U.S. patent application number 11/308515 was filed with the patent office on 2012-07-19 for seismic explosive system.
This patent application is currently assigned to SCHLUMBERGER TECHNOLOGY CORPORATION. Invention is credited to Philip Kneisl.
Application Number | 20120180678 11/308515 |
Document ID | / |
Family ID | 37965696 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120180678 |
Kind Code |
A1 |
Kneisl; Philip |
July 19, 2012 |
Seismic Explosive System
Abstract
An explosive package is provided for use in seismic exploration
which comprises a seismic charge and an addressable switch for
selecting that seismic charge for detonation. A fireset is
operatively coupled to the addressable switch for receiving a
firing voltage via the addressable switch and for producing an
actuation voltage. The actuation voltage may, for example be
produced by increasing the magnitude of the firing voltage. The
actuation voltage is provided to a Detonating Device, which is a
device that contains secondary explosives. Examples of a Detonating
Device include an exploding bridge wire detonator, an exploding
foil initiator detonator and a semiconductor bridge slapper device.
Such explosive packages may be arranged in a system for use in
seismic exploration which comprises a base unit for providing
selection, firing and trigger signals and a plurality of explosive
packages that are located at spaced intervals along the earth's
surface.
Inventors: |
Kneisl; Philip; (Pearland,
TX) |
Assignee: |
SCHLUMBERGER TECHNOLOGY
CORPORATION
Sugar Land
TX
|
Family ID: |
37965696 |
Appl. No.: |
11/308515 |
Filed: |
March 31, 2006 |
Current U.S.
Class: |
102/202.7 ;
102/202.5; 102/215 |
Current CPC
Class: |
F42D 1/055 20130101 |
Class at
Publication: |
102/202.7 ;
102/215; 102/202.5 |
International
Class: |
F42B 3/12 20060101
F42B003/12; F42B 3/10 20060101 F42B003/10; F23Q 21/00 20060101
F23Q021/00 |
Claims
1. An explosive package for use in seismic exploration that
requires a first arming signal, a second arming signal, and a
firing signal to be detonated, comprising: a seismic charge; an
addressable switch that receives the first arming signal and the
second arming signal, the addressable switch being responsive to
the first arming signal, the first arming signal being for use in
selecting the seismic charge for detonation, the second arming
signal being passed on to a fireset based on a response of the
addressable switch to the first arming signal; the fireset being
responsive to the second arming signal and being operatively
coupled to the addressable switch for receiving a firing signal via
the addressable switch and for producing an actuation voltage at
its output based on the firing signal; and a Detonating Device
which is operatively coupled to the output of the fireset for
detonating the seismic charge upon presentation of the actuation
voltage to the Detonating Device.
2. The explosive package of claim 1, wherein the Detonating Device
is selected from the group consisting of exploding bridge wire
detonators, exploding foil initiator detonators and semiconductor
bridge slapper detonators.
3. The explosive package of claim 1, wherein the fireset comprises
circuitry for increasing the magnitude of the firing signal to
produce the actuation voltage.
4. A system for use in seismic exploration, comprising: a plurality
of explosive packages wherein each said explosive package requires
a first arming signal, a second arming signal, and a firing signal
to be detonated wherein each said package comprises: a seismic
charge; an addressable switch which receives the first arming
signal and the second arming signal, the addressable switch being
responsive to the first arming signal and being operatively coupled
to said seismic charge, the second arming signal being passed on to
the fireset based on a response of the addressable switch to the
first arming signal; a fireset which is responsive to the second
arming signal and which is operatively coupled to the addressable
switch for receiving a firing signal via the addressable switch and
for producing an actuation voltage at is output based on the firing
signal; and a Detonating Device which is operatively coupled to the
output of the fireset for detonating the seismic charge upon
presentation of the actuation voltage to the Detonating Device.
5. The system of claim 4, wherein: the Detonating Device is
selected from the group consisting of exploding bridge wire
detonators, exploding foil initiator detonators, and semiconductor
bridge slapper detonators.
6. The system of claim 4, wherein: the fireset comprises circuitry
for increasing the magnitude of the firing signal to produce the
actuating voltage.
7. A system for use in seismic exploration, comprising: a) a base
unit comprising a computer and a power supply for providing
selection signals, firing signals and trigger signals; b) a
plurality of explosive packages located at spaced locations along
the earth's surface, which each explosive package requires a first
arming signal, a second arming signal, and a firing signal to be
detonated and wherein each explosive package comprises: (i) a
seismic charge; (ii) an addressable switch which is responsive to
the first arming signal, the addressable switch passing the second
arming signal on to a fireset based on a response of the
addressable switch to the first arming signal; (iii) the fireset
which receives the second arming signal from the base unit via the
selected addressable switch and which produces an actuation signal
at its output; and (iv) a Detonating Device which is operatively
coupled between the output of the fireset and the seismic charge
for receiving the actuation signal and for detonating the seismic
charge upon receipt of said actuation signal.
8. The system of claim 7, wherein the Detonating Device is selected
from the group consisting of exploding bridge wire detonators,
exploding foil initiator detonators, and semiconductor bridge
slapper detonators.
9. (canceled)
10. A method of detonating a particular one of a plurality of
explosive packages where each said explosive packages includes a
charge, comprising: (a) selecting the particular explosive package;
(b) providing a firing signal with an initial voltage to the
selected explosive package, the initial voltage of the firing
signal being insufficient to cause detonation of the charge in the
selected explosive package; and (c) increasing the amplitude of the
firing signal to a level sufficient to detonate the charge in the
selected explosive package.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an explosive system for
seismic charges which is safe from detonation by radio frequency
(RF) signals and electrostatic discharge (ESD).
[0003] 2. Description of the Prior Art
[0004] The current art of explosive seismic exploration relies on
fast-acting electric detonators that typically function in less
than 1 millisecond, and up to 1,000 detonators may be fired
essentially simultaneously by a relatively low-voltage capacitor
discharge. Because of their fast action, seismic electric
detonators rely on a very sensitive primary explosive like lead
styphnate, lead azide and diazodinitrophenol (DDNP). These seismic
electric detonators can never be considered totally safe because
they may be actuated by electrostatic discharge or stray voltage
and are also susceptible to actuation by stray current and distant
lightning strikes.
[0005] Accordingly, for safety reasons, seismic charges are
currently shipped from the factory without detonators, and the
detonators and charges are assembled and combined in the field. Of
course, assembly of the charges and detonators in the field
presents safety problems since RF signals and electrostatic
discharge can cause detonation as the charges are being
field-assembled.
[0006] An example of an exploding bridge wire (EBW) detonator is
illustrated in U.S. Pat. No. 4,777,878. An EBW detonator may, for
example, employ a two electrode arrangement in the detonator and
have an exploding bridge conductor between the two electrodes. The
exploding bridge is located at one end of a column of explosive
material used in the device. Within the column of explosive and
spaced a distance away from the exploding bridge portion of the
detonator is a shock reflector element on an inert but relatively
dense material having a high shockwave impedance. The cooperative
action of the exploding bridge and the shock reflector intensifies
the shockwave propagated through the explosive and causes a
detonation because of this intensification.
[0007] Exploding foil initiator (EFI) detonators have also been
available, and one such detonator is illustrated in U.S. Pat. No.
6,752,083, which is owned by the assignee of the present
application. An EFI detonator includes an electrically conductive
metal foil which is connected to a source of current. The metal
foil includes a narrow neck section that explodes or vaporizes when
a high current is discharged quickly through the neck section. The
exploding neck section of the foil shears a small flier from a disk
that is disposed in contact with the foil. The flier travels or
flies through a barrel to impact a secondary explosive, e.g.,
dynamite, to initiate a detonation.
[0008] Because EBW and EFI detonators contain only secondary
explosives (e.g. HNS, Nona, and RDX), and require very high power
to function, they are known to offer safety against electrostatic
discharge, stray current and even lightening strike hazards. These
detonators also have extremely short function times that meet or
surpass the standard seismic requirement of less than 1
millisecond. The disadvantage of this technology is the requirement
of very high voltages, e.g., over one thousand volts, and extremely
high currents, usually over one thousand amps to activate these
devices. The required voltage and current need only be applied for
a very short period of time, e.g., 1-2 microseconds and is
typically accomplished by the discharge of a high-voltage capacitor
into a low-inductance firing circuit.
[0009] A new technology which can operate at lower voltages and
currents but still provide very good safety is to use semiconductor
bridges (SCB) in place of the metal foil bridge of the EFI. SCB's
can be used in two ways. They can be placed in direct contact with
sensitive pyrotechnic and primary explosives in which case their
use offers only a slight improvement over typical hot-wire
low-voltage detonators because they are still susceptible to stray
voltages, currents and ESD. However, the SCB can also be used to
replace the metal foil bridge in a slapper type detonator. When
used this way with only secondary explosives the resulting
detonator is ESD safe. When an SCB slapper detonator is also
coupled to an addressable switch, then the whole assembly becomes
safe from stray voltages and currents and ESD.
[0010] Addressable switch technology has been commercially
available in the mining and blasting industry for several years.
Each of these systems incorporate an addressable switch to isolate
the firing circuit of the detonator from the lead wire input until
the detonator has been properly addressed and then armed. All
systems capable of firing multiple detonators also have built in
firing circuit diagnostic capability allowing the identification of
detonators that are not properly attached to the firing
circuit.
[0011] The U.S. Department of Defense and the U.S. Department of
Transportation consider it unsafe to transport or store explosive
charges which have been assembled with initiation systems without
additional safety precautions. Initiation systems that rely on
primary explosives must have a shutter that physically isolates the
primary explosive from the rest of the explosive train so that even
if the primary explosive accidentally detonates it will not
initiate the main charge. It is also required that these shutter
devices require two independent signals or actions to arm, i.e. to
couple the primary explosive component to the initiation circuit.
If a an explosive device containing primary explosive in its
initiation chain has such a shutter requiring two independent
signals to arm and another independent signal to fire, then such a
device is considered safe to transport and store with its
initiation system installed. For initiation systems that do not
contain primary explosives it is not required to have a physical
barrier, shutter, that interrupts the initiation chain. Rather in
these systems it is acceptable to require just two independent
signals to arm the device and a third signal to fire the device.
These signals can be mechanical or electrical. A further
restriction on such non-primary systems is that at signal of at
least 500 volts is required to fire the device.
SUMMARY OF THE INVENTION
[0012] In accordance with the present invention, a seismic
explosive package is provided which comprises a seismic charge, and
an addressable switch for use in selecting that seismic charge for
detonation. A seismic explosive package according to the present
invention further comprises a fireset which is interposed between
the addressable switch and the seismic charge. The fireset is for
receiving a firing voltage via the addressable switch and for using
the firing voltage to produce an actuation voltage. In one
embodiment, the actuation voltage may be formed by increasing the
magnitude of the firing voltage, and the fireset may, for example,
comprise a voltage multiplier for increasing the magnitude of the
firing voltage. A seismic explosive package according to the
present invention further comprises a Detonating Device, which
comprises a secondary explosive. The Detonating Device may, for
example, may be either an EBW detonator, an EFI detonator or a
Semiconductor Bridge (SCB) Slapper Detonator, which is interposed
between the fireset and the seismic charge. The actuation voltage
from the fireset is sufficient to cause the Detonating Device to
detonate, which in turn detonates the seismic charge.
[0013] In accordance with the present invention, a system for
detonating seismic explosives is provided which comprises a
plurality of explosive devices, as described above. The plurality
of explosive devices may be deployed in desired patterns at spaced
intervals at or near the earth's surface, and a system according to
the present invention may further comprise a base unit having a
computer and a power supply for providing selection, firing and
trigger signals to the plurality of explosive devices. The base
unit selects an explosive device for detonation by providing a
selection signal to the addressable switch associated with that
explosive device. The base unit also provides the firing signal via
the addressable switch to the fireset in the selected explosive
device. When a trigger signal is received from the base unit by the
fireset, the actuation voltage is presented to the Detonating
Device. This actuation voltage causes detonation of the Detonating
Device which in turn causes detonation of the seismic charge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In the accompanying drawings:
[0015] FIG. 1 is a pictorial drawing illustrating a system for use
in seismic exploration in accordance with the present
invention.
[0016] FIG. 2 is a schematic diagram in partial block diagram form
illustrating an explosive device in accordance with the present
invention for use in seismic exploration.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0017] It will be appreciated that the present invention may take
many forms and embodiments. In the following description, some
embodiments of the invention are described and numerous details are
set forth to provide an understanding of the present invention.
Those skilled in the art will appreciate, however, that the present
invention may be practiced without those details and that numerous
variations and modifications from the described embodiments may be
possible. The following description is thus intended to illustrate
and not to limit the present invention.
[0018] In this specification and the appended claims: (a) the term
"Detonating Device" means a device which contains only secondary
explosives and which when detonated causes a seismic charge to
detonate. Examples of a Detonating Device include EBWs, EFIs and
SBC slapper detonators; and (b) two items are "operative coupled"
if they are directly connected or connected through an intermediate
device.
[0019] With reference first to FIG. 1, there is illustrated a
system 100 in accordance with the present invention for use in
seismic exploration. System 100 comprises base unit 102 which
includes a computer and a power supply for providing selection,
firing and trigger signals to explosive packages 101(1), 101(2) . .
. 101(n), where n represents the number of explosive packages that
are arranged in a predetermined pattern at or near the earth's
surface. Each of the explosive devices 101(1), 101(2), . . . 101(n)
are constructed as illustrated in FIG. 2 and described below. Base
unit 102 utilizes the computer therein to generate a selection
signal or signals to select which explosive package 101(i) will be
detonated. Following selection of the explosive package 101(i) to
be detonated, base unit 102 generates a firing signal which is
received by the selected explosive device 101(i). The receipt of a
trigger signal by the selected explosive device causes seismic
charge in the selected explosive device to be detonated.
[0020] Referring now to FIG. 1 and 2, the structure and operation
of each explosive package 101(i) for i=1, 2, . . . n of FIG. 1 is
illustrated. Explosive package 101(i) comprises seismic charge 204
which may, for example, be dynamite. Explosive package 101(i) also
comprises addressable switch 201 which, when selected by the
selection signals from base unit, permits a firing signal to be
presented to fireset 202 which is operatively coupled to the
addressable switch 201. The output of fireset package 102 is
operatively coupled to Detonating Device 203, which in turn is
coupled to seismic charge 204.
[0021] In operation, explosive package 101(i) is coupled to base
unit 102 by appropriate cabling 103, and base unit 102 provides
selection, firing and trigger signals to explosive package 101(i)
via cabling 103. A selection signal is first provided which selects
the addressable switch associated with seismic charge 204 in
explosive package 101(i) for detonation. Thereafter, a firing
signal is provided by base unit 102 and this firing signal may, for
example, be a voltage between 300 and 500 volts. Addressable switch
201, which has been selected, allows the firing voltage to be
presented to fireset 202 which uses the firing voltage to charge a
capacitor to produce an actuation voltage. The fireset may, for
example, also comprise circuitry for increasing the magnitude of
the firing voltage from base unit 102 to produce the actuation
voltage. This increase in firing voltage may, for example, be
necessary when the Detonating Device is an EBW or EEI detonator and
may be accomplished by using a voltage multiplier circuit in
fireset 202. Such voltage multiplier circuitry is well known to
those skilled in the art. The output of fireset 202 is operatively
coupled to the input of Detonating Device 203, and when base unit
102 provides a trigger signal to the selected explosive device, the
actuation voltage, which is present at the output of fireset 202,
is presented to Detonating Device 203. Detonating Device is thus
detonated which in turn detonates seismic charge 204.
[0022] An explosive package 101(i) which is made in accordance with
the present invention has an advantage over the prior art in that
all explosive devices for use in a particular seismic operation may
be assembled in a factory as opposed to being assembled in the
field. Factory assembly of explosive package 101(i) should not only
be cheaper, but also safer than the field assembly of seismic
charges which is currently practiced.
[0023] An explosive package in accordance with the present
invention may also be safely transported and stored while assembled
with its own circuitry for initiation; which is of great advantage
to the seismic exploration industry. Such devices have not
previously been used or available to the seismic exploration
community and are possible only by coupling several dissimilar
technologies together to form a new invention. This invention
couples direct initiation of secondary explosive via EBW, EFI or
SCB Slapper technology with the use of addressable switch
technology and a seismic charge to create a seismic explosive
system with an initiation train requiring two independent arming
signals, and an independent firing signal, and an initiator
(detonator) that requires more than 500 volts to function. Such a
system is safe from accidental initiation due to commonly
encountered stray voltages, currents, electrostatic discharge and
simple human errors.
[0024] It will be appreciated by those skilled in the art that the
explosive devices 101(1), 101(2), . . . 101(n) may be arranged in
any pattern which the user deems appropriate for the seismic
exploration task at hand. A plurality of the explosive devices may,
for example, be arranged in series with one another and the series
connection of explosive devices may be arranged in parallel with
one another. It will also be appreciated by those skilled in the
art that the present inventive concept may be used in a detonator
package for downhole operation, e.g, for detonating a perforating
gun, jet cutter, propellant or other downhole device.
* * * * *