US2889773A - Detonator head - Google Patents

Description

INVENTORS.

TOR/VEKS June 9, 1959 H. E. sTAADT ETAL DETONATOR HEAD Filed July 20, 1956 Haro/d5. Sfaoo BY Joseph R. Hrao/e/ Mam nited DETONATOR HEAD Application Iuly 20, 1956, Serial No. 603,205 1 Claim. (Cl. 102-20) This invention relates to detonator heads, and particularly to detonator heads which are adapted for use with perforating guns of the type used in perforating the casing and bore hole wall of oil or gas wells or the like.

In the completion of oil or gas wells casing is often run into the well bore. Cement is then pumped down through the casing and up between the casing and well bore wall. A perforating gun, usually one having shaped explosive charges disposed along a light, frangible, usually tubular, frame, is lowered after the cement has set, into the well bore to the depth of the desired productive formation and is detonated. The shaped charges blast holes through the casing and cement and into the well bore wall. In order to detonate all the shaped charges substantially simultaneously a length of detonable fuse, such as Primacord, extends from a detonator head to each of the shaped charges. Normally a blasting cap,

disposed in the detonator head and tired by electrical means, is utilized to detonate the Primacord In most perforating guns the Primacord is carried within the tubular frame of the gun in order to protect the Primacord from fluid in the wall bore. The tubular frame of the gun is coupled to the detonator head into which the end or ends of the Primacord extend. Because of leakage due to the high uid pressures to which the gun is subjected and, occasionally, because of leakage induced by attack on the tubular gun frame by acid or other corrosive uid in the well bore, either the blasting cap or the Primacord fails to detonate when an attempt is made to re" the gun. Unsuccessful detonation of the blasting cap is often attributed to the high iluid pressure to which the cap is exposed when leakage of the tubular frame members or detonator head occurs, or to the shorting out of the electrical tiring circuit due to the presence of electrically conducting uid in the detonator head.

The failure of the Primacord to detonate when the blasting cap is tired is attributed to its being wetted by well bore fluids which may contain oil, acid, water, or

mixtures of these uids. The wetting of the detonable l fuse tends to make the fuse less sensitive to the shock produced by a detonating blasting cap.

Accordingly, a principal object of this invention is to provide an improved head for detonating detonable fuse materials.

Another object of this invention is to provide an improved, more reliable detonator head for a well bore perforating gun.

In accordance with this invention there is provided an elongated detonator head having a sealed, fluid impervious detonation initiating compartment and a detonable fuse receiving compartment, the two compartments having a common wall, and a shaped explosive charge so disposed in the detonation initiating compartment that its directional blast, when the charge is detonated, is towards the common -wall separating the two compartments.

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawings, in which:

Fig. l is an elevational view of a detonator head made in laccordance with this invention and disposed in a lluid lled well bore and having a perforating gun attached to the head; Y

Fig. 2 is an elevational view, partly in section, of the detonator head shown in Fig. l, and

Fig. 3 is a sectional View taken along the line 3-3 of Fig. 2.

Referring to the drawings, and particularly to Fig. 1, there is shown well bore perforating apparatus, indicated generally =by the numeral 10, disposed within the casing i2 of a Well bore 14. The space between the casing 12 and well bore 14 is lled with cement 16. The casing 12, as shown, is iilled with any uid 18 which may be present in the well such as oil, water, brine, drilling mud, and the like during the operation of the apparatus.

The `well bore perforating apparatus comprises a tiring or detonating head 20 which has an elongated, generally cylindrical configuration, suspended by a metal cable 22 having a central electrical conductor 24 which is insulated from the metal strands of the cable. The cable 22 is coupled to the detonator head by means of a socket 26.

A per'forating gun, indicated generally by the numeral 28, comprising a triangular frame-work composed of hollow, frangible tubes 32, is coupled to the lower end plug 34 of the detonator head by means of the threaded connectors36, the frame-work having containers 30 (one being shown) supported thereon in which theV shaped explosive charges are held.

Referring now to Figs. 2 and 3, as well as to Fig. l, it may be seen that the body 38 of the detonator head is hollow, contains two compartments, a detonation initiating compartment 46 and a detonable fuse receiving compartment 42, separated by a partition 68, and is of generally H shaped longitudinal cross sectional configuration. The upper end '44 and lower end 46 of the body of the detonator head 20 are closed, respectively, by an upper end plug 4S and a lower end plug 34. A fluid tight seal is eiected between each off the end plugs 48 and 34 and the body 38 by means of a ring sealing gasket 50a or Silb which is disposed in 'a groove 52a or 52b in the end plugs 48 and 34, respectively. A second groove 54a or 54b encircles the part of each end plug 48 or 34, respectively, which extends into the compartment 40 or 42, respectively. The wall of each compartment 40 and 42 contains a similar groove 56a or 5612 which is aligned with the groove in the plug 48 or 34 when the particular plug is inserted into its compartment. A bore 58a, 58b extends through the wall of each compartment 40, 42 of the body section 38 and communicates with the groove 56a or Sb, respectively, in the wall of the body section 38. By driving a nail (not shown) through cach of the bores 58a, 58b and along the grooves 54a, 54h and 56a, 56b the end plugs 48 and 34 are securely attached to the body section.

The lower end plug 34 contains three bores 60 which extend from the bottom plug 34 to the top end of the plug 34. All of the bores 60 open into a large central bore 62. The lower ends of each of the bores 6G are threaded to` receive the connectors 36 `for the tubing 32 of the gun 28.

The bores 60 permit the ends 66 of the detonable fuse, such as Primacord, to extend through the plug 34 and into the compartment 42. A liber centering bushing 64, disposed in the compartment 42, serves to keep the cord ends 66 centrally disposed in the compartment 42, although other centering means could be used. The bushing 64 has a central bore 67 through which the cords extend, the upper end of the bore 67 being counter 72 thereinpthefdepression 72=facingthetwall or partition` 68. The outer diameter of the charge 7tl is slightly less than the inner/diameter ofl the compartment at). The upper end part 74 of the shaped chargef70is-convexly shaped.

A fiber bushing 76 having an axial bore longitudinally; thereof and.having--a--concave depression 8l) in -itsalowerV end -part isA disposedfaboVe-,the shaped charge 70. The Abore 78is -counter bored from-the concave depression to near the upper end 82foflthebushing 76. A blasting cap 34 is disposed in the counter bored.

part of the bore 78-and is pressed kagainst lthe 4upper end of the shaped-charge 70 by means of-a spring 86'whicl1 is also disposedin the counter bored-'part of the bore 7 8.

A coil spring 88 extends from the lower end 9th of the upper endfplug 48 to-the upper end` 82 of the bushing 76. Thus, the spring Sti-presses downwardthe-bushing '76 and shaped charge 70.

A pair of. electricalleads 92, 94 extend upwardly from the blasting cap 84. The lead 92 isfconnecteclftok a ground terminal 96extending from theflower end 90 of the end plugl 48. Thelead 94 is electrically connected to the insulated-conductor 24 of the cable 22.2

The cablev22 extends through the socket-26 rand is connected rmly tov thesocket by a friction t. The socket 26, whose lowerend part is threaded,y is coupled to a threaded bore 98 opening onto the--top-ltlof the upper end plug 48. A smaller bore 101- coaxial with lthe bore 98, extends through the end plug 48.l TheV central conductor 24 passes through theaxial bore of -a rigid bushing.102 and Athen through an vexpendable rubber gasket 104 before passingthrough the bore-1M andbeing connected, as by the soldered connection 106,.for example to the lead 94.

In operation the detonator head 20l andr-perforating gun 28 are lowered down the well bore to the required depth. The blastingcap 84 is fired by applying an elec trical potential (potential sourcenot shown) through lead 24 to a ground'connection (not shown) totheleads 92, 94. The detonation of the blasting cap 84 tires the shaped charge .70,-which may be-as 'small asa 6 --gramvchargq for example, whose explosive force,=directeddownwardly, shatters the commonwall 68 separating the detonation initiating compartment ttll from the detonable fuse receiving compartment. Theblast from theshaped charge 70 is directed towards the ends 66 of the Prirnacord, detonating the Primacord andA also iiringthe shaped charge or charges 30 ofthe per-forating gun 2S.`

The blasting cap 84, beingin a sealed compartment 40 separate from the Primacord, is not subject to excessive pressures which occasionally prevail when the Primacord and the :blasting .capu84are in the'same compartitzalrnost' to `the cornmon--wall-of partition 68 which- 78 extending;

ment and a leak occurs. With a detonating device made in accordance'with this invention, the blasting cap 84, shaped charged and the Brimacord 66 are all red simultaneously, without failure, even though the compartment 42 may be filled with uid due to a leak in the tubing 32, connectors 36 or any other part of the device which communicat'eswith `the compartment 42.

In other words, the ybrute-forcev of theexploding shaped charge 70, directed towards the zPrimacordf will detonate the Jlrirnacordunizlervallsconditions to which the Primacord may besubjected.v

WeV claim:

A detonatorhead comprising afcylindrical bodymember having two axially aligned compartments separated by a partition, one Aof lsaid' 'compartments being a detonation initiating compartment and the other compartment being a detonable fuse receiving compartment, said detonation Linitiating compartment being closed` by a iirst end-.plugand fsaiddetonableqfuse receiving4 compartment being-.closed by a'secondy endplug,.said rst Vend plug having an electrical-ground connector'and havingan axial bore extendingiherethrough, a cable` having at least one insulated;electricalT conductorpand a ground conductor, said cable extendinginto said bore, the insulating conductor passingthroughy said bore and the ground conductor being connected to said ground connector, a shaped explosive charge having a concave surface, said charge 'beingdisposedin said detonation initiating compartment adjacent to -said partition with `said concave surface facing said partition, a blasting cap retaining ,memberhaving an axial bore-,extendingiv therethrough, said'blastig Vcap re taining member beingdisposed .in said detonation initiating compartment and adjacent to said shaped charge, said bore of theretaining member being counter bored, a'blastingcap, saidblasting cap being disposed in saidfcounter bored part of said ybore in the blasting cap retaining'member, aresilientspacer element, said resilient spacer element being disposed in saiddetonation initiating compartmentbetween said first. end plug'and blasting .cap retain ing member, said blasting -cap having two electrical leads, one` of said leads. being electrically connected to said ground. connector,- the other of said electrical leads being .electrically` connected to an insulated conductor of said cable, thesecond" end plug which lcloses said deto nable fuse receiving compartment -having fuse feedthrough bores extendingtherethrough and communicating with theinterior of said detonable fuse receiving compartment, and spacing means-disposed rwithin said detonable fuse, receiving .compartment for maintaining detonaf ble fuses in' generally axial. alignment'withfrespect-to said shaped explosive' chz'irgey inthe'detonation initiating compartment.

References Citedin the tlleof this patent UTDSTATES PTETS 2,494,256- Muskatet al. Jan. 10,7195() 2,629,325 Sweetman Feb. 24,1953 2,733,657 Bryant et al `Feb.'7,' 1956 2,766,690 LebourgI- a Oct.i16,.1956

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