CA1311189C - Method and apparatus for actuating a tubing conveyed perforating gun - Google Patents
Method and apparatus for actuating a tubing conveyed perforating gunInfo
- Publication number
- CA1311189C CA1311189C CA000584844A CA584844A CA1311189C CA 1311189 C CA1311189 C CA 1311189C CA 000584844 A CA000584844 A CA 000584844A CA 584844 A CA584844 A CA 584844A CA 1311189 C CA1311189 C CA 1311189C
- Authority
- CA
- Canada
- Prior art keywords
- firing
- piston
- actuation
- head
- releasable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title description 10
- 238000010304 firing Methods 0.000 claims abstract description 157
- 230000007246 mechanism Effects 0.000 claims description 27
- 239000003999 initiator Substances 0.000 claims description 20
- 230000000717 retained effect Effects 0.000 claims description 11
- 230000004044 response Effects 0.000 claims description 8
- 238000005474 detonation Methods 0.000 claims description 7
- 239000002360 explosive Substances 0.000 claims description 4
- 230000014759 maintenance of location Effects 0.000 claims 5
- 230000002706 hydrostatic effect Effects 0.000 abstract description 4
- 239000012530 fluid Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 102000012152 Securin Human genes 0.000 description 1
- 108010061477 Securin Proteins 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- KRTSDMXIXPKRQR-AATRIKPKSA-N monocrotophos Chemical compound CNC(=O)\C=C(/C)OP(=O)(OC)OC KRTSDMXIXPKRQR-AATRIKPKSA-N 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/11—Perforators; Permeators
- E21B43/116—Gun or shaped-charge perforators
- E21B43/1185—Ignition systems
- E21B43/11852—Ignition systems hydraulically actuated
Abstract
ABSTRACT OF THE INVENTION
A firing head which is actuatable by either mechanical or hydraulic force. The firing head includes two pistons, one releasable through mechanical force, and the other releasable through hydraulic force. The first piston is secured in position until application of either an impact or an upward tension on an actuation piston.
The second firing piston is responsive to hydrostatic pressure.
A firing head which is actuatable by either mechanical or hydraulic force. The firing head includes two pistons, one releasable through mechanical force, and the other releasable through hydraulic force. The first piston is secured in position until application of either an impact or an upward tension on an actuation piston.
The second firing piston is responsive to hydrostatic pressure.
Description
3 7 ~
METHODS AND APPARATUS FOR ACTUATING A
TV~ING CONVEYED PERFORATING GUN
BACKGROUND OF ~HE INVENTION
5~he present invention relates generally to methods and apparatus for actuating tubing conveyed perf~rating guns to perforate suhsurface formations, and more specifically relates to methods and apparatus which allo~
a tubing conveyed perforating gun to be actuated either mechanically or hydraulically.
Conventional firing heads for tubing conveyed perforating guns are typically actuated by either mechanical means or by hydraulical means. Mechanically-actuated firing heads are typically actuated by dropping a weighted member (commonly known as a "~o-devil") t into the well to impact a piston and drive a firing pin into an initiator charge. An example of this type of firing head may be found in U.S. Patent No. 3,7Q6,344, issued December 19, 1972 to Roy R. Vann, and assigne~ to the assignee of the present invention. Hydraulically-actuated firing h~ads typically cont~in a piston which is exposed on one side to the annulus pressure in the well surrounding the firing head. When the pressùre in the annulus exceeds a predetermined actuation pressure, the piston will move and drive a firing pin into an initiator charge.
Additionally, firing heads are known which are actuated by a combination of mechanical action and hydraulic action. For example, a go-devil will be used to impact a striking piston and to move the piston from a first position to a second position. The movement of the striking piston to the second position will release a locking mechanism on a hydraulic piston which will then be moved in response to hydraulic pressure in the annulus to ., , ` ~
bring a firing pin into con-tac-t wi-th an initiator charge. A firing head of this type is disclosed in U.S. Patent No. 4,901,802, issued February 20, 1990, inventor~ Flint R. George and Kevin R. George, and assigned to the assignee of the present application.
Well perforating opera-tions -take place under a wide varie-ty of environmental conditions which can be extremely severe. Severe or unexpectecl environmental conditions may cause unexpected problems insa-tis-factorily per:Eorming tubing conveyed perforating jobs. For example, a mechanically-ac-tua-ted firing head may be obstructed by particula-te solids in -the well which may prevent its opera-tion. Addi-tionally, factors such as devi.ation of the well may affect the abili-ty to practically actuate a firing head mechanically. Similarly, it is no-t always possible to ac-tuate a hydraulic firing head in a particular well. For example, defective or weak casing make it imprac-tical to apply increased pressure to the annulus to hydraulically actuate a firing head.
Accordingly, it is desirable to have alternative methods for actuating the firing head.
Accordingly, the present invention provides a new method and apparatus for actuating a perforating gun. The apparatus allows the perforating gun to be actua-ted either hydraulically or mechanically.
Additionally, a firing head in accordance with the present invention may he adapted to be responsive not only to longitudinal force in a downward direction, such as is accomplished with a-weighted member, but also to longitudinal force in an upward directi.on, as may be applied with a wireline or slickline.
:~c~ {!
SUMMARY OF THE INVENI'ION
In accordance with the invention there is provided a firing head for a tubing conveyed perfora-ting gun, comprising a pair of firing pistons, a firs-t of said firing pistons being movable at least partially in xesponse -to a mechanical force applied in said firing head, and -the second of said firing pistons being movable in response to hydraulic force applied in said firing head; means for causing detona-tion of said perforating gun, said detonation means responsive -to movement of either of said first and second firing pistons.
The present invention provides a firing head for actuating a tubing conveyed perforating gun which is adapted to be actuated either mechanically or hydraulically. Additionally, in a particularly pre-ferred embodiment, the firing head may be actuated mechanically by either an impact on the firing head or by tension placed upon a portion of the firing head. In this particularly preferred embodiment, the firing head includes two firing pistons, each of which is movable from a first, "normal", position to a second position which will actuate an initiator charge, -to initia-te either a burn or an explosion which will result in detonation of the perforating gun. Preferably, the firs-t firing piston is releasable through downward or upward movement of an actua-tion piston. This actuation piston preferably includes a head portion which may receive the impac-t from a go-devil detonating bar, or which may be easily latched onto by an overshot or similar mechanism. The second :Eiring piston is preferably responsive to hydraulic pressure applied to the interior of -the firing head.
'~;,L~BJ~r~i ~L 2~ . g ~
In a particularly preferred embodiment, the first and second firing pis-tons are concentric with one another and at least partial:Ly coextensive with one another; and are in concentric relation to the actua-tion piston. In this embodiment, the first firing pis-ton is securely retained in its first position by a plurality of releasable segmen-ts, or collets which are held in position by -the actuation piston. However, in -this embodiment, the second Eiring piston is retained in i-ts first position by a plurality of shear pins. Accordingly, while the first firing piston is releasable only -through movement of the actuation pis-ton, the second firing piston is releasable through hydraulic pressure acting upon the second piston and shearing the shear pins.
- ~a -_RIE~ DESCRIPT~ ,t,~ NGS
Fig. 1 depicts a firing head in ~ccordance with the present invention in a tool s~ring an operating configuration in a wellbore, illustrated partially in vertical section.
Eig. 2 depicts the firing head of Fig. 1 in greater detail and in vertical section.
Fig. 3 depicts the ac~uation mechanism of a firing head in accordance with the present invention in an exploded view.
Fig. 4 depicts the actuation mechanism of a firing head in accordance with the present in~ention prior to actuation, illustrated in vertical section.
Fig. 5 depicts the actuation mechanism of Fig. 4 after actuation by impact from a cetonating bar.
Fig. 6 depicts the actuation mechanism of Fig. 4 after actuation with an overshot.
~ig. 7 depicts the actuation mechanism of FigO 4 after actuation by application of hydraulic pressure.
Fig. 8 depicts an alternative em~odiment of a firing head in accordance with the present invention, illustrated in vertical section.
DETAILED DESCRIPTION_OF A PREEERRED EMBODIMENT
Referring now to the drawings in more detail, and particularly to Fig. 1, therein is depicted a firing head 10 in accordance with the present invention, in an operatiny configuration in a wellbore. Firing head l~ is situated above a perforating gun 12 in a tool string~
indicated generally at 14~ Tool string 14 extends into a wellbore 16. Tool string 14 may include a packer 18 to isolate an upper portion of the bor~hole Erom a lower portion of the borehole when perforating gun 12 is positioned adjacent a formation to be perforated. In one preferred embodiment, a ported member l9 will be included within tool string 14, such that the interior of firing head lO will be exposed to pressure in well~ore 16.
Referring now to Fig. 2, therein is depicted an exemplary embodiment of firing head 10 in vertical section. ~iring head lO includes a pri~ary hou~ing 20 in which an actuation mechanisrn, indicated generally at 22, is retained. Primary housing may be c,ne piece, or may include submembers, such as housing member 24, which may be joined, such as by a threaded coupling 26, to primary housing 20. Primary housing 20 will preferably couple at a lower end to firing head sub 28 in conventional manner.
As will be apparent from the discussion to follow, actuation mechanism 22 includes two firing pistons. A
first firing piston 48 is preferably secured in place by 2~ collets and is released throuyh mechanical actuation of an actuation piston 30O Second firing piston 62 is preferably secured in place by shear pins and is released through hydraulic pressure. Actuation mechanism 22 includes actuation piston 30 retained within a bore 32 in mandrel 34. Actuation piston 30 is lon9itudinally movable relative to mandrel 34, but is initially secured in a first, "normal", ~osition by a shear pin 36. Actuation piston 30 includes a first end 38 which iS adapted both to receive an impact to shear shear pin 36, or to be retrieved7 such as by with an overshot, so as to receive an upward tension to shear shear pin 36, and to thereby allow longitudi.nal movement of ~ctuation piston 30 relative to mandrel 34.
A second end of actuation piston 30, indicated generally at 40, includes a firs~ portion 42 of reduced diameter. Second end 40 of actuation piston 30 also includes a second portion 44 of an enlarged diameter relative to first portion 42 of actuation piston 30.
Second portion 44 of actuation piston 30 extends into a recess 46 in first firing piston 48. Mandrel 34 is coupled to second firing pi6ton 62. First firing piston 48 is secured in fixed position relative to mandrel 34 and second firing piston 62 by a plurality of releasable segments, or ~c0112ts~, 50 which cooperatively engage recesses 54 in second firing piston 62 and apertures 56 in irst firing piston 48. Collets 50 are held in position by enlarged second portion 44 of actuation piston 30.
First ~iring piston 48 includes a second end, indicated generally at 58, which sealingly engages bore ~0 in second firing piston 62. A firing pin 64 is coupled to second end 58 of first Çiring piston 48. Unless otherwise noted all sealed engagements described herein may be provided through use of conventional o-ring~type seals.
Second firing plston 62 is slideably and sealingly received within a bore 66 in securing sleeve 68. Securing sleeve 68 i5 received within housing 20 and preferably rests against a shoulder 70 in housing 20. Securing sleeve 68 is retained in position in housing 20 such as by a snap ring 72 which engages a relief 74 in housing 200 A
plurality oE apertures 76 are formed in securing sleeve 6 to receive shear pins 78. Shear pins 78 similarly engage apertures 80 in second firing piston 62~ First and second firing pistons 48 and 62, respectively, preferably each include apertures 43 and 41, respectively, to allow fluid ~ J ~
communication between the interior of housing 20 and recess 46 in first firing piston 48.
Firing pin 64 preferably includes a tapered contour designed to impact and detonate an initiator charge 82, such as a primer assembly, which is sealingly retained within a bore 84 in securing sleeve 68. Primer assembly 82 is secured to securin~ sleeve 68 by a primer block 83 which is preferably boltably secured to securing sleeve 68. Securing sleeve 68 includes an aperture 90 which allows the jet of hot gases emitted by the ignition of primer assembly 82 to enter a chamber 92 in housing 20.
Secured within chamber 92 is a delay element assembly 94.
Delay element assernbly 94 is threadably secured at 96 to a 15 rece' ving block 98 which is sealingly received within a bore 100 in housing ~0. The sealing engagements of primary firing piston 48 with secondary firing piston 62;
of secondary firing piston 62 with securing sleeve 68, of receiving block 48 with housing 20; and of securing sleeve 6B with housing 20, serve to form chambers 86 and 92 (on either side of initiator charge 32), which will be at atmospheric pressure. Accordingly, first firing piston 48 and second firing piston 62 are fluid responsive pistons responsive to pressure inside housing 20.
Delay element assembly 9~ is a pyrotechnic device which; upon ignition of an internal initiator, will burn for a period of time until detonating an explosive charge to detonate a booster charge to in turn detonate the perforating gun. In a presently preferred embodiment, delay element assembly 94 will burn for approxi~ately seven minutes after lnitial ignition. E~owever, other delay times clearly may be utilized. The structure of a delay element assembly suitable for use with the present invention is described in U.S. Patent No. 4,632,034, issued December 30, 1986 to Colley, Jr.
-~3-Perforating sub 28 coupled to lower end of housing 20 S includes a central bore 102. Contained within bore 102 is a lenyth of a conventional explosive type detonating cord 104 which extends through the perforating gun (32 in Fig.
1), and includes a booster charge 106 at a first end.
Once booster charge 106 is detonated by delay element assembly 94, booster charge 10~ and detonating cord 102 facilitate detonation of the pe~forating gun in a conventional manner.
Xeferring now to Figs. 4-7, therein is shown firing head 10 prior to actuation, and after actuation by each of three different methods. Referring specifically to Fig.
5, therein is shown firing head 10 after actuation by the dropping of a weighted member, such as a go-devil, 112 into contact with actuation piston 30. As go-devil 112 contacts actuation piston 30, actuation piston 30 is moved longitudinally downwardly. As actuation piston 30 is moved downwardly, recessed portion 42 of actuation piston 30 is brought into coextensive relation with collets 50~
The reduced diameter of section 42 of actuation piston 30 allows collets 50 to fall out of engagement with recesses 54 in second firing piston 62. Annulus fluid pressure in housing 20 acts, through ports 41 and 43, on first firing piston 48, driving it longitudinally with sufficient impact to cause firing pin 64 to activate initiator 82.
In a preferred embodiment, 1000 psi pressure is sufficient to drive first firing piston 48.
Referring now specifically to E'ig. 6, therein is depicted firing head 10 when it is actuated by moving actuation piston upwardly such as through use of an overshot 114. Actuation in this manner is similar to actuation through use of a go-devil, with the exception that as actuation piston 30 is moved upwardly, enlarged end 44 of actuation piston 30 is moved upwardly, out of the proximity of collets 50. Collets 50 then move out of recesses 54 in second firing piston 62, and first firing piston 48 will move downwardly, causing flring pin 64 to actuate initiator 82.
Referring now to Fig. 7, therein is shown Eiring head 10 after actuation solely through use of hydrostatic pressure. As indicated previously, chamber 86 beneath first and second ~irlng pi~tons 48 and ~2, respectl~ely, will be at atmospheric pressure. Also as indicated earlier herein, second firing piston 62 is retained in a first, upper, position by shear pins 78. Once hydrostatic pressure on the upper side of second firing piston 62 reaches a threshold value sufficient to shear shear pins 78, second ~iring plston 62, along with mandrel 34 and first firing piston 4B, will be driven downwardly to bring firing pin 64 into operative contact with initiator 82.
Thus, actuation mechanism 22 act~ as a piston withiR
securing sleeve 68 in response to hydro~tatic pressure.
Those skilled in the art will recognize that although the operation of firing head 10 has been described in the context ~f utili2ing annulus pressure within h~using 20 to move first and second firing pistons 4~ and 62, the interior of firing head 10 may instead be exposed to hydrostatic pressure in the tubing string to ef~ect operation of first and second firing pistons 48 and 62.
Referring now to Fig. 8, thereln is shown an alternative embodiment of a firing head 120 in accordance with the present invention. Firing head 120 differs from iring head 10 in that actuation mechanism 22 will impact a detonator explosive charge 122 to immediately detonate ~ 3~3~
perforating gun 12, rather than initiating an initiator charge to begin a time-delayed detonation of perforating gun 12 as was done with the embodiment of Figs. 1-7.
Because firing head 120 is similar in structure and operation ~o firing head 10, only the essential differences will be addressed herein.
Housing 124 o~ firing head 120 includes a ledge 126 against which an ignition block 128 is seated. Igni~ion block 128 includes a central bore 130 which houses a conventional initiator 122. Initiator 122 is sealed within bore 130, such as by o-rings 132, to assure that ch~mber 86 is at atmosphere pressure. Ignition block 12 may be retained within housing 124 by a retaining ring 134, or by any other conventional means. Detonator 122 is preferably retained within ignition block 128 by a retaining ring 136. The function of actuation mechanism 22 of firing head 120 i5 identical to that as previously described with respect to firing head 10 of Flgs. 1-7.
Thus, three alternative methods o~ actuation are provided to actuate firins head 120 and to thereby immediately detonate perforating gun 12.
Many modifications and variations may be made in the ~S techniques and structures described herein without departing from the spirit and scope of the present invention. Accordingly, it should be readily understood that the methods and embodiments described and illustrated herein are exemplary only and are not to be considered as limitations on the scope of the present invention.
METHODS AND APPARATUS FOR ACTUATING A
TV~ING CONVEYED PERFORATING GUN
BACKGROUND OF ~HE INVENTION
5~he present invention relates generally to methods and apparatus for actuating tubing conveyed perf~rating guns to perforate suhsurface formations, and more specifically relates to methods and apparatus which allo~
a tubing conveyed perforating gun to be actuated either mechanically or hydraulically.
Conventional firing heads for tubing conveyed perforating guns are typically actuated by either mechanical means or by hydraulical means. Mechanically-actuated firing heads are typically actuated by dropping a weighted member (commonly known as a "~o-devil") t into the well to impact a piston and drive a firing pin into an initiator charge. An example of this type of firing head may be found in U.S. Patent No. 3,7Q6,344, issued December 19, 1972 to Roy R. Vann, and assigne~ to the assignee of the present invention. Hydraulically-actuated firing h~ads typically cont~in a piston which is exposed on one side to the annulus pressure in the well surrounding the firing head. When the pressùre in the annulus exceeds a predetermined actuation pressure, the piston will move and drive a firing pin into an initiator charge.
Additionally, firing heads are known which are actuated by a combination of mechanical action and hydraulic action. For example, a go-devil will be used to impact a striking piston and to move the piston from a first position to a second position. The movement of the striking piston to the second position will release a locking mechanism on a hydraulic piston which will then be moved in response to hydraulic pressure in the annulus to ., , ` ~
bring a firing pin into con-tac-t wi-th an initiator charge. A firing head of this type is disclosed in U.S. Patent No. 4,901,802, issued February 20, 1990, inventor~ Flint R. George and Kevin R. George, and assigned to the assignee of the present application.
Well perforating opera-tions -take place under a wide varie-ty of environmental conditions which can be extremely severe. Severe or unexpectecl environmental conditions may cause unexpected problems insa-tis-factorily per:Eorming tubing conveyed perforating jobs. For example, a mechanically-ac-tua-ted firing head may be obstructed by particula-te solids in -the well which may prevent its opera-tion. Addi-tionally, factors such as devi.ation of the well may affect the abili-ty to practically actuate a firing head mechanically. Similarly, it is no-t always possible to ac-tuate a hydraulic firing head in a particular well. For example, defective or weak casing make it imprac-tical to apply increased pressure to the annulus to hydraulically actuate a firing head.
Accordingly, it is desirable to have alternative methods for actuating the firing head.
Accordingly, the present invention provides a new method and apparatus for actuating a perforating gun. The apparatus allows the perforating gun to be actua-ted either hydraulically or mechanically.
Additionally, a firing head in accordance with the present invention may he adapted to be responsive not only to longitudinal force in a downward direction, such as is accomplished with a-weighted member, but also to longitudinal force in an upward directi.on, as may be applied with a wireline or slickline.
:~c~ {!
SUMMARY OF THE INVENI'ION
In accordance with the invention there is provided a firing head for a tubing conveyed perfora-ting gun, comprising a pair of firing pistons, a firs-t of said firing pistons being movable at least partially in xesponse -to a mechanical force applied in said firing head, and -the second of said firing pistons being movable in response to hydraulic force applied in said firing head; means for causing detona-tion of said perforating gun, said detonation means responsive -to movement of either of said first and second firing pistons.
The present invention provides a firing head for actuating a tubing conveyed perforating gun which is adapted to be actuated either mechanically or hydraulically. Additionally, in a particularly pre-ferred embodiment, the firing head may be actuated mechanically by either an impact on the firing head or by tension placed upon a portion of the firing head. In this particularly preferred embodiment, the firing head includes two firing pistons, each of which is movable from a first, "normal", position to a second position which will actuate an initiator charge, -to initia-te either a burn or an explosion which will result in detonation of the perforating gun. Preferably, the firs-t firing piston is releasable through downward or upward movement of an actua-tion piston. This actuation piston preferably includes a head portion which may receive the impac-t from a go-devil detonating bar, or which may be easily latched onto by an overshot or similar mechanism. The second :Eiring piston is preferably responsive to hydraulic pressure applied to the interior of -the firing head.
'~;,L~BJ~r~i ~L 2~ . g ~
In a particularly preferred embodiment, the first and second firing pis-tons are concentric with one another and at least partial:Ly coextensive with one another; and are in concentric relation to the actua-tion piston. In this embodiment, the first firing pis-ton is securely retained in its first position by a plurality of releasable segmen-ts, or collets which are held in position by -the actuation piston. However, in -this embodiment, the second Eiring piston is retained in i-ts first position by a plurality of shear pins. Accordingly, while the first firing piston is releasable only -through movement of the actuation pis-ton, the second firing piston is releasable through hydraulic pressure acting upon the second piston and shearing the shear pins.
- ~a -_RIE~ DESCRIPT~ ,t,~ NGS
Fig. 1 depicts a firing head in ~ccordance with the present invention in a tool s~ring an operating configuration in a wellbore, illustrated partially in vertical section.
Eig. 2 depicts the firing head of Fig. 1 in greater detail and in vertical section.
Fig. 3 depicts the ac~uation mechanism of a firing head in accordance with the present invention in an exploded view.
Fig. 4 depicts the actuation mechanism of a firing head in accordance with the present in~ention prior to actuation, illustrated in vertical section.
Fig. 5 depicts the actuation mechanism of Fig. 4 after actuation by impact from a cetonating bar.
Fig. 6 depicts the actuation mechanism of Fig. 4 after actuation with an overshot.
~ig. 7 depicts the actuation mechanism of FigO 4 after actuation by application of hydraulic pressure.
Fig. 8 depicts an alternative em~odiment of a firing head in accordance with the present invention, illustrated in vertical section.
DETAILED DESCRIPTION_OF A PREEERRED EMBODIMENT
Referring now to the drawings in more detail, and particularly to Fig. 1, therein is depicted a firing head 10 in accordance with the present invention, in an operatiny configuration in a wellbore. Firing head l~ is situated above a perforating gun 12 in a tool string~
indicated generally at 14~ Tool string 14 extends into a wellbore 16. Tool string 14 may include a packer 18 to isolate an upper portion of the bor~hole Erom a lower portion of the borehole when perforating gun 12 is positioned adjacent a formation to be perforated. In one preferred embodiment, a ported member l9 will be included within tool string 14, such that the interior of firing head lO will be exposed to pressure in well~ore 16.
Referring now to Fig. 2, therein is depicted an exemplary embodiment of firing head 10 in vertical section. ~iring head lO includes a pri~ary hou~ing 20 in which an actuation mechanisrn, indicated generally at 22, is retained. Primary housing may be c,ne piece, or may include submembers, such as housing member 24, which may be joined, such as by a threaded coupling 26, to primary housing 20. Primary housing 20 will preferably couple at a lower end to firing head sub 28 in conventional manner.
As will be apparent from the discussion to follow, actuation mechanism 22 includes two firing pistons. A
first firing piston 48 is preferably secured in place by 2~ collets and is released throuyh mechanical actuation of an actuation piston 30O Second firing piston 62 is preferably secured in place by shear pins and is released through hydraulic pressure. Actuation mechanism 22 includes actuation piston 30 retained within a bore 32 in mandrel 34. Actuation piston 30 is lon9itudinally movable relative to mandrel 34, but is initially secured in a first, "normal", ~osition by a shear pin 36. Actuation piston 30 includes a first end 38 which iS adapted both to receive an impact to shear shear pin 36, or to be retrieved7 such as by with an overshot, so as to receive an upward tension to shear shear pin 36, and to thereby allow longitudi.nal movement of ~ctuation piston 30 relative to mandrel 34.
A second end of actuation piston 30, indicated generally at 40, includes a firs~ portion 42 of reduced diameter. Second end 40 of actuation piston 30 also includes a second portion 44 of an enlarged diameter relative to first portion 42 of actuation piston 30.
Second portion 44 of actuation piston 30 extends into a recess 46 in first firing piston 48. Mandrel 34 is coupled to second firing pi6ton 62. First firing piston 48 is secured in fixed position relative to mandrel 34 and second firing piston 62 by a plurality of releasable segments, or ~c0112ts~, 50 which cooperatively engage recesses 54 in second firing piston 62 and apertures 56 in irst firing piston 48. Collets 50 are held in position by enlarged second portion 44 of actuation piston 30.
First ~iring piston 48 includes a second end, indicated generally at 58, which sealingly engages bore ~0 in second firing piston 62. A firing pin 64 is coupled to second end 58 of first Çiring piston 48. Unless otherwise noted all sealed engagements described herein may be provided through use of conventional o-ring~type seals.
Second firing plston 62 is slideably and sealingly received within a bore 66 in securing sleeve 68. Securing sleeve 68 i5 received within housing 20 and preferably rests against a shoulder 70 in housing 20. Securing sleeve 68 is retained in position in housing 20 such as by a snap ring 72 which engages a relief 74 in housing 200 A
plurality oE apertures 76 are formed in securing sleeve 6 to receive shear pins 78. Shear pins 78 similarly engage apertures 80 in second firing piston 62~ First and second firing pistons 48 and 62, respectively, preferably each include apertures 43 and 41, respectively, to allow fluid ~ J ~
communication between the interior of housing 20 and recess 46 in first firing piston 48.
Firing pin 64 preferably includes a tapered contour designed to impact and detonate an initiator charge 82, such as a primer assembly, which is sealingly retained within a bore 84 in securing sleeve 68. Primer assembly 82 is secured to securin~ sleeve 68 by a primer block 83 which is preferably boltably secured to securing sleeve 68. Securing sleeve 68 includes an aperture 90 which allows the jet of hot gases emitted by the ignition of primer assembly 82 to enter a chamber 92 in housing 20.
Secured within chamber 92 is a delay element assembly 94.
Delay element assernbly 94 is threadably secured at 96 to a 15 rece' ving block 98 which is sealingly received within a bore 100 in housing ~0. The sealing engagements of primary firing piston 48 with secondary firing piston 62;
of secondary firing piston 62 with securing sleeve 68, of receiving block 48 with housing 20; and of securing sleeve 6B with housing 20, serve to form chambers 86 and 92 (on either side of initiator charge 32), which will be at atmospheric pressure. Accordingly, first firing piston 48 and second firing piston 62 are fluid responsive pistons responsive to pressure inside housing 20.
Delay element assembly 9~ is a pyrotechnic device which; upon ignition of an internal initiator, will burn for a period of time until detonating an explosive charge to detonate a booster charge to in turn detonate the perforating gun. In a presently preferred embodiment, delay element assembly 94 will burn for approxi~ately seven minutes after lnitial ignition. E~owever, other delay times clearly may be utilized. The structure of a delay element assembly suitable for use with the present invention is described in U.S. Patent No. 4,632,034, issued December 30, 1986 to Colley, Jr.
-~3-Perforating sub 28 coupled to lower end of housing 20 S includes a central bore 102. Contained within bore 102 is a lenyth of a conventional explosive type detonating cord 104 which extends through the perforating gun (32 in Fig.
1), and includes a booster charge 106 at a first end.
Once booster charge 106 is detonated by delay element assembly 94, booster charge 10~ and detonating cord 102 facilitate detonation of the pe~forating gun in a conventional manner.
Xeferring now to Figs. 4-7, therein is shown firing head 10 prior to actuation, and after actuation by each of three different methods. Referring specifically to Fig.
5, therein is shown firing head 10 after actuation by the dropping of a weighted member, such as a go-devil, 112 into contact with actuation piston 30. As go-devil 112 contacts actuation piston 30, actuation piston 30 is moved longitudinally downwardly. As actuation piston 30 is moved downwardly, recessed portion 42 of actuation piston 30 is brought into coextensive relation with collets 50~
The reduced diameter of section 42 of actuation piston 30 allows collets 50 to fall out of engagement with recesses 54 in second firing piston 62. Annulus fluid pressure in housing 20 acts, through ports 41 and 43, on first firing piston 48, driving it longitudinally with sufficient impact to cause firing pin 64 to activate initiator 82.
In a preferred embodiment, 1000 psi pressure is sufficient to drive first firing piston 48.
Referring now specifically to E'ig. 6, therein is depicted firing head 10 when it is actuated by moving actuation piston upwardly such as through use of an overshot 114. Actuation in this manner is similar to actuation through use of a go-devil, with the exception that as actuation piston 30 is moved upwardly, enlarged end 44 of actuation piston 30 is moved upwardly, out of the proximity of collets 50. Collets 50 then move out of recesses 54 in second firing piston 62, and first firing piston 48 will move downwardly, causing flring pin 64 to actuate initiator 82.
Referring now to Fig. 7, therein is shown Eiring head 10 after actuation solely through use of hydrostatic pressure. As indicated previously, chamber 86 beneath first and second ~irlng pi~tons 48 and ~2, respectl~ely, will be at atmospheric pressure. Also as indicated earlier herein, second firing piston 62 is retained in a first, upper, position by shear pins 78. Once hydrostatic pressure on the upper side of second firing piston 62 reaches a threshold value sufficient to shear shear pins 78, second ~iring plston 62, along with mandrel 34 and first firing piston 4B, will be driven downwardly to bring firing pin 64 into operative contact with initiator 82.
Thus, actuation mechanism 22 act~ as a piston withiR
securing sleeve 68 in response to hydro~tatic pressure.
Those skilled in the art will recognize that although the operation of firing head 10 has been described in the context ~f utili2ing annulus pressure within h~using 20 to move first and second firing pistons 4~ and 62, the interior of firing head 10 may instead be exposed to hydrostatic pressure in the tubing string to ef~ect operation of first and second firing pistons 48 and 62.
Referring now to Fig. 8, thereln is shown an alternative embodiment of a firing head 120 in accordance with the present invention. Firing head 120 differs from iring head 10 in that actuation mechanism 22 will impact a detonator explosive charge 122 to immediately detonate ~ 3~3~
perforating gun 12, rather than initiating an initiator charge to begin a time-delayed detonation of perforating gun 12 as was done with the embodiment of Figs. 1-7.
Because firing head 120 is similar in structure and operation ~o firing head 10, only the essential differences will be addressed herein.
Housing 124 o~ firing head 120 includes a ledge 126 against which an ignition block 128 is seated. Igni~ion block 128 includes a central bore 130 which houses a conventional initiator 122. Initiator 122 is sealed within bore 130, such as by o-rings 132, to assure that ch~mber 86 is at atmosphere pressure. Ignition block 12 may be retained within housing 124 by a retaining ring 134, or by any other conventional means. Detonator 122 is preferably retained within ignition block 128 by a retaining ring 136. The function of actuation mechanism 22 of firing head 120 i5 identical to that as previously described with respect to firing head 10 of Flgs. 1-7.
Thus, three alternative methods o~ actuation are provided to actuate firins head 120 and to thereby immediately detonate perforating gun 12.
Many modifications and variations may be made in the ~S techniques and structures described herein without departing from the spirit and scope of the present invention. Accordingly, it should be readily understood that the methods and embodiments described and illustrated herein are exemplary only and are not to be considered as limitations on the scope of the present invention.
Claims (16)
1. A firing head for a tubing conveyed perforating gun, comprising:
a housing;
first and second firing pistons within said housing, each piston movable from a first position in said housing to a second position in said housing;
a first retention mechanism operatively coupled to said first firing piston to retain said first firing piston in its said first position, said first retention mechanism being releasable at least partially in response to a mechanical force supplied either generally longitudinally downwardly or generally longitudinally upwardly in said firing head;
a second retention mechanism operatively coupled to said second firing piston to retain said second firing piston in its first said position, said second retention mechanism being releasable at least partially in response to hydraulic force applied in said firing head; and a single initiator assembly adapted to cause detonation of said perforating gun, said initiator responsive to movement of either of said first and second firing positions.
a housing;
first and second firing pistons within said housing, each piston movable from a first position in said housing to a second position in said housing;
a first retention mechanism operatively coupled to said first firing piston to retain said first firing piston in its said first position, said first retention mechanism being releasable at least partially in response to a mechanical force supplied either generally longitudinally downwardly or generally longitudinally upwardly in said firing head;
a second retention mechanism operatively coupled to said second firing piston to retain said second firing piston in its first said position, said second retention mechanism being releasable at least partially in response to hydraulic force applied in said firing head; and a single initiator assembly adapted to cause detonation of said perforating gun, said initiator responsive to movement of either of said first and second firing positions.
2. The firing head of claim 1, wherein said first firing piston includes a firing pin adapted to impact said initiator.
3. The firing head of claim 2, wherein said movement of said second firing piston causes movement of said first firing piston to cause said firing pin to impact said initiator.
4. The firing head of claim 1, wherein said first and second firing pistons are in coaxial relation to one another.
5. The firing head of claim 1, wherein said first retention mechanism comprises an actuation piston movably responsive to mechanical force to release and allow movement of said first firing piston.
6. A firing head for actuating a tubing conveyed perforating gun, comprising:
a housing; and an actuation mechanism within said housing, said actuation mechanism comprising, an actuation piston, a first firing piston movable from a first position to a second position, said first firing position operatively coupled to said actuation piston, means for releasably retaining said first firing piston in said first position, said releasable retaining means being responsive to mechanical force applied to move said actuation piston either upwardly or downwardly, a second firing piston movable from a first position to a second position, said second firing piston being in generally concentric and at least partially coextensive relation with said first firing piston, and means for releasably retaining said second firing piston in said first position, said releasable retaining means being releasable through application of hydraulic pressure to said actuation mechanism.
a housing; and an actuation mechanism within said housing, said actuation mechanism comprising, an actuation piston, a first firing piston movable from a first position to a second position, said first firing position operatively coupled to said actuation piston, means for releasably retaining said first firing piston in said first position, said releasable retaining means being responsive to mechanical force applied to move said actuation piston either upwardly or downwardly, a second firing piston movable from a first position to a second position, said second firing piston being in generally concentric and at least partially coextensive relation with said first firing piston, and means for releasably retaining said second firing piston in said first position, said releasable retaining means being releasable through application of hydraulic pressure to said actuation mechanism.
7. The firing head of claim 6, wherein said means for retaining said second firing piston in said first position comprises at least one shear pin adapted to retain said second firing piston in a first position relative to said housing.
8. The firing head of claim 6, wherein said first and second firing pistons are in concentric relation to each other, and wherein said first and second firing pistons are in concentric relation to said actuation piston.
9. A firing head for actuating a tubing conveyed perforating gun, comprising:
a housing; and an actuation mechanism within said housing, said actuation mechanism comprising, an actuation piston, a first firing piston movable from a first position to a second position, said first firing position operatively coupled to said actuation piston, means for releasably retaining said first firing piston in said first position, said releasable retaining means being responsive to mechanical force applied to said actuation piston, said means for releasably retaining said first firing piston in said first position comprising releasable segments normally engaging said first firing piston and said second firing piston, said segments retained in said engaging position by said actuation piston and releasable in response to movement of said actuation piston, a second firing piston movable from a first position to a second position, said second firing piston being in generally coaxial and concentric relation with said first firing piston, and means for releasably retaining said second firing piston in said first position, said releasable retaining means being releasable through application of hydraulic pressure to said actuation mechanism.
a housing; and an actuation mechanism within said housing, said actuation mechanism comprising, an actuation piston, a first firing piston movable from a first position to a second position, said first firing position operatively coupled to said actuation piston, means for releasably retaining said first firing piston in said first position, said releasable retaining means being responsive to mechanical force applied to said actuation piston, said means for releasably retaining said first firing piston in said first position comprising releasable segments normally engaging said first firing piston and said second firing piston, said segments retained in said engaging position by said actuation piston and releasable in response to movement of said actuation piston, a second firing piston movable from a first position to a second position, said second firing piston being in generally coaxial and concentric relation with said first firing piston, and means for releasably retaining said second firing piston in said first position, said releasable retaining means being releasable through application of hydraulic pressure to said actuation mechanism.
10. A firing head for actuating a tubing conveyed perforating gun, comprising:
a housing;
an actuation mechanism within said housing, said actuation mechanism comprising:
an actuation piston movable from a first position in response to force applied generally along the longitudinal axis of said perforating gun proximate said firing head to either of second or third positions on opposing sides of said first position;
a first firing piston in coaxial relation to said actuation piston, said first firing piston movable from a first position to a second position, said first firing position being retained in said first position when said actuation piston is in its respective said first position;
a second firing piston in coaxial and at least partially coextensive relation to said first firing piston, said second firing piston being movable from a first position to a second position;
means for releasably retaining said second piston in said first position, said releasable retaining means being releasable in response to hydraulic pressure; and an initiator responsive to movement of said first or second firing pistons to cause detonation of said perforating gun.
a housing;
an actuation mechanism within said housing, said actuation mechanism comprising:
an actuation piston movable from a first position in response to force applied generally along the longitudinal axis of said perforating gun proximate said firing head to either of second or third positions on opposing sides of said first position;
a first firing piston in coaxial relation to said actuation piston, said first firing piston movable from a first position to a second position, said first firing position being retained in said first position when said actuation piston is in its respective said first position;
a second firing piston in coaxial and at least partially coextensive relation to said first firing piston, said second firing piston being movable from a first position to a second position;
means for releasably retaining said second piston in said first position, said releasable retaining means being releasable in response to hydraulic pressure; and an initiator responsive to movement of said first or second firing pistons to cause detonation of said perforating gun.
11. The firing head of claim 10, wherein said first firing piston is secured in fixed relation to said second firing piston by said actuation piston when said actuation piston is in said first position.
12. The firing head of claim 10, wherein said actuation mechanism further comprises:
means for retaining said first firing piston in fixed relation to said second firing piston, said retaining means releasable through movement of said actuation piston away from said first position.
means for retaining said first firing piston in fixed relation to said second firing piston, said retaining means releasable through movement of said actuation piston away from said first position.
13. The firing head of claim 10, wherein said actuation mechanism further comprises a plurality of releasable members which engage said first and second firing pistons when said actuation piston is in said first position.
14. The firing head of claim 10, wherein said initiator comprises a primer assembly operatively associated with a delay element.
15. The firing head of claim 10, wherein said initiator comprises a detonator explosive charge.
16
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US128,383 | 1987-12-03 | ||
| US07/128,383 US4911251A (en) | 1987-12-03 | 1987-12-03 | Method and apparatus for actuating a tubing conveyed perforating gun |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1311189C true CA1311189C (en) | 1992-12-08 |
Family
ID=22435106
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000584844A Expired - Fee Related CA1311189C (en) | 1987-12-03 | 1988-12-02 | Method and apparatus for actuating a tubing conveyed perforating gun |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4911251A (en) |
| EP (1) | EP0319321B1 (en) |
| AU (1) | AU610302B2 (en) |
| CA (1) | CA1311189C (en) |
| DE (1) | DE3873890T2 (en) |
| NO (1) | NO180462C (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5161616A (en) * | 1991-05-22 | 1992-11-10 | Dresser Industries, Inc. | Differential firing head and method of operation thereof |
| US5148868A (en) * | 1991-08-12 | 1992-09-22 | Christian J B | Method and apparatus for perforating tubing |
| US5223665A (en) * | 1992-01-21 | 1993-06-29 | Halliburton Company | Method and apparatus for disabling detonation system for a downhole explosive assembly |
| US5571986A (en) * | 1994-08-04 | 1996-11-05 | Marathon Oil Company | Method and apparatus for activating an electric wireline firing system |
| US5680905A (en) * | 1995-01-04 | 1997-10-28 | Baker Hughes Incorporated | Apparatus and method for perforating wellbores |
| US5791417A (en) * | 1995-09-22 | 1998-08-11 | Weatherford/Lamb, Inc. | Tubular window formation |
| US5603384A (en) * | 1995-10-11 | 1997-02-18 | Western Atlas International, Inc. | Universal perforating gun firing head |
| US5700968A (en) * | 1996-09-30 | 1997-12-23 | Blimke; Ross Arthur | Perforating gun brake |
| US5887654A (en) | 1996-11-20 | 1999-03-30 | Schlumberger Technology Corporation | Method for performing downhole functions |
| US6035880A (en) * | 1997-05-01 | 2000-03-14 | Halliburton Energy Services, Inc. | Pressure activated switch valve |
| WO1999012872A1 (en) * | 1997-09-05 | 1999-03-18 | The Ensign-Bickford Company | Self-contained percussion output device |
| US5992289A (en) * | 1998-02-17 | 1999-11-30 | Halliburton Energy Services, Inc. | Firing head with metered delay |
| US6675896B2 (en) * | 2001-03-08 | 2004-01-13 | Halliburton Energy Services, Inc. | Detonation transfer subassembly and method for use of same |
| US6557636B2 (en) | 2001-06-29 | 2003-05-06 | Shell Oil Company | Method and apparatus for perforating a well |
| CA2451231C (en) | 2001-06-29 | 2009-09-08 | Shell Canada Limited | Method and apparatus for detonating an explosive charge |
| US20030001753A1 (en) * | 2001-06-29 | 2003-01-02 | Cernocky Edward Paul | Method and apparatus for wireless transmission down a well |
| US20030005844A1 (en) * | 2001-07-03 | 2003-01-09 | Chambers Paul A. | Plunger assembly |
| US6581519B1 (en) * | 2001-10-11 | 2003-06-24 | Leslie K. Adams | Blasting cap initiator system |
| US6708761B2 (en) | 2001-11-13 | 2004-03-23 | Halliburton Energy Services, Inc. | Apparatus for absorbing a shock and method for use of same |
| US20040118562A1 (en) * | 2002-12-20 | 2004-06-24 | George Flint R. | Retrievable multi-pressure cycle firing head |
| US6962202B2 (en) * | 2003-01-09 | 2005-11-08 | Shell Oil Company | Casing conveyed well perforating apparatus and method |
| WO2014171914A1 (en) * | 2013-04-15 | 2014-10-23 | Halliburton Energy Services, Inc. | Firing head actuator for a well perforating system and method for use of same |
| US8991496B2 (en) | 2013-04-15 | 2015-03-31 | Halliburton Energy Services, Inc. | Firing head actuator for a well perforating system and method for use of same |
| US11054233B2 (en) * | 2017-07-25 | 2021-07-06 | Hunting Titan, Inc. | Hydraulic time delay actuated by the energetic output of a perforating gun |
| US11193358B2 (en) * | 2018-01-31 | 2021-12-07 | DynaEnergetics Europe GmbH | Firing head assembly, well completion device with a firing head assembly and method of use |
| US11174713B2 (en) * | 2018-12-05 | 2021-11-16 | DynaEnergetics Europe GmbH | Firing head and method of utilizing a firing head |
| CN110529083B (en) * | 2019-08-13 | 2021-11-30 | 西安物华巨能爆破器材有限责任公司 | Multi-stage pressure coding detonating device for oil pipe transmission perforation |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2719485A (en) * | 1950-01-09 | 1955-10-04 | Eastman Oil Well Survey Co | Magnetic control devices |
| DE3206511C2 (en) * | 1982-02-24 | 1985-09-12 | L. & C. Steinmüller GmbH, 5270 Gummersbach | Waste heat boiler |
| US4509604A (en) * | 1982-04-16 | 1985-04-09 | Schlumberger Technology Corporation | Pressure responsive perforating and testing system |
| US4560000A (en) * | 1982-04-16 | 1985-12-24 | Schlumberger Technology Corporation | Pressure-activated well perforating apparatus |
| US4484632A (en) * | 1982-08-30 | 1984-11-27 | Geo Vann, Inc. | Well completion method and apparatus |
| US4690227A (en) * | 1983-03-31 | 1987-09-01 | Halliburton Company | Gun firing head |
| US4544034A (en) * | 1983-03-31 | 1985-10-01 | Geo Vann, Inc. | Actuation of a gun firing head |
| US4619333A (en) * | 1983-03-31 | 1986-10-28 | Halliburton Company | Detonation of tandem guns |
| US4614156A (en) * | 1984-03-08 | 1986-09-30 | Halliburton Company | Pressure responsive explosion initiator with time delay and method of use |
| US4632034A (en) * | 1984-03-08 | 1986-12-30 | Halliburton Company | Redundant detonation initiators for use in wells and method of use |
| US4650010A (en) * | 1984-11-27 | 1987-03-17 | Halliburton Company | Borehole devices actuated by fluid pressure |
| US4619319A (en) * | 1985-02-01 | 1986-10-28 | Halliburton Company | Packer and actuation portion of tubing conveyed completion system |
| US4629001A (en) * | 1985-05-28 | 1986-12-16 | Halliburton Company | Tubing pressure operated initiator for perforating in a well borehole |
| US4610312A (en) * | 1985-06-10 | 1986-09-09 | Baker Oil Tools, Inc. | Redundant firing mechanism for a well perforating gun |
| US4655298A (en) * | 1985-09-05 | 1987-04-07 | Halliburton Company | Annulus pressure firer mechanism with releasable fluid conduit force transmission means |
| US4678044A (en) * | 1986-03-31 | 1987-07-07 | Halliburton Company | Tubing pressure operated initiator for perforating in a well borehole |
| US4901802A (en) * | 1987-04-20 | 1990-02-20 | George Flint R | Method and apparatus for perforating formations in response to tubing pressure |
-
1987
- 1987-12-03 US US07/128,383 patent/US4911251A/en not_active Expired - Lifetime
-
1988
- 1988-12-02 CA CA000584844A patent/CA1311189C/en not_active Expired - Fee Related
- 1988-12-02 NO NO885382A patent/NO180462C/en unknown
- 1988-12-02 EP EP88311454A patent/EP0319321B1/en not_active Expired - Lifetime
- 1988-12-02 DE DE8888311454T patent/DE3873890T2/en not_active Expired - Fee Related
- 1988-12-05 AU AU26522/88A patent/AU610302B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| NO180462B (en) | 1997-01-13 |
| NO885382D0 (en) | 1988-12-02 |
| NO885382L (en) | 1989-06-05 |
| EP0319321B1 (en) | 1992-08-19 |
| US4911251A (en) | 1990-03-27 |
| AU2652288A (en) | 1989-06-08 |
| NO180462C (en) | 1997-04-23 |
| EP0319321A1 (en) | 1989-06-07 |
| DE3873890D1 (en) | 1992-09-24 |
| AU610302B2 (en) | 1991-05-16 |
| DE3873890T2 (en) | 1993-03-25 |
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Legal Events
| Date | Code | Title | Description |
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| MKLA | Lapsed |