US3194159A

US3194159A - Well perforating assembly

Info

Publication number: US3194159A
Application number: US238889A
Authority: US
Inventors: Ernest L Gillingham; Jack O Grunwald
Original assignee: Jet Research Center Inc
Current assignee: Jet Research Center Inc
Priority date: 1962-11-20
Filing date: 1962-11-20
Publication date: 1965-07-13
Anticipated expiration: 1982-07-13

Description

July 1 1955 E. GILLI NGHAM ETAL 3,194,159

WELL PERFORATING ASSEMBLY Filed Nov. 20, 1962 INVENTORS Ernesr L. Gllhnghum Jack O. Grunwold BY Wm.

ATTORNEY United States Patent 0 3,194,159 WELL PERFORATIN G ASSEMBLY Ernest L. Gillingham, Fort Worth, and Jack 0. Grunwald,

This invention relates to well perforating assemblies and particularly to an improved bull nose for use in Well perforating assemblies utilizing shaped explosive charge units having frangible cases.

The widespread use of permanent well completion techniques, in the practice of which tubing is run into a well and permanent well head equipment is installed prior to perforating the well, has spurred development ;in the application for United States Letters Patent filed October 8, 1954 byBlake M. Caldwell and Harrold D. Owen, Serial Number 461,236, now Patent No. 3,067,679, entitled Well Perforating Assembly.

The perforating apparatus disclosed in the foregoing patent application provides a firing head from which is suspended an elongated carrier having pivotally mounted, shaped explosive charge, perforating units thereon. The shaped charge units are urged by resilient means to assume a position transverse to the carrier but are held within the carrier in an. axially aligned position with respect to the carrier by interlock means provided on each charge unit. An explosive release means, such as a squib, abuts a detent on a terminal shaped charge unit to retain the charges in. axial alignment. After the perforating apparatus is run out of the lower end of the tubing, the squib is detonated from the earths surface and the terminal shaped charge unit pivots to the transverse position and releases the charge units thereabove to pivot to transverse positions. When the charge units are all in positions transverse to the carrier axis, the units are fired to perforate the. well by closing a switch on the earths surface. The squib of the foregoing perforating apparatus has, on occasion, been responsible for damage to the terminal charge unit. In such apparatus, the squib was positioned immediately adjacent one end of the terminal shaped charge unit and in abutment with the detent on that end of the charge unit. When the squib was fired, the force of the explosion would, on occasion, crack or otherwise damage the end of the frangible metal case of the charge unit, causing the unit to leak and fail to function properly.

' Recently, glass-cased shaped charge units for this particular perforating apparatus have come into use; such units are even more susceptible to damage from the blast effects of the squib than are metal-casedunits.

The present invention relates to improvements in the ice perforating apparatus of the aforesaid Caldwell and Owen application, specifically to. improvements in the means for releasing the terminal charge unit for pivoting. The present invention also relates to improvements in the various forms of release mechanisms for releasing the terminal pivotable. shaped charge in a well perforating assembly disclosed in another application for United States Letters Patent of Blake M. Caldwell and Harrold D. Owen filed February 7, 1961, Serial No. 87,714, for Well "Perforating Assembly, which application is a continuation of application Serial No. 570,004 filed March 7, 1956, now abandoned.

It is, therefore, an object of this invention to provide a perforating assembly having a shaped charge unit release means which, in operation, will not damage the shaped charge units.

Another object of this invention is to provide an improved bull nose structure for the lower end of a perforating assembly, which structure includes; a charge unit release means. The bull nose structure is simple to construct and economical to manufacture.

The foregoing and other objects and advantages of the invention as may appear hereinafter are realized in a well perforating assembly having a carrier and a shaped explosive charge unit with a frangible case. Means are provided pivotally mounting the unit on the carrier in a first position. The unit is pivotabl-e in the mounting means to a second position. Means are provided biasing the unit to pivot from the first position to the second position. Detent means are provided on the unit adjacent the frangible case. A frangible cantilever stop member hasits supported end fixed to the carrier at a point remote from the frangible case and its unsupported end projecting into engagement with the detent means to restrain the unit from pivoting to the second position. Explosive means are provided which are adapted to sever the unsupported end of the stop member from the supported end oflthe stop member to permit the unit to pivot to the second position. i

In its more specific aspects, the present invention is realized in a bull nose for well perforating assemblies which have pivotally mounted shaped explosive charge units axially aligned with the longitudinal axis of the assembly. The bull nose has a hollow, open-ended main body with a generally cylindrical side wall. An integrally formed, longitudinally extending web projects from the interior of the side Wall. A frangible, upstanding stop post is integrally formed with the Web and has an upper portion extending thereabove. The stop post provides a downwardly opening axial bore in the lower portion thereof adapted to receive an explosive squib. The bore in the stop post terminates a substantial distance from the upper end of the stop post.

In the drawings: r

FIG. 1 is a side elevational view, partly in vertical, axial section, of the lower end of a perforating assembly having an axially aligned, .pivotable shaped charge unit restrained by the bull nose of the present invention;

FIG. 2 is a side elevat-ional view, with portions broken away, of the perforating assembly of FIG. l showing the charge restraining portion of the bull nose destroyed and the shaped charge unit pivoted to the horizontal position; r r

' 12 after the units pivot to the horizontal position.

FIG. 3 is a perspective view of the bull nose of the assembly of FIGS. 1 and 2 with a portion broken away; and

FIG. 4 is a plan view of the bull nose.

For a detailed description of the general perforating assembly, reference is made to the aforementioned Caldwell and Owen application, Serial No. 461,236. The present disclosure is concerned with the cooperation of the lower end of an elongated carrier, the pivotally mounted lowermost shaped charge unit, and the improved bull nose structure carrying the destructible restraining means for maintaining the shaped charge units in axial alignment with respect to the carrier.

Referring now toFIGS. 1 and 2, there is shown a generally tubular, elongated carrier it) having longitudinally offset apertures 11 on opposite sides thereof. Shaped charge units 12 are pivotally mounted within the carrier as by pins 13. Each one of the shaped charge units is biased to extend horizontally by means of spring 14. The charge units are locked in axial disposition with respect to the carrier by interlocking detents (not shown) carried by each of the charge units. The detent 15 on the lower end of the bottom charge unit is engaged by an elongated, vertically mounted, frangible, cantilever stop post 16 which is a part of a bull nose structure, designated generally 17, that is attached to the lower end of the carrier by screws 18. Thus, it is seen that the stop post 16 is the element that maintains the shaped charges in axial disposition with respect to the carrier against the urging of the springs 14. The stop post 16 provides a downwardly opening axial bore 19 in the lower portion thereof.v An explosive element or squib, designated generally 20, is received in the bore 19 and is retained therein by the wedging action of a helically wound portion of one of the lead wires 21 which also serves to ground one leg of the squib to the carrier. A second lead wire 22 connects the squib through a switch (not shown) to a source of electrical energy at the surface of the earth. The squib includes a metal case 38 having a rubber plug 39 crimped into the lower end. The plug is moulded around the lead wires 21, 22 whose ends project above the top of the plug and are connected by a fusible bridge Wire 40. An ignition charge 4-1 is provided surrounding the bridge wire. A shearing charge 42 of a compressed detonating explosive is contained in the case above the ignition charge. The top surface of the shearing charge is provided with a conical recess which receives an inverted,'conically shaped, inert barrier plug 43 that extends into contact with the integral sealed end of the case 38. The barrier plug may be made of any suitable material, such as compressed aluminum powder, which will effectively deflect the major portion of the energy .of the detonating shearing charge 42 transversely to the axis of the squib. A squib having a construction similar to that set forth above is commercially available from the E. I. du Pont de Nemours & Co., Inc. as the 13-868 Combination Primer. A pressure-resistant, electric blasting cap 23 is positioned in the hollow interior of the bull nose '17. One lead wire 24 of the blasting cap extends upwardly through the carrier to a switch (not shown) and, thence, to a source of electrical energy at the surface of the earth. The other lead wire 25 is grounded by lug 37 to the bull nose 1'7, and through it to the carrier 10. A length of detonating fuse 2%, such as 70 gr. RDX Hycar Covered HV'Primacord, extends upwardly through the carrier and is positioned to be in detonating contact with each of the shaped charge units The lower end of the fuse is crimped into the end of a blasting cap 23. The blasting cap is covered by a synthetic rubber waterproof sleeve 27 which extends above the upper end of the cap and is sealed at each end by seizing 28, 28. A similar sleeve 29 covers a splice in lead wire 24. These sleeves not only serve to waterproof the blasting cap and wire splice, but also act to protect these items from damage that might be caused by flying metal particles upon detonation of the squib 20.

Referring now to FEGS. l, 3 and 4-, the bull nose 17 has a main body with two generally semi-cylindrical, opposite side wall portions 30 and Zitla. The semi-cylindrical side wall portion 39 has a radius equal that of the carrier 19 and is adapted to be slidingly received within the lowermost aperture 11 at the end of the carrier it). The outer cylindrical side wall portion 39a has a radius slightly smaller than that of the carrier and is adapted to make a sliding fit within the lower end of the carrier, as may be seen in FIG. 1. This construction assures that the bull nose will always be inserted in the lower end of the carrier with the stop post in proper disposition to contact the detent on the lowermost shaped charge. Oppositely disposed, fiat side portions 36 of the bull nose main body provide clearance for dimpled-in portions of the carrier 10 surrounding the holes (not shown) which accept the fiat head screws 18. The bottom portion 31 of the bull nose is tapered inwardly to guide the perforating assembly through tubing and prevent the assembly from hanging up on any projections that may be present within the tubing when the assembly is run into the well. A large opening 32 is provided in the bottom of the bull nose to permit well bore fluids to flew up through the perforating assembly thereby increasing the speed at which the assembly may be run into the well. The opening also enhances the breakup of the frangible bull nose into small sized debris when the shaped charge units are detonated. A longitudinally extending web 33 is integrally formed with and extends radially inwardly from the interior of the side wall portion Etta. The lower portion of stop post 16 is attached to the upper portion of the inwardly facing edge of web 33 by any suitable means, for example, by being integrally formed therewith, as shown. The bore 19 in the lower portion of the stop post 16 terminates at a transverse wall 34 that is located above the top edge of web 33. The upper portion of the stop post is provided with an axial bore 35 that terminates on the upper side of the transverse wall 34. The side wall of the lower portion of the stop post is sufiiciently thin to be readily sheared transversely by detonation of the squib 29. The upper bore 35 and lower bore 19 are illustrated as being substantially equal in length and, thus, the transverse wallfid is located in the middle of the stop post. For purposes of this invention, it is not essential that the bore 19 in the lower portion of the stop post be of any specific depth, but only that this bore terminate a sufficient distance below the end of the lowermost shaped charge unit 12 so that detonation of the squib 20 will not damage the lowermost shaped charge unit. If desired, the upper portion of the stop post may be made solid by omitting the bore 35 therein. The entire bull nose assembly 17 is preferably energy to the squib 20. The squib fires and shears the frangible stop post 16 immediately below the transverse wall 34 as may be seen in FIG. 2. The presence of the inert barrier plug 43 in the top of the squib directs the major portion of the explosive energy transversely to the axis of the squib and stop post 16. This laterally directed energy is concentrated on the annular thin wall section of the stop post 16 lying between the upper edge of the web 33 and the bottom of the transverse wall 34. The spring 14 attached to the lowermost shaped charge unit 12,

causes the charge to pivot to the horizontal position and, in so doing, the detent 15 on the lower end of the charge unit kicks the upper sheared-off portion of stop '5 post 16 outside of the carrier. After all the charge units have pivoted to the horizontal position, electrical energy is supplied to the blasting cap 23 to fire the detonating fuse 26 which, in turn, fires the shaped charge units 12.

By virtue of being enclosed in a downwardly opening bore which is spaced a substantial distance from the lower end of the bottom shaped charge unit, the squib can be safely detonated Without any danger of damaging the frangible case of the adjacent charge unit. Bull noses constructed in accordance with the present invention eliminate damage to pivotable shaped charge units 12 having outer cases made of highly frangible glass.

While there has been described what is at present considered a preferred embodiment of the present invention, it will be apparent to those skilled in the perforating art that various modifications and changes may be made without departing from the essence of the invention. Therefore, such modifications and changes are intended to be covered as come within the true scope and spirit of the appended claims.

We claim:

1. A well perforating assembly comprising:

(a) a carrier;

(b) a shaped explosive charge unit having a frangible case;

(c) means pivotally mounting said unit on said carrier in a first position, said unit being pivotable in said mounting means to a second position;

(d) means biasing said unit to pivot from said first position to said second position;

(e) detent means on said unit adjacent to said frangible case;

(f) a frangible cantilever stop member having its supported end fixed to said carrier at a point remote from said frangible case and its unsupported end projecting into engagement with said detent means to restrain said unit from pivoting to said second position; and

(g) an explosive squib located adjacent the supported end of said stop member and adapted upon detonation to sever the unsupported end of said stop member from the supported end of said stop member to permit said unit to pivot to said second position.

2. In a well perforating assembly the combination comprising:

(a) an elongated carrier;

(b) a terminal shaped explosive charge unit having a frangible case, said unit being pivotally mounted adjacent one end of said carrier in axial disposition with respect to said carrier;

(c) detent means on the end of said shaped explosive charge unit facing said one end of said carrier;

(d) resilient means urging said shaped explosive charge unit to pivot from said axial disposition;

(e) frangible restraining means attached to said carrier and engaging said detent means to restrain said shaped explosive charge unit in said axial disposition;

(f) an explosive squib positioned within a downwardly opening bore provided in a portion of said restraining means spaced a substantial distance from the end of said shaped explosive charge, said squib adapted to fragmentize a portion of said restraining means upon detonation to permit said shaped explosive charge unit to pivot from said axial disposition; and

(g) said bore in said restraining means having an end wall spaced below said end of said shaped explosive charge unit to prevent damage to said charge unit when said squib is detonated.

3. In a well perforating assembly the combination comprising:

(a) an elongated carrier;

(c) detent means on the end of said shaped explosive charge unit facing said one end of said carrier; (d) resilient means urging said shaped explosive charge unit to pivot from said axial disposition; (e) a frangible, elongated restraining member axially disposed with respect to said carrier and having one end engaging said detent means to restrain said shaped explosive charge in said axial disposition;

(f) means mounting said restraining member on said carrier; i j

(g) said restraining member providing a downwardly opening, axial bore at the end opposite said one end, the upper end of said bore being spaced a substantial distance from said end of said shaped explosive charge;

(h) an explosive squib received in said bore; and

(i) said restraining member being adapted to shear transversely adjacent the upper end of said squib upon detonation of said squib to permit said shaped explosive charge to pivot from said axial disposition without damage to said charge for detonation of said squib.

4. In a well perforating assembly the combination comprising:

(a) an elongated carrier;

(0) detent means on the end of said shaped explosive charge unit facing said one end of said carrier; ((1) resilient means urging said shaped explosive charge unit to pivot from said axial disposition;

(e) a frangible, elongated restraining member axially disposed with respect to said carrier and having one end engaging said detent means to restrain said shaped explosive charge in said axial disposition;

(f) means mounting said restraining member on said carrier;

(g) said restraining member providing a downwardly opening, axial bore .at the end opposite said one end, the upper end of said bore being spaced a substantial distance from said end of said shaped explosive charge;

(h) an explosive squib seated in said bore, said squib including a case having anintegral sealed end, a detonating shearing charge of explosive in said case, an inert barrier plug positioned between said shearing charge and said sealed end of said case, said barrier plug adapted to deflect the major portion of the energy resulting from detonation of said shearin charge in a direction transverse to the axis of said restraining member; and

(i) said restraining member being adapted to shear transversely adjacent the upper end of said squib upon detonation of said squib to permit said shaped explosive charge to pivot from said axial disposition without damage to said charge from detonation of said squib.

5. A bull nose for Well perforating assemblies having pivotable, shaped explosive charge units axially aligned with the longitudinal axis of the assembly comprising:

(a) an open-ended main body having generally cylindrical side walls;

(b) a longitudinally extending web projecting from the interior of said side wall;

(c) afrangible, upstanding stop post integrally formed with said web and having an upper portion extending thereabove;

(d) said stop post providing a downwardly opening,

7 axial bore in the lower portion thereof adapted to receive an explosive squib; and

(e) said bore terminating a substantial distance from the upper end of said stop post.

6. A bull nosev for well perforating assemblies having pivotable, shaped explosive charge units axially aligned with the longitudinal axis of the assembly comprising:

(a) an open-ended main body having generally cylindrical side walls;

(0) a frangible, upstanding'stop post integrally formed with said web and having an upper portion extending thereabove;

((1) said stop post providing an upper and a lower axial bore therein separated by an integral transverse wall; and

(e) the lower portion of said stop post surrounding said lower axial bore having a thin side wall immediately below said transverse wall adapted to be readily sheared by the detonation of an explosive equib received in said lower bore.

References Cited by the Examiner UNITED STATES PATENTS 2,556,672 6/51 Bergh et al. 891.5 X 2,990,774 7/61 Toelke 102-20 3,067,679 12/62 Caldwell et a1. l02--20 SAMUEL FEINBERG, Primary Examiner.

Claims

1. A WELL PERFORATING ASSEMBLY COMPRISING: (A) A CARRIER; (B) A SHAPED EXPLOSIVE CHARGE UNIT HAVING A FRANGIBLE CASE; (C) MEANS PIVOTALLY MOUNTING SAID UNIT ON SAID CARRIER IN A FIRST POSITION, SAID UNIT BEING PIVOTABLE IN SAID MOUNTING MEANS TO A SECOND POSITION; (D) MEANS BIASING SAID UNIT TO PIVOT FROM SAID FIRST POSITION TO SAID SECOND POSITIONS; (E) DETENT MEANS ON SAID UNIT ADJACENT TO SAID FRANGIBLE CASE; (F) A FRANGIBLE CANTILEVER STOP MEMBER HAVING ITS SUPPORTED END FIXED TO SAID CARRIER AT A POINT REMOTE FROM SAID FRANGIBLE CASE AND ITS UNSUPPORTED END PROJECTING INTO ENGAGEMENT WITH SAID DETENT MEANS TO RESTRAIN SAID UNIT FROM PIVOTING TO SAID SECOND POSITION; AND (G) AN EXPLOSIVE SQUIB LOCATED ADJACENT THE SUPPORTED END OF SAID STOP MEMBER AN ADAPTED UPON DETONATION TO SEVER THE UNSUPPORTED END OF SAID STOP MEMBER FROM THE SUPPORTED END OF SAID STOP MEMBER TO PERMIT SAID UNIT TO PIVOT TO SAID SECOND POSITION.