95 which extendsr upwardly from the insulating disk y8,8. A collapsible bellows 96 has its lower end secured to the upper end of the body 86 and this bellows completely encloses the guide sleeve 95. 'I'he upper end of the bellows is closed by a suitable plate 91 which has the wires 48h and 85a ex-y tending therethrough. The space around the wires extending through the plate 91 is packed off by packing collars 91. f

Confined within the bore 81 of the body 86 and surrounding the insulating sleeve 94 on the rod 93 is a metallic contact ring 98. This ring is movable between theswitch blades and 85 and is adapted to be engaged by the offset lower ends of said switch blades. However, when the rod 93 is moved upwardly within the housing, the contact ring 99 is arranged to be moved upwardly beyond the offset lower ends of the switch blades 85 and 85', as shown in Figure 2, whereby said offset lower ends engage the insulating sleeve 94 and are disengaged from said contact ring. -In this position, the circuit between the blades 85 and 85' is open and there is no current flowing between said blades. When the operating rod 93 isl moved downwardly to the position shown in Figure 4, the contact ring 98 moves between the oifset lower ends of the

blades

85 and 85 and since it is constructed of metal, serves to close the electrical circuit between said blades. Therefore, when the rod 93 is in the position shown in Figure 2, the switch formed by the blades 85 and- 85 is open and it is impossible to fire the cartridges; however, downward movement of the rod moves the ring 98 between the switch blades to close the circuit therebetween.

Theswitch blades are adapted to operate within an oil bath and to retain said oil within the bore 81 of the body 86, a second collapsible bellows 99 has its upper end secured to the closure disk 89 `which is threaded into the lower end ofthe body se. 'rne1ower end of the bellows is secured to a flanged collar |00 whichis confined between and external shoulder I 0| and ,the lower end of the insulating sleeve 94. With such arrangement the movement of the rod axially of the body 86 causes the lower bellows to be expanded or contracted in accordance with such movement. Thus,` the oil or other fluid which is Within' the bellows 99, body 86 and upper bellows 96 is retained in place and the switch blades 85 and 85' operate at all timeswithin such fluid.

The lower end of the operating rod 93 extends through a partition |02 which is mounted in a fixed position wi-thin the section I1, being fastened therein by means of screw |03 (Figure l0). The extreme lower end 0f the rod 93 is fastened to a plate |04 which is slidably mounted within the bore of the section I1. Theplate I 04 is disposed opposite or in horizontal alinement with a plurality of vertical slots |05 which are formed in the Wall of the section I1. A collar |06 surrounds the section I1 on the outer side of said slots and said ring is fastened to the slidable plate 04 by means of screws |01. Manlfestly, the ring I 06, plate |04 and the rod 93 fastened thereto are slidable vertically with relation to the section I1, such movement being limited by the -length of the slots |05. A coiled spring |08 'which lsurrounds the section I1 has its upper end engaging the underside of the collar |06, while itsl lower end rests on a fixed ring |09 suitably fastened to the exterior of the section by screws ||0. The coiled spring |08 constantly exerts its pressure to urge the collar |06 and the plate |04 upwardly, whereby the same are held in their uppermost positions at the upper end o! the slots |05. s A K A latch member III is located within the bore of the section and extends through a vertical slot I I2 provided in the stationary partition |02. A pivot pin I |3 which extends transversely of the slot ||2 also extends through the latch member |I|, whereby said member'is pivotally mounted in the partition. The upper portion of the latch member ||I is arranged to swing outwardly through an elongate opening ||4 which is formed in the wall ofthe section The lower end of the latch'member III is tapered or reduced and is normally conned behind a retaining lug |.|5 which extends upwardly from the slidable plate-A04. A at spring ||6, which is secured to the latch member engages' the inner wall of the section I1 and constantly urges the lower end of the latch member inwardly, whereby the upperl end of said latch member is urged outwardly through the slot ||4. The engagement of the lug ||5 with the lower end of the latch member prevents such swinging of the member and holds the same normally in a position as shown in y Figure 2.

For sliding the collar |06 'andthe plate |04 downwardly in the slots |05 under tension of the spring |08, whereby the operating rod 93 may be moved downwardly from the position shown in Figure 2, a vfriction carriage ||1 is provided, being slidable on the exterior of the section I1. 'I'his carriage includes a pair of spaced collars ||8 which are connected by friction springs IIS. The friction springs are constructed of a spring metal and are bowed outwardly, whereby they engage the bore of the well casing A. The friction spring carriage is arranged to engage the upper end of the collar |06 to force the same downwardly and thereby move the rod S3 downwardly so that an electrical connection between the switch blades 55 and 85' may be established, as will now be explained.

In operation, the timing mechanism T is set for a predetermined time, whereby such predetermined time is required to move the recess 42 of the cam 4| of said mechanism opposite the lug 45 of the operating lever 43. For example, if it is estimated that it will require thirty minutes to lower the device to a desired position in the well casing, then the timing mechanism is set for thirty-live or forty minutes whereby it will require thirty-five or forty minutes for the recess 42 of the cam 4| to move opposite the lug 45 of the operating lever and, therefore, the lever 43 is held in the position allowing the switch blade 48 to engage the contact 50 until such time has elapsed. When the switch blade 48 is engaging the contact 50, the battery 10 is grounded at only one terminal, as is clearly shown in Figure 13. At this time, the latch member III within the section I1 is in a retracted position as shown in Figure 2,Y being held in such position by the lug |I5 on the plate |04, which plate is in its uppermost position and is retained in such position by the coiled spring |08. Since the plate |04 is in its uppermost position, the rod 93 which controls the safety switch E is raised. whereby the contact ring 98 offset lower ends of the safety switch blades and 85. Thus, there is no electrical connection between the blades 85 and 85' and it is impossible to conduct any current to the cartridges 2| since such current must flowthrough said blades. With such arrangement, the device may be lowered into the well and thereis no danger of prematurely or accidentally firing the cartridges 2|.

As the device .is lowered into the well, the friction spring carriage rides upwardly on the lower section I1 of the housing, assuming the position lshown in Figure 2. The parts remain in'this position during the lowering operation and when the desired point, at which the device is to be set, is reached, lowering thereof is halted. Ihe cable I5 is then pulled upwardly whereby Vthe entire device is raised through the friction carriage I|1 which remains stationary due to the contact of its springs I|8 with the wall of the casing A. Upward movement of the device is continued until the collar |06 strikes the lower end of the friction carriage I|1 and when said collar engages said carriage a continued upward movement on the device will cause the collar |06 to be moved downwardly under tension of the spring |08 which is compressed. Itis pointed out that the springs IIS of the carriage are stronger than the spring |08, whereby said carriage will remain stationary while the spring |08 is compressed to move the collar |06 downwardly. Since the plate |04 is secured to the collar |06, said plate will move downwardly therewith, whereby the retaining lug I5 on said plate moves away from the lower end of the latch member As soon as said lug disengages this lower end, the latch member swings outwardly under tension of the spring |I6 to the posi-tion shown in Figure 5, whereby its upper end moves radially outwardly through the opening ||4 in the wall of the section I1. The downward movement of the plate |04 not only releases the latch member III, but also moves the operating rod 93 downwardly, whereby the contact ring 58 is moved into engagement with the switch blades 85 and 85' of the safety switch E so as to make an electrical connection therebetween. When this occurs, the electrical lcircuit to the commutator which controls the tiring of the cartridges is made ready, whereby when the switch blade 48 which is controlled by the timing mechanism T is engaged with the contact 52, the cartridges will be red.

After the switch blades 85 and 85' of ,the safety switch E have been electrically connected by the contact ring, the device is in its proper position in the well casing and the cartridges 2| are ready to be fired. At this time, the operating lever 43 has its lug riding on the periphery of the cam disk 4I, whereby the switch blade 48 is engaging the contact 50. The device is held in this position until the cam 4I has rotated sufficiently for the lug 45 on the operating lever to move or drop into the recess 42. At this time, the operating lever swings to swing the blade 48 into engagement with the contact 52. Such engagement of the blade 48 and the contact 52 conducts the electricalcurrent from the battery 10 through the wire 14a, then throughthe contact 52 and the blade 48, then through the wire 48a, contact prong B2, contact sleeve B' and wire 48h to the switch blade 85. From the blade 85, the current flows through the Contact ring 98, blade 85', wire 85a, contact is disengaged from the sleeve C', prong C2, and nally through the wire 85h to the switch arm 66 of the commutator.

At the same time that the operating lever 43 was swung to close the circuit between the switch blade 48 and the contact 52, the lower end of the lever was disengaged from the recess 55 of the retaining cam disk 56 of the commutator switch arm and, therefore, as soon -as the'circuit is closed to the switch arm, said switch arm besins its rotation around the commutator disk 69. Such rotation of thearm causes its contact 61 to successively engage the contacts 68 so as to make an electrical circuit through the wire 68a', contact prong D2 and contact sleeve D and then through the wire 68h to Ithe respective cartridges 2|, whereby the same are fired. Byconnecting the desired cartridges 2| with predetermined contacts 68 on the disk 69, it is possible to re the cartridges in any desired order.

- When it is desired to remove tfhe device from the well, the housing is lowered with relation to the friction spring carriage until the latch member is below said carriage. As soon as the carriage ||1 moves upwardly beyond the latch member, said latch member assumesthe position shown in Figure 12, that is, its upper end engages the underside of said carriage. It is then possible to lift upwardly on the cable vto remove the entire device from the well casing and the engagement of the latch memberjwith the carriage, moves said'carriage'upwardly therewith. The engagement of said latch member with the vcarriage prevents t'he spring carriage from moving downwardly into engagement with the collar |06, whereby the spring |08 holds the collar and the plate |04 attached thereto in its uppermost position during the lifting of the device. This maintains the operating rod 93 in its raised position, whereby therev is no electrical connection between the

switch blades

85 and 85 of the safety switch. Thus, by means of the latch member and its particular arrangement, accidental or unintentional ringof any of the cartridges which may remainA unred, 'is prevented during the raising of the device through the well casing. p

After the device is removed from the well, the timing mechanism T, as Well as the operating spring 64, and operating lever 43 are re-set, after which the device may again be lowered to a desired position in the well casing. It is pointed out that the device is relatively simple in construction and may be readily assembled or disassembled. When itis desired to replace' the bate tery 1'0, it is only necessary to remove the plug and lift the entire casing 26 out of the upper section I0. Such lifting is made possible because of the contact prongs which engage within the electrical receivingl socket 25.

In Figures 14 to 18, a slightly modified form of the invention is shown. In this form, the timing mechanism T is eliminated and a solenoid |20 is substituted therefor. This solenoid is mounted on the inside of the side plate 30. being bolted or otherwise fastened thereto. In this construction, the upper contact a of the battery is not directly grounded as is shown in Figure 1. Instead the spring pressed plunger 80 has a wire 80a leading upwardly therefrom and this wire extends through a conical connecting member|2| which is threaded onto the 'upper end of the plug The upper end of the wire has electrical connection with an annular contact ring |22 which ring surrounds and is insulated from an upwardly extending shank |23 which is made integral with the connecting member |2|. A second contact ring |24 is spaced fromthe ring |22 and is vthreaded onto `the upper endof the shank, whereby this ringis grounded.- With t'his arrangement, the upper end' of thebattery is not connected to ground duri-ng thelowering of the device into the well. f

Theother end 'l0' of the battery is connected by mean-s of a wire 10b which leads directly to the spring arm 85 of the safety switch E, the switch blade 48 and the contacts 50 and'52 of the first form, being eliminated. In this manner, when a ground is set up on the upper end of the battery, a circuit is completed directly tothe safety switch E.

For connecting the upper side of the battery 10 to ground, an elongate sleeve member |25 is arranged to be droppedrdownwandly on the 'cable |5. Thi-s sleeve member is provided with a pair oi flexible contact members |26 at its lower end, which vare adapted to engage the lower contact ring |22. 'The sleeve has a second set of contact members |21 which are arranged to contact the upper contact ring |24. When the sleevel25 is dropped downwardly on the cable |5 and encloses the contact rings as shown in Figure 18, an electrical connection is established between the ring |22 and the ring |24. Since the latter ring is grounded, such electrical connection will cause ground to be connected to the ring |22 and then through the wire a to the upper side of the battery 10. The current ilows from the battery through the wire 10b to the switch blade 85 of the safety switch E. W'hen the operating rod 9.8 of the device is moved downwardly, as has been explained. to connect the switch lblade 65 with the blade of the safety switch, the current will ilow from saidA blade 85' through the wireV 85a and to the switch arm 66 of the commutator. In this form, the commutatordisk is provided with an additional contact 68', onwhich contactrthe contact member 61 of the switch arm 66 normally rests. Therefore, as soon as the circuit is closed between the blades 85 and 85', a flow of current is directed to the contact 68 because the switch arm 66 is resting on this contact.

'I'he contact 68 is connected by means of a wire |28a to the solenoid |20, whereby said sole-` noid i-s energized when the safety switch is closed.

Energization of the solenoid v|20 -attracts an operating lever 43 which is similar in construction to the lever`43. As the lever 43' (Figure 17) moves inwardly toward the solenoid |20, its upper end is engaged beneath a latch member |26. which latch member is constructed of a spring steel or other flexible material. After so engaged, thelever is held in this position against the tension of a coiled spring. 46', which is connected to the lower end of said lever. `The extreme lower end of the lever 43' has the lug 54 thereon which is adapted to engage the recess 55 in the disk 56 of the commutator operating mechanism.

' From the above. itwill be seen that when the sleeve |25 is dropped downwardly on the cable, one side of the battery 10 is grounded. The 0pposite side is directly connected to the safety switch E and when said switch is closed, the current flows through the switch arm 66 of the commutator and thek contact 68' to energize the solenoid 20. As soon as this occurs, the operating lever 43 is swung to disengage its lug 54 from the cam disk 56. whereby said disk allows the switch arm 66 to be rotated by means vof the operating spring 64, as has been explained. The solenoid, after being energized, is of course deenergized as soon as the switch arm 66 moves off ofthe contact 68'. However, since the operating '.lever 43 has moved beneath the spring latch |28, said lever remains in this position until manuallydisengaged from said latch. 'I'he remainder` of the operation of this form of the invention is exactly the same as the rst form, hereinbefore described. Y

The foregoing description of the invention is explanatory thereof andvarious changes in the size, shape and materials, as well as in the .des tails ofv the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention. Y

What I claim and desire to secure by Letters Patent is:

1. A perforating device for a well casing including, a housing adapted' to vbe lowered into said casing onla flexible line, gun cartridges mounted in the casing and arranged tov be electrically fired to perforate the casing, a source of electrical current supply within the housing, a timing mechanism within thev housing' and control means comprising aspring actuated member associated with a timing mechanism within the housing for controlling. the flow of current from the source to the cartridges to ilre the same.

2. A perforatingdevice for a well casing including, a housingv adapted Yto be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be elec, trically red to perforate the casing, a source of electricalcurrent supply within the housing, andrrotatable spring actuated 'control means within. the housing fork controlling the flow of current from the sourcel to the cartridges to fire the same. I, y

3. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a flexible line,` gun cartridges mounted in the casing and arrangedto be electrically` red to perforate the casing, a source of electrical current supply within the housing, control means electrically connected to thesource of supply and'to the cartridges for controlling the flow of current to the cartridges, and means within the housing and associated with said controly means and connectedin the electrical circuit of the control means for preventing accidental or unintentional operation of the same, said last named means being operated to permit ilow of current to the control means uponk an upward movement `of the device within the well casing.

4. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be electrically fired to perforate the casing, a source of electrical current supply within the housing, control means electrically connected to the source of supply and to the cartridges for controlling the flow of current tothe cartridges, a safety switch connected in the electrical circuit between the source of current supply and the control means for preventing ow of current to the control means prior to the positioning of the device in the weil casing, and means actuated by an upward movement of the Ahousing within the well casing for moving the safety switch to a closed position to permit a flow Aof current to the control means, whereby said safety switchrmay be closed at any desired elevation oi the device within the well casing'. l

5. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a ilexible line, gun cartridges mounted in the casing and arranged to be electrically red to perforate the casing, a source of electrical current supply within the housing, means for electrically connecting the source of current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the flow of current to said cartridges, an operating lever associated with the control means and normally preventing operation thereof, and means for actuating the lever` to release the control means and permit the same to close the circuit to the cartridges.

6. A yperforating device for a well casing including, a housing adapted to be lowered into said casing on a exible line, gun cartridges mounted in the casing and arranged to be electricallyv tired to perforate the casing, a source of electrical current supply within` the housing, means for electrically connecting the source of current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the ilow of current to said cartridges, an operating lever associated with the control means and normally preventing operation thereof, and a timing mechanism within the housing for actuating the lever lat a predetermined time, whereby said lever releases the control means to permit the same to operate and close the circuit to the cartridges.

7. A perforating device for a well casing in cluding, a housing adapted to be lowered into said casing on a' exible line, gun cartridges mounted in the casing and arranged to be electrically tired to perforate the casing, a source of electrical current supply within the housing, a spring actuated commutatorconnected in the electrical circuit between the source of current supply and the cartridges for controlling the ilow of current to said cartridges, and means associated with said commutator for normally preventing loperation thereof, a timing mechanism for actuating said last named means to. release said commutator when desired to permit operation of the commutator, whereby the circuit to the cartridges is closed.

8. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be electrically' tired to perforate the casing, a source of electrical current supply within the housing, a spring actuated commutator connected in the electrical circuit between the source of current supply and the cartridges for controlling the flow of current to said cartridges, means associated with said commutator for normally preventing operation thereof, a timing mechanism for actuating said last named means to release said commutator when desired to permit operation of the commutator, whereby the circuit to the cartridges is closed, and a safety switch connected in the electricalcircuit between the source of current supply and the commutator and arrangedr to be closed when the device is properly positioned in the well casing, whereby current cannot iiow to the commutator and cartridges vuntil said device is in its desired position.

9. A perforating device for a well casing includinga housing adaptedv to be lowered into said vcasing on a flexible line, gun cartridges mounted inthe casing and arranged to be electricallyiired to perforate the casing, a source of electrical current supply within the housing, a spring actuated commutator connected in the electrical circuit between the source of current supply and the cartridges for controlling the ow of current to' said cartridges, means associated with said commutator for normally preventing operation thereof, a timing mechanism for actuating said last named means to release said commutator when desired to permit operation of the commutator, whereby the circuit to the cartridges is closed, a safety switch connected in the electrical circuit between the source of current supply and the commutator and arranged to be closed when the device is properly positioned in the well casing, whereby current cannot flow to the commutator and cartridges until said device is in its desired position, and means carried by the housing for preventing closure of the safety switch When'the device is being removed from the well, whereby unintentional firing of the cartridges during such removal is prevented.

10. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a ilexible line, gun cartridges mounted in the casing and arranged to be electrically fired to perforate the casing, a source of electrical current supply within the housing, a spring actuated commutator connectedk in the electrical circuit between the source of current supply and the cartridges for controlling the flow of current to said cartridges, means associated with said commutator for normally preventing operation thereof, means within the housing for actuating said last named means, to release said commutator when desired to permit operation of,-the commutator, whereby the circuit to the cartridges is closed,'a safety switch connected in the electrical circuit between the source of current supply and the commutator and arranged to be closed when the device is properly positioned in the well casing, whereby current cannot flow to the commutator and cartridges until said device is in its desired position, a friction spring carriage slidable on the housing and associated with the safety switch for closing said switch at the desired time, and a pivoted latch on the housing adapted to lock the carriage against downward movement on the housing and thereby prevent closing of the safety switch during removal of the device from the well casing.

11. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be electrically red to perforate the casing, a source of electrical current supply within the housing, control means electrically connected to the source of supply and to the cartridges for controlling the flow of current to the cartridges, means for actuating the control means at a predetermined time, a safety switch connected in the electrical circuit between the source of current supply and the control means for preventing fiow of current to the control means prior to the vpositioning of the device in the well casing, and means carried by the housing and co-acting with the safety switch for preventing closure of the safety switch when the device is being removed from the well, whereby unintentional firing of the cartridges during such removal is prevented.

12. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be electrically fired to perforate the casing, a source of electrical current lsupply within the housing, means for electrically connecting the source of current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the ow of current to said cartridges, an operating lever associated with the control means and normally preventing operationthereof, a timing mechanism within the housing for actuating the lever at a predetermined time, whereby said lever releases the control means to permit the same to operate and close the circuit tothe cartridges, and a safety switch connected in the electrical circuit between the source of current supply and the control means for preventing flow'of current to the control means prior to the positioning of the device in the well casing.

13. A perforating device for a well casing including, ahousing adapted to be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be electrically fired to perforate'the casing, a source of electrical current supply Within the housing, a spring actuated commutator connected inthe electrical circuit `between the source of current supply and the cartridges for controlling the flow of current to said cartridges, means associated with said commutator for normally preventing operation thereof and being arrangedy to release said commutator when desired to permit operation of the commutator, whereby the circuit to the cartridges is closed, a safety switch mounted within the housing and including a pair of switch blades connected in the circuit between the source of supply and the commutator,v an operating member movable within the housing and having a contact adapted to engage the blades toelectrically connect the same whereby current is conducted to the commutator,

and means carried by the housing for holding the operating member in a position With its contact disengaged from the switch blades during the raising and lowering of the device, through the well casing, whereby no current ilows to the commutator and cartridges during such movement of the device through the casing and accidental firing of the cartridges is prevented.

14. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a flexible line, gun vcartridges mounted in the casing and arranged to be electrically fired to perforate the casing, a source of electrical current supply Within the housing,

means for electrically connecting the source of.

current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the flow of current to said cartridges, an operating lever associated with the control means and normally preventing operation thereof, and electrically operated means for actuating the lever, whereby said lever releases the control means to permit the same to operate and close the lelectrical circuit to the cartridges.

15. A perforating device for a well casing including, a housing adapted to be lowered into said casing on a exible line, gun cartridges mounted in the casing and arranged to be electrically flredto perforate the casing, a source of electrical current supply within the housing,

means for electrically connecting the source of current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the now of current to said cartridges, an operating lever associated with the control means and normally preventing operation thereof, electrically operated means for actuating the lever, whereby said lever releases the controlmeans to'permit the same to operate and close the electrical circuit to the cartridges, Vand means adapted to rbe dropped from the surface for completing an electrical circuit to said electrically operated means, whereby the cartridges may be ilred at a desired time.

16. A perforating device for a well casing including, a housing adapted to `be lowered into said casing on a ilexible line, gun cartridges mounted in the casing and arranged to be electrically fired to perforate the casing, a source of electrical current supply within the housing, means for electrically connecting the source of current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the flow or current to said cartridges, an operating lever associated with the control means and normally preventing operation thereof, and a solenoid for actuating the lever, whereby said lever releases the control means to permitv the same to operate and close the electrical circuit to the cartridges.

17. A perforating device for aiwell casing including, a housing adapted to be lowered into said casing on a flexible line, gun cartridges mounted in the casing and arranged to be electrically red to perforate the casing, a source of electrical current supply within the housing, means for electrically connecting the source of current supply to the cartridges, a control means interposed in the circuit between the supply and the cartridges for controlling the flow of current to said cartridges, an operating lever associated with the control means and normally preventing operation thereof, a solenoid for actuating the lever, whereby said lever releases the control means to permit the same to operate and close the electrical circuit to the cartridges, and a safety switch connected in-the electrical circuit between the source of current supply and the control means for preventing flow of current to the control means prior to the positioning of the device in the well casing.

18. A perforating device for a well casing including, a housing adapted to be lowered into said casing, gun cartridges mounted in the casing and arranged to be electrically nred to perforate the well casing, a source of electrical current supply within the housing and connected with the cartridges, whereby said cartridges are fired when the current is conducted thereto, a safety switch' mounted within the housing and including Va. pair of switch blades connected in the electrical circuit between the source of supply and the cartridges, and a movable operating member movable between and arranged to coact with the switch blades to open and close the circuit, and means for releasably maintaining the operating member in a position holdin the circuit open during raising and lowering of the device through the casing, whereby no current may flow to the cartridges during such movement of the device.

19. A perforating device for a well casing including, a housing adapted to be lowered into said casing, gun cartridges mounted in the casing and arranged to be electrically red to perforate the well casing, a source of electrical current supply within the housing and connected with the cartridges, whereby said cartridges are red when the current is conducted thereto, a safety switch mounted within the housing and including a pair of switch blades connected in the electrical circuit between the source of supply and the cartridges, an operating member movable within the housing relative to` said blades and having a contact adapted to engage the blades to electrically connect the same whereby current may ilow to the cartridges, and means carried by the housing for holding the operating member in a position with its contact disengaged from the switch blades during raising and lowering of the device through the well c asing to prevent a ilow of current to the cartridges during such movement.

, LEONIDAS C. MILLER..