U.S. patent application number 16/994429 was filed with the patent office on 2022-02-17 for frac plug system with a setting mandrel and fluid bypass slots.
This patent application is currently assigned to CNPC USA Corp.. The applicant listed for this patent is CNPC USA Corp.. Invention is credited to Peng CHENG, Richard HERRERA, Yu LIU, Xu WANG, Jianpeng YUE.
Application Number | 20220049572 16/994429 |
Document ID | / |
Family ID | 1000006122297 |
Filed Date | 2022-02-17 |
United States Patent
Application |
20220049572 |
Kind Code |
A1 |
YUE; Jianpeng ; et
al. |
February 17, 2022 |
FRAC PLUG SYSTEM WITH A SETTING MANDREL AND FLUID BYPASS SLOTS
Abstract
The frac plug system includes a setting mandrel, a sleeve
member, a sealing member, a cone assembly, and a slip device. The
setting mandrel includes a plurality of fluid bypass slots. The
sleeve member includes a sleeve body with an abutment end. The
setting mandrel has a first configuration without fluid flow
through the frac plug system, and a second configuration with fluid
flow through the frac plug system. The methods of the present
invention include running the frac plug system in the first
configuration and the sealing member in an extended position for a
first setting stage, moving the setting mandrel to the second
configuration with the sealing member in an expanded position, and
then returning the setting mandrel to the first configuration for a
second setting state. If the placement is wrong, the method
includes removing the frac plug system in the first setting
stage.
Inventors: |
YUE; Jianpeng; (Sugar Land,
TX) ; CHENG; Peng; (Sugar Land, TX) ; LIU;
Yu; (Beijing, CN) ; WANG; Xu; (Beijing,
CN) ; HERRERA; Richard; (Spring, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CNPC USA Corp. |
Houston |
TX |
US |
|
|
Assignee: |
CNPC USA Corp.
|
Family ID: |
1000006122297 |
Appl. No.: |
16/994429 |
Filed: |
August 14, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 2200/01 20200501;
E21B 43/26 20130101; E21B 33/1293 20130101; E21B 33/1208
20130101 |
International
Class: |
E21B 33/12 20060101
E21B033/12; E21B 43/26 20060101 E21B043/26; E21B 33/129 20060101
E21B033/129 |
Claims
1. A frac plug system, comprising: a setting mandrel being
comprised of: a mandrel body with an outer mandrel surface, a seal
end and a flow end opposite said seal end; a plurality of fluid
bypass slots extending longitudinally along said mandrel body from
said flow end toward said seal end, each slot having an opened end
at said flow end of said mandrel body and a closed end 34 between
said seal end and said flow end; and a sealing shoulder surface at
said seal end, said closed end being between said sealing shoulder
surface and said flow end; a sleeve member being comprised of: a
sleeve body with an outer sleeve surface, an abutment end and a
free end opposite said abutment end, wherein said setting mandrel
has a first configuration with said seal end adjacent said abutment
end of said sleeve member, and a second configuration with said
closed end between said seal end and said abutment end; a sealing
member being mounted around said sleeve member between said
abutment end and said free end, said sealing member having an
expanded position and an extended position, said sealing member in
said expanded position having a diameter larger than said sealing
member in said extended position; a cone assembly being mounted
around said sleeve member and being in mechanical engagement with
said sealing member; and a slip device being mounted around said
sleeve member, said cone assembly being in sliding engagement with
said slip device, wherein said second configuration of said setting
mandrel corresponds to said sealing member in said expanded
position, and wherein said first configuration of said setting
mandrel corresponds to both said sealing member in said expanded
position and said sealing member in said extended position.
2. The frac plug system, according to claim 1, wherein said setting
mandrel is further comprised of an O-ring groove between said
closed end and said opened end of each slot, further comprising: an
O-ring set in said O-ring groove.
3. The frac plug system, according to claim 2, wherein said setting
mandrel is further comprised of an additional O-ring groove between
said closed end and said O-ring groove opened end of each slot,
further comprising: an additional O-ring set in said additional
O-ring groove.
4. The frac plug system, according to claim 1, wherein said
abutment end is comprised of a conical wedge having a first end
facing said sealing shoulder surface and a second end opposite said
first end, said first end being wider than said second end.
5. The frac plug system, according to claim 4, said first end being
in slide fit engagement with said sealing shoulder surface in said
first configuration.
6. The frac plug system, according to claim 4, wherein said second
end is in mechanical engagement with said sealing member so as to
transition said sealing member from said extended position to said
expanded position.
7. The frac plug system, according to claim 1, wherein said sealing
member is between said abutment end and said cone assembly, and
wherein said cone assembly is between said sealing member and said
slip device.
8. The frac plug system, according to claim 7, wherein said slip
device is farther from said sleeve member with said sealing member
in said expanded configuration than with said sealing member in
said extended configuration.
9. The frac plug system, according to claim 7, wherein said cone
assembly is closer to said slip device with said sealing member in
said expanded configuration than with said sealing member in said
extended configuration.
10. A method for isolating a zone in a wellbore, the method
comprising the steps of: running a frac plug system, according to
claim 1, in a borehole with a setting tool, said setting mandrel
being in said first configuration, said sealing member being in
said extended position; placing said frac plug system in a location
in the wellbore; transitioning said sealing member in said extended
position to said sealing member in said expanded position with said
frac plug system in said location; moving said setting mandrel from
said first configuration to said second configuration so as to form
a fluid connection through said fluid bypass slots in a first
setting stage; and moving said setting mandrel from said second
configuration to said first configuration so as to seal said fluid
connection in a second setting stage.
11. The method for isolating, according to claim 10, wherein the
step of placing said frac plug system in said location comprises
the step of breaking said setting mandrel with said setting
tool.
12. The method for isolating, according to claim 10, wherein the
step of transitioning said sealing member in said extended position
to said sealing member in said expanded position with said frac
plug system comprises the steps of: applying fluid pressure on said
sleeve member; and compressing said sealing member from said
extended position to said expanded position.
13. The method for isolating, according to claim 12, wherein said
abutment end is comprised of a conical wedge having a first end
facing said sealing shoulder surface and a second end opposite said
first end, said first end being wider than said second end, said
first end being in slide fit engagement with said sealing shoulder
surface in said first configuration, and wherein said second end is
in mechanical engagement with said sealing member so as to
transition said sealing member from said extended position to said
expanded position, the method further comprising the step of:
exerting pressure on said sealing member by said second end of said
abutment end.
14. The method for isolating, according to claim 12, wherein the
step of moving said setting mandrel from said first configuration
to said second configuration comprises the steps of: moving said
sleeve member towards said flow end of said mandrel body with said
fluid pressure; and placing said sleeve member between said closed
end and said flow end of said mandrel body in said first setting
stage with said fluid pressure.
15. The method for isolating, according to claim 12, wherein said
second end is in mechanical engagement with said sealing member so
as to move said setting mandrel from said second configuration to
said first configuration.
16. The method for isolating, according to claim 15, wherein the
step of moving said setting mandrel from said second configuration
to said first configuration comprises the steps of: applying
additional fluid pressure on said seal end of said mandrel body;
moving said setting mandrel towards said free end of said sleeve
member; and setting said sealing shoulder surface against said
abutment end of said sleeve member so as to seal said fluid
connection in said second setting stage.
17. A method for correcting placement in a wellbore, the method
comprising the steps of: running a frac plug system, according to
claim 1, in a borehole with a setting tool, said setting mandrel
being in said first configuration, said sealing member being in
said extended position; placing said frac plug system in a location
in the wellbore; transitioning said sealing member in said extended
position to said sealing member in said expanded position with said
frac plug system in said location; moving said setting mandrel from
said first configuration to said second configuration so as to form
a fluid connection through said fluid bypass slots in a first
setting stage; and injecting fluids through said fluid bypass slots
so as to remove said frac plug system.
18. The method for correcting placement, according to claim 17,
wherein the step of placing said frac plug system in said location
comprises the step of breaking said setting mandrel with said
setting tool.
19. The method for correcting placement, according to claim 17,
wherein the step of transitioning said sealing member in said
extended position to said sealing member in said expanded position
with said frac plug system comprises the steps of: applying fluid
pressure on said sleeve member; and compressing said sealing member
from said extended position to said expanded position.
20. The method for correcting placement, according to claim 17,
wherein the step of injecting fluids through said fluid bypass
slots so as to remove said frac plug system comprises the step of:
dissolving said frac plug system, said fluids being comprised of
acid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] See Application Data Sheet.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not applicable.
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC
OR AS A TEXT FILE VIA THE OFFICE ELECTRONIC FILING SYSTEM
(EFS-WEB)
[0004] Not applicable.
STATEMENT REGARDING PRIOR DISCLOSURES BY THE INVENTOR OR A JOINT
INVENTOR
[0005] Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0006] The present invention relates to isolating zones in a
wellbore. More particularly, the present invention relates a frac
plug system that sets in position and sets a seal for isolating
zones in a wellbore. Even more particularly, the present invention
relates to a frac plug system with a pre-set seal, while setting in
position in multiple stages.
2. Description of Related Art Including Information Disclosed Under
37 CFR 1.97 and 37 CFR 1.98.
[0007] Within a wellbore, the hydrocarbons are located at
particular depths within a rock formation. These depths can be
organized into production zones so that the delivery of production
fluids can be targeted to the location of the hydrocarbons. The
production fluids facilitate the recovery of the hydrocarbons from
the wellbore. Other depth levels do not contain hydrocarbons, which
can be called "non-productive zones". There is no need to waste
production fluids on non-productive zones without hydrocarbons.
Thus, the productive zones are isolated from the non-productive
zones for the recovery of hydrocarbons from the wellbore.
[0008] There are known downhole tools to separate a production zone
from a non-productive zone so that the production fluids can be
delivered to the production zone and not the non-productive zone.
Examples of downhole tools to isolate zones include a plug, a
packer or other tool with an isolation valve.
[0009] In the conventional process, the frac plug device is run to
a downhole location. When located in the correct place, the setting
tool that traveled with the frac plug device will set the packer,
i.e. expand the frac plug against the walls of the borehole. Then,
the settling tool is removed. The frac plug still must be activated
in order seal the zone. The frac plug is sealed to the borehole,
but fluid still flows through the packer. Conventionally, a frac
ball is dropped into the borehole. The frac ball travels to the
downhole location to sit on a ball seat, which triggers the actual
seal across the frac plug. Fracking can commence with the actual
seal across the packer. The frac fluids are only delivered to the
isolated zone, and production fluids are only harvested from the
isolated zone.
[0010] There also frac plug devices that do not require a frac
ball. U.S. Pat. No. 3,298,437, issued on 1967-01-17 to Conrad,
discloses background information for setting a plug. The mandrel is
solid, and there is not even a ball seat or other trigger. The seal
is formed when the plug is set. U.S. Pat. No. 4,784,226, issued on
1988-11-15 to Wyatt, and U.S. Pat. No. 7,424,909, issued on
2008-09-16 to Roberts et al also disclose the conventional setting
of a plug to create the sealed borehole as soon as set. U.S. Pat.
No. 6,796,376, issued on 2004-09-28 to Frazier discloses the
conventional sealed plug as setting with the shearing at the end of
the mandrel. This type of frac plug is a pre-set frac plug because
the frac plug is already sealed when set in position.
[0011] There are also versions of a pre-set frac plug system with a
frac ball. U.S. Pat. No. 2,627,317, issued on 1953-02-03 to Baker,
discloses a well tester with pre-set frac ball. The tester is run
in with the frac ball in place. The tester is triggered to seal
against the borehole wall. The ball member and ball valve can be
actuated by pressure to open the tester at the bottom. The frac
ball is deployed in place with the frac plug, so that the frac plug
forms the actual seal across the frac plug as soon as the setting
tool is used.
[0012] The problem with the pre-set frac plug is the risk of
accidentally triggering a pre-set frac plug. Boreholes are not
straight and smooth. There are bumps and turns. When a conventional
frac plug is accidentally triggered or accidentally set in position
at the wrong downhole location, strong acid is pumped into the
borehole to dissolve the plug. There is no frac ball, so there can
be fluid injection to remove the accidentally triggered frac plug.
However, with a pre-set frac plug in the wrong downhole location,
there is no pumping because the accidentally triggered pre-set frac
plug already has a pre-set seal across the frac plug. Thus, pre-set
frac plug are very risky.
[0013] There are frac plugs and packers with flow bypass systems
for delivery of fluids pasta frac plug or packer in a wellbore.
U.S. Pat. No. 2,143,251, issued on 1939-01-10 to Savitz, discloses
a tool with a circulating valve that actuates from a run-in
position to a set position. The mandrel moves the openings from a
sealed position to a flow position. U.S. Pat. No. 4,286,661, issued
on 1981-09-01 to Gazda, shows another equalizing valve with a run
in position and a set position. The open flow position can be
actuated by movement of the slit openings into a spaced window and
lower than the spaced window. U.S. Pat. No. 10,400,540, issued on
2019-09-03 to Williamson et al shows flow restriction channels
along the exterior of a mandrel that are selectively opened.
[0014] It is an object of the present invention to provide a frac
plug system to isolate zones in a wellbore.
[0015] It is an object of the present invention to provide a frac
plug system to be easily removed, if accidentally triggered in the
wellbore.
[0016] It is an object of the present invention to provide a frac
plug system with multiple stages for isolating a zone in a
wellbore.
[0017] It is another object of the present invention to provide a
frac plug system having a setting mandrel with fluid bypass slots
and a sleeve member.
[0018] It is an object of the present invention to provide a frac
plug system with multiple stages for isolating a zone with fluid
pressure variation.
[0019] It is an object of the present invention to provide a frac
plug system that is removeable during different stages of the
process of isolating a zone.
[0020] It is another object of the present invention to provide a
frac plug system that is removeable by injecting a strong acid.
[0021] These and other objectives and advantages of the present
invention will become apparent from a reading of the attached
specification, drawings and claims.
BRIEF SUMMARY OF THE INVENTION
[0022] Embodiments of the present invention include a frac plug
system with a pre-set seal. Once the frac plug system is set in
position within a wellbore, there is no need for a frac ball or
other operation to form the seal at the position within the
wellbore. The frac plug system of the present invention has
components so that setting in position is split into multiple
stages, which allows quick removal if the trigger to start the
setting in position was wrong or accidental.
[0023] The present invention is a frac plug system comprising a
setting mandrel, a sleeve member, a sealing member, a cone
assembly, and a slip device. The setting mandrel includes a mandrel
body, a plurality of fluid bypass slots, and a sealing shoulder
surface. The fluid bypass slots extend longitudinally along the
mandrel body. Each slot has an opened end and a closed end. In some
embodiments, the setting mandrel can have O-ring grooves for
O-rings in sliding engagement between the sleeve member and the
setting mandrel. the sleeve member includes a sleeve body with an
outer sleeve surface, an abutment end and a free end. The setting
mandrel has a first configuration without fluid flow through the
packer system because the closed ends of the slots are covered by
the sleeve member. The setting mandrel has a second configuration
with the closed ends of each slot open and fluid connection through
the frac plug system.
[0024] In embodiments of the present invention, the abutment end of
the sleeve member is mechanically engaged with a seal end of the
setting mandrel. The mechanical engagement includes direct contact,
like being adjacent, or other connection so as to exert force on
each other. In one embodiment, the abutment end is a conical wedge
cooperative with a sealing shoulder surface of the setting
mandrel.
[0025] Embodiments of the sealing member, cone assembly, and slip
device of the present invention include conventional components of
a frac plug to set the frac plug system in position in the
wellbore. The slip device anchors to the wellbore. The sealing
member seals against the wellbore so that there is no fluid flow
around the frac plug system. The cone assembly slides into the slip
device to press the slip device into the wellbore. The sealing
member has an extended position and an expanded position with a
diameter for sealing against the wellbore larger than the diameter
of the extended position.
[0026] In the present invention, the second configuration of the
setting mandrel only corresponds to the sealing member in the
expanded position at the first setting stage. The first
configuration of the setting mandrel corresponds to both the
sealing member in the expanded position at the second setting stage
and the sealing member in the extended position, while being run-in
before any setting stages.
[0027] Embodiments of the present invention include the method for
isolating a zone in a wellbore. The method includes running a frac
plug system in a borehole with a setting tool. The setting mandrel
is in the first configuration, and the sealing member is in the
extended position. Next, the frac plug system is placed in a
location in the wellbore, which can include breaking the setting
mandrel with the setting tool.
[0028] The method now includes transitioning the sealing member in
the extended position to the sealing member in the expanded
position at the location and moving the setting mandrel from the
first configuration to the second configuration so as to form a
fluid connection through the fluid bypass slots in a first setting
stage of setting in position. In some embodiment, fluid pressure is
applied to exert force on the abutment end of the sleeve member,
which compresses the sealing member and moves the sleeve member
along the setting mandrel to the second configuration of the
setting mandrel. The fluid bypass slots are now in fluid connection
through the frac plug system. The closed ends of the slots allow
fluid flow and pumping through the frac plug system.
[0029] Next, the method includes moving the setting mandrel from
the second configuration to the first configuration so as to seal
the fluid connection in a second setting stage. The pre-set seal at
the seal end of the sleeve member is finally moved into place. In
the embodiments with fluid pressure, additional fluid pressure is
applied to the seal end to exert force on the setting mandrel. With
the sleeve member anchored by the sealing member and slip device,
the setting mandrel now moves toward the sleeve member. The setting
mandrel returns back to the first configuration, closing the fluid
bypass slots in the second setting stage. In the second setting
stage, the setting in position is completed so that the pre-set
seal can form a seal across the frac plug system to isolate a
zone.
[0030] Alternative embodiments of the method of the present
invention include the step of injecting fluids to remove the frac
plug system. If the frac plug system is in the wrong place by
accident or unintentionally, strong acid can be injected to
dissolve the frac plug system or at least components of the frac
plug system so that the frac plug system is removed from the wrong
place in the wellbore. The fluid bypass slots allow pumping acid or
other additives to be delivered to the frac plug system.
[0031] The present invention provides a frac plug system with
multiple stages to isolate zones in a wellbore. The frac plug
system is pre-set because no additional stage is needed to set the
seal. A frac ball and related ball seat are no longer needed. The
present invention includes components for multiple stages for
setting in position to isolate the wellbore.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0032] FIG. 1 is a side elevation view of an embodiment of the
setting mandrel and fluid bypass slots of the frac plug system
according to the present invention.
[0033] FIG. 2 is a sectional view of an embodiment of the frac plug
system according to the present invention with the setting mandrel
in the first configuration and the sealing member in an extended
position.
[0034] FIG. 3 is a sectional view of an embodiment of the frac plug
system according to the present invention with the setting mandrel
in the second configuration and the sealing member in an expanded
position.
[0035] FIG. 4 is a sectional view of an embodiment of the frac plug
system according to the present invention with the setting mandrel
in the first configuration and the sealing member in an expander
position.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Conventional frac plugs and packers set in position and set
a seal in separate stages. Pre-set frac plugs are set in position
and set a seal in a single stage, and there is no need for another
stage. Although efficient, there is high risk of setting position
and setting the seal in the wrong location accidentally. The
present invention is a frac plug system that is pre-set because
setting the seal remains concurrent with setting in position. The
seal is pre-set. The frac plug system of the present invention has
components so that setting in position is split into multiple
stages, which allows quick removal if the trigger to start the
setting in position was wrong. There are multiple stages for
setting in position, even though setting the seal is pre-set.
[0037] Referring to FIGS. 1-4, the present invention is a frac plug
system 10, including a setting mandrel 20, a sleeve member 40, a
sealing member 60, a cone assembly 70, and a slip device 72. FIG. 1
shows the setting mandrel 20 being comprised of a mandrel body 22,
a plurality of fluid bypass slots 30, and a sealing shoulder
surface 36. The mandrel body 22 has an outer mandrel surface 24, a
seal end 26 and a flow end 28 opposite the seal end 26. The fluid
bypass slots 30 extend longitudinally along the mandrel body 22
from the flow end 28 toward the seal end 26. Each slot 30 has an
opened end 32 at the flow end 28 of the mandrel body 22 and a
closed end 34 between the seal end 26 and the flow end 28. The
sealing shoulder surface 36 is at the seal end 26 so that the
closed end 34 is between the sealing shoulder surface 36 and the
flow end 28.
[0038] In some embodiments, the setting mandrel 20 is further
comprised of an O-ring groove 31 between the closed end 34 and the
opened end 32 of each slot 30. FIGS. 2-4 show an O-ring 35 set in
the O-ring groove 31 in sliding engagement with the sleeve member
40. There can also be an additional O-ring groove 33 between the
closed end 34 and the O-ring groove 31 of each slot 30 and an
additional O-ring 37 set in the additional O-ring groove 33.
[0039] FIGS. 2-4 show the sleeve member 40 being comprised of a
sleeve body 42 with an outer sleeve surface 44, an abutment end 46
and a free end 48 opposite the abutment end 46. The setting mandrel
20 has a first configuration with the seal end 26 adjacent the
abutment end 46 of the sleeve member, and a second configuration
with the closed end 36 of each slot 30 between the seal end 26 and
the abutment end 46. The first configuration has the sleeve member
40 mechanically engaged to the seal end 26 of the setting mandrel
20. Mechanically engaged means that the sleeve member 40 is in
physical contact with the setting mandrel 20 or adjacent so that
sleeve member 40 and setting mandrel can exert pressure on each
other.
[0040] In one embodiment, the abutment end 46 is adjacent to the
seal end 26. The abutment end 46 is comprised of a conical wedge 50
having a first end 52 facing the sealing shoulder surface 36 of the
setting mandrel 20 and a second end 54 opposite the first end 52.
The first end 52 is wider than the second end 54 so as to set the
orientation of the cone shape. FIGS. 2 and 4 show the first end 52
being in slide fit engagement with the sealing shoulder surface 36
in the first configuration.
[0041] FIGS. 2-4 also show the sealing member 60 being mounted
around the sleeve member 40 between the abutment end 46 and the
free end 48, the cone assembly 70 being mounted around the sleeve
member 40 and being in mechanical engagement with the sealing
member 60, and the slip device 72 being mounted around the sleeve
member 40 and being in sliding engagement with the cone assembly
70. The sealing member 60 has an expanded position (FIGS. 3-4) and
an extended position (FIG. 2). The sealing member 60 in the
expanded position of FIGS. 3-4 having a diameter 62 larger than the
sealing member 60 in the extended position of FIG. 2. In the
embodiment with the abutment end 46 being comprised of a conical
wedge 50, the second end 54 is in mechanical engagement with the
sealing member 60 so as to transition the sealing member 60 from
the extended position to the expanded position. That is, the second
end 54 is adjacent or in contact with the sealing member 60 so as
to exert pressure on the sealing member 60. The pressure can
compress the sealing member 60 in the extended position of FIG. 2
into the expanded position of FIGS. 3-4.
[0042] In the present invention, the second configuration of the
setting mandrel 20 corresponds to the sealing member 60 in the
expanded position of FIG. 3. The first configuration of the setting
mandrel 20 corresponds to both the sealing member 60 in the
expanded position (FIG. 4) and the sealing member 60 in the
extended position (FIG. 2).
[0043] The sealing member 60, cone assembly 70, and slip device 72
can be conventional components of a packer to set the frac plug
system 10 in position in the wellbore. The anchoring to the
wellbore by the slip device 72, the sealing against the wellbore by
the sealing member 60, and the sliding of the cone assembly 70 to
press the slip device 72 into the wellbore are shown in FIGS. 2-4.
The particular embodiments show the sealing member 60 between the
abutment end 46 of the sleeve member 40 and the cone assembly 70
and the cone assembly 70 between the sealing member 60 and the slip
device 72. The slip device 72 is farther from the abutment end 46
of the sleeve member 40 with the sealing member 60 in the expanded
position (FIG. 2) than with the sealing member 60 in the extended
position (FIGS. 3-4). The cone assembly 70 is closer to the slip
device 72 with the sealing member 60 in the expanded position
(FIGS. 3-4) than with the sealing member 60 in the extended
position (FIG. 2).
[0044] FIGS. 2-4 also show the method for isolating a zone in a
wellbore as an embodiment of the present invention. The method
comprises the step of running a frac plug system 10 in a borehole
with a setting tool 80. FIG. 2 shows the step of running with the
setting mandrel 20 in the first configuration and the sealing
member 60 in the extended position. The sealing member 60 has the
smaller diameter 62 so that the packer system 10 can pass through
the wellbore more easily. The method of the present invention
further includes placing the frac plug system 10 in a location in
the wellbore. The step of placing the frac plug system in the
location can comprise the step of breaking the setting mandrel 20
with the setting tool 80 (FIG. 2 attached, FIGS. 3-4 detached).
[0045] FIG. 3 shows the steps of transitioning the sealing member
60 in the extended position to the sealing member 60 in the
expanded position at the location and moving the setting mandrel 20
from the first configuration to the second configuration so as to
form a fluid connection through the fluid bypass slots 30 in a
first setting stage of setting in position. The sealing member 60,
cone assembly 70, and slip device 72 anchor the packer system 10 to
the wellbore, but setting in position is not yet complete. The
setting mandrel 20 is not yet in a final position. The pre-set seal
at the seal end 26 is not in position yet.
[0046] In some embodiments, the step of transitioning the sealing
member 60 in the extended position to the sealing member 60 in the
expanded position includes applying fluid pressure on the sleeve
member 40 so as to compress the sealing member 60 from the extended
position to the expanded position. FIG. 3 shows the abutment end 46
as the conical wedge 50, so the first end 52 is in slide fit
engagement with the sealing shoulder surface 36 in the first
configuration and the second end 54 is in mechanical engagement
with the sealing member 60 so as to transition the sealing member
60 from the extended position to the expanded position. The fluid
pressure applied to the second end 54 of the abutment end 46 of the
sleeve member 60 exerts force on the sealing member 60, cone
assembly 70, and slip device 72 to anchor to the wellbore and
slides the sleeve member 40 relative to the setting mandrel 20 to
the second configuration (FIG. 3). The fluid pressure moves the
sleeve member 40 towards the flow end 28 of the mandrel body 22 so
as to position the sleeve member 40 between the closed end 34 of
each fluid bypass slot 30 and the flow end 28 of the mandrel body
22 for the second configuration of the setting mandrel 20.
[0047] At this first setting stage for setting in position, FIG. 3
shows the fluid connection through the frac plug system 10. The
frac plug system 10 is anchored in place, but the seal end 26 has
not yet sealed the wellbore. When the position of the frac plug
system 10 within the wellbore is acceptable, the method of the
present invention proceeds with the step of moving the setting
mandrel 20 from the second configuration to the first configuration
so as to seal the fluid connection in a second setting stage (FIG.
4).
[0048] FIG. 4 shows the second setting stage with the second end 54
of the abutment end 46 in mechanical engagement with the sealing
member 60 so as to move the setting mandrel 20 from the second
configuration to the first configuration. The mechanical engagement
is being adjacent or other contact so as to exert force on each
other. The sealing member 60 is now anchored in the wellbore in the
expanded position and with the slip device 72 attached to the
wellbore. Thus, the sleeve member 40 is now anchored in place. The
method of the present invention now includes the step of moving the
setting mandrel 20 from the second configuration back to the first
configuration.
[0049] In some embodiments, the moving back to the first
configuration comprises the step of applying additional fluid
pressure on the seal end 26 of the mandrel body 22. The original
amount of fluid pressure is sufficient to move the sleeve member 40
until the sleeve member 40 was anchored in place. An additional
fluid pressure is now applied to move the setting mandrel 20
towards the free end 48 of the sleeve member 40. The sealing
shoulder surface 36 is back against the abutment end 46 of the
sleeve member 40 so as to seal the fluid connection in the second
setting stage.
[0050] In the second setting stage, the setting in position is
completed so that the pre-set seal can form a seal across the frac
plug system 10 to isolate a zone.
[0051] Embodiments of the method of the present invention further
include an alternative at the first setting stage of FIG. 3, when
the frac plug system 10 is anchored in place, but the seal end 26
has not yet sealed the wellbore. When the frac plug system 10 is in
the wrong place, the method of the present invention now includes
the step of injecting fluids through the fluid bypass slots 30 so
as to remove the frac plug system 10. If triggered by accident, the
frac plug system 10 is no longer sealed concurrent with setting in
position. Strong acid can be injected to dissolve the frac plug
system 10 so that the frac plug system is removed from the wrong
place in the wellbore. The fluid bypass slots 30 allow pumping acid
or other additives to be delivered to the frac plug system 10.
[0052] The method of this embodiment is the same steps for placing
the frac plug system 10 in the location by breaking the setting
mandrel 20 with the setting tool 80 and moving the setting mandrel
20 from the first configuration to the second configuration by
applying fluid pressure on the sleeve member 40, moving the sleeve
member 40 towards the flow end 28 of the mandrel body 22, and
moving the sleeve member 40 between the closed end 34 of at least
one fluid bypass slot 30 and the flow end 28 of the mandrel body
22. Instead of applying additional fluid pressure to move the
setting mandrel 20 to the now anchored sleeve member 40, this
alternative embodiment injects strong acid to dissolve components
of the frac plug system 10 so that the frac plug system 10 is
removed from the location within the wellbore.
[0053] The present invention provides a frac plug system to isolate
zones in a wellbore. The frac plug system is pre-set because no
additional stage is needed to set the seal. A frac ball is not
dropped to form the seal. There is no ball seat or other valve seat
to accommodate a frac ball in the frac plug system of the present
invention. The time, components, and risk of a frac ball for form
the seal is avoided. Additionally, the risk of accidental
triggering the frac plug with a pre-set frac ball is also avoided.
The present invention further includes the frac plug system having
multiple stages for setting in position to isolate the wellbore.
Despite this pre-setting of the seal, the setting in position
includes multiple stages. Before all stages of setting in position
are complete, it is possible to remove the frac plug system by
injecting strong acid to dissolve components of the frac plug
system. If the frac plug system was accidentally triggered in the
wellbore to set position, there is no longer an automatic set
position and set seal that cannot be easily removed.
[0054] Embodiments of the present invention include a frac plug
system having a setting mandrel with fluid bypass slots and a
sleeve member. These components are positioned and have structures
for fluid connection relationships so that fluid pressure variation
controls isolating a zone. Also, the fluid pressure actuation of
the setting mandrel and sleeve member allows the frac plug system
to be removed at a first setting stage before a second setting
stage.
[0055] The foregoing disclosure and description of the invention is
illustrative and explanatory thereof. Various changes in the
details of the illustrated structures, construction and method can
be made without departing from the true spirit of the
invention.
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