U.S. patent application number 13/332112 was filed with the patent office on 2013-01-17 for novel device and methods for firing perforating guns.
This patent application is currently assigned to Owen Oil Tools LP. The applicant listed for this patent is Lyle W. Andrich, John A. Barton, Timothy Edward LaGrange. Invention is credited to Lyle W. Andrich, John A. Barton, Timothy Edward LaGrange.
Application Number | 20130014990 13/332112 |
Document ID | / |
Family ID | 42665948 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130014990 |
Kind Code |
A1 |
Barton; John A. ; et
al. |
January 17, 2013 |
Novel Device and Methods for Firing Perforating Guns
Abstract
A perforating gun train for perforating two or more zones of
interest includes two or more gun sets made up of guns, one or more
activators, and other associated equipment. An illustrative
apparatus may include a first perforating gun; an activator
responsive to the firing of the first perforating gun and a fuse
element detonated by the activator; and a second perforating gun
that is fired by the fuse element. An illustrative method for
perforating a subterranean formation may include forming a
perforating gun train using at least a first perforating gun and a
second perforating gun; and energetically coupling the first
perforating gun and the second perforating gun with an
activator.
Inventors: |
Barton; John A.; (Arlington,
TX) ; Andrich; Lyle W.; (Grandview, TX) ;
LaGrange; Timothy Edward; (Rainbow, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Barton; John A.
Andrich; Lyle W.
LaGrange; Timothy Edward |
Arlington
Grandview
Rainbow |
TX
TX
TX |
US
US
US |
|
|
Assignee: |
Owen Oil Tools LP
Houston
TX
|
Family ID: |
42665948 |
Appl. No.: |
13/332112 |
Filed: |
December 20, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12393862 |
Feb 26, 2009 |
8079296 |
|
|
13332112 |
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|
11069600 |
Mar 1, 2005 |
7913603 |
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12393862 |
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Current U.S.
Class: |
175/2 |
Current CPC
Class: |
F42D 1/043 20130101;
E21B 43/1185 20130101; E21B 43/11852 20130101 |
Class at
Publication: |
175/2 |
International
Class: |
E21B 43/1185 20060101
E21B043/1185; E21B 43/116 20060101 E21B043/116 |
Claims
1. An apparatus for perforating a subterranean formation,
comprising: a first perforating gun that is configured to perforate
the subterranean formation; an activator responsive to the firing
of the first perforating gun; a fuse element detonated by the
activator; a second perforating gun that is configured to perforate
the subterranean formation, the second perforating gun having a
detonator activated by the fuse element.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/393,862 filed Feb. 26, 2009, now U.S. Pat.
No. 8,079,296 issued Dec. 20, 2011 which is a continuation in part
of U.S. patent application Ser. No. 11/069,600, filed on Mar. 1,
2005, now U.S. Pat. No. 7,913,603 issued Mar. 29, 2011, all of
which are incorporated herein by reference in their entirety.
BACKGROUND OF THE DISCLOSURE
[0002] 1. Field of the Disclosure
[0003] The present disclosure relates to devices and methods for
selective actuation of wellbore tools. More particularly, the
present disclosure is in the field of control devices and methods
for selective firing of a gun assembly.
[0004] 2. Description of the Related Art
[0005] Hydrocarbons, such as oil and gas, are produced from cased
wellbores intersecting one or more hydrocarbon reservoirs in a
formation. These hydrocarbons flow into the wellbore through
perforations in the cased wellbore. Perforations are usually made
using a perforating gun loaded with shaped charges. The gun is
lowered into the wellbore on electric wireline, slickline, tubing,
coiled tubing, or other conveyance device until it is adjacent the
hydrocarbon producing formation. Thereafter, a surface signal
actuates a firing head associated with the perforating gun, which
then detonates the shaped charges. Projectiles or jets formed by
the explosion of the shaped charges penetrate the casing to thereby
allow formation fluids to flow through the perforations and into a
production string. In wells that have long or substantial gaps
between zones, an operator must consider the efficiency and cost of
perforating the zones. The zones can be perforated separately via
multiple trips into the well, which requires running the work
string in and out of the well for each zone to be perforated. This
increases rig and personnel time and can be costly.
[0006] These conventional firing systems for various reasons, such
as capacity, reliability, cost, and complexity, have proven
inadequate for these and other applications. The present disclosure
addresses these and other drawbacks of the prior art.
SUMMARY OF THE DISCLOSURE
[0007] In aspects, the present disclosure provides an apparatus for
perforating a subterranean formation. The apparatus may include a
first perforating gun; an activator responsive to the firing of the
first perforating gun and a fuse element detonated by the
activator; and a second perforating gun having a detonator
activated by the fuse element. In arrangements, a first detonator
cord may explosively couple the first perforating gun to the
activator. Also, in embodiments, the activator may include an
energetic material, a pin positioned adjacent to the energetic
material, and an igniter positioned adjacent to the pin. A shock
wave generated by the energetic material may propel the pin into
the igniter. In such embodiments, the igniter may include an
energetic material that detonates the fuse element. In further
arrangements, the apparatus may include a second detonator cord
explosively coupled to the second perforating gun; and a detonator
energetically coupling the second detonator cord to the fuse
element. Also, the apparatus may include a housing that receives
the firing pin and a frangible element that connects the firing pin
to the housing. The frangible element may break in response to the
shock wave generated by the energetic material. In arrangements,
the fuse element may deflagrate. In applications, a second
detonator cord associated with the second perforating gun may be
explosively coupled to the fuse element.
[0008] In aspects, the present disclosure also provides a
perforating apparatus that may include a first perforating gun that
has a pressure activated firing head; an activator that may include
a firing head responsive to the detonation of the first perforating
gun and an igniter detonated by the firing head; and a fuse element
including an energetic material, the fuse element energetically
coupled to and detonated by the igniter; and a second perforating
gun having a detonator activated by the fuse element. The apparatus
may also include a detonator cord and a booster element that
energetically couple the first perforating gun to the activator.
Further, the apparatus may include a second detonator cord and a
second booster element that energetically couple the fuse element
to the second perforating gun.
[0009] In aspects, the present disclosure also provides a method
for perforating a subterranean formation. The method may include
forming a perforating gun train using at least a first perforating
gun and a second perforating gun that has a detonator;
energetically coupling the first perforating gun and the second
perforating gun; firing the first perforating gun; and firing the
second perforating gun. The energetic coupling may include an
activator responsive to the firing of the first perforating gun;
and a fuse element detonated by the activator. The fuse element may
activate the detonator of the second perforating gun. The method
may further include conveying the perforating gun train into a
wellbore formed in the subterranean formation. In certain
deployments, the method may involve firing the first perforating,
wherein the firing of the first perforating gun initiates the
firing of the second perforating gun.
[0010] In aspects, the present disclosure further provides a
perforating method that may include forming a perforating gun train
using a first perforating gun and a second perforating gun; and
energetically coupling the first perforating gun and the second
perforating gun using an activator and a fuse element. The
activator may include a firing head responsive to the detonation of
the first perforating gun; and an igniter configured to be
detonated by the firing head. The fuse element may include an
energetic material that is energetically coupled to and detonated
by the igniter.
[0011] It should be understood that examples of the more important
features of the disclosure have been summarized rather broadly in
order that detailed description thereof that follows may be better
understood, and in order that the contributions to the art may be
appreciated. There are, of course, additional features of the
disclosure that will be described hereinafter and which will form
the subject of the claims appended hereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For detailed understanding of the present disclosure,
references should be made to the following detailed description of
the preferred embodiment, taken in conjunction with the
accompanying drawings, in which like elements have been given like
numerals and wherein:
[0013] FIG. 1 schematically illustrates a deployment of a
perforating gun train utilizing one embodiment of the present
disclosure;
[0014] FIG. 2A schematically illustrates one embodiment of the
present disclosure that is adapted to selectively permit
transmission of signals to a downhole tool;
[0015] FIG. 2B schematically illustrates an embodiment of the
present disclosure that is adapted to selectively permit
transmission of signals to a downhole tool using a time delay;
[0016] FIG. 3 schematically illustrates a firing system according
to one embodiment of the present disclosure;
[0017] FIG. 4 schematically illustrates further details of the FIG.
3 embodiment; and
[0018] FIG. 5 schematically illustrates another firing system
according to one embodiment of the present disclosure.
DESCRIPTION OF THE DISCLOSURE
[0019] The present disclosure relates to devices and methods for
firing two or more downhole tools. The present disclosure is
susceptible to embodiments of different forms. There are shown in
the drawings, and herein will be described in detail, specific
embodiments of the present disclosure with the understanding that
the present disclosure is to be considered an exemplification of
the principles of the disclosure, and is not intended to limit the
disclosure to that illustrated and described herein.
[0020] Referring initially to FIG. 1, there is shown a well
construction and/or hydrocarbon production facility 30 positioned
over subterranean formations of interest 32, 34 separated by a gap
section 36. The teachings of the present disclosure, however, may
be applied to any type of subsurface formation. The facility 30 can
be a land-based or offshore rig adapted to drill, complete, or
service a wellbore 38. The wellbore 38 can include a wellbore fluid
WF that is made up of formation fluids such as water or
hydrocarbons and/or man-made fluids such as drilling fluids. The
facility 30 can include known equipment and structures such as a
platform 40 at the earth's surface 42, a wellhead 44, and casing
46. A work string 48 suspended within the well bore 38 is used to
convey tooling into and out of the wellbore 38. The work string 48
can include coiled tubing 50 injected by a coiled tubing injector
52. Other work strings can include tubing, drill pipe, wire line,
slick line, or any other known conveyance means. The work string 48
can include telemetry lines or other signal/power transmission
mediums that establish one-way or two-way telemetric communication
from the surface to a tool connected to an end of the work string
48. A suitable telemetry system (not shown) can be known types as
mud pulse, electrical signals, acoustic, or other suitable systems.
A surface control unit (e.g., a power source and/or firing panel)
54 can be used to monitor and/or operate tooling connected to the
work string 48.
[0021] In one embodiment of the present disclosure, a perforating
gun train 60 is coupled to an end of the work string 48. An
exemplary gun train includes a plurality of guns or gun sets 62a-c,
each of which includes perforating shaped charges 64a-c, and
detonators or firing heads 66a-c. To control the time delay between
successive firings, the guns 62a-c are operatively connected to one
another by an activator 68. Other equipment associated with the gun
train 60 includes a bottom sub 51, a top sub 53, and an accessories
package 55 that may carry equipment such as a casing collar
locator, formation sampling tools, casing evaluation tools, etc.
Tubular members such as subs may be used to physically or
structurally interconnect the guns 62a-c. It should be understood
that more than the perforating gun train 60 can include two or more
guns. Also, while a `top-down` firing sequence is described, it
should be understood that a `bottom-up` sequence may also be
utilized. That is, instead of the top most gun being fired first
with the lower guns sequentially firing, the bottom most gun may be
fired with the upper guns sequentially firing.
[0022] Referring now to FIG. 2A, the energy released by the gun 62a
can also be used to indirectly initiate a firing sequence for gun
62b. In FIG. 2A, an activator 80 is used to initiate the firing
sequence for gun 62b while the energy released by the gun 62a is
used to actuate the activator 80. The activator 80 can be actuated
explosively, mechanically, electrically, chemically or other
suitable method. For example, the energy release may include a high
detonation component that detonates material in the activator 80, a
pressure component that moves mechanical devices in the activator
80, or a vibration component that jars or disintegrates structural
elements in the activator 80. When actuated, the activator 80
transmits an activation signal, such as a pressure change,
electrical signal, or projectile, to the firing head 66b of the gun
62b. The type of activation signal will depend on the configuration
of the firing head 66b, i.e., whether it has pressure sensitive
sensors, a mechanically actuated pin, electrically actuated
contact, etc.
[0023] In certain embodiments, the tubular connector may be omitted
and the activator may utilize operational features such as a time
delay. Referring now to FIG. 2B, there is shown in functional block
diagram format another embodiment of an activator 68 that may be
used to initiate the firing of and/or control one or more
characteristics of a firing sequence for the guns 62a-c. The
activator 68 may include an internally activated initiator 70 and a
time delay mechanism 72. An externally activated firing head 74 may
be used to fire the first perforating gun 62a. By "externally
activated" firing head, it is meant that a signal or condition
external to or not associated with the perforating guns 62a-c
actuates the initiator. Such signals or conditions include, but are
not limited to, a surface transmitted signal, a "drop bar,"
wellbore conditions such as pressure and/or temperature (e.g., a
firing device actuated upon detection of one or more specified
wellbore conditions), time (e.g., a firing head coupled to a
timer), etc. The activator 68 may be constructed to initiate the
firing sequence for gun 62b in response to the firing of the gun
62a. The internally activated initiator 70 may be triggered
explosively, mechanically, electrically, chemically or other
suitable method. The time delay mechanism 72 may be constructed to
control the time interval between the firing of the gun 62a and
62b. As noted above, in configurations where the perforating gun 60
includes a third gun 62c, a second firing control device 100 may be
inserted between the second gun 62b and the third gun 62c. Of
course, a similar arrangement may be used to add four or more
guns.
[0024] Referring now to FIG. 3, there is shown further details of
an activator that, for convenience, will be referred to as a firing
control device 100. In one embodiment, the firing control device
100 includes an initiator 102 and a time delay 104. The initiator
102 may include an explosive booster charge 106 that is
energetically coupled to a detonator cord 108 associated with an
immediately adjacent perforating gun 62a, a firing pin housing 110
that receives a firing pin 112, and an igniter assembly 114. These
components may be positioned within a housing 116. The booster
charge 106 may include an energetic material that, when detonated,
generates a shock wave or pressure pulse that is applied to the
firing pin 112. In arrangements, a retainer 118 may be used to
house and retain the booster charge 106. The retainer 118 may also
contain the energy released by the booster charge 106 in a manner
that protects or shields the housing 110 from the detonation. The
firing pin housing 110 includes a bore 120 in which the firing pin
112 translates. The housing 110 may also be configured to protect
the housing 116 from detonation effects associated with the firing
of the perforating gun 62a and booster charge 106. A portion of the
booster charge 106 may be retained in an end cap 124.
[0025] In one embodiment, the firing pin 112 may be calibrated to
maintain structural integrity when exposed to a base line or normal
operating pressure and break when subjected to a shock associated
with a firing of the booster charge 106. As best seen in FIG. 4, in
one arrangement, the firing pin 112 may include a protrusion 126
that seats within a recess 128. For example, the protrusion 126 may
be formed as a flange that rests inside a machined groove. The
protrusion 126 may be coupled or attached to a body 130 of the pin
112 with a tube 132 or other frangible element that breaks when
subjected to a force or stress of a predetermined magnitude. When
released from the protrusion 126, the firing pin body 130 is
propelled by the detonation force of the booster charge 106 into
and against the igniter assembly 114 with sufficient force to cause
the igniter assembly 114 to detonate. The igniter assembly 114
includes an energetic material that is capable of igniting the time
delay mechanism 104 (FIG. 3). Additionally, seals 140 may be
utilized to provide a liquid-tight, gas-tight, or fluid-tight,
environment for the booster charge 106, the firing pin 112 and the
igniter assembly 114.
[0026] In embodiments, the time delay mechanism 104 may include a
housing 142 and one or more fuse(s) element 144 that is/are
energetically coupled to a detonator 150 of an adjacent gun (e.g.,
gun 62c). In embodiments, a time delay mechanism adjusts or
controls the time needed for the energy train to travel to the
detonator 150 for the gun 62b. By adjustable or controllable, it is
meant that the time delay mechanism 104 can be configured to
increase or decrease the time between the firing of the first gun
62a and the eventual firing of the gun 62b. In one embodiment, the
time delay mechanism 104 includes a combination of energetic
materials, each of which exhibit different burn characteristics,
e.g., the type or rate of energy released by that material. By
appropriately configuring the chemistry, volume, and positioning of
these energetic materials, a desired or predetermined time delay
can be in the firing sequence. Generally, the energetic materials
can include materials such as RDX, HMX that provides a high order
detonation and a second energetic material that provides a low
order detonation. The burn rate of an energetic material exhibiting
a high order detonation, or high order detonation material, is
generally viewed as instantaneous, e.g., on the order of
microseconds or milliseconds. The burn rate of an energetic
material exhibiting a low order detonation, or low order detonation
material, may be on the order of seconds. In some conventions, the
high order detonation is referred to simply as a detonation and the
low order detonation is referred to as a deflagration. Also, the
number of fuses 144 may be varied to control the duration of the
time delay.
[0027] In variants, the time delay mechanism 104 may utilize other
methodologies for activating the detonator 150. For instance, the
detonator 150 may incorporate a pressure activated device. Thus,
the time delay mechanism 104 may apply a pressure or other induced
generated force in sufficiency to break a shear pin or other
similar element and allow the firing pin to impact a detonator or
igniter. In other variants, a shear stud could be used in place of
"shear pins" to function with the application of pressure,
differential pressure or other method or device that would generate
a sufficient force to cause failure of the shear stud and allow the
firing pin to impact a detonator or igniter. Shear studs and shear
pins are representative of calibrated frangible elements that
utilize material(s) and machining methods that allow these elements
to withstand a determined amount of force until ultimate failure.
In embodiments, a rupture disc may be used to withstand a
predetermined amount of pressure or force and fail at a know amount
of pressure or force to allow pressure or force to act against a
piston or firing pin to and allow the firing pin to impact a
detonator or igniter. Similarly, a bulkhead, which is machined
directly into the component, may be fabricated to fail at a known
application of pressure or force to allow the firing pin to impact
a detonator or igniter. In these variants, the components are
configured to withstand pressure from the well up to a
predetermined amount and then to fail in such a way as to activate
or cause to be activated other components to cause the successful
functioning of a detonator or igniter.
[0028] The configuration of the detonator 150 may depend on the
nature of the energy transfer from the time delay mechanism 104 to
the adjacent gun 62b. In some embodiments, the detonator 150 may
utilize an energetic material, such as but not limited to those
described above, formed as a booster element or charge to transform
a deflagration input to a high-order detonation output. Also, the
detonator 150 may utilize a firing head to generate a high-order
detonation output from a deflagration input or firing signal (e.g.,
pressure increase). In embodiments where a high-order detonation is
the input, then the detonator 150 may be configured to transfer the
high-order detonation to the adjacent gun 62b via a suitable
energetic connection.
[0029] Referring now to FIGS. 1-3, in an illustrative deployment,
the gun train 60 is assembled at the surface and conveyed into the
wellbore via a coiled tubing or standard tubing 50. After the gun
system 60 is positioned adjacent a zone to be perforated, a firing
signal is transmitted from the surface to the gun system 60. This
firing signal may be caused by increasing the pressure of the fluid
in the wellbore via suitable pumps (not shown), an electrical
signal, or a dropped device such as a bar. Upon receiving the
firing signal, the firing head 68 generates a high order detonation
that fires the perforating gun 62a. This detonation may be
transmitted to the firing control mechanism 100 via the detonator
cord 108. Upon being detonated by the detonator cord 108, this high
order detonation also actuates the activator 102. For example, the
high-order detonation of the detonator cord 108 detonates the
booster charge 106, which in response, generates a shock wave or
pressure pulse. The shock wave breaks the connection between the
protrusion 126 and the body 130 of the pin 112. The now-released
firing pin body 130 is propelled by the shock wave into and against
the igniter assembly 114 with sufficient force to cause the igniter
assembly 114 to detonate. The igniter assembly 114 detonates the
fuse element 144, which then burns for a predetermined amount of
time. Eventually, the fuse element 144 transfers the high-order
detonation to the detonator 150 of the second perforating gun 62b.
The detonator 150 thereafter detonates the detonator cord 155 of
the second perforating gun 62b, which causes the second perforating
gun 62b to fire.
[0030] In some situations, the time delay between the firing of
successive guns may be used to facilitate the surface monitoring of
the firings and to determine whether all the guns have fired. In
other situations, the time delay may be used to move the gun train
from one depth to another in a wellbore. For example, referring now
to FIG. 1, the gun 36 may be initially positioned at a depth
corresponding with the reservoir 34. Once so positioned, the gun
may be fired by actuating the externally activated firing head 66a.
The subsequent firing of gun 62a activates the activator 68 and
it's time delay device. During the time delay, the gun 36 may be
moved to a depth corresponding with the reservoir 32. Once the time
delay expires, the gun 62b fires. This process may be repeated as
necessary for any remaining guns in the gun train.
[0031] Referring now to FIG. 5, there is shown another embodiment
of a firing control device 200. In one embodiment, the firing
control device 200 includes an initiator 202 and a time delay 204.
The initiator 202 may include an explosive booster charge 206 that
is energetically coupled to a detonator cord 108 associated with an
immediately adjacent perforating gun 62a, a firing pin housing 210
that receives a firing pin 212, and an igniter assembly 214. These
components may be positioned within a housing 216, which has a bore
220 in which the firing pin 212 translates. The booster charge 206
may include an energetic material that, when detonated, generates a
shock wave or pressure pulse that is applied to the firing pin 212.
As described previously, the firing pin 212 may be calibrated to
maintain structural integrity when exposed to a base line or normal
operating pressure and break when subjected to a shock associated
with a firing of the booster 206. Illustrative structural details
for and operation of a firing pin has been discussed in connection
with the firing pin 112 of FIG. 4 and will not be repeated here.
The igniter assembly 214 includes an energetic material that is
capable of igniting the time delay mechanism 82 (FIG. 3), an
embodiment of which is shown as the time delay mechanism 204.
[0032] In embodiments, the time delay mechanism 204 may include a
housing 242 and one or more fuse element(s) 244 that is/are
energetically coupled to an adjacent gun (e.g., gun 62b). An
exemplary energetic coupling may include a booster charge 207 that
is coupled to a detonator cord 108. In embodiments, the time delay
mechanism adjusts or controls the time needed for the energy train
to travel to the gun 62b. By adjustable or controllable, it is
meant that the time delay mechanism 204 can be configured to
increase or decrease the time between the firing of the first gun
62a and the eventual firing of the gun 62b. As described
previously, the time delay mechanism 204 includes a combination of
energetic materials, each of which exhibit different burn
characteristics, e.g., the type or rate of energy released by that
material. The time delay may also be varied by varying the number
of time delay fuses.
[0033] In embodiments, the firing control device 200 may be
inserted into a gun train by using subs 218. The subs 218 may be
constructed as modular elements that may be selected to mate with
different diameter sizes of perforating guns. A tube 219 secures
the detonator cord 108 within a bore of the sub 218 and ensures
that the boosters 206, 207 are held in the proper position; i.e.,
within a distance across which the explosive energy can be conveyed
to the firing head and fuse, respectively.
[0034] In an illustrative deployment, the firing of the perforating
gun 62a detonates the detonator cord 108 leading to the initiator
202. In turn, the detonator cord 108 actuates the initiator 202.
For example, the high-order detonation of the detonator cord 108
detonates the booster charge 206, which in response, generates a
shock wave or pressure pulse. The shock wave releases and propels
the firing pin 212 into and against the igniter assembly 214 with
sufficient force to cause the igniter assembly 214 to detonate. The
igniter assembly 214 detonates the fuse element(s) 244, which then
burns for a predetermined amount of time. Eventually, the fuse
element 244 transfers the high-order detonation to the booster
charge 207 and associated detonator cord 108 of the second
perforating gun 62b. The detonator cord 108 fires the second
perforating gun 62b. The firing pin 212 may include sealing
elements that provide fluid isolation after detonation.
[0035] From the above, it should be appreciated that what has been
described includes, in part, an apparatus for perforating a
subterranean formation. The apparatus may include a first and a
second perforating gun, an activator responsive to the firing of
the first perforating gun and a fuse element detonated by the
activator that fires the second perforating gun. The second
perforating gun may include a detonator that is activated by the
fuse element. The detonator may be a firing head, a booster element
formed of an energetic material, or other device suitable for
outputting a high-order detonation. In arrangements, a first
detonator cord may explosively couple the first perforating gun to
the activator. Also, in embodiments, the activator may include an
energetic material, a pin positioned adjacent to the energetic
material, and an igniter positioned adjacent to the pin. A shock
wave generated by the energetic material may propel the pin into
the igniter. In such embodiments, the igniter may include an
energetic material that detonates the fuse element. In further
arrangements, the apparatus may include a second detonator cord
explosively coupled to the second perforating gun; and a detonator
energetically coupling the second detonator cord to the fuse
element. Also, the apparatus may include a housing that receives
the firing pin and a frangible element that connects the firing pin
to the housing. The frangible element may break in response to the
shock wave generated by the energetic material. In arrangements,
the fuse element may deflagrate. In applications, a second
detonator cord associated with the second perforating gun may be
explosively coupled to the fuse element.
[0036] From the above, it should be appreciated that what has been
described includes, in part, a perforating apparatus that may
include a first perforating gun that has a pressure activated
firing head; an activator that may include a firing head responsive
to the detonation of the first perforating gun and an igniter
detonated by the firing head; and a fuse element including an
energetic material, the fuse element being energetically coupled to
and detonated by the igniter; and a second perforating gun having a
detonator fired by the fuse element. The apparatus may also include
a detonator cord and a booster element that energetically couple
the first perforating gun to the activator. Further, the apparatus
may include a second detonator cord and a second booster element
that energetically couple the fuse element to the second
perforating gun.
[0037] From the above, it should be appreciated that what has been
described includes, in part, a method for perforating a
subterranean formation. The method may include forming a
perforating gun train using at least a first perforating gun and a
second perforating gun; and energetically coupling the first
perforating gun and the second perforating gun with an activator
responsive to the firing of the first perforating gun; and a fuse
element detonated by the activator. The method may further include
conveying the perforating gun train into a wellbore formed in the
subterranean formation. In certain deployments, the method may
involve firing the first perforating, wherein the firing of the
first perforating gun initiates the firing of the second
perforating gun.
[0038] From the above, it should be appreciated that what has been
described includes, in part, a perforating method that may include
forming a perforating gun train using a first perforating gun and a
second perforating gun; and energetically coupling the first
perforating gun and the second perforating gun using an activator
and a fuse element. The activator may include a firing head
responsive to the detonation of the first perforating gun; and an
igniter configured to be detonated by the firing head. The fuse
element may include an energetic material that is energetically
coupled to and detonated by the igniter.
[0039] The foregoing description is directed to particular
embodiments of the present disclosure for the purpose of
illustration and explanation. It will be apparent, however, to one
skilled in the art that many modifications and changes to the
embodiment set forth above are possible without departing from the
scope and the spirit of the disclosure. For example, while a "top
down" firing sequence has been described, suitable embodiments can
also employ a "bottom up" firing sequence. Moreover, the activator
can be used to supplement the energy release of a perforating gun
to initiate the firing sequence rather than act as the primary or
sole device for initiating the firing sequence. It is intended that
the following claims be interpreted to embrace all such
modifications and changes.
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