US3717095A - Select fire jet perforating apparatus - Google Patents

Abstract

JACENT ELECTRODE WHICH CAN BE SUBSEQUENTLY CONTACTED BY A SOURCE OF CURRENT SO AS TO DETONATE THE PERFORATING MEANS TO WHICH IT IS ELECTRICALLY CONNECTED.

A PERFORATING APPARATUS HAVING SEPARATE CHAMBERS FORMED THEREIN, AND WITHIN WHICH THERE IS DISPOSED ELECTRICALLY ACTUATED EXPLOSIVE PERFORATING MEANS. THE APPARATUS INCLUDES A FIRING HEAD HAVING A PLURALITY OF ELECTRODES RECEIVED THEREIN AND SUPERIMPOSED ONE UPON ANOTHER AND ELECTRICALLY INSULATED FROM ONE ANOTHER. ONE OF EACH ELECTRODE IS ELECTRICALLY CONNECTED TO AT LEAST ONE OF THE PERFORATING MEANS SO THAT WHEN A SOURCE OF CURRENT IS APPLIED TO THE ELECTRODE IT DETONATES THE PERFORATING MEANS, WHEREAFTER THE ELECTRODES IS REMOVED FROM THE FIRING HEAD SO AS TO OPERATIVELY EXPOSED THE NEXT BELOW AD-

Description

1973 R. R. VANN 3,7115

SELECT FIRE JET PERFORATING APPARATUS Filed June '7, 1971 ii ya MARCUS LBATES H/5 HGEN? United States Patent 3,717,095 SELECT FIRE JET PERFORATING APPARATUS Roy R. Vann, Midland, Tex. (Box 40-A, Star Rte. W., Artesia, N. Mex. 88210) Filed June 7, 1971, Ser. No. 150,304 Int. Cl. E21b 43/116 US. Cl. 102-21.6 Claims ABSTRACT OF THE DISCLOSURE A perforating apparatus having separate chambers formed therein, and within which there is disposed electrically actuated explosive perforating means. The apparatus includes a firing head having a plurality of electrodes received therein and superimposed one upon another and electrically insulated from one another. One of each electrode is electrically connected to at least one of the perforating means so that when a source of current is applied to the electrode it detonates the perforating means, whereafter the electrode is removed from the firing head so as to operatively expose the next below adjacent electrode which can be subsequently contacted by a source of current so as to detonate the perforating means to which it is electrically connected.

BACKGROUND OF THE INVENTION Oil and gas well completion techniques often require closely spaced multiple perforating at selected depths so as to perforate downhole piping or casing at various selected elevations in a well. Usually a single perforation at a particular depth is required, however, the perforation must be formed at precisely the elevation within the borehole which the geologist has determined to be the most optimum location. It is customary to detonate one or a group of the shaped charges, after which the gun apparatus is repositioned adjacent to the next desired level whereupon the gun is again fired so as to provide the next perforation. This sequence of events is generally continued until all of the desired perforations have been made.

Several prior art patents teach the fabrication of a select firing system for use downhole in a borehole for selectively firing a jet perforator as evidenced by the patents to Coleman, 3,010,396; Boop, 3,208,378; and Bell, 3,246,707, to which reference is made for further background of this invention.

The prior art apparatus generally includes complicated circuitry and mechanism which generally depends upon energy derived from each explosion so as to sequentially arm the next above adjacent shaped charge apparatus associated with the gun apparatus. Usually, a single misfire precludes further detonation of the remaining charges and presents a dangerous situation in that the misfire must be brought uphole and disarmed.

It is desirable to make available a select fire jet perforation apparatus which can be positioned downhole in a borehole and the gun fired in a manner whereby each of the charges are positively exploded as a result of direct control exercised from above the surface of the ground.

It is furthermore desirable to provide a jet perforating apparatus which can be continued in the sequential firing thereof even though one of the charges should fail to fire.

It is further desirable to have made available a select fire jet perforating apparatus which has a minimum of moving parts, is simple in design, and which is fool-proof in operation.

SUMMARY OF THE INVENTION This invention comprehends a perforating apparatus having separate chambers formed therein within which there is disposed electrically actuated explosive perforating means. The perforating means is detonated by a power package which is brought into electrical contact with a firing head. The head has disposed therein a plurality of electrodes each superimposed upon and spaced apart from and insulated from one another. Each electrode is removably received within the firing head and has associated therewith means by which it can be removed therefrom. Circuit means electrically connect each electrode to at least one of the explosive perforating means, and each of the electrodes are adapted to be removed one at a time from the firing head. A self-contained supply of current can be run downhole on a slick line to where it contacts the uppermost electrode thereby detonating a lowermost of the unexploded explosive charges.

Each electrode has associated therewith two branch circuits having diodes of opposite polarity arranged therein, with each diode being connected to the detonator of an explosive charge to thereby enable the supply of current, when of the proper polarity, to cause sequential detonation of two adjacent lowermost explosive charges.

A primary object of this invention is the provision of a system for selectively firing a plurality of well casing perforating guns.

Another object of the invention is to provide a selective firing system for a plurality of perforating guns.

A further object of this invention is the provision of circuitry and apparatus for selectively and sequentially detonating a plurality of sub-surface explosive devices.

A still further object of the present invention is to provide apparatus for perforating the wall of a borehole, and which is inexpensive to manufacture, simple to operate, and dependable in performance.

Another and still further object of this invention is the provision of a reliable system for selectively and separately detonating one of a plurality of shaped charges in a predetermined sequential manner.

An additional object of the present invention is the provision of a positively acting arming means which preferably is actuated after the preceding shaped charges have been detonated in a predetermined sequence.

These and various other objects and advantages of this invention will become readily apparent to those skilled in the art upon reading the following detailed description and claims and by referring to the accompanying drawings.

The above objects are attained in accordance with the present invention by the provision of a combination of elements which are fabricated in a manner substantially as described in the above abstract and summary.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematical representation which shows the present invention as being operatively disposed within a borehole;

FIG. 2 is a diagrammatical presentation of the present invention;

FIG. 3 is an enlarged part cross-sectional fragmentary side view of the present invention;

FIG. 4 is a cross-sectional view taken alongline 44 of FIG. 3;

FIG. 5 is an enlarged part cross-sectional view of part of the apparatus disclosed in FIG. 3;

FIG. 6 is an enlarged cross-sectional view taken along line 6-6 of FIG. 5; and

FIG. 7 is a reduced schematical representation of part of the present invention, showing one detail of operation thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is seen a borehole which has been formed through the surface of theearth 10, within which there is disposed oil well casing and tubing flow connected to a Christmastree 11.Production tubing 12 has apacker 13 attached thereto and supports aperforated nipple 14.Numeral 15 generally indicates various oil bearing strata from which hydrocarbon production may be obtained.

Apower package 19 is connected to a slick line 19'. Afiring head 18 forms the upper marginal end of a perforating apparatus. The appartus includes agun 20 connected bysub 21 to anOther gun 22, with each of the guns having at least one chamber formed therein and with each chamber containing electrically actuated explosive perforating means.

Looking now to FIGS. 2, 3, and 4, in conjunction with the remaining figures, the before mentioned power pack is in the form of a self-contained electrical supply and is seen to include contact means at 26 which is electrically connected to a double poledouble throw switch 27 which in turn is connected to a storage battery by means of thecircuitry 28.

Electrode assembly 29, which can be the uppermost electrode, has an upstanding portion thereof which is axially aligned with the longitudinal axis of the firing head. Circumferentially spaced from the electrode and connected to the exterior metal portions which houses the firing head is a series of radially spaced apart groundingsprings 30 which preferably are in the form of inwardly directed spring steel wires.Insulation 31 is formed into a series of communicating counterbores, each having the illustrated shoulders so as to receive and support each of theelectrodes 29, 32, and 33 thereon. While three electrodes are disclosed, it should be understood that two or more can be employed while remaining with in the teachings of this invention.

Electrical conduit 34 is connected to the uppermost electrode and continues down through the interior of the gun assembly tojunction 34 where the circuitry branches, as one leg continues to the resistor R, thediode 35, the electrically fired cap C and to ground so as to complete the circuit. The cap is attached to the prima cord P, which detonates an explosive charge. =From junction 34' the remaining leg of the branch continues to the illustrated resistor and to thediode 35. 'Fromdiode 35 the circuit leads to a cap associated with prima cord and an explosive charge.

Electrical conductor 36 is connected to the before mentionedsecond electrode 32 and todiodes 37', 37. Diode 37' is electrically connected to the explosive charge at 38 whilediode 37 is connected to the explosive charge located withinchamber 120.

Thelowermost electrode 33 is anchored to a bulkhead and electrically connected to the two uppermost explosive containing chamber, with the circuitry splitting into two brances at 39 to enable current to flow at 42 or 142 so as to provide a source of current withinchambers 20 and 22. The remaining branch circuit provides a flow path fromjunction 39 throughresistor 142 to the electrically detonatedcap 43,primer cord 143 which is connected at 44 to theshaped charge 144, as in the before described manner. Closuremember 45 prevents flow of fluid into thechamber 20.

Looking noW particularly to FIG. 4 in conjunction with FIG. 3,electrode 32 is seen to have an outwardly directed base having aperipheral edge portion 46 which reduces in diameter into the metallic current conducting upstanding shaft-like portion 47.

A series ofapertures 48 allow individual wire conductors to freely pass therethrough, such asconductor 34, 34 for example.

Theinsulator 31 has formed therethrough afirst counterbore 49 which reduces in diameter to formshoulder 5% and continues in a downward direction ascounterbore 51 which reduces in diameter to form asecond shoulder 52, and with thelast counterbore 53 terminating in a bulkhead at its lower extremity so as to seal the 4 interior of theuppermost chamber 20 from the counterbores.

Coupling 54 interconnects the firinghead 18 with the uppermost explosive containingchamber 20. Each of the coupling members, orsubs 21, provide a sealed passageway from onechamber 20 to anotherchamber 22, for example. Furthermore, each of the subs include acylindrical insert member 57 having the illustrated 0- rings disposed thereabout so as to enable the insert to sealingly engage the interior passageway of the coupling member and at the same provide ascalable passageway 58. The last named passageway, after the wires are extended therethrough, is filled with epoxy resin so as to provide a positive fluid seal for preventing fluid flow thereacross. The contoured outwardly diverging passageway at 59 cooperates with the plastic seal formed therewithin to provide a high pressure seal assembly.Resilient washers 60, 61, 63 are stacked one upon another and when the threadednut 62 compresses the washers, the electrical conduits extending throughpassageways 68, 64 are provided with a secondary seal.End portion 61 can also be provided with resilient washers and a nut, such an expedient being an optional detail of design.

Where deemed desirable, theinserts 57 together with the wires and the epoxy filling may be made up as a preassembled unit with the length of the wire therebetween being of the proper value so that the tool may be assembled from prefabricated parts. Hence the inserts can be extended into the couplings where the wires are available for use in the various chambers through which they extend.

Looking in particular again to 'FIG. 3, each of theelectrodes 29, 32 and 33 are seen to have attached thereto an electrical conduit such as illustrated at 34, 36. Theinsulated wire 34 is rigidly attached toelectrode 29 and continues through one of theapertures 48 ofelectrode 32, for example, where the wire then continues at 34' and engages terminal 134 by means of a bayonet or bananatype connection such as seen at 65. Alternatively, the connection at 65 can be a rigid connection and the wire size selected so that whenelectrode 29 is picked up with sufficient force by an overshot, the wire will break some where between the terminal and the electrode.

OPERATION In operation, the select firing jet perforating apparatus is placed downhole in a borehole with the distance between the shaped charges contained within asingle gun 20 being selected in any desired manner and number so as to enable any particular perforation pattern to be effected upon a zone 15'.Gun assembly 22 is spaced apart from gun assembly 20 a predetermined amount so as to place the second gun adjacent to another pay zone 15'. Other additional guns may be employed.

The firinghead 18 is supported by the vent string, although those skilled in the art will realize and understand that the gun could be connected directly to the production tubing, suspended within the casing by a wire line, or anchored to the casing wall by any number of diiferent expcdients.

When it is desired to fire the lowermost gun, a power package is adjusted to provide a polarity which corresponds with current flow through diode 35', and is run downhole on a slick line until electrical contact is made so as to provide a difference in potential between the electrode and the grounding wires. At this time current flows from theelectrode 29 alongconductor 34 and to junction 34'. Since the current polarity is incorrect or opposite to that required for current flow throughdiode 35, the perforating charge associated therewith cannot possibly be detonated. However, current can flow from junction 34', through resistor R, through diode 35', and to the detonator C which is electrically detonated when the proper current values are imposed thereon. The cap C detonates prima cord P which in turn detonates one of the shaped charges,

as seen at 144. The shaped charge penetrates closure means 44, thecasing 9, and communicates the interior of the casing with a pay zone 15'. Production fluid generally is allowed to enter the casing, flow up the casing annulus, into the apertures ofvent string 14, and on up theproduction tubing 12 to theChristmas tree 11 where the production flow can be controlled.

The next lowermostunexploded gun 122 is fired by changing the polarity of the power package so that the current flow can now be traced from the power package, throughelectrode 29,conductor 34, junction 34', resistor R, diode 35', and On to the remainder of the explosive train (not shown) of thegun 220.

Thethird gun 122 as well as thefourth gun 120 is to be fired byelectrode 32. Accordingly, an overshot 41, the details of which are known to those skilled in the art, is run downhole on a slick line where it engages the upstanding metallic portion ofelectrode 29. The overshot is lifted bringing with it the electrode andconductor 34 which detaches from the banana terminal located within the bulkhead ofcounterbore 53. After removal of theelectrode 29, the power package is adjusted to proper polarity and again run downhole on a slick line where it againcontacts electrode 32. Assuming proper selection of polarity, the current flow can be traced from the power package to theelectrode 32, throughconductor 36, to the junction where the circuitry splits into two branch legs, which one diode connecting the current flow to theexplosive charge 38 ofgun chamber 122 and the remainingdiode 37 conducting current flow to the shaped charge ofgun chamber 120, all as in the before described manner of the two lowermost guns.

The select firing of the apparatus is continued in this sequential manner until each of the pay zones have been properly perforated. The number ofindividual guns 20, 22 will of course depend upon the number ofdifferent formations 15 which are to be perforated.

Looking in greater detail again to FIG. 3, groundingelectrodes 30, 30' are electrically connected to the firinghead 18 so as to make a plurality of contacts relative to the outer peripheral wall surface ofpower package 19. Internally of the power package there is disposed the illustrated electrodes which are insulated from the wall of the package and which engage the upstanding metallic portion of the electrode. Hence, current flows from the power package to the electrode, to the various circuitry associated with the blasting cap (or detonator), and back to ground by utilizing the entire gun housing and package housing as the return ground circuit.

FIG. 7 schematically illustrates an overshot 41 connected to aslick line 119, which has retrievedelectrode 29 from the dot-dashedposition 29 so as to leaveelectrode 32 operatively disposed within the firing head, ready to be contacted bypower package 19.

It will occur to those skilled in the art to utilize mechanically actuated apparatus which can be reciprocated downhole so as to change the polarity of the power package. One possible apparatus of this type is disclosed in my cigpeirgdilng patent application Ser. No. 116,948, filed Feb.

Those skilled in the art will also envision the provision of a combination overshot and power package which will enable the two to be combined together into a single unit, and such an expedient is considered to fall within the comprehension of this invention.

Moreover, while only three electrodes have been disclosed for purposes of illustration, those skilled in the art will understand that any number of electrodes may be used, the limiting factor being the physical dimensions of the firing head itself. Furthermore, it is considered obvious to employ a current carrying wire line in lieu of the slick line and power package, and such a variation is deemed to be within the comprehension of this invention.

I claim:

1. A perforating apparatus havingseparate chambers 6 formed therein with each chamber containing electrically actuated explosive perforating means;

a firing head, a plurality of electrodes contained Wlthm said firing head, means by which said electrodes are electrically insulated from one another and super1mposed one upon the other and removably received within said firing head; means by which the uppermost of said electrodes can be contacted by a supply of electrical current;

means by which at least one said electrode can be removed from said firing head;

circuit means electrically connecting each electrode to at least one of said electrically actuated explosive perforating means;

whereby: a supply of current can be electrically connected to the uppermost electrode to thereby detonate one of the explosive perforating means, and upon removal of an uppermost electrode, an adjacent electrode can be contacted by a supply of current so as to detonate the explosive charge to which it is connected.

2. The apparatus of claim 1, and further including two diodes of opposite polarity, said circuit means connecting one of said diodes to one said electrode and to one said explosive perforating means and a second of said diodesto the last said electrode and to an adjacent of said exploslve perforating means, whereby:

a lowermost explosive perforating means may be detonated and thereafter the polarity of the current changed so as to detonate the remaining explosive perforating means.

3. The apparatus of claim 1, wherein said firing head includes concentrically arranged chambers of diminishing diameters with the largest chamber being the uppermost chamber and communicating with the remaining chambers by means of shoulders,

said electrode having a base adapted to contact and be supported by a shoulder with said base being smaller in diameter than the chamber within which the electrode is disposed so as to enable removal thereof.

4. The apparatus ofclaim 3 wherein said electrode includes an upstanding portion which is adapted to be r trieved by an overshot apparatus.

5. The apparatus of claim 1 wherein said circuit means further includes electrical detonation means connected from an uppermost electrode to two lowermost explosive charges; and, electrical detonating means connected t another of said electrodes and to an uppermost two of said explosive charges;

said circuit means further including means for preventing positive current flow connected to one of said two lowermost explosive charges and to one of Said uppermost explosive charges; and, means for preventing negative current fiow connected to the remaining two lowermost explosive charges and to the remaining two uppermost explosive charges.

6. The apparatus of claim 1 wherein an uppermost electrode is connected to a lowermost explosive perforating means, and a lowermost electrode is connected to an uppermost explosive perforating means.

7. The apparatus of claim 1 wherein said circuit means includes an electrical conductor connected from said electrode to a junction, said conductor adapted to be parted upon removal of said electrode;

and further including two branch circuit legs; each said leg including a diode and an electrical detonator; the diodes of each leg being arranged for passing current of opposite polarity.

8. The apparatus of claim 7 wherein said junction and said diode, are located in a common chamber.

The pparatus of claim 1 wherein said electrode has a base from which an upstanding current carrying conductor depends; apertures formed in said base; said circuit means includes electrical conductors extending through said apertures.

10. In an electrically actuated perforating gun employing a plurality of explosive charges therein and adapted to be placed within a well bore, the combination comprising:

a firing head for selectively firing the explosive charges;

said firing head having a plurality of electrodes contained therewithin; means electrically insulating each of said electrodes from one another; each said electrode being axially arranged relative to one another and superimposed one upon the other with the uppermost of said electrodes having a portion thereof di posed for contact with a supply of current; means by which the uppermost of said electrodes is removably supported within said firing head so that when the uppermost of said electrodes is removed the underlying electrode can be contacted by a supply of current;

circuit means electrically connecting different ones f said electrodes to different ones of the electrically actuated explosive perforating means so that when a supply of current is connected to an electrode, the explosive perforating means to which said electrode is connected will be detonated;

and means forming a supply of current which can be brought into electrical contact with the uppermost of said electrodes.

11. The combination of claim and further including two diodes of opposite polarity, said circuit means connecting one of said diodes to one said electrode and to one said explosive perforating means and a second of said diodes to the last said electrode and to an adjacent of said explosive perforating means, whereby:

a lowermost explosive perforating means may be detonated and thereafter the polarity of the current changed so as to detonate the remaining explosive perforating means.

12. The combination ofclaim 10 wherein said firing head includes axially arranged chambers of diminishing diameters with the largest chamber being the uppermost chamber and communicating with the remaining chambers by means of shoulders,

said electrode having a base adapted to contact and be supported by a shoulder with said base being smaller in diameter than the chamber within which the electrode is disposed so as to enable removal thereof.

13. The combination ofclaim 10 wherein said electrode includes an upstanding portion which is adapted to be retrieved by an overshot apparatus.

14. The combination ofclaim 10 wherein said electrode includes an upstanding portion which is adapted to be retrieved by an overshot apparatus;

said electrode having a base from which an upstanding current carrying conductor depends;

apertures formed in said base; said circuit means includes electrical conductors extending through Sai apertures.

15. A perforating apparatus having separate chambers formed therein with each chamber containing electrically actuated explosive perforating means;

a firing head, a plurality of electrodes contained within said firing head, means by which said electrodes are electrically insulated from one another and superimposed one upon the other and removably received within said firing head; means by which the uppermost of said electrodes can be contacted by a supply of electrical current;

means by which at least one said electrode can be removed from said firing head;

circuit means electrically connecting each electrode to at least one of said electrically actuated explosive perforating means;

said firing head includes concentrically arranged chambers of diminishing diameters with the largest chamber being the uppermost chamber and communicating with the remaining chambers by means of shoulders,

said electrode having a base adapted to contact and be supported by a shoulder with said base being smaller in diameter than the chamber within which the electrode is disposed so as to enable removal thereof;

whereby: a supply of current can be electrically connected to the uppermost electrode to thereby detonate one of the explosive perforating means, and upon removal of an uppermost electrode, an adjacent electrode can be contacted by a supply of current so as to detonate the explosive charge to which it is connected.

References Cited UNITED STATES PATENTS

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