Note: Descriptions are shown in the official language in which they were submitted.
201701-3CA
STRADDLE PACKER WITH FLUID PRESSURE PACKER
SET AND VELOCITY BYPASS
FIELD OF THE INVENTION
This invention relates in general to precision fracking systems and, in
particular,
to a novel straddle packer with fluid pressure packer set and velocity bypass
used
for cased wellbore or open hole well stimulation or remediation.
BACKGROUND OF THE INVENTION
Wel!bore pressure isolation tools, commonly referred to as "straddle packers",
are
known and used to pressure isolate a downhole area of interest in a cased or
open hydrocarbon wellbore for the purpose of what is known as focused or
precision well stimulation or remediation. Straddle packers designed for this
purpose are well known, but their use has been associated with operational
issues that frequently render them unreliable.
There therefore exists a need for a novel straddle packer with fluid pressure
packer set and velocity bypass that overcomes the operational issues
associated
with known prior art straddle packers.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a straddle packer with
fluid
pressure packer set and velocity bypass.
The invention therefore provides a straddle packer with fluid pressure packer
set,
comprising: a multicomponent mandrel that extends from an upper end to a lower
end of the cased bore straddle packer, the multicomponent mandrel including an
active mandrel tube component with active mandrel tube fluid ports that permit
high pressure fluid to flow from a central passage of the multicomponent
mandrel
through the active mandrel tube component; an upper packer element and a
lower packer element that respectively surround the multicomponent mandrel in
a spaced apart relationship, the upper packer element and the lower packer
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element respectively being in a normally relaxed condition; a modular pressure
cylinder that reciprocates within a restricted range on the active mandrel
tube
component, the modular pressure cylinder including at least two interconnected
pressure cylinder modules having interconnected pressure cylinder walls and
interconnected pressure pistons that reciprocate within pressure cylinders,
the
interconnected pressure pistons including pressure cylinder fluid ports that
permit
fluid flowing through the active mandrel tube fluid ports to enter the
pressure
cylinders and simultaneously urge the interconnected pressure cylinder walls
and
the interconnected pressure pistons to move in opposite directions along an
axis
of the active mandrel tube component to compress the respectively normally
relaxed upper and lower packer elements to a packer set condition.
The invention further provides a straddle packer with fluid pressure packer
set
and velocity bypass, comprising: a multicomponent mandrel having a central
passage that extends from an upper end to a lower end of the multicomponent
mandrel, the multicomponent mandrel having a completion string connection
mandrel component at an upper end of the straddle packer to permit the
connection of a tubing string to the straddle packer and a velocity bypass
crossover at a lower end of the straddle packer to permit the connection of a
velocity bypass sub; an upper packer element and a lower packer element that
respectively surround the multicomponent mandrel in a spaced apart
relationship;
a modular pressure cylinder that reciprocates within a restricted range on an
active mandrel tube component of the multicomponent mandrel, the modular
pressure cylinder including a plurality of interconnected pressure cylinder
modules connected end-to-end; an upper compression bell that compresses the
upper packer element and a lower compression bell that compresses the lower
packer element when fluid is pumped into the straddle packer at a flow rate
that
exceeds a flow rate threshold, the upper compression bell being connected to
an
upper end of a sliding sleeve that is connected by a crossover to an upper end
of
interconnected cylinder walls of the modular pressure cylinder, and the lower
compression bell being connected to a lower end of interconnected pistons of
the
modular pressure cylinder; an upper and a lower mandrel tube of the
multicomponent mandrel, the upper mandrel tube being connected on a top end
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to the completion string mandrel component and on a lower end to a mandrel
flow
sub, and an upper end of the lower mandrel tube being connected to a lower end
of the mandrel flow sub and on a lower end to the active mandrel tube
component
of the multicomponent mandrel, the mandrel flow sub including at least one
mandrel flow sub nozzle; and the velocity bypass sub having a central passage
in fluid communication with the central passage of the multicomponent mandrel
and housing a velocity bypass valve having the flow rate threshold, whereby
fluid
pumped through the completion tubing string into the multicomponent mandrel
flows through the at least one mandrel flow sub nozzle and the velocity bypass
valve until a flow rate of the fluid exceeds the flow rate threshold, after
which the
velocity bypass valve closes and the fluid flows only through the at least one
mandrel flow sub nozzle and into fluid ports of the modular pressure cylinder,
urging pressure pistons of the modular pressure cylinder in a first direction
and
pressure cylinder walls of the modular pressure cylinder in an opposite
direction
along an axis of the active mandrel tube component to compress the respective
packer elements to a packer set condition.
The invention yet further provides a straddle packer with fluid pressure
packer set
and velocity bypass, comprising: a multicomponent mandrel having a completion
string connection component which is threadedly connected to an upper mandrel
tube; a mandrel flow sub connected to a downhole end of upper mandrel tube; at
least one mandrel flow sub nozzle in the mandrel flow sub; a lower mandrel
tube
connected to a downhole end of the mandrel flow sub; a mandrel tube crossover
component connected to a downhole end of the lower mandrel tube; the active
mandrel tube component connected to a downhole end of the mandrel tube
crossover component; a lower packer element mandrel sleeve component
connected to a downhole end of the active mandrel tube component; a lower
crossover sub connected to the downhole end of the lower packer element
mandrel sleeve component; an upper packer element and a lower packer element
that respectively surround the multicomponent mandrel in a spaced apart
relationship; a modular pressure cylinder that reciprocates within a
restricted
range on an active mandrel tube component of the multicomponent mandrel, the
modular pressure cylinder including a plurality of interconnected pressure
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cylinder modules connected end-to-end, each modular pressure cylinder
including: a pressure cylinder wall; a pressure piston with a pressure piston
seal
that seals against an inner surface of the pressure cylinder wall; each
pressure
piston reciprocating within a pressure cylinder chamber; pressure cylinder
seals
that respectively inhibit the migration of fluid out of the respective
pressure
cylinder chambers; each pressure piston having a pressure cylinder male
coupling sleeve and a pressure cylinder female coupling sleeve; the respective
pressure cylinder male coupling sleeves having an external thread that engages
an internal thread in the respective pressure cylinder female coupling sleeves
to
connect the respective pressure pistons together; respective pressure cylinder
coupling seals to inhibit any migration of fluid between the pressure cylinder
male
coupling sleeves and the pressure cylinder female coupling sleeves; a pressure
cylinder fluid port to let the high pressure fluid flow through the active
mandrel
tube fluid ports into the respective pressure cylinder chambers; and pressure
cylinder pressure equalization ports in the respective pressure cylinder walls
to
equalize pressure behind the respective pressure pistons with ambient wellbore
pressure; an upper compression bell that compresses the upper packer element
and a lower compression bell that compresses the lower packer element when
high pressure fluid is pumped into the straddle packer at a flow rate that
exceeds
a predetermined flow rate threshold, the upper compression bell being
connected
to an upper end of a sliding sleeve that is connected by a crossover to an
upper
end of interconnected cylinder walls of the modular pressure cylinder, and the
lower compression bell being connected to a lower end of interconnected
pistons
of the modular pressure cylinder; an upper and a lower mandrel tube of the
multicomponent mandrel, the upper mandrel tube being connected on an upper
end to the completion string mandrel component and on a lower end to a mandrel
flow sub, and an upper end of the lower mandrel tube being connected to a
lower
end of the mandrel flow sub and on a lower end to the active mandrel tube
component of the multicomponent mandrel, the mandrel flow sub including at
least one mandrel flow sub nozzle; and a velocity bypass sub connected to the
velocity bypass sub crossover, the velocity bypass sub having a central
passage
in fluid communication with the central passage of the multicomponent mandrel
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and housing a velocity bypass valve having the flow rate threshold, whereby
fluid
pumped through the completion tubing string into the multicomponent mandrel
flows through the at least one mandrel flow sub nozzle and the velocity bypass
valve until a flow rate of the fluid exceeds the flow rate threshold, after
which the
fluid flows only through the at least one mandrel flow sub nozzle and into
fluid
ports of the modular pressure cylinder, urging pressure pistons of the modular
pressure cylinder in a first direction and pressure cylinder walls of the
modular
pressure cylinder in an opposite direction along an axis of the active mandrel
tube
component, to compress the respective packer elements to a packer set
condition.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the nature of the invention, reference will
now
be made to the accompanying drawings, in which:
FIG. 1 is a perspective view of an embodiment of a straddle packer with fluid
pressure packer set in accordance with the invention in a run-in condition;
FIG. 2 is a cross-sectional view of the straddle packer shown in FIG. 1, in
the run-
in condition;
FIG. 3a is an exploded cross-sectional view of mandrel tubes and mandrel flow
sub of the straddle packer shown in FIG. 2;
FIG. 3b is an exploded side elevational view of the mandrel tubes and the
mandrel
flow sub shown in FIG. 3a;
FIG. 3c is an exploded cross-sectional view of sliding sleeves that
reciprocate,
from the run-in condition to the packer set condition, on the mandrel tubes of
the
straddle packer shown in FIG. 3b;
FIG. 4 is a cross-sectional view of the embodiment of the straddle packer
shown
in FIG. 1 in the packer set condition;
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FIG. 5a is a cross-sectional view of a velocity bypass sub of the straddle
packer
shown in FIGs. 1, 2 and 4, with a velocity bypass valve of the velocity bypass
sub
in an open condition; and
[0001] FIG. 5b is a cross-sectional view of the velocity bypass sub of the
straddle
packer shown in FIG. 5a, with the velocity bypass valve of the velocity bypass
sub in a closed condition.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention provides a straddle packer with a fluid pressure boosted packer
set
and velocity bypass for use in precision well stimulation or remediation
treatments
in either open hole or cased wellbores (hereinafter referred to collectively
as
"wellbores"). The straddle packer has spaced-apart upper and lower packer
elements that bracket a mandrel flow sub component of a multicomponent
mandrel that extends from an upper end to a lower end of the straddle packer.
The mandrel flow sub has at least one abrasion-resistant fluid nozzle used to
inject well stimulation or well remediation fluid (hereinafter referred to
collectively
as "high pressure fluid") into a section of a wellbore that is pressure
isolated by
the respective spaced-apart upper and lower packer elements when the
respective packer elements are in a packer set condition. In this document,
"flow
sub nozzle" means any orifice, permanent or interchangeable, through which
high
pressure fluid may be pumped, including but not limited to a bore and a slot.
In
the packer set condition the respective upper and lower packer elements are in
high pressure sealing contact with a wellbore. The respective upper and lower
packer elements are compressed to the packer set condition by a modular
pressure cylinder that is activated by the high pressure fluid pumped through
a
tubing string connected to the straddle packer. The modular pressure cylinder
is
assembled from a plurality of identical, interconnected pressure cylinder
modules.
Each hydrualic cylinder module has a cylinder wall, a cylinder chamber and a
piston that reciprocates within the cylinder chamber. The pistons of the
respective
pressure cylinder modules are interconnected by piston coupling sleeves. High
pressure fluid pumped through the tubing string enters the respective cylinder
chambers via respective pressure cylinder fluid ports in the piston coupling
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sleeves. The high pressure fluid urges the pistons and the cylinder walls in
opposite directions along an axis of the active mandrel component, which
compresses the upper and lower packer elements to the packer set condition.
When the pumping of high pressure fluid stops, the upper and lower packer
elements return back to the run-in condition. The plurality of interconnected
pistons provide a large piston area exposed to the high pressure fluid. The
piston
area can be adjusted by adding or removing cylinder modules to/from the
modular
pressure cylinder. A velocity bypass valve on a downhole end of the straddle
packer permits high pressure fluid to flow through the fluid nozzles and the
velocity bypass valve so long as a threshold rate of flow remains at or below
the
predetermined threshold rate of flow. This has the advantages of permitting
the
wellbore to be flushed in an area of the straddle packer to remove debris
before
the packers are set. It also permits the tool to rapidly depressurize and
return to
the run-in condition once high pressure fluid pumping has terminated,
minimizing
a probability that the straddle packer will become "stuck in the hole".
Part No. Part Description
10 Straddle packer
11 Multicomponent mandrel
12 Completion string connection component
13 Multicomponent mandrel central passage
14 Completion string connection
15 Upper packer element compression shoulder
16 Upper packer element sleeve
18 Upper packer element
Upper compression bell
21a, 21b Upper compression bell pressure equalization ports
22 Upper mandrel tube
23 Upper compression bell shoulder
24 Upper sliding sleeve
Upper sliding sleeve threaded connection
26 Upper sliding sleeve coupling
27 Slotted sliding sleeve female coupling end
28 Slotted sliding sleeve
29a, 29b Sliding sleeve finger components
Mandrel flow sub
31 Mandrel flow sub grooves
32a-32h Mandrel flow sub nozzles
33 Slotted sliding sleeve captured end thread
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33a Slotted sliding sleeve coupling thread
34 Lower sliding sleeve coupling
34a Lower sliding sleeve coupling upper thread
34b Lower sliding sleeve coupling lower thread
36 Lower sliding sleeve
37 Lower sliding sleeve threaded connection
38 Slotted sliding sleeve captured end coupling ring
40a,40b Cap screws
42 Lower mandrel tube
44 Mandrel tube crossover component
46 Active mandrel tube component
48 Modular pressure cylinder
49a-49h Active mandrel tube fluid ports
50 Sleeve/cylinder crossover
52a-52j Pressure cylinder pressure equalization ports
53a-53d Active mandrel tube axial grooves
54a-54d Pressure cylinder modules
55a-55d Pressure cylinder walls
56a-56d Pressure pistons
57a-57h Pressure cylinder fluid ports
58a-58d Pressure cylinder male coupling sleeves
59a-59b Pressure cylinder chambers
60a-60d Pressure cylinder female coupling sleeves
62 Pressure cylinder crossover sleeve
64 Lower compression bell
65a, 65b Lower compression bell equalization ports
66a-66d Pressure piston seals
66j Compression bell seal
67a-67d Pressure cylinder seals
68a-68e Pressure cylinder coupling seals
69 Pressure cylinder crossover sleeve seal
70 Lower compression bell male coupling sleeve
72 Lower packer element mandrel sleeve component
74 Lower packer element
76 Lower crossover sub
78 Lower packer element compression shoulder
80 Lower crossover sub male connector
82 Velocity bypass sub
83 Velocity bypass sub threaded downhole end
84 Velocity bypass valve
85a Velocity bypass sub connector end
85b Velocity bypass sub valve end
86 High pressure fluid seal
88a-88b Velocity bypass valve ports
90 Velocity bypass valve spring
92 Velocity bypass valve jet nozzle
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94a, 94b Cap screws
96 Lower end cap
FIG. 1 is a perspective view of one embodiment of the straddle packer 10 with
fluid pressure packer set in accordance with the invention in the run-in
condition.
The straddle packer 10 has a multicomponent mandrel 11, the majority of which
can only be seen in a cross-sectional view (see FIG. 2). The multicomponent
mandrel 11 extends from the uphole end to the downhole end of the straddle
packer 10. On the uphole end of the multicomponent mandrel 11, a completion
string connection component 12 includes a completion string connection 14
(best
seen in FIGs. 2 and 4). A configuration of the completion string connection 14
is
a matter of design choice and dependent on whether the straddle packer 10 is
to
be operated using a coil tubing string (not shown) or jointed tubing string
(not
shown), as is well understood in the art.
The completion string connection component 12 has an upper packer element
compression shoulder 15 and an upper packer element sleeve 16 (see FIGs. 2
and 4) that supports an elastomeric upper packer element 18, the function of
which will be explained below with reference to FIG. 4. On a downhole side of
the
upper packer element 18 is an upper compression bell 20 having an upper
compression bell shoulder 23 for compressing the upper packer element 18. The
upper compression bell 20 slides over the upper element packer sleeve 16, as
will be explained below with reference to FIG. 4. An upper sliding sleeve 24
is
connected to a downhole side of the upper compression bell 20. The upper
sliding
sleeve 24 is connected to an upper sliding sleeve coupling 26, which is in
turn
connected to a female coupling end 27 of a slotted sliding sleeve 28. In one
embodiment, the slotted sliding sleeve 28 has four slotted sliding sleeve
finger
components 29a-29d, two of which, 29a, 29d, can be seen in this view. The
slotted sliding sleeve finger components 29a-29d define four slots that
respectively expose at least one mandrel flow sub nozzle of a mandrel flow sub
30. In this embodiment, the mandrel flow sub 30 has a plurality of mandrel
flow
sub nozzles, 32a-32h (only 32a and 32b are visible in this view - better seen
in
FIGs. 3a and 3b). It should be understood the number of mandrel flow sub
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nozzles is a matter of design choice. A downhole end of the sliding sleeve
finger
components 29a-29d are threadedly connected to a slotted sliding sleeve
captured end coupling ring 38 that surrounds a lower sliding sleeve coupling
34
(see FIG.2) that is threadedly connected to a lower sliding sleeve 36. A
downhole
end of the lower sliding sleeve 36 is connected to a sleeve/cylinder crossover
50
that is in turn connected to a modular pressure cylinder 48 assembled by
interconnecting a plurality of pressure cylinder modules, 54a-54d in this
embodiment. The pressure cylinder module 54d is connected to a lower
compression bell 64 that slides over a lower packer element mandrel sleeve
component 72 (see FIGs. 2 and 4) of the multicomponent mandrel 11, which
supports an elastomeric lower packer element 74. Connected to the lower packer
element mandrel sleeve component 72 is a lower crossover sub 76 having a lower
packer element compression shoulder 78. In one embodiment a velocity bypass
sub 82, which will be explained below with reference to FIGs. 5a and 5b, is
connected to a downhole side of the lower crossover sub 76. A lower end cap
96,
which caps the downhole end of the multicomponent mandrel 11, is connected to
the lower crossover sub 76 or the velocity bypass sub 82 when the velocity
bypass sub 82 is incorporated into the straddle packer 10.
FIG. 2 is a cross-sectional view of the straddle packer 10 shown in FIG. 1 in
the
run-in condition in which the upper packer element 18 and lower packer element
74 are in a relaxed, unset condition suitable for moving the straddle packer
10 to
a desired location in a wellbore. As explained above, the slotted sliding
sleeve 28
is connected to the lower sliding sleeve 36 by the lower sliding sleeve
coupling
34, which is threadedly connected to both the slotted sliding sleeve 28 and
the
lower sliding sleeve 36. The slotted sliding sleeve captured end coupling ring
38
that covers the lower sliding sleeve coupling is likewise threadedly connected
to
the slotted sliding sleeve 28. Rotation of the slotted sliding sleeve captured
end
coupling ring 38 is inhibited by cap screws 40a, 40b.
As explained above, the elastomeric upper packer element 18 is supported on
the upper packer element sleeve 16 of the completion string connection
component 12 of the multicomponent mandrel 11. The multicomponent mandrel
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11 has a central passage 13 that provides an uninterrupted fluid path through
the
multicomponent mandrel 11. The multicomponent mandrel 11 includes the
following interconnected components: the completion string connection
component 12, which is threadedly connected to an upper mandrel tube 22; the
mandrel flow sub 30 connected to a downhole end of upper mandrel tube 22; the
wear-resistant, replaceable mandrel flow sub nozzle(s), in this embodiment 32a-
32h (only 6 of which, 32a-32b, 32c-32d and 32e-32f, are visible in this view);
a
lower mandrel tube 42 connected to a downhole end of the mandrel flow sub 30;
a mandrel tube crossover component 44 connected to a downhole end of the
lower mandrel tube 42; an active mandrel tube component 46 that supports the
modular pressure cylinder 48 is connected to a downhole end of the mandrel
tube
crossover component 44; the lower packer element mandrel sleeve component
72 connected to a downhole end of the active mandrel tube component 46; the
lower crossover sub 76 connected to the downhole end of the lower packer
element mandrel sleeve component 72; and the optional velocity bypass sub 82
connected to a lower crossover sub male connector 80 of the lower crossover
sub 76.
In one embodiment the velocity bypass sub 82 has a threaded downhole end 83
to permit the connection of another downhole tool or, in this embodiment, a
lower
end cap 96 that caps the central passage 13 of the multicomponent mandrel 11
and prevents debris from entering the velocity bypass sub 82 and the central
passage 13 if the straddle packer 10 is run into a downhole proppant plug, or
other debris in a wellbore. In an alternate embodiment the lower end cap 96 is
connected directly to the lower crossover sub 76.
The active mandrel tube component 46 slidably supports the respective pressure
cylinder modules 54a-54d of the modular pressure cylinder 48. As explained
above, the number of pressure cylinder modules used in the straddle packer 10
is a matter of design choice, but four modules has been found to be
appropriate
for many applications. If the number of pressure cylinder modules is changed,
a
length of the active mandrel tube component 46 is modified accordingly, as
will
be readily understood by those skilled in the art. In this embodiment, the
active
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mandrel tube component 46 has two active mandrel tube fluid ports
(collectively
49a-49h) that provide fluid communication between the central passage 13 and
each of the respective pressure cylinder modules 54a-54d. Active mandrel tube
axial grooves 53a-53d respectively ensure fluid communication with the
respective pressure cylinder modules 54a-54d regardless of a relative rotation
of
the active mandrel tube component 46 with respect to the modular pressure
cylinder 48. The active mandrel tube axial grooves 53a-53d also ensure fluid
communication between the central passage 13 and the respective pressure
cylinder modules 54a-54d when the straddle packer 10 is shifted from the run-
in
condition the to set condition shown in FIG. 4.
In this embodiment, each of the pressure cylinder modules 54a-54d are
identical
and each pressure cylinder module 54a-54d respectively includes the following
components: a pressure cylinder wall 55a-55d; a pressure piston 56a-56d with
respective pressure piston seals 66a-66d that respectively seal against an
inner
surface of the respective pressure cylinder walls 55a-55d; each pressure
piston
56a-56d reciprocates within a pressure cylinder chamber 59a-59d; pressure
cylinder seals 67a-67d respectively inhibit the migration of fluid out of the
respective pressure cylinder chambers 59a-59d; each pressure piston 56a-56d
has a pressure cylinder male coupling sleeve 58a-58d and a pressure cylinder
female coupling sleeve 60a-60d; in one embodiment the respective pressure
cylinder male coupling sleeves 58b-58d may have an external thread that
engages an internal thread in the respective pressure cylinder female coupling
sleeves 60a-60c to connect the respective pressure pistons 56a-56d together,
in
another embodiment the respective cylinder modules 54a-54d are overlapped as
shown but not threadedly connected and held together by compression between
the upper packer element 18 and the lower packer element 74; respective
pressure cylinder coupling seals 68b-68d inhibit any migration of fluid
between
the pressure cylinder male coupling sleeves 58b-58d and the pressure cylinder
female coupling sleeves 60a-60c; pressure cylinder fluid ports 57a-57h let the
high pressure fluid flow through active mandrel tube fluid ports 49a-49h into
the
respective pressure cylinder chambers 59a-59d; pressure cylinder pressure
equalization ports 52a-52j in the respective cylinder walls 55a-55d equalize
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pressure behind the respective pressure pistons 56a-56d with ambient wellbore
pressure. In one embodiment the active mandrel tube fluid ports 49a-49h and
the pressure cylinder pressure equalization ports 52a-52j are provided with
high
pressure fluid filters (for example, sintered metal filters that known in the
art (not
shown)) that permit fluid to pass through the respective active mandrel tube
fluid
ports 49a-49h and pressure cylinder pressure equalization ports 52a-52j but
inhibit particulate matter from migrating into the respective pressure
cylinder
chambers 59a-59d.
A pressure cylinder crossover sleeve 62 caps the pressure cylinder male
coupling
sleeve 58a of the pressure cylinder module 54a. A pressure cylinder crossover
sleeve seal 69 provides a fluid seal between the pressure cylinder crossover
sleeve 62 and the active mandrel tube component 46, and a pressure cylinder
coupling seal 68a provides a fluid seal between the pressure cylinder
crossover
sleeve 62 and the pressure cylinder male coupling sleeve 58a. The pressure
cylinder female coupling sleeve 60d is threadedly connected to a lower
compression bell male coupling sleeve 70. A pressure cylinder coupling seal
68e
provides a high pressure fluid seal between the pressure cylinder female
coupling
sleeve 60d and the lower compression bell male coupling sleeve 70. A
compression bell seal 66j prevents the migration of fluid between the lower
compression bell male coupling sleeve 70 and the active mandrel tube
component 46.
When high pressure fluid is pumped into the straddle packer 10, the modular
pressure cylinder 48 compresses the upper packer element 18 and the lower
packer element 74 to isolate a section of the wellbore between the two packer
elements 18, 74 after a pumped fluid rate exceeds a flow rate of the flow sub
nozzle(s) 32a-32h. If the optional velocity bypass sub 82 is present, the
modular
pressure cylinder 48 compresses the upper packer element 18 and the lower
packer element 74 to isolate a section of the wellbore between the two packer
elements 18, 74 after the velocity bypass valve closes, as will be explained
below
in detail with reference to FIG. 4.
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FIG. 3a is an exploded cross-sectional view of mandrel tubes 22, 42 and
mandrel
flow sub 30 of the straddle packer 10 shown in FIG. 2. As explained above, the
upper mandrel tube 22 is threadedly connected to the mandrel flow sub 30. In
this embodiment, the mandrel flow sub 30 has eight replaceable mandrel flow
sub nozzles 32a-32h, though the number of mandrel flow sub nozzles is a matter
of design choice. The lower mandrel tube 42 is threadedly connected to the
downhole side of the mandrel flow sub 30.
FIG. 3b is an exploded side elevational view of the mandrel tubes 22, 42 and
the
mandrel flow sub 30 shown in FIG. 3a. In this embodiment, the mandrel flow sub
30 is generally cylindrical but has four spaced apart axial mandrel flow sub
grooves 31 in a top surface thereof that respectively receive one of the
slotted
sliding sleeve finger components 29a-29d (see FIG. 3c). When the slotted
sliding
sleeve 28 is slid over the mandrel flow sub 30, a top surface of the sliding
sleeve
finger components is flush with outer surfaces of the mandrel flow sub 30, as
can
be seen in FIGs. 2 and 4.
FIG. 3c is an exploded cross-sectional view of sliding sleeves 24, 28, 36 that
reciprocate, from the run-in condition to the upper packer set condition and
back
to the run-in condition, on the upper mandrel tube 22, the mandrel flow sub 30
and the lower mandrel tube 42 shown in FIG. 3b. The upper sliding sleeve 24
slides over the upper mandrel tube 22. As explained above, the upper sliding
sleeve 24 is threadedly connected by upper sliding sleeve thread connection 25
to the upper sliding sleeve coupling 26. The upper sliding sleeve coupling 26
is
in turn threadedly connected to the slotted sliding sleeve female coupling end
27
of the slotted sliding sleeve 28. The slotted sliding sleeve finger components
29a-
29d (only 29b and 29c are visible in this view) are threadedly connected by a
slotted sleeve coupling thread 33a to a lower sliding sleeve coupling upper
thread
34a. The lower sliding sleeve 36 is threadedly connected to the lower sliding
sleeve coupling 34 by a lower sliding sleeve coupling lower thread 34b that
engages a lower sliding sleeve threaded connection 37. As explained above, the
slotted sliding sleeve captured end coupling ring 38 covers the lower sliding
sleeve coupling 34 and threadedly engages the slotted sliding sleeve captured
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end thread 33. After the slotted sliding sleeve captured end coupling ring 38
is
fully threaded onto the slotted sleeve captured end thread 33 of the slotted
sliding
sleeve 28, the cap screws 40a, 40b are tightened to inhibit rotational
movement.
FIG. 4 is a cross-sectional view of the embodiment of the straddle packer 10
shown in FIG. 1 in the packer set condition. All of the components of the
straddle
packer 10 have been explained with reference to FIGs. 1-3, with the exception
of
some of the parts of the velocity bypass sub 82, which will be explained below
with reference to FIGs. 5a and 5b, and that explanation of those parts will
not be
repeated, except insofar as is necessary to describe the functioning of the
straddle packer 10.
As explained above, when high pressure fluid is pumped into the straddle
packer
10, it exits through the mandrel flow sub nozzle(s) 32a-32h and, if the
optional
velocity bypass sub 82 is present, the velocity bypass valve jet nozzle 92 and
velocity bypass sub ports 88a, 88b of the open velocity bypass valve 84 (see
FIG.
2) until the pump rate exceeds a threshold pump rate predetermined by an
orifice
size of the velocity bypass valve jet nozzle 92. In one embodiment, the
threshold
pump rate is, for example, about 3 bbl/minute. When the threshold pump rate is
exceeded, the velocity bypass valve 84 is forced close, as shown in this view,
and fluid flow through velocity bypass valve ports 88a, 88b ceases. When fluid
flow through the velocity bypass sub 82 ceases, fluid pressure rapidly builds
within the central passage 13 of the multicomponent mandrel 11 because the
rate
of discharge from the central passage 13 is throttled by the mandrel flow sub
nozzle(s) 32a-32h. Consequently, the high pressure fluid is forced through the
active mandrel tube fluid ports 49a-49h and flows through the pressure
cylinder
fluid ports 57a-57h of the respective pressure cylinder modules 54a-54d and
into
the respective pressure cylinder chambers 59a-59d. As explained above with
reference to FIG. 2, in one embodiment the pressure pistons 56a-56d are
connected to the lower compression bell 64, and the pressure cylinder walls
55a-
55d are connected to the interconnected sliding sleeves (lower sliding sleeve
36,
slotted sliding sleeve 28 and upper sliding sleeve 24), which are in turn
connected
to the upper compression bell 20. The high pressure fluid forced into the
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respective pressure cylinder chambers 59a-59d simultaneously urges the
pressure pistons 56a-56d and the pressure cylinder walls 55a-55d in opposite
directions along an axis of the active mandrel tube component 46. Since the
opposite ends of the straddle packer 10 are immovably connected to the
multicomponent mandrel 11, the upper compression bell 20 is urged to slide
over
the upper packer element sleeve 16 by the movement of the pressure cylinder
walls 55a-55d, and the lower compression bell 64 is urged to slide over the
lower
packer element mandrel sleeve component 72 by the movement of the pressure
pistons 56a-56d. The upper compression bell 20 compresses the upper packer
element 18 and the lower compression bell 64 compresses the lower packer
element 74 into respective sealing contact with a wellbore. As the upper
compression bell 20 slides over the upper packer element sleeve 16, pressure
within the upper compression bell 20 is equalized by fluid passing through
upper
compression bell pressure equalization ports 21a, 21b. Likewise, as the lower
compression bell 64 slides over the lower packer element mandrel sleeve
component 72, pressure within the lower compression bell 64 is equalized by
fluid
passing through lower compression bell pressure equalization ports 65a, 65b.
In
one embodiment the pressure equalization ports 21a, 21b and 65a, 65b are all
provided with particulate filters (not shown) to inhibit the migration of
solids into
the respective upper compression bell 20 and the lower compression bell 64. As
understood by those skilled in the art, the higher the fluid pressure of the
high
pressure fluid, the greater the compression of the upper packer element 18 and
the lower packer element 74.
After the pumping of the high pressure fluid is completed and pumping stops,
the
high pressure fluid may or may not continue to flow through the mandrel flow
sub
nozzle(s) 32a-32h. If the optional velocity bypass sub 82 is present, once the
rate
of flow of the high pressure fluid drops below the predetermined threshold,
the
velocity bypass valve 84 opens and fluid rapidly drains from the central
passage
13, which drains the respective pressure cylinder chambers 59a-59d. As the
pressure cylinder chambers 59a-59d are drained, the upper packer element 18
and the lower packer element 74 return to the relaxed condition, which urges
the
pressure cylinder walls 55a-55d and the pressure pistons 56a-56d back to the
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run-in condition seen in FIG. 2. The straddle packer 10 can then be moved to
another location in the wellbore or removed from the well.
FIG. 5a is a cross-sectional view of the velocity bypass sub 82 of the
straddle
packer 10 shown in FIGs. 1, 2, with the velocity bypass valve 84 in the open,
run-
in condition. In order to permit assembly and servicing of the velocity bypass
valve 84, the velocity bypass sub 82 is constructed in two parts, a velocity
bypass
sub connector end 85a that threadedly connects to the lower crossover sub male
connector 80 of the lower crossover sub 76; and, a velocity bypass sub valve
end
85b that threadedly connects to the velocity bypass sub connector end 85a. Cap
screws 94a, 94b inhibit rotation of the velocity bypass sub valve end 85b with
respect to the velocity bypass sub connector end 85a. A velocity bypass valve
spring 90 constantly urges the velocity bypass valve 84 to the open condition.
A
high pressure seal 86 inhibits fluid migration around the velocity bypass
valve 84.
As explained above, in the open position high pressure fluid flows through a
replaceable velocity bypass valve jet nozzle 92 and out through the open
velocity
bypass valve ports 88a, 88b. A nozzle size of the velocity bypass valve jet
nozzle
92 determines a threshold rate of flow required to overcome the resilience of
the
velocity bypass valve spring 90 to force the velocity bypass valve 84 to the
closed
condition shown in FIG. 5b.
FIG. 5b is a cross-sectional view of the velocity bypass sub 82 of the
straddle
packer 10 shown in FIG. 4, when the straddle packer 10 is in the set condition
or
in transition to or from the set condition. As can be seen, the velocity
bypass valve
84 has been urged, by a rate of high pressure fluid flow that exceeds the
threshold
determined by the velocity bypass jet nozzle 92, to the closed condition in
which
high pressure fluid no longer flows through the velocity bypass valve ports
88a-
88b. In this condition of the velocity bypass valve 84, the high pressure
fluid sets
the upper packer element 18 and the lower packer element 74, as explained
above in detail.
The explicit embodiments of the invention described above have been presented
by way of example only. The scope of the invention is therefore intended to be
limited solely by the scope of the appended claims.
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