U.S. patent application number 12/204580 was filed with the patent office on 2010-03-04 for perforating gun assembly.
This patent application is currently assigned to INTEGRATED PRODUCTION SERVICES LTD.. Invention is credited to Joseph Melvin Farnel, Terry Lee Mytopher.
Application Number | 20100051278 12/204580 |
Document ID | / |
Family ID | 41723619 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100051278 |
Kind Code |
A1 |
Mytopher; Terry Lee ; et
al. |
March 4, 2010 |
PERFORATING GUN ASSEMBLY
Abstract
A perforating gun assembly including: an upper end; a
perforating gun connected to the upper end; a hydraulically
actuated tool connected to the perforating gun on an end opposite
the upper end; and a fluid conduit extending through the upper end
and to the hydraulically actuated tool, the fluid conduit allowing
fluid communication past the perforating gun to the hydraulically
actuated tool such that fluid can be communicated through the upper
end to actuate the hydraulically actuated tool.
Inventors: |
Mytopher; Terry Lee; (Grand
Prairie, CA) ; Farnel; Joseph Melvin; (Red Deer,
CA) |
Correspondence
Address: |
BENNETT JONES LLP;C/O MS ROSEANN CALDWELL
4500 BANKERS HALL EAST, 855 - 2ND STREET, SW
CALGARY
AB
T2P 4K7
CA
|
Assignee: |
INTEGRATED PRODUCTION SERVICES
LTD.
Calgary
CA
|
Family ID: |
41723619 |
Appl. No.: |
12/204580 |
Filed: |
September 4, 2008 |
Current U.S.
Class: |
166/298 ;
166/55.2 |
Current CPC
Class: |
E21B 43/119 20130101;
E21B 43/116 20130101 |
Class at
Publication: |
166/298 ;
166/55.2 |
International
Class: |
E21B 43/116 20060101
E21B043/116 |
Claims
1. A perforating gun assembly comprising: an upper end; a
perforating gun connected to the upper end; a hydraulically
actuated tool connected to the perforating gun on an end opposite
the upper end; and a fluid conduit extending through the upper end
and to the hydraulically actuated tool, the fluid conduit allowing
fluid communication past the perforating gun to the hydraulically
actuated tool such that fluid can be communicated through the upper
end to actuate the hydraulically actuated tool.
2. The perforating gun assembly of claim 1 wherein the upper end
includes a connector for connecting the assembly to a tubing
string
3. The perforating gun assembly of claim 1 wherein the upper end
includes a connector for connecting the assembly to continuous
tubing.
4. The perforating gun assembly of claim 1 further comprising a
plug in the fluid conduit between the hydraulically actuated tool
and the perforating gun such that the perforating gun is isolated
from communication with fluid pressure communicated to actuate the
hydraulically actuated tool.
5. The perforating gun assembly of claim 4 wherein the plug is
openable.
6. The perforating gun assembly of claim 4 wherein the plug is a
fixed wall.
7. The perforating gun assembly of claim 1 wherein the fluid
conduit includes a bore passing through the upper end and a bypass
line extending from a junction to the bore to the hydraulically
actuated tool.
8. The perforating gun assembly of claim 7 further comprising a
plug in the bore between the bore/by pass line junction and the
perforating gun such that the perforating gun is isolated from
communication with fluid pressure communicated to actuate the
hydraulically actuated tool.
9. The perforating gun assembly of claim 7 wherein the bypass line
extends externally along the perforating gun
10. The perforating gun assembly of claim 7 wherein the bypass line
extends at least in part internally through the perforating
gun.
11. The perforating gun assembly of claim 7 wherein the bypass line
is positioned out of the explosive paths of any charges in the
perforating gun.
12. The perforating gun assembly of claim 1 further comprising a
check valve in the fluid conduit uphole of the bypass line.
13. The perforating gun assembly of claim 1 wherein the perforating
gun is actuated hydraulically, mechanically or electrically.
14. The perforating gun assembly of claim 1 wherein the perforating
gun is actuated by hydraulic pressure communicated through at least
one of (a) the upper end and (b) an annulus about the perforating
gun.
15. The perforating gun assembly of claim 1 further comprising a
second perforating gun between the upper end and the hydraulically
actuated tool.
16. The perforating gun assembly of claim 15 wherein the second
perforating gun is actuated by system including a time delay
mechanism.
17. The perforating gun assembly of claim 1 further comprising a
fluid outlet sub operable to direct fluid from the perforating gun
assembly into an annulus about the perforating gun assembly.
18. The perforating gun assembly of claim 1 further comprising a
swivel.
19. The perforating gun assembly of claim 1 further comprising a
centralizer.
20. The perforating gun assembly of claim 1 wherein the
hydraulically actuated tool includes one or more of a packer, a
plug, a shear mechanism, a time delay assembly and a perforating
gun.
21. A method for perforating a well comprising: (a) providing a
perforating gun assembly including an upper end, a perforating gun,
a hydraulically actuated tool connected to the perforating gun on
an end opposite the upper end and a fluid conduit extending through
the upper end and to the hydraulically actuated tool, the fluid
conduit providing a fluid path past the perforating gun to the
hydraulically actuated tool; (b) running the perforating gun
assembly to a position in a well; and (c) in any order (i)
communicating fluid to the fluid conduit to actuate the
hydraulically actuated tool; and (ii) actuating the perforating gun
to perforate the well.
22. The method of claim 21 wherein running includes hanging the
assembly on continuous tubing and moving the continuous tubing and
assembly into the wellbore.
23. The method of claim 21 wherein actuating the perforating gun
includes applying hydraulic pressure to the perforating gun's
firing head.
24. The method of claim 21 wherein actuating the perforating gun
includes a time delay.
25. The method of claim 21 wherein actuating the hydraulically
actuated tool includes employing a pressure lower than that
required when actuating the perforating gun.
26. The method of claim 21 further comprising moving an inoperable
check valve into an operative position to control flow upwardly
through the fluid conduit.
27. The method of claim 21 wherein the hydraulically actuated tool
is a bridge plug and communicating fluid to the fluid expands an
annular seal on the bridge plug to seal the well at the bridge
plug.
28. The method of claim 21 further comprising circulating well
treatment fluids from the perforating gun assembly into the well.
Description
BACKGROUND
[0001] Perforating guns are used to access the formation behind a
wellbore casing. In wellbore operations it is common to run into
and out of a well a number of times to create isolated sections of
the wellbore, perforate and treat the well. However, the increasing
costs of well bore operations, including the rental rates for a rig
and lost time, are urging operators to speed all wellbore service
operations including those relating to wellbore perforating.
SUMMARY
[0002] In accordance with a broad aspect of the present invention
there is provided a perforating gun assembly including an upper
end, a perforating gun connected to the upper end, a hydraulically
actuated tool connected to the perforating gun on an end opposite
the upper end and a fluid conduit extending through the upper end
and to the hydraulically actuated tool, the fluid conduit allowing
fluid communication past the perforating gun to the hydraulically
actuated tool such that fluid can be communicated through the upper
end to actuate the hydraulically actuated tool.
[0003] In accordance with another broad aspect of the present
invention, there is provided a method for perforating a well
including: (a) providing a perforating gun assembly including an
upper end, a perforating gun, a hydraulically actuated tool
connected to the perforating gun on an end opposite the upper end
and a fluid conduit extending through the upper end and to the
hydraulically actuated tool, the fluid conduit providing a fluid
path past the perforating gun to the hydraulically actuated tool;
(b) running the perforating gun assembly to a position in a well;
and (c) in any order (i) communicating fluid to he fluid conduit to
actuate the hydraulically actuated tool; and (ii) actuating the
perforating gun to perforate the well.
[0004] It is to be understood that other aspects of the present
invention will become readily apparent to those skilled in the art
from the following detailed description, wherein various
embodiments of the invention are shown and described by way of
illustration. As will be realized, the invention is capable for
other and different embodiments and its several details are capable
of modification in various other respects, all without departing
from the spirit and scope of the present invention. Accordingly the
drawings and detailed description are to be regarded as
illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Referring to the drawings wherein like reference numerals
indicate similar parts throughout the several views, several
aspects of the present invention are illustrated by way of example,
and not by way of limitation, in detail in the figures,
wherein:
[0006] FIG. 1 is an axial section through a wellbore with a
perforating gun assembly positioned therein.
[0007] FIG. 2 is an axial section through another wellbore with
another perforating gun assembly positioned therein.
[0008] FIG. 3 is an axial section through an upper junction of a
perforating gun useful in a perforating gun assembly.
[0009] FIGS. 4a and 4b are axial sectional views through a check
valve assembly useful in a perforating gun assembly.
DESCRIPTION OF VARIOUS EMBODIMENTS
[0010] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
embodiments of the present invention and is not intended to
represent the only embodiments contemplated by the inventor. The
detailed description includes specific details for the purpose of
providing a comprehensive understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practiced without these specific
details.
[0011] A perforating gun assembly is proposed that includes a
number of tools thereon including a perforating gun and enables an
operator to both hydraulically actuate a tool below the perforating
gun and fire the perforating gun to perforate the wellbore casing
wall. In particular, the perforating gun assembly includes a bypass
line that communicates hydraulic fluid from surface past the
perforating gun to a tool located therebelow. The tool below the
perforating gun can be one or more of a plug (drill out,
retrievable, etc.), a packer, another perforating gun, a time delay
assembly, a shear assembly, etc.
[0012] FIG. 1 shows one possible embodiment of a perforating gun
assembly according to the present invention. The perforating gun
assembly is intended to be run into and operated in a wellbore, as
defined by wall 8, and includes an upper end including, for
example, a connector 10 for connecting the assembly to a tubing
string 12, such as one of continuous tubing, for example, coiled
tubing as shown, and a tubing arrangement 14. A perforating gun 16
is connected to the upper end and a hydraulically actuated tool 18
is installed therebelow. Tool 18 is positioned on the other side of
the perforating gun from the upper end, which in wellbore
terminology would be considered downhole from the perforating
gun.
[0013] Connector 10 and tubing arrangement 14 include at least
partly therethrough a longitudinal bore 20 creating an inner
diameter through which fluid can be received from the inner
diameter of tubing string 12, as communicated from surface. Bore 20
may include a plug 22 permanently or releasably installed therein.
Plug 22, if it is in place, blocks fluid communication to the
perforating gun through the bore.
[0014] The assembly further includes a bypass line 24 extending
from bore 20 to tool 18, acting as a conduit through which fluid
can be communicated from the tubing arrangement to the tool to
allow hydraulic actuation thereof. Bypass line 24 allows fluid to
get past the perforating gun to be communicated to tool 18. In one
embodiment, fluid conveyed through bore 20 can pass through bypass
line 24 to reach the tool below the perforating gun. In some
embodiments, when plug 22 is present, fluid may be communicated to
tool 18, without also being communicated to perforating gun 16. In
such an embodiment, bypass line 24 and plug 22 may isolate fluid
from the perforating gun.
[0015] Connector 10 may take various forms depending on the form of
tubing string intended to be used with the assembly and the
downhole manipulation of the assembly which is sought to be
achieved. For example, the assembly may conveniently be used with
coiled tubing and, therefore in such an embodiment, a crossover
connector suitable for connecting to coiled tubing may be
employed.
[0016] Perforating gun 16 may take various forms depending on the
wellbore conditions, the type of perforating job that is sought to
be accomplished, operator preferences, etc. For example,
perforating gun may be hydraulically, mechanically or electrically
actuated to immediately detonate or after a time delay. For
example, the gun may be actuated by a mechanical device, such as a
ball, bar or dart dropped or otherwise conveyed from surface, an
electrical device such as a wireline connected or downhole
programmable logic controller, or hydraulically by various fluids
and mechanisms.
[0017] Since the assembly is intended to facilitate hydraulic
operations for tools to be actuated before or after the firing of
the gun, it may be useful to also select a hydraulically actuated
perforating gun. Such a gun may be actuated by hydraulic pressure
in the annulus 27 about the gun or by through tubing pressures. In
the illustrated embodiment of FIG. 1, perforating gun 16 is
selected to be hydraulically actuated by annulus pressure. As such,
perforating gun 16 includes an upper gun sub 28 including a
pressure activated firing head 30 and a ported wall sub 32 through
which annular pressure is communicated to firing head 30. Ports 34
in sub 32 allow fluid from the annulus about the tool assembly to
be communicated to a chamber 36 of the sub and therethrough to a
piston face 37 of firing head 30 positioned therein. Ports 34 may
be removably closed by frangible members, such as glass, to protect
against the entry of debris into chamber 36. Of course, if a gun is
used that is actuated by tubing pressure, ported sub 32 may not be
required as actuating pressure will be conveyed through bore 20 to
the piston face, once flow past the plug in bore 20, such as by use
of a removable or openable form of plug 22, is achieved.
[0018] Perforating gun 16, in the illustrated embodiment, further
includes a charge tube in a housing sleeve 38, which is the outer
perforated sleeve shown in the drawing. The charges installed along
the charge tube are detonated by hydraulic operation of firing head
30.
[0019] As noted, perforating gun 16 can take various forms and
configurations. As shown in FIG. 2, for example, a plurality of
guns 116 can be used with or without time delay mechanisms for one
or more of the guns. Although four guns 116a, 116b, 116c, 116d are
shown, any number of guns can be used, as obviously limited by size
and operational constraints. In the illustrated embodiment,
uppermost gun 116a is detonated by a firing head 130 actuated, in
this illustration, only by through tubing hydraulic pressure
communicated through bore 120. Each of guns II 6b, 116c, 116d are
installed with a time delay detonator 139b, 139c, 139d which is
actuated by gas pressure generated from the perforating gun
installed adjacent thereto. For example, the pressure shock
generated by the detonation of gun 116a may act on time delay
detonator 139b that causes gun 116b to detonate after a selected
time. As will be appreciated, an example of a time delay detonator
includes time delay hardware, an igniter, an electronic time delay
or pyrotechnical time delay fuse, and a firing pin cartridge. The
time delay may allow for a selected delay time of, for example, 5
to 10 minutes, between the activation of the firing head to the
release of a firing pin into a receiving gun. This delay time
interval may allow the perforating gun assembly to be repositioned
in the well, such as moved axially along the well to a new depth or
to perform another operation, as desired. To control the selected
time, the rating or number of fuses may be selected, or an
electronic controller may be used, for any one or more of the time
delay detonators.
[0020] Tubing arrangement 14 may include an unmodified tubular sub
or may include one or more subs with straight tubing or any of
various mechanisms, as desired, considering the operation of the
assembly including the operation of the perforating gun and
selected downhole operations to be conducted. For example, the
tubing arrangement may include any or all of a swivel, a shear
release, a fluid outlet sub, or other mechanisms. For example, a
fluid outlet sub may be incorporated in the tubing arrangement
where it is desired to direct fluid from the assembly into the
annulus. A fluid outlet sub including, for example, a valve, an
openable port, etc. may allow fluid to be contained in the tubing
arrangement until it is desired to open the outlet to the exterior
of the assembly. Such an outlet sub may be for example, a
sleeve-closed port such as the tubing drain 40, as shown, or
otherwise. Tubing drain 40, in the illustrated embodiment, includes
a pressure release connection with a shear pin arrangement 42 that
can be overcome by fluid pressure to create an opening through the
wall of the drain. The shear pin arrangement can, for example,
release the connection between a telescoping outer sleeve and an
inner tube into which bore 20 extends and ports 44 are formed. It
may be desired to open fluid communication to the outer surface,
and thereby annulus 27 about the perforating gun assembly, for
annular hydraulic actuation of a perforating gun, such as is shown
in FIG. 1, for wellbore treatment such as conveying an acid or
other fluid through the tubing string, for pressuring testing a
packer or plug, and/or for equalizing pressure between the tubing
string/perforating gun assembly and the wellbore.
[0021] In another embodiment, where it is not desirable to open
fluid access to the outer surface of the tool and annulus about the
tool until nearer the time or after the perforating gun is
detonated, a port can be provided in association with the firing
head. For example, a port can be provided that is positioned to be
covered by the firing head body or an extension thereof and which
is opened by movement of the firing head, after the firing head has
been sufficiently hydraulically actuated to initiate detonation of
the perforating gun.
[0022] As a further example, it may be useful to employ a swivel in
the tubing arrangement to allow the assembly to be rotated relative
to the tubing string long axis. In the illustrated embodiment, a
swivel 46 is incorporated in the tubing arrangement. Swivel 46
allows, for example, the assembly to be rotated to allow a side of
the assembly, for example that side carrying bypass line 24, to be
out of contact with the wellbore wall.
[0023] Although the illustrated components of the tubing
arrangement, swivel 46 and tubing drain 40, are shown positioned in
a particular orientation and formed in a particular way. Of course,
other positional orientations and forms can be employed, if these
components are used at all.
[0024] As noted, bore 20 of tubing arrangement 14 may include a
plug, such as plug 22, that can be a valve, a frangible member, or
a permanent member such as a wall. Plug 22, when it is in place,
isolates perforating gun 16, from through tubing conveyed hydraulic
pressure, for example, when using bypass line 24 and hydraulically
manipulating tool 18. In particular, plug 22 blocks fluid passage
along bore 20 such that pressure applied to the tubing string inner
bore passes through bypass line 24 rather than acting on the
perforating gun's firing head. Plug 22 may be positioned anywhere
between the intersection of bypass line 24 and bore 20 and firing
head 30. Of course, a plug can be omitted where the firing head is
connected, as by selection of shear or biased connections, to only
be moved by pressures in selected ranges that are different than
those pressure ranges selected to actuate tool.
[0025] If perforating gun is hydraulically actuated using any
source of tubing conveyed hydraulic pressure, such pressure must
eventually be communicated from bore 20 to the firing head. Where
an embodiment as shown in FIG. 1 is employed, such communication
may be through tubing drain 40 and, as such, plug 22 can be a
permanent installation, such as a wall across the bore, as may be
provided by a blanking sub, which in the illustrated embodiment is
a part of upper sub 28. The embodiment of FIG. 2 shows an
embodiment where perforating gun 116a is actuated entirely by
through tubing pressure acting against firing head 130. In such an
embodiment, a plug 122 may be positioned in bore 120 to direct flow
to bypass line 124 and to block fluid communication to the
perforating gun. In such an embodiment, plug 122 is openable to
allow fluid communication to the firing head, when desired. For
example, plug 122 may be frangible such as by use of a burst disc
or shear pin released sleeve to open communication through bore 120
to firing head 130. Alternately, plug 122 may be omitted, allowing
the actuating pressure for tool 118 to reach firing head 130, and
instead rely on the pressure rating of the firing head's shear pin
connection to select pressure that will detonate the perforating
gun.
[0026] Bypass line 24, as noted above, conveys a flow of fluid from
bore 20 to a tool 18 positioned on the other side of the
perforating gun from bore 20, which in wellbore operations would be
considered downhole from the perforating gun. Hydraulic actuation
can be by various fluids including liquid or gas, such as including
but not limited to drilling mud, water, nitrogen, etc. Line 24 is
selected to withstand the rigors of downhole use and to convey
fluid and hold pressure at the differentials selected for
operation. In some embodiments, it may be possible to position and
form line 24 to withstand and retain its fluid conveying function
even after perforating gun has been detonated. This may be achieved
by forming the line of durable materials and positioning line 24
out of alignment with the explosive path of the perforating gun
charges.
[0027] In one embodiment, bypass line 24 is connected between an
upper sub 48 and a lower sub 50. An example of an upper sub 248 is
shown in FIG. 3, which is useful, for example, in an embodiment
such as FIG. 1 or FIG. 2.
[0028] Using upper sub 248 as an example of a form useful for the
upper sub and the lower sub for retaining bypass line 224, the sub
includes connections such as a threaded connections 252, 253 that
permit the sub to be connected into a tubular string. As an upper
sub, one end 252 is connected to the next adjacent component of the
tubing arrangement, such as tubing swivel 46 in FIG. 1. The other
end 253 is connected directly or indirectly to an end of
perforating gun, such as to the blanking sub or to upper gun sub 28
and therethrough to perforating gun 16.
[0029] Sub 248 also includes a bore 220a that may be connected into
communication with a bore of the tubing arrangement, such as bore
20 in FIG. 1. Sub 248 further includes a port 254 from bore 220a
onto which bypass line 224 can be fit. Sub 248 may include supports
255 that extend to support and protect line 224 at positions
between the line's installed ends. The bypass line can be for
example a durable tube, such as of metal or polymer including as
one possible example a stainless steel tube. Bypass line 224 is
connected at its other end in a similar manner to a substantially
similar, but vertically reversed, lower sub. Upper sub 248 and the
lower sub are positioned on opposite ends of the perforating gun
such that the bypass line spans the perforating gun without opening
thereto. Any connections between the line and the sub are selected
to be substantially fluid tight, such that any fluid communicated
to sub 248 can get past the perforating gun by flowing through line
224 and into a lower sub to pass to a tool to be actuated.
[0030] While bypass line is shown as an external line in FIGS. 1 to
3, it is to be understood that bypass line can alternately extend
partly or fully through the perforating gun. For example, a conduit
extend along the perforating gun inside the perforating gun housing
sleeve 38 and, for example, can be formed through the perforating
gun and other components between the bypass upper and lower subs
such as by drilling or installing a line through the parts. For
example, aligned channels, such as holes or indentations, can be
formed through and along the bypass upper and lower subs and the
various parts between the bypass upper and lower subs. In one
embodiment, a conduit such as a stainless steel line can be
installed to form the bypass line. To avoid fluid passage outside
the line, seals, such as O-rings can be installed between the line
and the parts through which it passes. For example, a seal may be
placed between the upper sub body and the conduit such that fluid
passing through the upper sub bore passes into the conduit rather
than around it. A moving part, such as the firing head, can include
a hole therethrough to accommodate the line and can be formed to
ride axially along the line. The line can extend between or through
the charge tube, if outside the tube, the charges therealong can be
positioned to allow the line to pass therethrough. In any event,
the line and affected parts of the perforating gun can be formed
such that fluid can pass through the line from an upper bypass sub
to a lower bypass sub such that fluid conveyed through the line can
pass from above the perforating gun to a tool on the other side of
the perforating gun (i.e. downhole of the perforating gun from the
actuating fluid supply). In some embodiments, the upper sub and the
bypass conduit line will be selected such that the fluid passing in
the bypass line will be maintained in isolation from the gun and
the gun's components.
[0031] Tool 18 can take various forms, as noted above, including,
for example, a packer, a plug, a shear mechanism, a time delay
assembly, a perforating gun, etc. In one embodiment, the tool may
include a bridge plug. The form and operations of bridge plugs is
well known in the art. For example, a bridge plug may carry an
annular seal 60 that can be expanded to set in and seal against a
wellbore wall 8. A bridge plug may be carried on the assembly to
permit the wellbore below a selected area to be perforated to be
sealed off. The seal created by the bridge plug may be useful to
restrict wellbore fluid to an area above the plug, to allow the
wellbore section above the plug to be pressured up, etc. Various
hydraulically actuated bridge plugs are known. When hydraulic
pressure is communicated to such a bridge plug, the annular seal is
caused to be expanded radially outwardly to seal the well about the
plug body 61 and set the plug in the well. It may be useful to
provide a centralizer with, for example adjacent, the bridge plug
to ensure an appropriate setting position for the plug and to
protect it from abrasion. In one embodiment, for example, an offset
sub 64 can be installed in the assembly to act as a centralizer. An
offset sub includes a sub that has axially offset end connections.
While the center long axis of perforating gun 16 may be offset to
allow room for bypass line 24 to extend therealong, offset sub 64
positioned below the perforating gun, allows the bridge plug body
and annular seal 60 to be returned to a more central position in
the well.
[0032] Tool 18 can further include a shear release mechanism such
as one also actuated by hydraulic pressure. A shear release
mechanism allows the assembly thereabove, including for example,
perforating gun 16 to be separated from the tool components,
including for example the bridge plug, below the shear mechanism,
when desired. The shear release mechanism can include, for example,
a shear pin connection between parts that can be separated by
pressuring up the tool beyond the holding force of the shear pins.
Since in some embodiments it is necessary to continue to hold
pressure within the assembly to hydraulically actuate further
components thereof, a valve may be provided in relation to the
shear release to continue to provide a closed system in at least
bore 20 and possibly also bypass line 24.
[0033] It will be appreciated that in the embodiment of FIGS. 1 and
2, the assembly is in open communication for reverse flow to
surface. In particular, there is no valve in the assembly to
prevent reverse flow from the assembly to the coiled tubing. This
presence of a check valve during all operations of the embodiments
of FIGS. 1 and 2 may create problems. However, in some
applications, it may be desirable to provide a reverse flow check
valve for well control. For example, a reverse flow check valve may
be useful to control well kicks, prevent through tubing passage of
sour gas to surface and generally prevent debris from migrating up
the tubing string. As such, in one embodiment a check valve may be
provided in an inoperative position in the assembly for example in
tubing arrangement 14, which check valve can be moved into an
operative condition when the presence of a check valve is
acceptable and desired.
[0034] One possible embodiment of a useful check valve sub 470 is
shown in FIG. 4. Check valve sub 470 can be installed on an end or
along the length of tubing arrangement 414. Sub 470 includes a
housing 472 including ends 472a, 472a for connection of the check
valve inline with other components of the assembly. Within the
housing is a check valve assembly including one or more valves,
which in this illustrated embodiment, include two valve bodies 474
and 476, each providing operative support for a pivotal flapper
type check valves, 478, 479, respectively. When in an operative
condition (FIG. 4B), the flapper valves are each capable of opening
in response to downward flow of fluid from the tubing string
through a central flow passage 420b in line with, and forming a
portion of, bore 420 of the tubing arrangement toward the
perforating gun and are moved to the closed positions thereof, with
flapper valves seated against seats 480, 481 of the bodies, in
response to upward or reverse flow of fluid through housing
472.
[0035] As shown in FIG. 4A, the check valves may be initially
provided in an inoperative position, where an inner sleeve 482 is
inserted into bore 420b to hold flapper valves 478, 479 open. In
this condition, fluid flow can move in either direction through the
inner diameter of inner sleeve 482 and the remainder of bores 420,
420b. Inner sleeve 482 includes a lower end positioned in sealed
relation with the housing inner diameter and able to ride
therealong. Inner sleeve 482 also includes a ball seat 484.
Although inner sleeve is maintained by shear pins 485 initially in
a position holding the check valves in the inoperative position,
force can be applied by dropping or pumping a ball 486, or other
seal such as a dart, to land in seat 484, the pressure which is
built up behind the ball and seat acting to drive the inner sleeve
out of the region of the flapper valves such that they are free to
act. The sleeve can be formed to be retained in the assembly but to
be of such a form or size such that the ball and sleeve, when moved
down, do not create a blockage to fluid flow in either
direction.
[0036] To facilitate installation and construction, a tubular
insert 487, which is sealed as by use of o-rings 488 against the
inner wall of housing 472, can be used to provide a stepped region
in the inner diameter in which the lower end of sleeve 482 can
initially be sealed and can ride along.
[0037] In use, a perforating gun assembly, such as one of the
various embodiments with or without the optional features described
hereinbefore, can be run into a position in a well. Thereafter,
fluid can be communicated the fluid conduit through the assembly
including the bypass line to actuate the hydraulically actuated
tool below the perforating gun. Before or after the tool is
actuated, the perforating gun may be actuated to perforate the
well.
[0038] In an assembly such as that shown in FIG. 1, wherein the
assembly is hung on and run in on coiled tubing and the assembly
itself includes a hydraulically actuated perforating gun acted on
at least in part by through tubing conveyed fluid pressure, the
method may include the use of staged pressure ratings. For example,
the hydraulically actuated tool may be actuated by a first selected
pressure differential between the annulus and the fluid conduit,
including bore 20, bypass line 24, and any hydraulic chambers of
tool 18. Once the hydraulically actuated tool is actuated, the
pressure may then be increased to open access between the fluid
conduit and the perforating gun firing head. For example, the
pressure may be increased to a pressure greater than the first
selected pressure differential to open tubing drain 40 (FIG. 1) or
to open a burst element of plug 122 (FIG. 2), depending on the
nature of operation selected for the assembly. Thereafter, the
pressure may again be increased to actuate the perforating gun
firing head. This may include flowing fluid down through the coiled
tubing alone or through both the coiled tubing and the
casing/tubing annulus, depending on the mode of operation of the
perforating gun.
[0039] The wellbore can be treated by circulation of various
fluids, such as acid, at some point, for example, after
hydraulically actuating tool 18.
[0040] The perforating gun assembly may alternately be used to
first detonate perforating gun 16 and then actuate tool 18. This
can be achieved in various ways, such as, for example, by
mechanically or electrically actuating the perforating gun followed
by hydraulically actuating the tool or by selecting the perforating
gun to be detonated hydraulically by pressures less than those
required to actuate tool 18.
[0041] If a check valve such as one of FIG. 4 is provided, a ball
can be dropped to render the check valve operable to act against
flow uphole through the tubing string, when desired.
[0042] The previous description of the disclosed embodiments is
provided to enable any person skilled in the art to make or use the
present invention. Various modifications to those embodiments will
be readily apparent to those skilled in the art, and the generic
principles defined herein may be applied to other embodiments
without departing from the spirit or scope of the invention. Thus,
the present invention is not intended to be limited to the
embodiments shown herein, but is to be accorded the full scope
consistent with the claims, wherein reference to an element in the
singular, such as by use of the article "a" or "an" is not intended
to mean "one and only one" unless specifically so stated, but
rather "one or more". All structural and functional equivalents to
the elements of the various embodiments described throughout the
disclosure that are know or later come to be known to those of
ordinary skill in the art are intended to be encompassed by the
elements of the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. No claim element is
to be construed under the provisions of 35 USC 112, sixth
paragraph, unless the element is expressly recited using the phrase
"means for" or "step for".
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