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Patent 3143562 Summary

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(12) Patent Application: (11) CA 3143562
(54) English Title: BULKHEAD FOR A PERFORATING GUN ASSEMBLY
(54) French Title: CLOISON POUR UN ASSEMBLAGE DE PERFORATEUR
Status: Examination Requested
Bibliographic Data
(51) International Patent Classification (IPC):
  • E21B 43/117 (2006.01)
  • E21B 43/116 (2006.01)
(72) Inventors :
  • SULLIVAN, SHELBY L. (United States of America)
(73) Owners :
  • XCONNECT, LLC (United States of America)
(71) Applicants :
  • XCONNECT, LLC (United States of America)
(74) Agent: DEETH WILLIAMS WALL LLP
(74) Associate agent:
(45) Issued:
(22) Filed Date: 2021-12-21
(41) Open to Public Inspection: 2022-08-13
Examination requested: 2022-06-08
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
17/175,651 United States of America 2021-02-13
17/547,053 United States of America 2021-12-09

Abstracts

English Abstract


A bulkhead for transmitting detonation signals. The bulkhead is designed for
use with a
perforating gun assembly. The bulkhead comprises an elongated tubular body
having a first
end, a second end opposite the first end, and a bore extending from the first
end to the second
end. The bulkhead also includes a signal pin residing within the bore of the
bulkhead. The
signal pin also has a first end, and a second end opposite the first end. An
electrically
conductive wire is connected to the second end of the signal pin at the second
end of the
bulkhead. The bulkhead also comprises an end piece extending from the second
end of the
bulkhead. The end piece closely holds the conductive wire in place.
Preferably, the second
bulkhead is over-molded to securely hold the detonator wire.


Claims

Note: Claims are shown in the official language in which they were submitted.


CLAIMS
I claim:
1. A bulkhead for transmitting detonation signals, comprising:
an elongated tubular body having a first end, a second end opposite the first
end, and
a bore extending from the first end to the second end;
a signal pin residing within the bore of the bulkhead, the signal pin also
having a first
end, and a second end opposite the first end;
an electrically conductive wire connected to the second end of the signal pin
at the
second end of the bulkhead; and
an end piece extending from the second end of the bulkhead, closely and
frictionally
holding the conductive wire in place.
2. The bulkhead of claim 1, wherein the second end of the signal pin
resides within the
end piece of the body.
3. The bulkhead of claim 2, wherein the first end of the signal pin
comprises a banana
clip.
4. The bulkhead of claim 3, wherein the banana clip extends out from the
first end of the
bulkhead.
5. The bulkhead of claim 3, wherein the end piece is integral to the
tubular body.
6. The bulkhead of claim 2, wherein
the signal pin comprises a plurality of grooves; and
the tubular body has a bore that comprises a profile for mating with the
plurality of
grooves for increasing shear strength of the bulkhead.
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7. The bulkhead of claim 6, wherein the signal pin further comprises a
frusto-conical
portion proximate the first end of the signal pin shaft that fits into a
mating conical profile of
the bore.
8. The bulkhead of claim 6, wherein:
the tubular body resides within a tandem sub, and is fabricated from a non-
conductive
material; and
the electrical contact pin is fabricated substantially from brass.
9. The bulkhead of claim 8, wherein the plurality of grooves comprises at
least three
grooves equi-distantly spaced along the signal pin.
29
Date recue / Date received 2021-12-21

Description

Note: Descriptions are shown in the official language in which they were submitted.


BULKHEAD FOR A PERFORATING GUN ASSEMBLY
Field of the Invention
[0012] The present disclosure relates to the field of hydrocarbon recovery
operations.
More specifically, the invention relates to a perforating gun assembly used
for the perforation
of steel casing in a wellbore. Further still, the invention relates to a
bridged bulkhead for a
perforating gun assembly, wherein a first signal pin in the bulkhead delivers
detonation
instructions in a first direction, while a second signal pin in the bulkhead
delivers detonation
signals from an addressable switch and back to a detonator in a second
direction.
[0013] This section is intended to introduce various aspects of the art, which
may be associated
with exemplary embodiments of the present disclosure. This discussion is
believed to assist in
providing a framework to facilitate a better understanding of particular
aspects of the present
disclosure. Accordingly, it should be understood that this section should be
read in this light,
and not necessarily as admissions of prior art.
Background of the Invention
[0014] For purposes of this disclosure, pending U.S. patent application no.
16/996,692 will
be referred to as "the parent application."
[0015] In the drilling of an oil and gas well, a near-vertical wellbore is
formed through the
earth using a drill bit urged downwardly at a lower end of a drill string.
After drilling to a
predetermined depth, the drill string and bit are removed and the wellbore is
lined with a string
of casing. An annular area is thus formed between the string of casing and the
formation
penetrated by the wellbore.
[0016] A cementing operation is conducted in order to fill or "squeeze" the
annular volume
with cement along part or all of the length of the wellbore. The combination
of cement and
casing strengthens the wellbore and facilitates the zonal isolation, and
subsequent completion,
of hydrocarbon-producing pay zones behind the casing.
1
Date recue / Date received 2021-12-21

[0017] In connection with the completion of the wellbore, several strings
of casing having
progressively smaller outer diameters will be cemented into the wellbore.
These will include
a string of surface casing, one or more strings of intermediate casing, and
finally a string of
production casing. The process of drilling and then cementing progressively
smaller strings of
casing is repeated until the well has reached total depth. In some instances,
the final string of
casing is a liner, that is, a string of casing that is not tied back to the
surface.
[0018] Within the last two decades, advances in drilling technology have
enabled oil and
gas operators to "kick-off' and steer wellbore trajectories from a vertical
orientation to a near-
horizontal orientation. The horizontal "leg" of each of these wellbores now
often exceeds a
length of one mile, and sometimes two or even three miles. This significantly
multiplies the
wellbore exposure to a target hydrocarbon-bearing formation. The horizontal
leg will typically
include the production casing.
[0019] Figure 1 is a side, cross-sectional view of a wellbore 100, in one
embodiment. The
wellbore 100 defines a bore 10 that has been drilled from an earth surface 105
into a subsurface
110. The wellbore 100 is formed using any known drilling mechanism, but
preferably using a
land-based rig or an offshore drilling rig operating on a platform.
[0020] The wellbore 100 is completed with a first string of casing 120,
sometimes referred
to as surface casing. The wellbore 100 is further completed with a second
string of casing 130,
typically referred to as an intermediate casing. In deeper wells, that is,
wells completed below
7,500 feet, at least two intermediate strings of casing will be used. In
Figure 1, a second
intermediate string of casing is shown at 140.
[0021] The wellbore 100 is finally completed with a string of production
casing 150. In
the view of Figure 1, the production casing 150 extends from the surface 105
down to a
subsurface formation, or "pay zone" 115. The wellbore 100 is completed
horizontally,
meaning that a near-horizontal "leg" 156 is provided. The production casing
150 extends
substantially across the horizontal leg 156.
2
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[0022] It is observed that the annular region around the surface casing 120
is filled with
cement 125. The cement (or cement matrix) 125 serves to isolate the wellbore
100 from fresh
water zones and potentially porous formations around the casing string 120.
[0023] The annular regions around the intermediate casing strings 130, 140
are also filled
with cement 135, 145. Similarly, the annular region around the production
casing 150 is filled
with cement 155. However, the cement 135, 145, 155 is optionally only placed
behind the
respective casing strings 130, 140, 150 up to the lowest joint of the
immediately surrounding
casing string. Thus, a non-cemented annular area 132 is typically preserved
above the cement
matrix 135, a non-cemented annular area 142 may optionally be preserved above
the cement
matrix 135, and a non-cemented annular area 152 is frequently preserved above
the cement
matrix 155.
[0024] The horizontal leg 156 of the wellbore 100 includes a heel 153 and a
toe 154. In
this instance, the toe 154 defines the end (or "TD") of the wellbore 100. In
order to enhance
the recovery of hydrocarbons, particularly in low-permeability formations, the
casing 150
along the horizontal section 156 undergoes a process of perforating and
fracturing (or in some
cases perforating and acidizing). Due to the very long lengths of new
horizontal wells, the
perforating and formation treatment process is typically carried out in
stages.
[0025] In one method, a perforating gun assembly 200 is pumped down towards
the end
of the horizontal leg 156 at the end of a wireline 240. The perforating gun
assembly 200 will
include a series of perforating guns (shown at 210 in Figure 2), with each gun
having sets of
charges ready for detonation. The charges associated with one of the
perforating guns are
detonated and perforations (not shown) are "shot" into the casing 150. Those
of ordinary skill
in the art will understand that a perforating gun has explosive charges,
typically shaped, hollow
or projectile charges, which are ignited to create holes in the casing (and,
if present, the
surrounding cement) 150 and to pass at least a few inches and possibly several
feet into the
formation 115. The perforations create fluid communication with the
surrounding formation
115 (or pay zone) so that hydrocarbon fluids can flow into the casing 150.
3
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[0026] After perforating, the operator will fracture (or otherwise
stimulate) the formation
115 through the perforations (not shown). This is done by pumping treatment
fluids into the
formation 115 at a pressure above a formation parting pressure. After the
fracturing operation
is complete, the wireline 240 will be raised from the surface and the
perforating gun assembly
200 will be positioned at a new location (or "depth") along the horizontal
wellbore 156. A
plug (such as plug 112) is set below the perforating gun assembly 200 using a
setting tool 160,
and new shots are fired in order to create a new set of perforations.
Thereafter, treatment fluid
is again pumping into the wellbore 100 and into the formation 115. In this
way, a second set
(or "cluster") of fractures is formed away from the wellbore 156.
[0027] The process of setting a plug, perforating the casing, and
fracturing the formation
is repeated in multiple stages until the wellbore has been completed, that is,
it is ready for
production. A string of production tubing (not shown) is then placed in the
wellbore to provide
a conduit for production fluids to flow up to the surface 105.
[0028] In order to provide perforations for the multiple stages without
having to pull the
perforating gun 200 after every detonation, the perforating gun assembly 200
employs multiple
guns in series. Figure 2 is a side view of an illustrative perforating gun
assembly 200, or at
least a portion of an assembly. The perforating gun assembly 200 comprises a
string of
individual perforating guns 210.
[0029] Each perforating gun 210 represents various components. These
typically include
a "gun barrel" 212 which serves as an outer tubular housing. An uppermost gun
barrel 212 is
supported by an electric wire (or "e-line") 240 that extends from the surface
105 and delivers
electrical energy down to the tool string 200. Each perforating gun 210 also
includes an
explosive initiator, or "detonator" (shown in phantom at 229). The detonator
229 is typically
a small aluminum housing having a resistor inside. The detonator 229 receives
electrical
energy from the surface 105 and through the e-line 240, which heats the
resistor.
[0030] The detonator 229 is surrounded by a sensitive explosive material
such as RDX.
When current is run through the detonator 229, a small explosion is set off by
the electrically
heated resistor. Stated another way, the explosive compound is ignited by the
detonator 229.
4
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This small explosion sets off an adjacent detonating cord (not shown). When
ignited, the
detonating cord initiates one or more shots, typically referred to as "shaped
charges." The
shaped charges (shown at 320 in Figure 3) are held in an inner tube (shown at
300 in Figure
3), referred to as a carrier tube, for security and discharge through openings
215 in the selected
gun barrel 212. As the RDX is ignited, the detonating cord propagates an
explosion down its
length to each of the shaped charges 320 along the carrier tube 300.
[0031] The perforating gun assembly 200 may include short centralizer subs
220. The
assembly 200 also includes the inner tubes 300, which reside within the gun
barrel housings
212 and are not visible in Figure 2. In addition, tandem subs 225 are used to
connect the gun
barrel housings 212 end-to-end. Each tandem sub 225 comprises a metal threaded
connector
placed between the gun barrels 210. Typically, the gun barrels 210 will have
female-by-female
threaded ends while the tandem sub 225 has opposing male threaded ends.
[0032] The perforating gun assembly 200 with its long string of gun barrels
(the housings
212 of the perforating guns 210 and the carrier tubes 300) is carefully
assembled at the surface
105, and then lowered into the wellbore 10 at the end of the e-line 240. The e-
line 240 extends
upward to a control interface (not shown) located at the surface 105. An
insulated connection
member 230 connects the e-line 240 to the uppermost perforating gun 210. Once
the assembly
200 is in place within a wellbore, an operator of the control interface sends
electrical signals
to the perforating gun assembly 200 for detonating the shaped charges 320 and
for creating
perforations into the casing 150.
[0033] After the casing 150 has been perforated and at least one plug 112
has been set, the
setting tool 120 and the perforating gun assembly 200 are taken out of the
wellbore 100 and a
ball (not shown) is dropped into the wellbore 100 to close the plug 112. When
the plug 112 is
closed, a fluid (e.g., water, water and sand, fracturing fluid, etc.) is
pumped by a pumping
system down the wellbore (typically through coiled tubing) for fracturing
purposes. For a
formation fracturing operation, the pump rate will create downhole pressure
that is above the
formation parting pressure.
Date recue / Date received 2021-12-21

[0034] As noted, the above operations may be repeated multiple times for
perforating
and/or fracturing the casing 150 at multiple locations, corresponding to
different stages of the
well. Multiple plugs may be used for isolating the respective stages from each
other during
the perforating phase and/or fracturing phase. When all stages are completed,
the plugs are
drilled out and the wellbore 100 is cleaned using a circulating tool.
[0035] It can be appreciated that reliable electrical connections must be
made between the
gun barrels 210 in the tool string 200 through each tandem sub 225. Some of
those connections
are made through so-called bulkheads. Bulkheads are small, electrically
insulative tubular
bodies that hold one or more signal pins. The connection between signal wires
and the ends
of the signal pins represents a point of potential weakness.
[0036] Therefore, a need exists for a bulkhead wherein the non-conductive
outer housing
is molded over (or "over-molded onto") the electrical wires. A need further
exists for a
detonation system wherein a pair of bulkheads are bridged together in fixed
relation, with a
first signal pin in the bulkhead delivering detonation instructions in a first
direction, while a
second signal pin in the bulkhead delivers detonation signals from an
addressable switch and
back to a detonator in a second direction. A need further exists for a bridged
bulkhead
assembly that resides within a carrier end plate, wherein the end plate seals
off a tandem sub
from wellbore fluids and debris following detonation of explosive charges in
an associated
perforating gun.
SUMMARY OF THE INVENTION
[0037] A bulkhead for transmitting detonation signals is provided. The
bulkhead is
designed for use with a perforating gun assembly for perforating a wellbore.
[0038] The bulkhead comprises an elongated tubular body having a first end,
and a second
end opposite the first end. A bore extends from the first end to the second
end.
[0039] The bulkhead includes a signal pin residing within the bore of the
bulkhead. The
signal pin also has a first end, and a second end opposite the first end. An
electrically
6
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conductive wire is connected to the second end of the signal pin at the second
end of the
bulkhead.
[0040] The bulkhead also comprises an end piece. The end piece extend from
and is
preferably integral to the second end of the bulkhead. The end piece closely
holds the
conductive wire in place. Preferably, the second end of bulkhead is over-
molded to securely
hold the detonator wire.
[0041] In one aspect, the second end of the signal pin resides within the
end piece of the
body. In one aspect, the first end of the signal pin comprises a banana clip
that extends out
from the first end of the bulkhead.
Brief Description of the Drawings
[0042] So that the manner in which the present inventions can be better
understood, certain
illustrations, charts and/or flow charts are appended hereto. It is to be
noted, however, that the
drawings illustrate only selected embodiments of the inventions and are
therefore not to be
considered limiting of scope, for the inventions may admit to other equally
effective
embodiments and applications.
[0043] Figure 1 is a cross-sectional side view of a wellbore. The wellbore
is being completed
with a horizontal leg. A perforating gun assembly is shown having been pumped
into the
horizontal leg at the end of an e-line.
[0044] Figure 2 is a side view of a perforating gun assembly. The
perforating gun assembly
represents a series of perforating guns having been threadedly connected end-
to-end. Tandem subs
are shown between gun barrels of the perforating guns, providing the threaded
connections.
[0045] Figure 3 is a perspective view of an illustrative carrier tube for a
perforating gun. A
charge is shown in separated relation.
7
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[0046] Figure 4A is a perspective view of the carrier tube of Figure 3. The
carrier tube has
received a top end plate and a bottom end plate. An electric line is shown
extending through
the carrier tube and to the bottom end plate.
[0047] Figure 4B is a first side view of the carrier tube of Figure 4A.
[0048] Figure 4C is a second side view of the carrier tube of Figure 4A,
opposite the view
of Figure 4B.
[0049] Figure 4D is a perspective view of the carrier tube of Figure 4A.
Here, the carrier
tube is being slidably received within a gun barrel housing.
[0050] Figure 5A is a first perspective view of the bottom end plate of
Figure 4A. The end
plate is connected to the carrier tube. Three electrical pins are shown
extending out of the end
plate.
[0051] Figure 5B is a second perspective view of the bottom end plate of
Figure 4A. The
carrier tube has been removed for illustrative purposes.
[0052] Figure 6A is a first perspective view of a bridged bulkhead assembly
of the present
invention, in one embodiment. The bulkhead assembly holds a signal
transmission pin and a
separate detonation pin.
[0053] Figure 6B is a second perspective view of the bridged bulkhead
assembly of Figure
6A. Here, the view is seen from an opposite end.
[0054] Figure 7A is a top view of the bridged bulkhead assembly of Figures
6A and 6B
[0055] Figure 7B is a bottom view of the bridged bulkhead assembly of
Figures 6A and
6B
[0056] Figure 8A is a front end view (or downstream view) of the bulkhead
assembly of
Figures 6A and 6B.
8
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[0057] Figure 8B is a rear end view (or upstream view) of the bulkhead
assembly of
Figures 6A and 6B.
[0058] Figure 8C is a side view of the bridged bulkhead assembly of Figure
6A.
[0059] Figure 9 is a cross-sectional view of the bridged bulkhead assembly
of Figures 6A
and 6B.
[0060] Figure 10A is a side, cross-sectional view of an explosive
initiation assembly of the
present invention, in one embodiment. The explosive initiation assembly is
threadedly
connected at opposing ends to gun barrel housings, forming a portion of a
perforating gun
assembly. The explosive initiation assembly includes, among other components,
a tandem sub,
a switch housing and an addressable switch.
[0061] Figure 10B is a side view of a bulkhead and contact pin as used in
the explosive
initiation assembly of Figure 10A to transmit signals downstream.
[0062] Figure 10C is a perspective view of the contact pin and bulkhead of
Figure 10B.
[0063] Figure 11A is a perspective view of a top end plate that is part of
a perforating gun
assembly. The top end plate seats against the downstream end of the tandem sub
of Figure
10A.
[0064] Figure 11B is a perspective view of a bottom end plate that is part
of the perforating
gun assembly. The bottom end plate seats against the upstream end of the
tandem sub of Figure
10A, and receives the bridged bulkhead assembly of Figures 6A and 6B. Note
that Figure 5B
shows the same end plate.
[0065] Figure 12 is a perspective view of the top end plate of Figure 11A.
A contact pin
and supporting bulkhead are seen extending up from the top end plate, while an
electric line
extends down. The view of Figure 12 is the same as in Figure 4A, but with the
carrier tube
and bottom end plate removed to show the electric line.
9
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[0066] Figure 13 presents a flow chart showing steps for a method of
detonating explosive
charges associated with a perforating gun, in one embodiment.
Definitions
[0067] For purposes of the present application, it will be understood that
the term
"hydrocarbon" refers to an organic compound that includes primarily, if not
exclusively, the
elements hydrogen and carbon. Hydrocarbons may also include other elements,
such as, but
not limited to, halogens, metallic elements, nitrogen, carbon dioxide, and/or
sulfuric
components such as hydrogen sulfide.
[0068] As used herein, the terms "produced fluids," "reservoir fluids" and
"production
fluids" refer to liquids and/or gases removed from a subsurface formation,
including, for
example, an organic-rich rock formation. Produced fluids may include both
hydrocarbon
fluids and non-hydrocarbon fluids. Production fluids may include, but are not
limited to, oil,
natural gas, pyrolyzed shale oil, synthesis gas, a pyrolysis product of coal,
nitrogen, carbon
dioxide, hydrogen sulfide and water.
[0069] As used herein, the term "fluid" refers to gases, liquids, and
combinations of gases
and liquids, as well as to combinations of gases and solids, combinations of
liquids and solids,
and combinations of gases, liquids, and solids.
[0070] As used herein, the term "subsurface" refers to geologic strata
occurring below the
earth's surface.
[0071] As used herein, the term "formation" refers to any definable
subsurface region
regardless of size. The formation may contain one or more hydrocarbon-
containing layers,
one or more non-hydrocarbon containing layers, an overburden, and/or an
underburden of any
geologic formation. A formation can refer to a single set of related geologic
strata of a specific
rock type, or to a set of geologic strata of different rock types that
contribute to or are
encountered in, for example, without limitation, (i) the creation, generation
and/or entrapment
of hydrocarbons or minerals, and (ii) the execution of processes used to
extract hydrocarbons
or minerals from the subsurface region.
Date recue / Date received 2021-12-21

[0072] As used herein, the term "wellbore" refers to a hole in the
subsurface made by
drilling or insertion of a conduit into the subsurface. A wellbore may have a
substantially
circular cross section, or other cross-sectional shapes. The term "well," when
referring to an
opening in the formation, may be used interchangeably with the term
"wellbore."
[0073] Reference herein to "one embodiment" or "an embodiment" means that a
particular
feature, structure, or characteristic described in connection with an
embodiment is included in
at least one embodiment of the subject matter disclosed. Thus, the appearance
of the phrases
"in one embodiment" or "in an embodiment" in various places throughout the
specification is
not necessarily referring to the same embodiment.
Detailed Description of Certain Embodiments
100741 The following description of the embodiments refers to the
accompanying
drawings. The same reference numbers in different drawings identify the same
or similar
elements. The following detailed description does not limit the invention;
instead, the scope
of the invention is defined by the appended claims.
[0075] The following embodiments are discussed, for simplicity, with regard
to attaching
two perforating guns to each other through a tandem sub. In the following, the
terms
"upstream" and "downstream" are being used to indicate that one gun barrel of
a perforating
gun may be situated above and one below, respectively. However, one skilled in
the art would
understand that the invention is not limited only to the upstream gun or only
to the downstream
gun, but in fact can be applied to either gun. In other words, the terms
"upstream" and
"downstream" are not necessarily used in a restrictive manner, but only to
indicate, in a specific
embodiment, the relative positions of perforating guns or other components.
100761 Figure 3 is a perspective view of an illustrative carrier tube 300
for a perforating
gun 210. The carrier tube 300 defines an elongated tubular body 310 having a
first end 302
and a second end 304 opposite the first end 302. The carrier tube 300 has an
inner bore 305
dimensioned to receive charges. A single illustrative charge is shown at 320
in exploded-apart
11
Date recue / Date received 2021-12-21

relation. Openings 312 are provided for receiving the charges 320 and enabling
the charges
320 to penetrate a surrounding casing string 150 upon detonation.
[0077] Figure 4A is a perspective view of the carrier tube 300 of Figure 3.
In this view,
a pair of end plates have been threadedly connected to opposing ends of the
carrier tube 300,
forming a part of a perforating gun assembly 400. These represent a top end
plate 420
connected at end 302, and a bottom end plate 430 connected at the bottom end
304. The end
plates 420, 430 have mechanically enclosed the top 302 and bottom 304 ends of
the carrier
tube 300, respectively.
[0078] The end plates 420, 430 help center the carrier tube 300 and its
charges 320 within
an outer gun barrel (not shown in Figure 4A but shown at 510 in Figure 4B).
For this reason,
they may be referred to as "carrier plates" 420, 430.
[0079] It is understood that each opening 312 along the carrier tube body
310 will receive
and accommodate a shaped charge 320. Each shaped charge 320, in turn, is
designed to
detonate in response to an explosive signal passed through a detonating cord.
It is understood
that the carrier tube 300 and the shaped charge 320 of Figures 3 and 4A are
illustrative, and
that the current inventions are not limited to any particular type, model or
configuration of
charges, carrier tubes or gun barrels unless expressly so provided in the
claims.
[0080] An electronic detonator (shown at 229 in Figure 2) and a detonating
cord reside
inside the carrier tube 300. The carrier tube 300 and the gun barrel 510 are
intended together
to be illustrative of any standard perforating gun, so long as the gun
provides a detonator and
detonating cord internal to the carrier tube 300.
[0081] Extending up from the top end plate 420 is a bulkhead 475. The
bulkhead 475
encloses a contact pin 470. The contact pin 470 is configured to transmit
detonation and
communication signals from the surface, and down to addressable switches (not
shown) along
the perforating gun string 200. The contact pin 470 and bulkhead 475 are shown
in greater
detail in Figures 10B and 10C, described below.
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100821 A signal transmission line 410 is seen extending down from the
contact pin 470 and
through the carrier tube 300. The signal line 410 further extends through the
bottom end plate
430, and down to a next perforating gun (not shown). A signal carried by the
signal line 410
is transmitted through a signal transmission pin 720'. An earlier embodiment
of the signal
transmission pin 720' is discussed in greater detail in Figures 7A, 22A and
22B of the parent
application.
100831 At the opposite end of the carrier tube 300, the bottom end plate
430 is shown. The
bottom end plate 430 has a closed end surface 435 (shown at 435 in Figures 5A
and 5B). Three
pins are shown extending out of the closed end surface 435. These represent a
ground pin 710
and two electrical pins 720', 720". In one aspect, ground pin 710 connects to
the bottom end
plate 430 as an electrical ground, while electrical pins 720', 720" connect to
white and green
wires, respectively. Electrical pin 720' serves as a signal transmission pin
while electrical pin
720" serves as a detonator pin.
100841 Details concerning the ground pin 710 are discussed in connection
with Figures 9A
and 9B of the parent application and need not be repeated herein. For
reference, ground pin
710 is seen in the cross-sectional view of Figure 10A herein. Note that the
ground pin 710
does not extend through the end plate 430 but simply extends from the end
surface 435.
100851 Figure 4B is a first side view of the carrier tube 300 of Figure 4A.
Figure 4C is a
second side view of the carrier tube 430 of Figure 4A, opposite the view of
Figure 4B. Of
interest, the charges 320 have been removed, leaving the signal transmission
line 410 visible.
100861 Figure 4D is another perspective view of the carrier tube 300 of
Figure 3. Here,
the carrier tube 300 is being slidably received within a gun barrel housing
510. The gun barrel
housing 510 has an upper end 502 and a lower end 504. The gun barrel housing
510 has a
length that is generally conterminous with the length of the carrier tube 300.
The gun barrel
housing 510 includes openings 512 that align with openings 312 of the carrier
tube body 310
when the gun barrel housing 510 is slid in place over the carrier tube 300.
13
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[0087] In the view of Figure 4D, the gun bane! housing 510 is shown in
phantom when
placed over the carrier tube 300. The upper end is indicated at 502' while the
lower end is
shown at 504'. Openings along the gun barrel housing 510 are provided at 512'.
It is
understood that this assembly typically takes place at the shop before
delivery of a perforating
gun assembly 400 to a well site.
[0088] In the arrangement of Figures 4A through 4D, the carrier tube body
310 and gun
barrel housing 510 are downstream from the contact pin 470. However, it is
understood that a
separate carrier tube and gun bane! housing reside upstream from the contact
pin 470.
Similarly, separate carrier tubes and gun bane! housings reside downstream
from the pins 710,
720', 720", forming what may be a long series of perforating guns in a gun
bane! string.
[0089] Figure 5A is a first perspective view of the bottom end plate 430 of
Figure 4A.
The end plate 430 is slidably connected to the body 310 of the carrier tube
300 at end 304. A
bolt 810 threadedly connects a proximal end 432 of the end plate 430 to the
lower end 304 of
the carrier tube 300.
[0090] Figure 5B is a second perspective view of the bottom end plate 430.
In this view,
the proximal end 432 and distal end 434 of the carrier plate 430 are visible.
Also shown is the
closed end surface 435 and a central flange 436. The central flange 436
receives the lowermost
end 504 of the gun barrel housing 510. The central flange 436 also receives
bolt 820. Of
interest, the ground pin 710 and electrical pins 720', 720" are visible.
[0091] Pins 720' and 720" reside within separate bulkheads. Because the
pins 720' and
720" and their associated bulkheads are extremely small (certainly smaller
than bulkhead 475
of Figure 4A), the bulkheads may be referred to as "mini-bulkheads." In the
present
disclosure, a unique "bridged" bulkhead assembly is provided. The bridged
bulkhead
assembly provides an efficient way to installed pre-wired pins into the
carrier end plate 430
for field-connection with the addressable switch (shown at 760 in Figure 10A).
14
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[0092] Figure 6A is a first perspective view of a bridged bulkhead assembly
600 of the
present invention, in one embodiment. The bulkhead assembly 600 holds the
signal
transmission pin 720' and the detonation pin 720".
[0093] Figure 6B is a second perspective view of the bridged bulkhead
assembly 600 of
Figure 6A. Here, the view is seen from an end that is opposite the end of
Figure 6A. Note
that the assembly 600 has also been flipped upside down relative to Figure 6A.
[0094] In each of Figures 6A and 6B, a first bulkhead is shown at 610,
while a second
bulkhead is shown at 620. Bulkhead 610 has a first end 612, and a second end
614 opposite
the first end 612. Similarly, bulkhead 620 has a first end 622, and a second
end 624 opposite
the first end 622. Bulkhead 610 is made up of body 615 while bulkhead 620 is
made up of
body 625. Each of bodies 615, 625 is fabricated from an electrically non-
conductive material.
In one aspect, the bodies 615, 625 are fabricated through an additive
manufacturing process.
[0095] Signal transmission line 410 feeds into the first end 612 of the
first bulkhead 610.
The signal transmission line 410 is securely connected to a first end of the
signal transmission
pin 720'. This is seen more fully in the cross-sectional view of Figure 9,
discussed below.
[0096] In a similar way, a detonator wire 540 extends out from the first
end 622 of the
second bulkhead 620. The detonator wire 540 is securely connected to a first
end of the
detonator pin 720". This is also shown more fully in the cross-sectional view
of Figure 9.
[0097] Of interest, a second end 618 of the signal transmission pin 720'
extends out from
the second end 614 of the first bulkhead 610. Similarly, a second end 628 of
the detonator pin
720" extends out from the second end 624 of the second bulkhead 620. Each of
these second
ends 618, 628 represents a banana clip.
[0098] Figures 6A and 6B also show a bridge 630. The bridge 630 connects
and also
spaces apart the first 610 and second 620 bulkheads.
[0099] Figure 7A is a top view of the bridged bulkhead assembly 600 of
Figures 6A and
6B. Figure 7B is a bottom view of the bridged bulkhead assembly 600 of Figures
6A and 6B.
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In the views of Figures 7A and 7B, the wires 410 and 540 have been removed for
illustrative
purposes.
101001 Figure 8A is a front end view of the bulkhead assembly 600 of
Figures 6A and 6B.
Figure 8B is a rear end view of the bulkhead assembly of Figures 6A and 6B. In
these views,
openings 613, 623 are shown. The opening 613 receives the body 615 of the
first bulkhead
610, while the opening 623 receives the body 625 of the second bulkhead 620.
In one aspect,
the openings 613, 623 are true through-openings extending through the bridge
630 for
receiving the respective bodies 615, 625. Alternatively, the bridge 630 and
the bodies 615,
625 are integral pieces having been formed through injection molding or
through an additive
manufacturing process.
101011 Figure 8C is a side view of the bridged bulkhead assembly 600 of
Figures 6A and
6B. This view is taken from the side of the first bulkhead 610. It is
understood that signal
transmission line 410 (not shown) will extend out of the first end 612.
101021 Figure 9 is a cross-sectional view of the bridged bulkhead assembly
600 of Figures
6A and 6B. In this view, the signal transmission pin 720' is seen residing
within the body 615
of the first bulkhead 610. At the same time, the detonator pin 720" is seen
residing within the
body 625 of the second bulkhead 620. Each of the signal transmission pin 720'
and the
detonator pin 720" is an electrically conductive pin. Preferably, each of the
pins 720', 720"
represents a single pin housed within a respective bulkhead that transmits
electrical signals
through the bulkheads 610, 620, respectively, in support of downhole
perforating operations.
The brass pins 720', 720" have a series of radial steps designed to keep the
pins 720', 720"
within the respective bulkheads 610, 620 to ensure a high pressure barrier
when the upstream
perforating gun is detonated.
[0103] It can be seen in Figure 9 that the signal transmission line 410 is
now connected to
the signal transmission pin 720' at the first end 612 of the first bulkhead
610. At the same
time, a detonator wire 540 is connected to the detonator pin 720" at the first
end 622 of the
second bulkhead 620. Preferably, the first bulkhead 610 is over-molded at the
first end 612 to
securely hold the signal transmission line 410, while the second bulkhead 620
is over-molded
16
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at its first end 622 to securely hold the detonator wire 540. It is understood
that each of wires
410 and 540 will be properly insulated.
[0104] It is noted that over-molding the wires 410, 540 removes the need to
connect the
wires during assembly in the field. Over-molding also removes the risk of the
wires being
installed incorrectly and removes the need for separate insulators to cover
the exposed
brass/wire connection. The wires 410, 540 are internally connected to the
respective brass pins
720', 720" via crimping without need of a transition terminal. Additional seal
surfaces or
components are not required, provided that the mold is sealed to the wire
insulation without
damaging it.
[0105] During assembly, the signal transmission line 410 is crimped to a
bullet terminal,
and the bullet terminal is then connected to the brass pin 720'. Similarly,
the detonator wire
540 is crimped to a bullet terminal, and the bullet terminal is then connected
to the brass pin
720". The over-molding then takes place. The result is that the "gun shop" no
longer has to
connect the terminal and wire to the bulkhead or add insulator boots, and a
much more secure
connection is provided.
[0106] In a preferred arrangement, the body 615 of the first bulkhead 610
extends into a
first opening of the carrier end plate 430. At the same time, the body 625 of
the second
bulkhead 620 extends into a second opening of the end plate 430. 0-rings 650
circumnavigate
the bodies 615, 625, providing a seal within the openings of the end plate
430. As noted in
connection with Figures 4A and 5A, the end plate 430 is a carrier end plate
that resides at a
lower end 304 of a perforating gun carrier tube 300.
101071 Preferably, each bulkhead 610, 620 includes compliant tabs. The tabs
are seen
partially at 425 in Figure 4A. The tabs 425 are configured to mate with slots
325 in the carrier
tube 300 at end 304. This ensures a proper orientation of the pins 720', 720".
Once the
bulkheads 610, 620 are installed, the bulkheads 610, 620 are unable to back
out of the end plate
430. This removes the need for retainer nuts or other retention parts.
17
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[0108] The signal transmission pin 720' transmits detonation signals
through the end plate
430 in a first direction. At the same time, the detonator pin 720" transmits
the detonation
signals back up through the end plate 430 in a second direction opposite the
first direction.
Preferably, the first direction is downstream while the second direction is
upstream.
101091 Figure 10A is a side, cross-sectional view of an explosive
initiation assembly 1000
of the present invention, in one embodiment. The explosive initiation assembly
1000 is
threadedly connected at opposing ends to gun barrel housings 510, forming, for
example, a
part of the perforating gun assembly 200 of Figure 2.
101101 The explosive initiation assembly 1000 first includes a tandem sub
700. The
tandem sub 700 represents a short tubular body having male threads at opposing
ends 702, 704.
Each opposing end 702, 704 is connected to a gun barrel housing 510.
Intermediate the
opposing ends 702, 704 is a shoulder 706. The gun barrels 510 are threaded
onto the tandem
sub 700 until they meet the shoulder 706. Additional details concerning the
tandem sub 700
are described in the parent application in connection with Figure 4.
[0111] Residing within the tandem sub 700 is a switch housing 750. A
perspective view
of the switch housing 750 is shown in Figure 12 of the parent application. The
switch housing
750 holds an addressable switch 760. A perspective view of the addressable
switch 760 is
shown in Figure 13 of the parent application.
[0112] The addressable switch 760 receives signals from the surface as sent
by an operator,
through signal transmission pin 720', and filters those signals to identify an
activation signal.
If an activation signal is identified, then a signal is separately sent for
detonation of charges in
an adjacent (typically upstream) perforating gun 210 through detonator pin
720". Note that
neither the pin 710 nor the pin 720' is at any time in electrical
communication with the
detonator 229. Additional details of the switch housing 750 and the
addressable switch 760
are also provided in the parent application in connection with Figures 12, 13,
16 and 17 and
need not be repeated herein.
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[0113] The tandem sub 700 and its switch housing 750 reside between the
bottom end plate
430 and the top end plate 420. Figure 11A is a perspective view of the top end
plate 420, in
one embodiment. The top end plate 420 has a proximal end 422 and a distal end
424.
Intermediate the proximal 422 and distal 424 ends is the flange 426. As shown
in Figure 10,
the downstream end of the tandem sub 700 shoulders out against the flange 426.
[0114] The proximal end 422 of the top end plate 420 comprises a threaded
opening 421.
The threaded opening 421 is configured to receive a bolt or pin (not shown)
that radially fixes
the top end plate 420 to the top of the carrier tube 300.
[0115] Figure 11B is a perspective view of the bottom end plate 430 that is
part of the
perforating gun assembly 400, in one embodiment. The bottom end plate 430
seats against the
upstream end of the tandem sub 700. As noted above, the bottom end plate 430
has a proximal
end 432 and a distal end 434. Intermediate the proximal 432 and distal 434
ends is a flange
436.
[0116] At the proximal end 432 of the end plate 430 are two openings 442,
444. One of
the openings 442 is dimensioned to receive the detonator pin 720" and the
corresponding mini-
bulkhead 620. The other opening 444 receives the signal transmission pin 720'
and its own
corresponding mini-bulkhead 610. As seen in Figure 10A, the transmission pin
720' and the
detonator pin 720" extend through the bottom end plate 430 and into the switch
housing 750.
[0117] Flange members 436, 426 associated with the bottom end plate 430 and
the top end
plate 420, respectively, abut opposing ends of the tandem sub 700.
Beneficially, the end plates
430, 420 mechanically seal the tandem sub 700, protecting the addressable
switch 760 from
wellbore fluids and debris generated during detonation of the charges 320.
[0118] Referring back to Figure 10A, the explosive initiation assembly 1000
also includes
a contact pin 470. The contact pin 470 resides within a non-conductive
bulkhead 475. This is
the same contact pin 470 and bulkhead 475 as are presented in Figure 4A,
discussed above.
A first (or proximal) end of the contact pin 470 extends into the switch
housing 750 while a
second (or distal) end of the contact pin 470 extends into the top end plate
420. The contact
19
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pin 470 is used to transmit signals through the tandem sub 700 down to a next
perforating gun,
while the bulkhead 475 provides electrical insulation between the brass
contact pin 470 and
the surrounding metal tandem sub 700.
[0119] Figure 10B is an enlarged side view of the contact pin 470 and
bulkhead 475 of
Figure 10A. Figure 10C is a perspective view of the contact pin 470 and
bulkhead 475. It
can be seen that the bulkhead 475 defines a generally tubular body 810. The
body 810 has an
upstream end 802 and a downstream end 804. 0-rings 850 are provided to ensure
a seal relative
to the surrounding tandem sub 700.
[0120] Of interest, the downstream end 804 includes an extended end piece
830. The end
piece 830 offers a tip 835 that is over-molded onto the wire 410. The tip 825
secures the wire
410, preventing the wire 410 from becoming separated from the pin 470 during
run-in and
operation. Preferably, the wire 410 is crimped before over-molding. An
opposite end of the
pin 470 defines a banana clip 808. The banana clip 808 resides within or at
least extends well
into the tandem sub 700.
[0121] Note that the bulkhead 475 and the contact pin 470 play no role in
preventing a
pressure wave from reaching the electronics or an upstream perforating gun
after charges are
detonated. That function is provided solely by the top end plate 420. Note
also that neither
the top end plate 420 nor the bottom end plate 430 is a so-called "tandem sub
adapter." Indeed,
the top end plate 420 and the bottom end plate 430 butt up against opposing
ends 704, 702 of
the tandem sub 700.
[0122] Figure 12 is a perspective view of the top end plate 420. The
contact pin 470 and
supporting bulkhead 475 are seen extending up from the top end plate 420. The
electric line
410 is connected to the contact pin 470 at distal end 474 and extends down.
Note that the view
of Figure 12 is the same as in Figure 4A, but with the carrier tube 300 and
bottom end plate
430 removed to show the electric line 410.
[0123] In operation, a detonation signal is sent from the surface 105
through the electric
line 240. The signal reaches the perforating gun assembly 400 (including
multiple perforating
Date recue / Date received 2021-12-21

guns as shown in Figure 2). Typically, a lowest perforating gun is designated
for first
explosive initiation. In that case, the signal passes along the internal
transmission line 410
through each perforating gun 210 and is then passed along by the applicant's
novel
transmission pins 720', the novel addressable switches 760 in each tandem sub
700, and the
contact pins 470 until the signal reaches a lowest tandem sub 700 and its
addressable switch
760. According to the present disclosure, the addressable switch 760 then
sends a detonation
signal back up through the detonator pin 720", through wire 540, and to a
detonator 229.
[0124] It is understood that the relative arrangement of the gun barrel
212, the bottom end
plate 430, the tandem sub 700, the electronic switch housing 760 and all other
components of
the perforating gun assembly 400 and explosive initiation assembly 1000 may be
"flipped." In
this way, the tandem sub 700 is protected from a pressure wave upon detonation
of charges in
a downstream gun barrel 212.
[0125] As can be seen, a novel detonation system 1000 is provided. The
detonation system
provides protection for the electronics within the tandem sub 700 during
detonation of an
upstream (or adjacent) perforating gun. In one embodiment, the detonation
system first
includes the novel tandem sub. The tandem sub defines a generally tubular body
having a first
end and a second end. The first end and the second end each comprise male
connectors. This
allows the tandem sub to be threadedly connected, in series, to respective
perforating guns.
Thus, the first end is threadedly connected to a first perforating gun (or,
more precisely, a
female threaded end of a gun barrel), while the second end is threadedly
connected to a second
perforating gun (or, again, a female threaded end of an opposing gun barrel).
[0126] The first end of the tandem sub abuts a first (or bottom) end plate.
Similarly, the
second opposing end of the tandem sub abuts a second (or top) end plate. These
may be in
accordance with the bottom 430 and top 420 carrier end plates described above.
An inner bore
is formed between the first end and the second end of the tandem sub.
[0127] An electronic switch housing resides within the inner bore at the
first end of the
tandem sub. The switch housing holds an addressable switch configured to
receive instruction
signals from an operator at the surface.
21
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[0128] In addition, a receptacle is formed within the inner bore of the
tandem sub. The
receptacle is dimensioned to closely receive a so-called "big bulkhead." The
big bulkhead,
shown at 475, comprises:
a tubular body having a first end, a second end and a bore extending there
between;
an electrical contact pin 470 having a shaft extending through the bore of the

bulkhead body and having an upstream end and a downstream end, wherein the
shaft
resides within the bore, and wherein the electrical contact pin transmits
current from
the upstream end to the downstream end 830 of the bulkhead; and
a contact head 472 located at the upstream end of the electrical contact pin
outside of the bulkhead body and extending into the switch housing.
[0129] The electrical contact pin and its contact head are fabricated
substantially from a
conductive material such as brass. Of interest, the bulkhead is over-molded
over a wire that
exits the downstream end of the contact pin.
[0130] The bottom end plate comprises a bore that defines a first opening
and a second
opening. A signal transmission pin 720' extends through the first opening and
into the carrier
tube. Instruction signals are sent through the signal transmission pin 720'. A
separate
detonator pin 720" extends through the second opening and into the carrier
tube. The detonator
pin 720" is in electrical communication with a detonator residing within the
first perforating
gun. The detonator is configured to receive activation signals from the
addressable switch,
and ignite an explosive material within a detonating cord. The explosive
material travels to
shaped charges associated with the first perforating gun to ignite the
charges.
[0131] All electrical connections for the detonation system may be made at
the gun
building facility, that is, except for the wires being connected to the
detonator and the
addressable switch. The end plate on the gun barrel (or gun carrier) is
removed, and the pre-
wired electronic switch assembly (that is, the switch housing 750 and
encapsulated switch 760)
is installed. Beneficially, the bulkheads for the two electrical signal pins
720', 720" associated
22
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with the bottom end plate 430 are pre-installed over bulkheads 610, 620
associated with the
pins 720', 720" together as part of the novel bridged bulkhead 600.
[0132] The bottom end plate 430 is slid against the upstream end 402 of the
tandem sub
700. The pre-wired switch assembly can be tested at the gun building facility
to reduce the
chance of a mis-wired connection.
[0133] As an alternative, the addressable switch can be installed on the
bottom endplate in
the shop and sent out. This leaves only the detonator to install.
[0134] Note again that the tandem sub 700 need not have a side port.
Removing the port
from the sub 700 eliminates problems associated with known ports such as gun-
flooding due
to a missing o-ring and pinched wires under the plug port. The detonator is
installed later in
the field to comply with DOT and ATF regulations and API-RP67 recommendations.
[0135] In addition to the explosive initiation assembly 1000 discussed
above, a method of
detonating explosive charges associated with a perforating gun is presented
herein. The
perforating gun utilizes an addressable switch that transmits a detonation
signal to a detonator
in an adjacent perforating gun. The detonator, in turn, ignites an explosive
material, creating
an explosion that is passed through a detonating cord. The detonating cord
then ignites shaped
charges along the perforating gun.
[0136] Figure 13 represents a flow chart showing steps for a method 1300 of
detonating
explosive charges associated with a perforating gun. In one aspect, the method
1300 first
comprises providing a bridged bulkhead assembly. This is provided in Box 1310
of Figure
13A. As discussed above, the bridged bulkhead assembly comprises:
a first bulkhead;
a signal transmission pin residing within the first bulkhead;
a second bulkhead;
a detonator pin residing within the second bulkhead; and
23
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a bridge fixedly connecting and spacing apart the first bulkhead with the
second
bulkhead.
[0137] In a preferred embodiment, the first bulkhead comprises a body
having a first end,
and a second end opposite the first end. Similarly, the second bulkhead
comprises a body
having a first end, and a second end opposite the first end. Each of the first
bulkhead and the
second bulkhead is fabricated from an electrically non-conductive material.
For purposes of
service in a perforating gun assembly, each of the first and second bulkheads
is considered a
"mini-bulkhead."
[0138] The bridge comprises a body having first and second through-
openings. The first
through-opening of the bridge fixedly receives the signal transmission pin,
while the second
through-opening of the bridge fixedly receives the detonator pin.
[0139] The method 1300 also includes connecting the bridged bulkhead
assembly to a
carrier end plate. This is shown in Box 1320. In this step, the first bulkhead
(and signal
transmission pin) extends into a first opening of the carrier end plate while
the second bulkhead
(and detonator pin) extends into a second opening of the carrier end plate.
The carrier end
plate may be configured in accordance with the carrier end plate 430 described
above, with
banana clips 618, 628 protruding downstream from the end plate 430 to be
placed into a tandem
sub 700.
[0140] The method 1300 further comprises sending a detonation signal (or IE
signal) from
a surface, down an electric line, and into a wellbore. This is seen in Box
1330.
[0141] The method 1300 also includes further sending the detonation signal
through a
perforating gun and through the signal transmission pin 720'. This is provided
in Box 1340.
[0142] The electric line 410 is connected to the signal transmission pin
720' at the first end
of the first bulkhead 610. At the same time, a detonator wire 540 is connected
to the detonator
pin 720" at the first end of the second bulkhead 620. This may be in
accordance with the
24
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bulkhead assembly 600 of Figures 6A and 6B, which uses over-molding to protect
the wire
connections.
[0143] The second end of the signal transmission pin 720' extends from the
second end of
the first bulkhead 610 and down to the banana clip 618. The banana clip 618 of
the signal
transmission pin 720' is in electrical communication with an addressable
switch 760.
Similarly, the second end of the detonator pin 720" extends from the second
end of the second
bulkhead 620 and also comprises a banana clip 628. Note that the banana clip
628 of the
detonator pin 720" is never in electrical communication with the electric line
410 or the banana
clip 618 of the signal transmission pin 720'.
[0144] The method 1300 includes further sending the detonation signal into
the
addressable switch, wherein the addressable switch determines whether the
detonation signal
is addressed to the specific perforating gun. The addressable switch resides
within a tandem
sub below the perforating gun. This is offered in Box 1350.
[0145] The method 1300 additionally comprises identifying that the
detonation signal is
addressed to the perforating gun. This is shown in Box 1360 of Figure 13B. In
response, the
addressable switch sends a detonation signal to the detonator pin 720" and
back through the
carrier end plate 430.
[0146] The method 1300 then includes sending the detonation signal to a
detonator to
initiate explosive charges residing within the perforating gun. This is seen
in Box 1370. Note
that the carrier end plate isolates the addressable switch from wellbore
fluids and a pressure
wave generated in response to the detonation of the explosive charges. In
other words, an
upstream perforating gun may be activated without damaging the electronic
switch assembly
in the tandem sub 700. The switch assembly 760 may be reused for another
perforation
operation. Similarly, the contact pin 470, the big bulkhead 475, and the
tandem sub 700 itself
are protected for later re-use.
[0147] In the method 1300, the addressable switch 760 is configured to
monitor instruction
signals received through the signal line 410. Stated another way, the
addressable switches
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filter instruction signals from the operator at the surface. When an
addressable switch receives
a signal associated with its tandem sub and perforating gun, the switch 660 is
armed and a
window of time is opened (typically about 30 seconds) in which to send a
detonation signal
from the surface. Upon receiving confirmation, the addressable switch will
send a detonation
signal through the detonation pin and back up to a detonator through line 540.
The detonator,
in turn, ignites the explosive material that passes through the detonating
cord and on to the
charges along the carrier tube.
[0148] If the instruction signal is not recognized as a detonation signal
for that tandem sub
700, the signal is sent on through the contact head 472 residing inside of the
switch housing
750 associated with the contact pin 470 From there, the signal is sent through
the contact pin
470, through the top end plate 420, and on to a next perforating gun and a
next bridged
bulkhead.
[0149] Before the detonation of the upstream perforating gun, the
electronic switch can
feed current down to a next perforating gun (or to a bulkhead associated with
a next perforating
gun), depending on the instruction.
[0150] As another way of expressing the sequence, an IE signal enters the
perforating gun
assembly via a big bulkhead 475, passes down the next downstream carrier tube
via line 410,
goes through the transmission pin 710' and into the addressable switch 760. If
a detonation
signal is present, a detonation signal is sent back upstream through the
detonator pin 720" and
into the detonator (shown at 229 in the parent application). Otherwise, it can
continue
downstream from the addressable switch 760, through wire 711, through a next
contact pin
470, down wire 410, and to the next downstream perforating gun. The process
then repeats.
[0151] After production casing has been perforated at a first level, the
operator may pull
the perforating gun assembly 200 up the wellbore 100. The operator then sends
a next
detonation signal down through the electric line 240, through the signal
transmission line 410
of the perforating gun assembly 200 and the various tandem subs 700 and
contact pins 470,
and down to a next-lowest tandem sub 700. The detonation signal is recognized
by the
addressable switch 760 in the next-lowest tandem sub 700 and a detonation
signal is sent
26
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through a detonator pin 720" and wire 540 to a next associated detonator 229.
The detonation
charge in the detonator 229 ignites the explosive material in the detonator
cord and the charges
320 of the next upstream gun bane! 212.
101521 The pressure wave from the charges acts against the bottom end plate
430,
protecting the tandem sub 700 and housed electronics 760 from damage from the
upstream
perforating gun 210. Similarly, a top end plate 420 protects the electronics
in a further
upstream gun from the pressure wave.
[0153] The disclosed embodiments provide methods and systems for preventing

electronics located inside a switch sub from being damaged by detonation of an
adjacent
perforating gun. It should be understood that this description is not intended
to limit the
invention.; on the contrary, the exemplary embodiments are intended to cover
alternatives,
modifications, and equivalents, which are included in the spirit and scope of
the invention as
defined by the appended claims. Further, in the detailed description of the
exemplary
embodiments, numerous specific details are set forth in order to provide a
comprehensive
understanding of the claimed invention. However, one skilled in the art would
understand that
various embodiments may be practiced without such specific details.
[0154] Further, variations of the detonation system and of methods for
using the detonation
system within a wellbore may fall within the spirit of the claims, below. It
will be appreciated
that the inventions are susceptible to other modifications, variations, and
changes without
departing from the spirit thereof.
27
Date recue / Date received 2021-12-21

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date Unavailable
(22) Filed 2021-12-21
Examination Requested 2022-06-08
(41) Open to Public Inspection 2022-08-13

Abandonment History

There is no abandonment history.

Maintenance Fee

Last Payment of $100.00 was received on 2023-11-20


 Upcoming maintenance fee amounts

Description Date Amount
Next Payment if small entity fee 2024-12-23 $50.00
Next Payment if standard fee 2024-12-23 $125.00

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Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee 2021-12-21 $408.00 2021-12-21
Request for Examination 2025-12-22 $814.37 2022-06-08
Maintenance Fee - Application - New Act 2 2023-12-21 $100.00 2023-11-20
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
XCONNECT, LLC
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
Documents

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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
New Application 2021-12-21 7 174
Abstract 2021-12-21 1 20
Description 2021-12-21 27 1,317
Claims 2021-12-21 2 42
Drawings 2021-12-21 16 302
Request for Examination 2022-06-08 4 103
Representative Drawing 2022-09-14 1 13
Cover Page 2022-09-14 1 44
Examiner Requisition 2023-09-13 4 170
Amendment 2023-11-07 11 386
Maintenance Fee Payment 2023-11-20 1 33
Claims 2023-11-07 2 67