Note: Descriptions are shown in the official language in which they were submitted.
201701-20CA
STRADDLE PACKER WITH FLUID PRESSURE PACKER
SET AND VELOCITY BYPASS FOR PROPPANT-LADEN
FRACTURING FLUIDS
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
for
proppant-laden fracturing fluids used for cased wellbore or open hole well
stimulation or remediation.
BACKGROUND OF THE INVENTION
Wellbore 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. In addition, many straddle
packers
are set and unset using work string manipulations controlled at the surface.
However, controlled work string manipulation becomes difficult, if not
impossible,
in the very long lateral bores that are common now. This is due to the
frictional
drag on the work string that results from the inherent corkscrew character of
those
very long lateral bores. Furthermore, hydrocarbon well completion and re-
completion work frequently requires the placement of large quantities of
heavily
proppant-laden stimulation fluids. Those fluids tend to cause "wash" and/or
"screen out" in a straddle packer. Most straddle packers are poorly designed
to
resist proppant wash or recover from proppant screen out.
There therefore exists a need for a novel straddle packer with fluid pressure
packer set and velocity bypass for proppant-laden fracturing fluids that
overcomes the operational issues associated with known prior art straddle
packers.
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SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a long-reach straddle
packer
with fluid pressure packer set and velocity bypass for proppant-laden
fracturing
fluids.
The invention therefore provides a straddle packer with fluid pressure packer
set
for proppant-laden fracturing fluids, comprising a proppant filtration plug
body that
occludes a central passage of the straddle packer downhole of radial fluid
paths
through a frac sub of the straddle packer and uphole of fluid ports of a
compression cylinder of the straddle packer, the proppant filtration plug body
excluding solid components of high-pressure fluid pumped into the central
passage while permitting fluid components of the high-pressure fluid to flow
therethrough.
The invention further provides a straddle packer with fluid pressure packer
set for
proppant-laden fracturing fluids, comprising a slotted frac hub having a
central
passage and at least one frac hub slot in fluid communication with the central
passage, the slotted frac hub supporting a proppant filtration plug body that
occludes the central passage downhole of the at least one frac hub slot, the
proppant filtration plug body excluding solid components of high-pressure
fluid
pumped into the straddle packer from a central passage of the straddle packer
downhole of the slotted frac hub, while permitting fluid components of the
high-
pressure fluid to flow therethrough.
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 long-reach straddle packer
with fluid pressure packer set and velocity bypass for proppant-laden
fracturing
fluids 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;
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FIG. 3 is a cross-sectional view taken between lines labeled "FIG. 3" of the
straddle packer shown in FIG. 2;
FIG. 4 is a perspective view of a slotted frac hub shown in FIG. 3;
FIG. 5 is a perspective view of one embodiment of a proppant filter body
retained
by the slotted frac hub shown in FIGs. 3 and 4;
FIG. 6a is a perspective view of another embodiment of a proppant filter body
retained by the slotted frac hub shown in FIGs. 3 and 4;
FIG. 6b is an end view of the proppant filter body shown in FIG. 6a;
FIG. 7 is a cross-sectional view between lines labeled "FIG. 7" of the
straddle
packer shown in FIG. 2;
FIG. 8a is a perspective view of one embodiment of a pressure cylinder
pressure
equalization port sleeve filter of the straddle packer shown in FIG. 2;
Fig. 8B is a cross-sectional view of the sleeve filter shown in FIG. 8a;
FIG. 9a is a perspective view of one embodiment of a compression bell pressure
equalization sleeve filter of the straddle packer shown in FIG. 2; and
Fig. 9b is a cross-sectional view of the sleeve filter shown in FIG. 9a.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention provides a long-reach straddle packer with fluid pressure packer
set and velocity bypass for proppant-laden fracturing fluids designed to be
used
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 slotted
frac hub component of a multicomponent mandrel that extends from an upper
end to a lower end of the straddle packer. In one embodiment, the slotted frac
hub has at least one slot used to inject proppant-laden well stimulation or
well
remediation fluid (hereinafter referred to collectively as "high-pressure
fluid") into
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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. It should be understood that the slotted frac hub may be
replaced with a frac hub having ports, nozzles, or the like as a matter of
design
choice. As used in this document "slotted frac hub" means a frac hub having a
central passage and radial fluid paths (slots, ports or nozzles) that provide
fluid
communication from the central passage through a sidewall of the frac hub.
In the packer set condition the respective upper and lower packer elements are
in high-pressure sealing contact with the wellbore. The respective upper and
lower packer elements are compressed to the packer set condition by a pressure
cylinder that is activated by the high-pressure fluid pumped through a tubing
string connected to the straddle packer. In one embodiment, the pressure
cylinder
is a modular pressure cylinder is assembled from a plurality of identical,
interconnected pressure cylinder modules. The pressure cylinder is isolated
from
proppant in the high-pressure fluid by a proppant filtration plug body. In one
embodiment, the proppant filtration plug body is supported by a downhole end
of
the slotted frac hub. The proppant filtration plug body may be supported
anywhere in a central passage of the straddle packer downhole of the slotted
frac
hub fluid passages and uphole of pressure cylinder fluid ports. Filtered high-
pressure fluid pumped through the tubing string enters respective cylinder
chambers via respective pressure cylinder fluid ports in piston coupling
sleeves.
The filtered high-pressure fluid urges the pistons and cylinder walls in
opposite
directions along an axis of an active mandrel component of the pressure
cylinder,
which simultaneously compresses the upper and lower packer elements to the
packer set condition. As the pistons move in the piston chambers, fluid in an
annulus of the well bore is drawn into the modular cylinder through respective
groups of pressure equalization ports having respective filtration sleeve
bodies
that inhibit an entry into the pressure cylinder of proppant in the annulus of
the
well bore.
A velocity bypass valve 84 on a downhole end of the straddle packer permits
filtered fluid to flow through the velocity bypass valve 84 and out through
fluid
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ports so long as a pump rate of the fluid remains at or below a predetermined
threshold. This permits the tool to rapidly depressurize and return to the run-
in
condition once high-pressure fluid pumping into the straddle packer has been
terminated, and assists in clearing proppant surrounding the straddle packer
in
the event of a screen out, minimizing a probability that the straddle packer
might
become "stuck in the hole".
Part No. Part Description
Straddle packer
11 Multicomponent mandrel
12 Completion string connection component
13 Multicomponent mandrel central passage
14 Completion string connection
Upper packer element compression shoulder
16 Upper packer element sleeve
18 Upper packer element
Upper compression bell
21 Upper compression bell pressure equalization ports
22 Upper mandrel tube
23 Upper packer element compression ring
24 Upper sliding sleeve
26 Upper sliding sleeve coupling
27 Slotted sliding sleeve female coupling end
28 Slotted sliding sleeve
29 Slotted sliding sleeve fingers
Slotted frac hub
31 Slotted frac hub grooves
32 Slotted frac hub slots
33 Anti-preset floating ring
34 Lower sliding sleeve coupling
Proppant filtration plug body
35c Proppant filtration plug body sintered metal core
35a Proppant filtration plug body ¨ alternate embodiment
35ac Proppant filtration plug body sintered metal core ¨
alternate
35rn Proppant filtration plug body retainer nut
36 Lower sliding sleeve
38 Slotted sliding sleeve captured end coupling ring
42 Lower mandrel tube
44 Mandrel tube crossover component
46 Active mandrel tube components
47 Inactive mandrel tube component
48 Modular pressure cylinder
50 Sleeve/cylinder crossover
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51 Crossover pressure equalization ports
51sf Crossover pressure equalization port sleeve filter
52 Pressure cylinder pressure equalization ports
52sf Pressure cylinder pressure equalization port sleeve filters
54 Pressure cylinder modules
55 Pressure cylinder walls
56 Pressure pistons
57 Pressure cylinder fluid ports
59 Pressure cylinder chambers
62 Pressure cylinder crossover sleeve
64 Lower compression bell
66 Lower compression bell equalization ports
66st Lower compression bell equalization port sleeve filter
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
84 Velocity bypass valve
85a Velocity bypass sub connector end
85b Velocity bypass sub valve end
88 Velocity bypass valve ports
90 Velocity bypass valve spring
92 Velocity bypass valve jet nozzle
96 Lower end cap
FIG. 1 is a perspective view of one embodiment of the straddle packer 10 with
fluid pressure packer set for proppant-laden fracturing fluids 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 FIG. 2). 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.
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The completion string connection component 12 has an upper packer element
compression shoulder 15 and an upper packer element sleeve 16 (see FIGs. 2)
that supports an elastomeric upper packer element 18, the function of which is
explained in Applicant's above-referenced co-pending patent application. On a
downhole side of the upper packer element 18 is an upper compression bell 20
having upper compression bell equalization ports 21, and an upper packer
element compression ring 23 for compressing the upper packer element 18. The
upper compression bell 20 slides the upper packer element compression ring 23
over the upper element packer sleeve 16. 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 three slotted sliding sleeve finger components
29. In
this embodiment, the slotted sliding sleeve finger components 29 define three
slots that respectively expose a slotted frac hub slot 32 of a slotted frac
hub 30.
It should be understood the number of slotted sliding sleeve finger components
29 and frac hub slots 32 is a matter of design choice. An anti-preset floating
ring
33, having the same external shape as the slotted frac hub 30, is received in
the
slotted sliding sleeve 28 and reciprocates in a limited range on the multiple
component mandrel 11. The anti-preset floating ring 33 permits the straddle
packer 10 to be suspended in a vertical orientation without compressing the
upper
packer element 18 or a lower packer element 74. It therefore inhibits pre-set
when
the straddle packer 10 is run into a vertical well bore or is being pushed
through
a deviated well bore.
A downhole end of the sliding sleeve finger components 29 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 having a group of crossover
pressure equalization ports 51 and a crossover pressure equalization sleeve
filter
51sf (see FIG. 2) to inhibit a migration of well bore debris into the
sleeve/cylinder
crossover 50. The sleeve/cylinder crossover 50 is in turn connected to a
modular
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pressure cylinder 48 assembled by interconnecting a plurality of pressure
cylinder
modules 54, respectively having a respective group of pressure cylinder
pressure
equalization ports 52. The modular pressure cylinder 48 is connected to a
lower
compression bell 64 having a group of lower compression bell pressure
equalization ports 66. The lower compression bell 64 slides over a lower
packer
element mandrel sleeve component 72 (see FIG. 2) 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 this
embodiment a velocity bypass sub 82, described in detail in Applicant's above-
referenced co-pending United States patent application, is connected to a
downhole side of the lower crossover sub 76. The velocity bypass sub 82 has a
velocity bypass valve 84 that supports a velocity bypass valve jet nozzle 92
that
lets fluid pass therethrough at a predetermined rate. A velocity bypass valve
spring 90 urges the velocity bypass valve 84 to a normally open position in
which
a plurality of velocity bypass valve ports 88 let fluid flow out of the
central passage
13. When a predetermined fluid pump rate is exceeded, the bias of the velocity
bypass spring 90 is overcome and the velocity bypass valve 84 closes the
velocity
bypass valve ports 88. A lower end cap 96, which caps the downhole end of the
multicomponent mandrel 11, is connected to a downhole end of the velocity
bypass sub 82.
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 the lower packer
element 74 are in a relaxed, unset condition suitable for moving the straddle
packer 10 to a desired location in a well bore. 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 34 is likewise
threadedly connected to the slotted sliding sleeve 28.
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As also 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
11 has a central passage 13 that provides a fluid path through an entire
length of
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
slotted frac hub 30 connected to a downhole end of upper mandrel tube 22; a
lower mandrel tube 42 connected to a downhole end of the slotted frac hub 30;
a
mandrel tube crossover component 44 connected to a downhole end of the lower
mandrel tube 42; interconnected active mandrel tube components 46 that support
the respective modular pressure cylinder modules 54 are connected to a
downhole end of the mandrel tube crossover component 44; the lower packer
element mandrel sleeve component 72 connected to an inactive mandrel tube
component 47, which is connected to a downhole end of the last 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 velocity
bypass sub 82 connected on a velocity bypass sub connector end 85a 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, the
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.
The active mandrel tube components 46 collectively slidably support the
respective pressure cylinder modules 54 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 have been found to be
appropriate for many applications. If the number of pressure cylinder modules
is
changed, the number of the active mandrel tube components 46 is also
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correspondingly changed, as will be readily understood by those skilled in the
art.
In this embodiment, the active mandrel tube components 46 respectively have
pressure cylinder fluid ports (collectively 57) that provide fluid
communication
between the central passage 13 and a pressure cylinder chamber 59 of each of
the respective pressure cylinder modules 54.
In this embodiment, each of the pressure cylinder modules 54 are identical and
each pressure cylinder module 54 respectively includes the following
components: a pressure cylinder wall 55; a pressure piston 56; each pressure
piston 56 reciprocates within the pressure cylinder chamber 59. The pressure
cylinder fluid ports 57 let the high-pressure fluid flow into the respective
pressure
cylinder chambers 59; respective groups of pressure cylinder pressure
equalization ports 52 in the respective pressure cylinder walls 55 equalize
pressure behind the respective pressure cylinder pistons 56 with ambient
wellbore pressure. The pressure cylinder pressure equalization port sleeve
filters
52sf exclude wellbore proppant from the modular pressure cylinder 48.
A pressure cylinder crossover sleeve 62 caps the last pressure cylinder module
54. The pressure cylinder crossover sleeve 62 is connected to the lower
compression bell 64 having the group of lower compression bell pressure
equalization ports 66. A lower compression bell pressure equalization port
sleeve
filter 66sf inhibits migration of wellbore debris into the lower compression
bell 64
through the group of lower compression bell pressure equalization ports 66.
When proppant-laden high-pressure fluid is pumped into the straddle packer 10,
a proppant filtration plug body 35 supported in a lower end of the slotted
frac hub
excludes proppant from the central passage 13 downhole of the slotted frac
25 hub 30, while permitting fluid components of the high-pressure fluid to
flow
therethrough. In one embodiment, the proppant filtration plug body is a 3-D
printed body with a sintered metal core, as will be explained in more detail
with
reference to FIGs. 3, 5, 6A and 6B. The proppant-free fluid that flows through
the
proppant filtration plug body 35 activates the modular pressure cylinder 48.
The
30 modular pressure cylinder 48 simultaneously compresses the upper packer
element 18 and the lower packer element 74 to isolate a section of the
wellbore
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between the two packer elements 18, 74 after the velocity bypass valve 84
closes
when the pump rate exceeds the velocity bypass threshold, as explained in
detail
in Applicant's above-referenced co-pending United States patent application,
which explains in detail the operation and function of the modular pressure
cylinder 48.
FIG. 3 is a cross-sectional view taken between lines labeled "FIG. 3" of the
straddle packer shown in FIG. 2. As can be seen, the proppant filtration plug
body
35 has a proppant filtration plug body sintered metal core 35c that permits
fluid
components of the high-pressure fluid to flow through the proppant filtration
plug
body 35, but excludes solid components and diverts excluded solid components
through the slotted frac hub slots 32. In one embodiment, the sintered metal
core
35c is 3D-printed. A filtration plug body retainer nut 35rn retains the
proppant
filtration plug body 35 in the downhole end of the slotted frac hub 30.
FIG. 4 is a perspective view of a slotted frac hub shown in FIG. 3. In this
embodiment, the slotted frac hub 30 includes three slotted frac hub grooves 31
that respectively receive one of the slotted sliding sleeve fingers 29 (see
FIG. 1).
As explained above, the number of slotted frac hub slots 32, and hence the
number of slotted frac grooves 31 is a matter of design choice. As will be
understood by those skilled in the art, the slotted frac hub 30 may also have
more
than one slotted frac hub slot 32 between each slotted frac hub groove 31.
FIG. 5 is a perspective view of one embodiment of a proppant filtration plug
body
retained by the slotted frac hub 30 shown in FIGs. 3 and 4. In this
embodiment,
the proppant filtration plug body 35 has a frusta-conical uphole end.
FIG. 6a is a perspective view of another embodiment of a proppant filtration
plug
body 35a with a sintered metal core 35ac retained by the slotted frac hub 30
shown in FIGs. 3 and 4. In this embodiment, the proppant filtration plug body
35a
has three circum-inclined flat surfaces that respectively divert high-pressure
fluid
into the respective slotted frac hub slots 32. In one embodiment the sintered
metal
core 35ac is 3D-printed.
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FIG. 6b is an uphole end view of the proppant filtration plug body 35a shown
in
FIG. 6a.
FIG. 7 is a cross-sectional view between lines labeled "FIG. 7" of the
straddle
packer shown in FIG. 2, providing an enlarged view of one pressure cylinder
pressure equalization port sleeve filter 52sf and the lower compression bell
sleeve filter 66sf. In one embodiment, each of these sleeve filters 51sf, 52sf
and
66sf are 3D printed sintered metal bodies. As understood by those skilled in
the
art, other sintered metal forming or casting techniques may also be used to
create
the respective sleeve filters 51sf, 52sf and 66sf.
FIG. 8a is a perspective view of one embodiment of a pressure cylinder
pressure
equalization port sleeve filter 52sf of the straddle packer 10 shown in FIG.
2, and
Fig. 8B is a cross-sectional view of the pressure cylinder pressure
equalization
port sleeve filter 52sf shown in FIG. 8a.
FIG. 9a is a perspective view of one embodiment of a compression bell pressure
equalization sleeve filter 66fs of the straddle packer 10 shown in FIG. 2. Due
to
the shape of the receiving cavity in the lower compression bell 64 (see FIG.
7) in
this embodiment, the compression bell pressure equalization sleeve filter 66fs
is
axially bifurcated to facilitate insertion into the lower compression bell 64.
Fig. 9b
is a cross-sectional view of the filter body shown in FIG. 9a.
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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