US008091477B2
`
`(12) United States Patent
`US 8,091,477 B2
`(10) Patent No.:
`Brooks et al.
`(45) Date of Patent:
`Jan. 10, 2012
`
`(54)
`
`INTEGRATED DETONATORS FOR USE
`WITH EXPLOSIVE DEVICES
`
`(56)
`
`References Cited
`
`(75)
`
`Inventors: James E. Brooks, Manvel, TX (US);
`N013“ C- Lerdles Stafford: TXKUS);
`Anthony F- Veneruso, Mlssoun Clty, TX
`(US)
`
`-
`(73) Assignee: Schlumberger Technology
`corporatlon’ sugar Land’ TX (Us)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(1)) by 811 days.
`
`(21) App]. No.: 10/711,809
`(22)
`Filed:
`Oct. 6, 2004
`
`U.S. PATENT DOCUMENTS
`
`6/1972 Lunt et al
`3 670 653 A *
`102/210
`
`3/1973 Thakore .................
`3,721,884 A *
`361/251
`3,913,224 A * 10/1975 Preissinger et a1.
`..... 29/832
`
`3,963,966 A *
`6/1976 Mohr .....................
`361/260
`....... 102/218
`4,227,461 A * 10/1980 Beezley et a1.
`
`.......
`,
`,
`e 0 er .
`~~ 1021/33/2213
`j’igi’égg : : Egg; $311251; ~~~~~~~~~~~~
`
`8/1985 Malone ......................... 313/325
`4,538,088 A *
`
`(Continued)
`
`CN
`
`FOREIGN PATENT DOCUMENTS
`2178346 Y
`9/1994
`
`(Continued)
`
`OTHER PUBLICATIONS
`
`(65)
`
`Prior Publication Data
`US 2005/0178282 A1
`Aug. 18, 2005
`
`Related US. Application Data
`
`(63) Continuation-in-part of application No. 10/304,205,
`filed on Nov. 26, 2002, now Pat. No. 7,549,373.
`(60) Provisional application No. 60/521,088, filed on Feb.
`19, 2004, provisional application No. 60/333,586,
`filed on Nov. 27, 2001.
`
`(51)
`
`Int Cl
`(2006 01)
`F453 3'/10
`(2006.01)
`F42C 11/00
`(200601)
`F23Q 7/00
`102/202 7. 102/202 14. 102/206‘
`(52) U S Cl
`102/207102/215. 102/2173 102/218: 162/275 .1 13
`,
`361/248' 361/249' 361/251' 361/2523
`(58) Field of Classification Search ............... 102/2025
`102/202.7, 202.14, 206, 207, 210, 215, 217,
`102/218, 275.11; 361/248, 249, 251, 252
`See application file for complete search history.
`
`R.L. Wahlers , C.Y.D. Huang, M.R. Heinz and AH. Feingold; Low
`Profile Ltcc Transformers; Presented at the International Microelec-
`tronics and Packaging Society IMAPS, Symposium; Denver, CO;
`Sep. 4-6, 2002.
`
`.
`.
`.
`.
`Primary Exammer 7 Mlchael DaVId
`(74) Attorney, Agent, or Firm 7 Dan Hu; Kevm MCGOff
`
`(57)
`
`ABSTRACT
`
`A detonator assembly includes a capacitor, an initiator, a
`transformer and an addressable chip. The initiator is electri-
`cally connected to the capacitor, the transformer is mechani-
`cally and electrically connected to the capacitor and the
`addressable chip is mechanically and electrically connected
`to the transformer. The initiator may be bonded or fused to the
`capacitor, and the transformer may be bonded or fused to the
`caPaCim The caPaCitors initiators Hangman“ and address‘
`able chip form a unified integrated detonating unit.
`
`56 Claims, 10 Drawing Sheets
`
`
`
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 001
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 001
`
`

`

`US 8,091,477 B2
`
`Page 2
`
`US. PATENT DOCUMENTS
`
`3/1989 Kirbyetal.
`RE32,888 E *
`-
`*
`5/1989 Wlker et al.
`4,829,899 A
`4,870,902 A * 10/1989 Simon etal.
`
`................... 102/217
`
`. 102/206
`.................. 102/201
`
`5:309:87” A
`5,341,742 A *
`5,347,929 A *
`5,369,579 A
`5,436,791 A
`5,444,598 A
`
`5/1994 Hafimmetal.
`8/1994 Alford et al.
`............... 102/202.8
`9/1994 Lerche et al.
`............ 102/202.14
`“/1994 Anderson
`7/1995 Turano
`8/ 1995 Aresco
`
`................... 280/735
`3/1998 Belan etal.
`5,725,242 A *
`3/1998 0 Brlen et al.
`5,731,538 A
`.
`6/1999 LaJaunle et al.
`............. 175/4.56
`5,908,365 A *
`1/2001 Pathe
`6,173,651 B1
`1/2001 Vaynshteyn
`6,179,064 B1
`.
`3/2001 Martlnez-Tovar et al.
`6,199,484 B1
`.
`.
`8/2001 Baglnskl et al.
`................. 86/1.1
`6,272,965 B1 *
`10/2001 Swan et 31.
`6,302,024 B1
`................ 102/202.5
`6,318,267 B1* 11/2001 Swan et al.
`..................... 361/793
`6,356,455 B1*
`3/2002 Carpenter
`6,385,031 B1
`5/2002 Lerche et a1.
`
`6,386,108 B1
`
`6,903,938 32
`
`5/2002 Brooks et al.
`.
`*
`....................... 102/206
`6,470,803 131* 10/2002 Lluetal.
`6,598,682 B2
`7/2003 Johnson et al.
`............... 166/370
`*
`/
`aff
`h 'd
`/
`62005 W en“ m” ~~~~~~~~~~~~~ 361779
`
`.................. 102/217
`................ 361/247
`
`7,191,706 B2*
`7,236,345 B1*
`2004/0003743 A1
`2006/0144278 A1*
`
`3/2007 Chase etal.
`6/2007 Roesler et al.
`1/2004 Brooks et 31.
`7/2006 Gerez ........................ 102/202.5
`
`FOREIGN PATENT DOCUMENTS
`
`0555651 A1
`EP
`0561499 A1
`EP
`2253683 A
`GB
`2352261 A
`GB
`2357825 A
`GB
`2388420 A
`GB
`WO 00/20820 A2
`W0
`W001/46638 A1
`W0
`02099356 A2
`WO
`.
`.
`* crted by examlner
`
`8/1993
`9/1993
`9/1992
`1/2001
`7/2001
`11/2003
`4/2000
`6/2001
`12/2002
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 002
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 002
`
`

`

`U.S. Patent
`
`Jan. 10, 2012
`
`Sheet 1 of 10
`
`US 8,091,477 B2
`
`FIG
`
`.1A
`
`FIG
`
`.13
`
`
`
`FIG. 2
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 003
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 003
`
`
`

`

`US. Patent
`
`Jan. 10, 2012
`
`Sheet 2 of 10
`
`US 8,091,477 B2
`
`FIG. 3
`
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`
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`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 004
`
`

`

`US. Patent
`
`Jan. 10, 2012
`
`Sheet 3 of 10
`
`US 8,091,477 B2
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 005
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 005
`
`

`

`US. Patent
`
`Jan. 10, 2012
`
`Sheet 4 of 10
`
`US 8,091,477 B2
`
`FIG. 7
`
`410
`
`416
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`412
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`114
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`WI/I/I/I/I/I/I/Il/I/I/Il/I/I/I/Ilill/IJ
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 006
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 006
`
`

`

`US. Patent
`
`Jan. 10, 2012
`
`Sheet 5 of 10
`
`US 8,091,477 B2
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`SURFACE
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`FIG. 9
`
`OPERATIONAL SEQUENCE TIME—>
`
`FIRE
`
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`DISCONNECT
`
`F'RE
`
`LEEP
`
`SENSEAND
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`DISCONNECT
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`
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`
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`
`SLEEP
`
`SENSE AND
`DISCONNECT
`
`FIRE
`
`
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 007
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 007
`
`

`

`U.S. Patent
`
`Jan.10
`
`9
`
`2012
`
`Sheet60f10
`
`US 8,091,477 B2
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`Hunting Titan, Inc.
`Ex. 1021
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 008
`
`
`
`

`

`U.S. Patent
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 009
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 009
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`
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`

`

`U.S. Patent
`
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`Hunting Titan, Inc.
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`
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`
`

`

`US. Patent
`
`Jan. 10, 2012
`
`Sheet 9 of 10
`
`US 8,091,477 B2
`
`FIG. 13A
`
`JET CUTTER
`
`CENTRAL \
`
`AXIS
`
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`
`LINER
`
`/’/ ’’’’’ L
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`CUTTER
`EXPLOSIVE
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`PELLET
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`FIG. 13B
`
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`CENTRAL
`AXIS
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 011
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 011
`
`

`

`US. Patent
`
`Jan. 10, 2012
`
`Sheet 10 of 10
`
`US 8,091,477 B2
`
`FIG. 14A
`
`FIG. 14B
`
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 012
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`Hunting Titan, Inc.
`Ex. 1021
`Pg. 012
`
`

`

`1
`
`2
`
`US 8,091,477 B2
`
`INTEGRATED DETONATORS FOR USE
`WITH EXPLOSIVE DEVICES
`
`energy source, with one end of the resistor being electrically
`connected to one of the electrodes.
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This claims the benefit under 35 U.S.C. §119(e) of US.
`Provisional Patent Application Ser. No. 60/521,088, entitled,
`“MICROELECTROMECHANICAL DEVICES,” filed on
`Feb. 19, 2004. This is also a continuation-in-part of US. Ser.
`No. 10/304,205, filed Nov. 26, 2002, which claims the benefit
`under 35 U.S.C. §119(e) of US. Provisional Patent Applica-
`tion Ser. No. 60/333,586, entitled, “INTEGRAL CAPACI-
`TOR DISCHARGE UNIT,” filed on Nov. 27, 2001.
`
`10
`
`15
`
`BACKGROUND
`
`20
`
`In some example embodiments, resistors are formed on the
`surface of the capacitor with thick-film deposition. For
`example, one type of resistor is a charging resistor. Another
`type of resistor is a bleed resistor that connects the two elec-
`trodes. The surface of the capacitor is used to attach electri-
`cally a switch and/or an initiator, such as an exploding foil
`initiator (EFI).
`In other example embodiments, an improved detonator
`includes an EFI, switch, capacitor, bleed resistor, transformer,
`and addressable chip integrated to form a monolithic unit
`having the size of a conventional hot-wire detonator. The
`monolithic unit may also include a line protection filter and an
`explosive.
`In another example embodiment, an improved detonator
`may be embedded in a tubing cutter or used to initiate the
`firing of a tubing cutter orjet cutter. Alternatively, an embodi-
`ment of the improved detonator may be used to initiate one or
`more shaped charges.
`Other features and embodiments will become apparent
`from the following description, from the drawings, and from
`the claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`invention relates generally to activating
`The present
`devices, and more particularly to an integrated detonator for
`use in activating explosives.
`Explosives are used in many types of applications, such as
`hydrocarbon well applications, seismic applications, military
`armament, and mining applications. In seismic applications,
`explosives are discharged at the earth surface to create shock
`waves into the earth subsurface so that data regarding the 25
`characteristics of the subsurface may be measured by various
`FIGS. 1A and 1B illustrate two tool strings according to
`sensors. In the hydrocarbon well context, a common type of
`some embodiments of the invention.
`explosive that is used includes shaped charges in perforating
`FIG. 2 is a schematic electrical diagram of a detonator
`guns. The shaped charges, when detonated, create perforating
`jets to extend perforations through any surrounding casing or 30 assembly that can be used in the tool string according to FIG.
`1A or 1B.
`liner and into the surrounding formation to allow communi-
`cation offluids between the formation and the wellbore. Also,
`in a well, other tools may also contain explosives. For
`example, explosives can be used to set packers or to activate
`other tools.
`
`To detonate explosives, detonators are used. Generally,
`detonators can be of two types: electrical and percussion. A
`percussion detonator responds to some type of mechanical
`force to activate an explosive. An electrical detonator
`responds to a predefined electrical signal to activate an explo-
`sive. One type of electrical detonator is referred to as an
`electro-explosive device (EED), which may include hot-wire
`detonators, semiconductor bridge (SCB) detonators, explod-
`ing bridge wire (EBW) detonators, or exploding foil initiator
`(EFI) detonators.
`With certain types ofelectrical detonators, a local electrical
`source is placed in the proximity of the detonator. Such an
`electrical source may be in the form of a capacitor discharge
`unit that includes a capacitor that is charged to a predeter-
`mined voltage. In response to an activation signal, the charge
`stored in the capacitor is discharged into another device to
`perform a detonation operation. Typically, due to the rela-
`tively large amount of energy that is needed, the capacitor
`discharge unit can be quite large, which leads to increased
`sizes of housings in downhole tools that contain such capaci-
`tor discharge units. Further, because of relatively large sizes,
`the efficiencies of conventional capacitor discharge units are
`reduced due to increased resistance and inductance of elec-
`
`trical paths in a detonator.
`
`SUMMARY
`
`In general, an improved detonator is provided that is
`smaller in size and that is more efficient. For example, in one
`embodiment, a detonator assembly includes an energy source
`(e. g., a capacitor) having a surface, the energy source further
`having electrodes. A resistor is formed on the surface of the
`
`35
`
`FIG. 3 is a perspective view of the detonator assembly.
`FIG. 4 is a bottom view of the detonator assembly.
`FIG. 5 is a schematic side view of a capacitor in the deto-
`nator assembly.
`FIGS. 6 and 7 illustrate two different types of switches used
`in the detonator assembly of FIG. 2.
`FIGS. 8A and 8B illustrates an embodiment of the micro-
`
`40
`
`switch of the present invention as used in an integrated deto-
`nator device.
`
`FIG. 9 illustrates an example of the addressable function-
`ality of an embodiment of the integrated detonator device of
`FIGS. 8A and 8B.
`
`45
`
`FIG. 10 illustrates an example of an embodiment of the
`voltage step-up transformer of the integrated detonator
`device.
`
`50
`
`55
`
`60
`
`65
`
`FIG. 11 illustrates an embodiment of the triggered spark
`gap circuitry of the integrated detonator device.
`FIG. 12 illustrates an embodiment of the piezoelectric
`transformer of the integrated detonator device.
`FIG. 13A-B illustrate an embodiment ofthe jet cutter ofthe
`integrated detonator device.
`FIGS. 14A-C illustrate an embodiment of the present
`invention for use in detonating a shaped charge or a set of
`shaped charges in a shot-by-shot operation to achieve selec-
`tive firing.
`
`DETAILED DESCRIPTION
`
`In the following description, numerous details are set forth
`to provide an understanding of the present invention. How-
`ever, it will be understood by those skilled in the art that the
`present invention may be practiced without these details and
`that numerous variations or modifications from the described
`
`embodiments may be possible.
`As used herein, the terms “connect”, “connection” “con-
`nected”, “in connection wit ”, and “connecting” are used to
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 013
`
`Hunting Titan, Inc.
`Ex. 1021
`Pg. 013
`
`

`

`US 8,091,477 B2
`
`3
`mean “in direct connection with” or “in connection with Via
`
`the terms “mechanically connect”,
`another element”;
`“mechanical connection”, and “mechanically connected”,
`“in mechanical connection with”, and “mechanically con-
`necting” means in direct physical connection to form a mono-
`lithic unit such as bonded, fused, or integrated; and the term
`“set” is used to mean “one element” or “more than one ele-
`
`ment”; the terms “up” and “down”, “upper” and “lower”,
`“upwardly” and downwardly”, “upstream” and “down-
`stream”; “above” and “below”; and other like terms indicat-
`ing relative positions above or below a given point or element
`are used in this description to more clearly describe some
`embodiments of the invention. However, when applied to
`equipment and methods for use in wells that are deviated or
`horizontal, such terms may refer to a left to right, right to left,
`or other relationship as appropriate. As used here, the terms
`“up” and “down”; “upper” and “lower”; “upwardly” and
`downwardly”; “above” and “below”; and other like terms
`indicating relative positions above or below a given point or
`element are used in this description to more clearly describe
`some embodiments of the invention. However, when applied
`to equipment and methods foruse in wells that are deviated or
`horizontal, or when such equipment are at a deviated or hori-
`zontal orientation, such terms may refer to a left to right, right
`to left, or other relationship as appropriate.
`Referring to FIG. 1A, an embodiment of a tool string
`includes a perforating string having a perforating gun 20 and
`a firing head 18. The perforating string is attached at the end
`of a carrier line 12, such as a wireline, electrical cable, slick-
`line, tubing, and so forth. In the embodiment of FIG. 1A, the
`firing head 18 includes an exploding foil initiator (EFI) deto-
`nator assembly 22 according to one embodiment. As dis-
`cussed below, the EFI detonator assembly 22 includes an
`integrated assembly of a capacitor discharge unit (CDU) and
`EFI. It should be noted, in the embodiments using wireline or
`tubing to suspend the perforating string, a downhole battery
`may be used to supply power to the EFI.
`More generally, the integrated capacitor discharge unit has
`a capacitor and a charging and bleed resistor. The integrated
`capacitor discharge unit includes a thick-film circuit that elec-
`trically connects the capacitor and the resistor, as well as other
`components.
`The detonator assembly 22 is coupled to a detonating cord
`24, which is connected to a number of shaped charges 26.
`Activation of the detonator assembly 22 causes initiation of
`the detonating cord 24, which in turn causes detonation ofthe
`shaped charges 26. Detonation of the shaped charges 26
`causes the formation of perforating jets from the shaped
`charges 26 to extend openings into the surrounding casing 10
`and to extend perforation tunnels into the surrounding forma-
`tion 14.
`
`FIG. 1B shows another embodiment of the perforating
`string, which includes a firing head 30 and a perforating gun
`32. The perforating gun 32 also includes multiple shaped
`charges 34. However, instead of the shaped charges 34 being
`connected to a detonating cord, each shaped charge 34 is
`associated with a respective local detonator assembly 36. In
`one embodiment, each of the detonator assemblies 36
`includes EFI detonator assemblies that are configured simi-
`larly to the detonator assembly 22 of FIG. 1A. The detonator
`assemblies 36 are connected by an electrical cable 38, which
`provides an electrical signal to the detonator assemblies 36 to
`activate such detonator assemblies. The firing head 30
`receives a remote command from elsewhere in the wellbore
`16 or from the surface of the wellbore.
`
`A benefit offered by the perforating string ofFIG. 1B is that
`the shaped charges 34 can be substantially simultaneously
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`detonated in response to an activating signal or voltage sup-
`plied down the electrical cable 38, or fired in any desired
`sequence or with any desired delay. This is contrasted to the
`arrangement of FIG. 1A, where detonation of successive
`shaped charges 26 is delayed by the speed of a detonation
`wave traveling down the detonating cord 24.
`Although the arrangement of FIG. 1B includes multiple
`detonating assemblies 36, as compared to the single detonator
`assembly 22 in the arrangement of FIG. 1A, the small size of
`the detonating assemblies 36 according to some embodi-
`ments allows such detonating assemblies to be included in the
`perforating gun 32 without substantially increasing the size of
`the perforating gun 32.
`As noted above, in one embodiment, an electrical signal is
`provided to the firing head 22 or 30 to activate the perforating
`gun 20 or 32. However, in alternative embodiments, the acti-
`vating signal can be in the form of pressure pulse signals,
`hydraulic pressure, motion signals transmitted down the car-
`rier line 12, and so forth.
`Instead of perforating strings, detonator assemblies
`according to some embodiments can be used in other types of
`tool strings. Examples of other tool strings that contain explo-
`sives include the following: pipe cutters, setting devices, and
`so forth. Also, detonator assemblies according to some
`embodiments can also be used for other applications, such as
`seismic applications, mining applications, demolition, or
`military armament applications. In seismic applications, the
`detonator assemblies are ballistically connected to explosives
`used to generate sound waves into the earth sub-surface for
`determining various characteristics of the earths sub-surface.
`As noted above, in one embodiment, the detonator assem-
`bly 22 includes an EFI detonator assembly. EFIs include an
`exploding foil “flyer plate” initiator or an exploding foil
`“bubble activated” initiator. Other types of detonator assem-
`blies can use other types of electrical initiators, such as
`exploding bridge wire (EBW) initiators and semiconductor
`bridge (SCB) initiators.
`As shown in FIG. 2, an electrical schematic diagram of one
`embodiment of a detonator assembly 100. The detonator
`assembly 100 can be either the detonator assembly 22 of FIG.
`1A or the detonator assembly 36 of FIG. 1B. The detonator
`assembly 100 includes a capacitor discharge unit (CDU) 102,
`an EFI 104, and a high explosive (HE) 106.
`The CDU 102 includes a capacitor 108, a charging resistor
`110, and a bleed resistor 112. In addition, the CDU 102
`includes a switch 114 for coupling charge stored in the
`capacitor 108 to the EFI 104 to activate the EFI 104. When
`activated, the EFI 104 produces a flyer that is propelled at
`usually hyper-sonic velocity and traverses a gap 116 to impact
`the high explosive 106. In some embodiments, the flyer may
`be fabricated from a metal-foil or polymer-foil material. The
`impact of the flyer against the high explosive 106 causes
`detonation of the explosive 106. The explosive 106 is ballis-
`tically coupled to either the detonating cord 24 (FIG. 1A) or
`to an explosive of a shaped charge 34 (FIG. 1B). In some
`embodiments, the internal resistance of the capacitor may be
`sufficient and a separate charging resistance not necessary.
`The capacitor 108 is charged by applying a suitably high
`DC voltage at line 118. The voltage is supplied through the
`charging resistor 110 into the capacitor 108. The charging
`resistor 110 is provided for limiting current (in case of a short
`in the capacitor 108 or elsewhere in the CDU 102). The
`charging resistor 110 also provides isolation of the CDU 102
`from other CDUs in the tool string.
`The bleed resistor 112 allows the charge in the capacitor
`108 to bleed away slowly. This is in case the detonator assem-
`bly 100 is not fired after the tool string has been lowered into
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`Ex. 1021
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`US 8,091,477 B2
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`6
`electrically connected to the electrode 204, while the other
`end 308 of the resistor 110 is electrically connected to a
`contact pad 310. The contact pad 310 allows electrical con-
`nection of charging the resistor 110 with the electrical wire
`210.
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`5
`the wellbore. The bleed resistor 112 prevents the CDU 102
`from becoming a safety hazard when a tool string with un-
`fired detonator assemblies 100 have to be retrieved back to
`well surface.
`In other embodiments, other detonator assemblies with
`other types of energy sources (other than the capacitor 108)
`can be employed.
`The detonator assembly 100 includes an integrated assem-
`bly of the CDU 102 and EFI 104 to provide a smaller deto-
`nator assembly package as well as to improve efficiency in
`performance of the detonator assembly 100. Efficient CDUs
`need to have fast discharge times (such as nanosecond reac-
`tion rates through a low inductance path) through the EFI with
`low energy loss (low resistance). One way to increase the
`efficiency is to reduce as much as possible the inductance (L)
`and resistance (R) of the total circuit in the discharge loop of
`the CDU 102. By integrating the CDU 102 into a smaller
`package,
`the inductance and resistance can be reduced,
`thereby improving the efficiency of the CDU 102.
`the
`According to some embodiment of the invention,
`charging resistor 110 and bleed resistor 112 are implemented
`as resistors formed on a surface ofthe capacitor 108. Further,
`in some embodiments, the switch 114 is also integrated onto
`the surface of the capacitor 108, which further reduces the
`overall size of the CDU 102.
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`The material and geometry (thickness, length, width) of
`each resistor 110 and 112 are selected to achieve a target sheet
`resistance so that desired resistance values of resistors 110
`and 112 can be achieved. In other embodiments, instead of
`thick-film or thin-film resistors, other types of resistors that
`can be deposited, bonded, or otherwise formed on the capaci-
`tor housing can be used.
`To form the resistors on a surface (or surfaces) of the
`capacitor housing, a groove or notch can be formed in the
`outer surface(s) of the capacitor housing, followed by the
`deposition or introduction of resistance material into the
`groove or notch. Alternatively, a resistive material may be
`silk-screened or printed onto the surface(s), or other tech-
`niques may be used.
`FIG. 5 shows a schematic representation ofthe layers ofthe
`capacitor 108. Electrically conductive layers 312 are con-
`nected to the first electrode 204, while electrically conductive
`layers 314 are connected to the electrode 206. In some
`embodiments, the electrically conductive layers 312 and 314
`are formed of a metal, such as copper, silver-palladium alloy,
`or other electrically conductive metal. Dielectric layers are
`FIG. 3 shows the CDU 102 according to one embodiment.
`provided between successive layers 312 and 314.
`The capacitor 108 in one embodiment includes a ceramic
`According to one embodiment, the switch 114 (FIG. 2) is
`capacitor, which has an outer ceramic housing 202 formed of
`a ceramic material. However, in other embodiments, other
`implemented as an over-voltage switch. As shown in FIG. 6,
`one embodiment of the over-voltage switch 114 includes a
`types of capacitors can be used. The capacitor 108 includes a
`first electrically conductive layer 402 and a second electri-
`first group of one or more electrically conductive layers that
`are connected to one electrode, referred to as a cathode. A
`cally conductive layer 406. Interposed between the electri-
`cally conductive layers 402 and 406 is an insulating (dielec-
`second group of one or more electrically conductive layers in
`tric)
`layer 404.
`In one example implementation,
`the
`the capacitor 108 are connected to another electrode of the
`capacitor, referred to as an anode. One or more layers of 35 electrically conductive layers 402 and 406 are formed of
`dielectric material are provided between the cathode and
`copper or other electrically conductive metal. In one example
`anode electrically conductive layers. The cathode layers,
`implementation, the insulating layer 404 is formed of a poly-
`anode layers, and dielectric layers are provided inside the
`imide material.
`outer housing 202 of the capacitor 108. As shown in FIG. 3,
`The insulating layer 404 has a thickness and a doping
`the capacitor 108 has a first electrode 204 and second elec- 40 concentration controlled to cause the switch 114 to activate at
`trode 206. The electrodes 204 and 206 form the cathode and
`a selected voltage difference between electrically conductive
`layers 402 and 406. Once the voltage crosses over some
`predefined threshold level, the insulating layer 404 breaks
`down to electrically connect the first and second electrically
`to anode ofthe charging resistor (not shown in FIG. 3), which 45 conductive layers 402 and 406 (thereby closing the switch
`is formed on the lower surface 212 of the capacitor 108.
`114).
`Further, the EFI 104 is attached on an upper surface 222 of
`Optionally, the breakdown voltage of the insulating layer
`the capacitor 108. One side of the EFI 104 is connected by an
`404 can be controlled by having the geometry of overlapping
`electrically conductive plate 215 to the electrode 206 of the
`electrically conductive layers 402 and 406 be somewhat
`capacitor 108. The other side of the EFI 104 is electrically 50 pointed to increase the potential gradient at the points. Fur-
`connected to an electrically conductive plate 214, which is in
`ther, depositing a hard metal such as tungsten on contact areas
`turn connected to one side ofthe switch 114. The other side of
`of the first and second electrically conductive layers 402 and
`406 can prevent bum-back of the electrically conductive lay-
`ers. The contact areas are provided to electrically connect the
`electrically conductive layers 402 and 406 to respective
`wires. The hardened metal also provides for a more efficient
`switch. Also,
`for increased efficiency,
`the gap distance
`between points is made small, such as on the order of a few
`thousands of an inch.
`
`anode of the capacitor 108.
`The capacitor electrode 206 is electrically contacted to an
`electrical wire 208. Another electrical wire 210 is connected
`
`the switch 114 is electrically connected by another electri-
`cally conductive plate 216 to the capacitor electrode 204.
`Electrical connections are provided by thick-film deposition,
`or other equivalent methods. Any number of types of small
`switches can be used, such as those disclosed in U.S. Pat. No.
`6,385,031 and U.S. Ser. No. 09/946,249, filed Sep. 5, 2001,
`both hereby incorporated by reference. Also, the EFI may
`include an integral switch as part of its construction.
`A bottom view of the CDU 102 is shown in FIG. 4. The
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`bleed resistor 112 and charging resistor 110 are both arranged
`as thick-film or thin-film resistors on the lower surface 212 of
`
`the capacitor 108. One end 302 of the bleed resistor 112 is
`electrically connected to the electrode 204, while the other
`end 304 of the resistor 112 is electrically connected to the
`electrode 206. One end 306 of the charging resistor 110 is
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`FIG. 7 illustrates another type of switch 114. This altema-
`tive switch is a triggered switch that adds another electrically
`conductive layer that is connected to a trigger voltage. As
`shown in FIG. 7, the triggered switch 114 includes top and
`bottom electrically conductive layers 410 and 414, in addition
`to an intermediate electrically conductive layer 412. Insulat-
`ing layers 416 and 418 are provided between successively
`electrically conductive layers. In operation, a high voltage
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`US 8,091,477 B2
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`7
`(reference to ground) with a fast rise time is applied to the
`trigger anode 412. The trigger voltage has sufficient ampli-
`tude to cause the insulating layers 416 and 418 to break down
`to allow conduction between the top and bottom electrically
`conductive layers 410 and 414.
`In other embodiments ofthe detonator ofthe present inven-
`tion, micro-switches may be integrated to form a small, low-
`cost detonator utilizing Exploding Foil Initiator technology.
`For example, in one embodiment, a micro-switchable EFI
`detonator is small enough to fit inside a standard detonator
`housing, thereby simplifying logistics and packaging, easing
`assembly, and improving overall reliability while replacing
`the less safe hot-wire detonator. A “micro-switch” may be
`used as disclosed in US. Ser. No. 10/708,182, filed Feb. 13,
`2004, which is hereby incorporated by reference. Such a
`micro-switch may include, but is not limited to, a microelec-
`tromechanical system (MEMS) switch, a switch made with
`microelectronic techniques similar to those used to fabricate
`integrated circuit devices, a bistable microelectromechanical
`switch, a spark gap switch, a switch having nanotube electron
`emitters (e.g., carbon nanotubes), a metal oxide silicon field-
`effect transistor (MOSFET), an insulated gate field-effect
`transistor (IGFET), and other micro-switching devices.
`With respect to FIGS. 8A and 8B, in general, an embodi-
`ment ofthe present invention may include a small, monolithic
`detonator 800 with all components integrated into a single
`unit. The components may include, but are not limited to: an
`integrated capacitor discharge unit 808 including a charging
`resistor and bleeder resistor that are fused or bonded together
`with a micro-switch and an initiator (e.g., an EFI, EBW, SCB,
`hot-wire, or other initiator), an initiating explosive 806, a
`conventional explosive 804 (e.g., PETN, RDX, HMX,
`CL-20, HNS, NONA and/or other explosive), a step-up trans-
`former 810 for receiving a low voltage input and stepping up
`to a high voltage output, and an addressable chip 812. In
`another embodiment, a microchip may be employed for ease
`of design. The resultant size ofthe integrated detonator 800 is
`small enough to be packaged inside a standard detonator
`housing 802 and may receive power via a standard plug 814.
`An embodiment of the detonator 800 has a size and shape
`substantially equal to that of a standard cylindrical hot-wire
`detonator. For example, some standard hot-wire detonators
`have a cross-sectional diameter ofapproximately 0.28 inches.
`In another example, an embodiment ofthe detonator 800 may
`have the same diameter as the detonating cord 24 (FIG. 1A) to
`which the detonator is coupled. This relatively small-sized
`detonator may be desirable over large-sized prior art detona-
`tors, which generally consist of a bulky capacitor discharge
`unit (CDU) (inclu