U.S. patent application number 16/442282 was filed with the patent office on 2020-12-17 for slips with internal buttons.
The applicant listed for this patent is Nine Downhole Technologies, LLC. Invention is credited to Donald Jonathan Greenlee, Donald Roy Greenlee.
Application Number | 20200392807 16/442282 |
Document ID | / |
Family ID | 1000004160142 |
Filed Date | 2020-12-17 |
![](/patent/app/20200392807/US20200392807A1-20201217-D00000.png)
![](/patent/app/20200392807/US20200392807A1-20201217-D00001.png)
![](/patent/app/20200392807/US20200392807A1-20201217-D00002.png)
![](/patent/app/20200392807/US20200392807A1-20201217-D00003.png)
United States Patent
Application |
20200392807 |
Kind Code |
A1 |
Greenlee; Donald Roy ; et
al. |
December 17, 2020 |
SLIPS WITH INTERNAL BUTTONS
Abstract
A slip for use in a downhole tool that includes internal buttons
on an internal surface of the slip that engages a setting cone. The
internal buttons may be made of a hard material, such as a ceramic,
among others, to increase the coefficient of friction between the
slip and the cone when the downhole tool is set.
Inventors: |
Greenlee; Donald Roy;
(Murchison, TX) ; Greenlee; Donald Jonathan;
(Murchison, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nine Downhole Technologies, LLC |
Houston |
TX |
US |
|
|
Family ID: |
1000004160142 |
Appl. No.: |
16/442282 |
Filed: |
June 14, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/129 20130101;
E21B 33/0422 20130101 |
International
Class: |
E21B 33/129 20060101
E21B033/129; E21B 33/04 20060101 E21B033/04 |
Claims
1. A slip, comprising: an outer surface enabled to engage a
wellbore surface; and an inner surface enabled to be engaged by a
setting cone of a downhole tool, wherein the inner surface includes
at least one inner button enabled to contact the setting cone when
the setting cone engages the inner surface.
2. The slip of claim 1, wherein the outer surface includes at least
one outer button enabled to contact the wellbore surface.
3. The slip of claim 1, wherein the inner button comprises a
material that has a higher coefficient of friction than the
coefficient of friction of the inner surface of the slip when in
contact with the setting cone.
4. The slip of claim 3, wherein the inner surface of the slip in
the downhole tool is parallel to the setting cone.
5. The slip of claim 1, wherein an exposed surface of the inner
button facing the setting cone is not parallel with the setting
cone.
6. The slip of claim 1, wherein the setting cone comprises a metal
and the inner button comprises a non-metal.
7. The slip of claim 1, wherein the inner button comprises a
composite material including at least one non-metal.
8. The slip of claim 1, wherein the inner button comprises a
metal.
9. The slip of claim 1, wherein the inner button is substantially
cylindrical in shape.
10. The slip of claim 1, wherein the inner button is shaped
substantially as a polygonal prism.
11. The slip of claim 1, wherein an exposed surface of the inner
button that faces a surface of the setting cone is not parallel
with the surface of the setting cone.
12. The slip of claim 1, wherein an exposed surface of the inner
button that faces a surface of the setting cone is parallel with
the surface of the setting cone.
13. The slip of claim 1, wherein the wellbore surface is a
casing.
14. A downhole tool, comprising: a setting cone enabled to engage a
plurality of slips located circumferentially about the setting cone
when the downhole tool is set; and wherein the slips further
comprise: an external surface enabled to engage a casing when the
downhole tool is set; and an internal surface enabled to engage the
setting cone when the downhole tool is set; wherein at least one of
the slips further comprises: the internal surface of the slip
including at least one internal button enabled to contact the
setting cone when the downhole tool is set.
15. The downhole tool of claim 14, wherein the external surface of
the slip includes at least one exterior button enabled to contact
the casing.
16. The downhole tool of claim 14, wherein the internal button
comprises a material that has a higher coefficient of friction than
the coefficient of friction of the internal surface of the slip
when in contact with the setting cone.
17. The downhole tool of claim 14, wherein the setting cone
comprises a metal, and the internal button comprises a
non-metal.
18. The downhole tool of claim 14, wherein the internal button
comprises a composite material including at least one
non-metal.
19. The downhole tool of claim 14, wherein the internal button
comprises a metal.
20. The downhole tool of claim 14, wherein the internal surface of
the slip is parallel to the setting cone.
21. The downhole tool of claim 14, wherein an exposed surface of
the internal button that faces a surface of the setting cone is not
parallel with the surface of the setting cone.
22. The downhole tool of claim 14, wherein an exposed surface of
the internal button that faces a surface of the setting cone is
parallel with the surface of the setting cone.
23. The downhole tool of claim 14, wherein the internal button is
substantially cylindrical in shape.
24. The downhole tool of claim 14, wherein the internal button is
shaped substantially as a polygonal prism.
25. A method for engaging downhole tools in wellbores, the method
comprising: running a downhole tool to a depth in a casing, wherein
the downhole tool comprises a setting cone enabled to engage a
plurality of slips located circumferentially about the setting cone
when the downhole tool is set; setting the downhole tool in the
casing, including causing the plurality of slips to engage a
setting cone, the slips further comprising: an outer surface
enabled to engage the casing when the downhole tool is set; and an
inner surface enabled to engage the setting cone when the downhole
tool is set; wherein at least one of the slips is an inner button
slip further comprising: the inner surface of the slip including at
least one inner button; and wherein causing the plurality of slips
to engage the setting cone further comprises: forcing the plurality
of slips against the setting cone; and wherein the plurality of
slips include the at least one inner button slip, and wherein the
inner button contacts the setting cone as the plurality of slips
engage the casing.
26. The method of claim 25, wherein the plurality of slips engaging
the setting cone further comprises: at least one outer button
located at the outer surface of the slip engaging the casing.
27. The method of claim 25, wherein the inner button comprises a
material that has a higher coefficient of friction than the
coefficient of friction of the inner surface of the slip when in
contact with the setting cone.
28. The method of claim 25, wherein the setting cone comprises a
metal, and the inner button comprises a non-metal.
29. The method of claim 25, wherein the inner button comprises a
composite material including at least one non-metal.
30. The method of claim 25, wherein the inner button comprises a
metal.
31. The method of claim 25, wherein the inner surface of the slip
is parallel to the setting cone in the downhole tool.
32. The method of claim 25, wherein an exposed surface of the inner
button that faces a surface of the setting cone is not parallel
with the surface of the setting cone.
33. The method of claim 25, wherein an exposed surface of the inner
button that faces a surface of the setting cone is parallel with
the surface of the setting cone.
34. The method of claim 25, wherein the inner button is
substantially cylindrical in shape.
35. The method of claim 25, wherein the inner button is shaped
substantially as a polygonal prism.
Description
RELATED APPLICATIONS
[0001] This application is related to the U.S. non-provisional
utility patent application titled "COMPACT DOWNHOLE TOOL", attorney
docket number NSC100/4-013US, filed concurrently herewith and
hereby incorporated by reference in its entirety herein.
BACKGROUND
Field of the Disclosure
[0002] The present disclosure relates generally to parts used in
downhole assemblies and, more particularly, to a slip with internal
buttons for use in a downhole assembly.
Description of the Related Art
[0003] During drilling or reworking of wells, tubing or other pipe
(e.g., casing) in the wellbore may be sealed at a particular
location, such as for pumping cement or other fluids down the
tubing, and forcing fluid out into a formation. Various downhole
tools have been designed to effect this sealing or to isolate a
particular zone of the wellbore. Many such downhole tools used for
sealing a wellbore employ slips to contact casing in the wellbore
with sufficient friction under pressure to hold the downhole tool
in place and maintain the seal in the wellbore for the desired
application.
[0004] Multiple slips may be arranged around an exterior surface of
a cylindrically-shaped downhole tool, and are pushed outward by a
cone in the downhole tool that moves the slips to be in contact
with a surface of the wellbore, such as the wall of the wellbore,
or casing within a wellbore, when the downhole tool is set. Typical
slips may be equipped with buttons on the exterior surface to
increase the friction between the slip and the surface of the
wellbore.
[0005] Various types of downhole tools may also employ an
elastomeric member and spherical element with a cone and slip
arrangement to effect a seal in the wellbore, such as packers,
bridge plugs, and frac plugs. In a frac plug, the slips hold the
elastomeric member of the frac plug in place against the wellbore
when the frac plug is set and may enable the frac plug to withstand
a certain amount of pressure or flow rate while maintaining the
seal in the wellbore and holding the frac plug in place. Certain
frac plugs may further be enabled to remain in the wellbore and
held in place by slips during production from the well.
SUMMARY
[0006] In one aspect, a slip haying internal buttons is disclosed.
The slip may include an outer surface enabled to engage a wellbore
surface, and an inner surface enabled to be engaged by a setting
cone of a downhole tool. In the slip, the inner surface may include
at least one inner button enabled to contact the setting cone when
the setting cone engages the inner surface.
[0007] In any of the disclosed embodiments of the slip, the outer
surface may include at least one outer button enabled to contact
the wellbore surface.
[0008] In any of the disclosed embodiments of the slip, the inner
button may include a material that has a higher coefficient of
friction than the coefficient of friction of the inner surface of
the slip when in contact with the setting cone.
[0009] In any of the disclosed embodiments or the slip, the inner
surface of the slip in the downhole tool may be parallel to the
setting cone.
[0010] In any of the disclosed embodiments of the slip, an exposed
surface of the inner button facing the setting cone may be
non-parallel with the setting cone.
[0011] In any of the disclosed embodiments of the slip, the setting
cone may include a metal and the inner button may include a
non-metal. In the slip, the inner button may include a composite
material including at least one non-metal. In the slip, the inner
button may include a metal.
[0012] In any of the disclosed embodiments of the slip, the inner
button may be substantially cylindrical in shape.
[0013] In any of the disclosed embodiments of the slip, the inner
button may be shaped substantially as a polygonal prism.
[0014] In any of the disclosed embodiments of the slip, an exposed
surface of the inner button that faces a surface of the setting
cone may be non-parallel with the surface of the setting cone.
[0015] In any of the disclosed embodiments of the slip, an exposed
surface of the inner button that faces a surface of the setting
cone may be parallel with the surface of the setting cone.
[0016] In any of the disclosed embodiments of the slip, the
wellbore surface may be a casing.
[0017] In another aspect, a downhole tool is disclosed. The
downhole tool may include a setting cone enabled to engage a
plurality of slips located circumferentially about the setting cone
when the downhole tool is set. In the downhole tool, the slips may
further include an external surface enabled to engage a casing when
the downhole tool is set, and an internal surface enabled to engage
the setting cone when the downhole tool is set. In the downhole
tool, at least one of the slips may further include the internal
surface of the slip including at least one internal button enabled
to contact the setting cone when the downhole tool is set.
[0018] In any of the disclosed embodiments of the downhole tool,
the external surface of the slip may include at least one exterior
button enabled to contact the casing.
[0019] In any of the disclosed embodiments of the downhole tool,
the internal button may include a material that has a higher
coefficient of friction than the coefficient of friction of the
internal surface of the slip when in contact with the setting
cone.
[0020] In any of the disclosed embodiments of the downhole tool,
the setting cone may include a metal, and the internal button
comprises a non-metal.
[0021] In any of the disclosed embodiments of the downhole tool,
the internal button may include a composite material including at
least one non-metal. In the downhole tool, the internal button may
include a metal.
[0022] In any of the disclosed embodiments of the downhole tool,
the internal surface of the slip may be parallel to the setting
cone.
[0023] In any of the disclosed embodiments of the downhole tool, an
exposed surface of the internal button that faces a surface of the
setting cone may be non-parallel with the surface of the setting
cone.
[0024] In any of the disclosed embodiments of the downhole tool, an
exposed surface of the internal button that faces a surface of the
setting cone may be parallel with the surface of the setting
cone.
[0025] In any of the disclosed embodiments of the downhole tool,
the internal button may be substantially cylindrical in shape.
[0026] In any of the disclosed embodiments of the downhole tool,
the internal button may be shaped substantially as a polygonal
prism.
[0027] In yet another aspect, a method for engaging downhole tools
in wellbores is disclosed. The method may include running a
downhole tool to a depth in a casing. In the method, the downhole
tool may include a setting cone enabled to engage a plurality of
slips located circumferentially about the setting cone when the
downhole tool is set. The method may further include setting the
downhole tool in the casing, including causing the plurality of
slips to engage a setting cone. In the method, the slips may
further include an outer surface enabled to engage the casing when
the downhole tool is set, and an inner surface enabled to engage
the setting cone when the downhole tool is set. In the method, at
least one of the slips may be an inner button slip that may further
include the inner surface of the slip including at least one inner
button. In the method, causing the plurality of slips to engage the
setting cone may further include forcing the plurality of slips
against the setting cone. In the method, the plurality of slips may
include the at least one inner button slip, while the inner button
may contact the setting cone as the plurality of slips engage the
casing.
[0028] In any of the disclosed embodiments of the method, the
plurality of slips engaging the setting cone may further include at
least one outer button located at the outer surface of the slip
engaging the casing.
[0029] In any of the disclosed embodiments of the method, the inner
button may further include a material that has a higher coefficient
of friction than the coefficient of friction of the inner surface
of the slip when in contact with the setting cone.
[0030] In any of the disclosed embodiments of the method, the
setting cone may include a metal, while the inner button may
include a non-metal.
[0031] In any of the disclosed embodiments of the method, the inner
button may include a composite material including at least one
non-metal. In any of the disclosed embodiments of the method, the
inner button may include a metal.
[0032] In any of the disclosed embodiments of the method, the inner
surface of the slip may be parallel to the setting cone in the
downhole tool.
[0033] In any of the disclosed embodiments of the method, an
exposed surface of the inner button that faces a surface of the
setting cone may be non-parallel with the surface of the setting
cone.
[0034] In any of the disclosed embodiments of the method, an
exposed surface of the inner button that faces a surface of the
setting cone may be parallel with the surface of the setting
cone.
[0035] In any of the disclosed embodiments of the method, the inner
button may be substantially cylindrical in shape.
[0036] In any of the disclosed embodiments of the method, the inner
button may be shaped substantially as a polygonal prism.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] For a more complete understanding of the present disclosure
and its features and advantages, reference is now made to the
following description, taken in conjunction with the accompanying
drawings, in which:
[0038] FIG. 1 is a depiction of a frac plug having slips with
internal buttons;
[0039] FIG. 2 is a partial sectional view of slip loading with an
internal button;
[0040] FIG. 3 is a flow chart of a method using a slip with
internal buttons;
[0041] FIG. 4A is a depiction of a frac plug having slips with
internal buttons; and
[0042] FIG. 4B is a depiction of a frac plug having slips with
internal buttons.
DESCRIPTION OF PARTICULAR EMBODIMENT(S)
[0043] In the following description, details are set forth by way
of example to facilitate discussion of the disclosed subject
matter. It should be apparent to a person of ordinary skill in the
field, however, that the disclosed embodiments are exemplary and
not exhaustive of all possible embodiments.
[0044] Throughout this disclosure, a hyphenated form of a reference
numeral refers to a specific instance of an element and the
un-hyphenated form of the reference numeral refers to the element
generically or collectively. Thus, as an example (not shown in the
drawings), device "12-1" refers to an instance of a device class,
which may be referred to collectively as devices "12" and any one
of which may be referred to generically as a device "12". In the
figures and the description, like numerals are intended to
represent like elements.
[0045] As noted above, slips are parts in downhole tools, such as
packers, bridge plugs, and frac plugs, among others, that may be
used for anchoring against a surface of a wellbore, typically by
using a cone-shaped member to force the slips against the surface
of a wellbore. The gripping force that the slips are capable of
exerting can be a key factor in the design and implementation of
the downhole tool. The frictional performance of the slip may be
determinative for the strength of the seal formed by the downhole
tool and the amount of pressure that the seal and the downhole tool
can withstand. Seals and downhole tools that can withstand higher
pressures or higher flow rates are desirable because they enable
wider ranges of operating conditions for well operators.
Accordingly, slips having hard external or exterior buttons, such
as ceramic buttons, have been used to improve the coefficient of
friction between the slip and the casing, thereby improving the
frictional force applied by the slip.
[0046] As will be disclosed in further detail herein, a slip with
internal buttons for use in a downhole assembly, such as in a
downhole tool, is disclosed. The slip with internal buttons for use
in a downhole assembly disclosed herein may enable an increased
frictional force between the slip and a setting cone in a downhole
tool, for example. Accordingly, the slip with internal buttons for
use in a downhole assembly disclosed herein may enable an improved
design for a downhole tool, such as by using a single setting cone
with slips in the downhole tool instead of a pair of setting cones
with respective pairs of slips, which may enable a substantially
more compact downhole tool for a given frictional force, which is
desirable. The slip with internal buttons for use in a downhole
assembly disclosed herein may be implemented using a variety of
materials for the slip body and or the internal buttons, as
disclosed herein.
[0047] Referring now to the drawings, FIG. 1 shows a portion of a
frac plug 100 having slips 104. FIG. 1 is a schematic diagram for
descriptive purposes and is not drawn to scale or perspective. In
FIG. 1, the depicted portion of frac plug 100 includes a setting
cone 106 (or simply, cone 106). In particular embodiments, cone 106
may have a frustoconical shape. Frac plug 100 may operate to plug a
wellbore, such as a cased wellbore having a casing diameter of 3.5
inches, 4 inches, 4.5 inches, or 5.5 inches, among other casing
diameters. It will be understood that frac plug 100 may include
other elements, such as additional sets of setting cones and
corresponding slips, in various embodiments. For example in some
embodiments, frac plug 100 may include an elastomeric member that
expands to seal the casing diameter when frac plug 100 is set in
place. Frac plug 100 may be set in place by compressing frac plug
100, such that slips 104 are engaged to firmly hold frac plug 100
in a particular location in a corresponding wellbore, such as
within a casing of the wellbore. The frictional force of slips 104
pressing against the interior surface of the wellbore (or the
casing) holds frac plug 100 in place in the set or "plugged"
condition. Accordingly, the force that maintains the plug 100 in
the set or plugged condition is achieved by virtue of the material
strength of slips 104 as well as a frictional force between slips
104 and cone 106.
[0048] As shown in FIG. 1, in frac plug 100, cone 106 is located
adjacent to slips 104, which may be a plurality of parts arranged
axially next to each other and may be bound together with at least
one ring clamp (not shown) prior to downhole introduction and
engagement. When slips 104 are forced against cone 106 in the
direction given by arrow 120 (i.e., the frac plug is compressed),
cone 106 works with appreciable force against an inner surface of
each individual composite slip 104, which may cause a ring clamp to
fail and to release slips 104. Because slips 104 are nonetheless
contained in the downhole setting, slips 104 are forced outward to
press against the wellbore or the casing. Also shown are ceramic
buttons 110, which may be embedded at an outer surface of slips 104
to provide increased friction and hardness to improve the securing
of frac plug 100 by slips 104. As will be described in further
detail, slips 104 may have internal (or inner) buttons (not visible
in FIG. 1, see FIGS. 2 and 4B), as disclosed herein, that provide
increased friction and hardness to improve the engagement of cone
106 against an internal (or inner) surface of slips 104.
[0049] Although a frac plug 100 is shown incorporating slips 104,
it will be understood that other types of downhole tools, such as
bridge plugs, packers or other sealing devices, may incorporate
slips 104 having internal buttons.
[0050] Referring now to FIG. 2, a slip loading 200 with an internal
button 222 is shown as a cross-sectional schematic diagram. FIG. 2
is a schematic diagram for descriptive purposes and is not drawn to
scale or perspective. In FIG. 2, the operation of slip 104 being
forced against cone 106 in direction given by arrow 120 is
illustrated at one side of a casing 230. As a result, as the slips
move in direction 120, cone 106 engages slip 104 with appreciable
force and causes slip 104 to be forced towards casing 230 in
direction 220. At an outer surface of slip 104, an external button
110 may be used to improve engagement of slip 104 with casing 230,
such as by increasing friction or by mechanical deformation (not
shown) of casing 230. Thus, as cone 106 is engaged when frac plug
100 is set, a cone surface 106-1 may engage with an angled surface
104-1 of slip 104, which applies force to slip 104 in direction
220.
[0051] Also shown in FIG. 2 is internal button 222, located at
angled surface 104-1 of slip 104. Angled surface 104-1 may
represent an internal or inner surface of slip 104. In particular,
angled surface 104-1 may be parallel to cone surface 106-1 that is
designed to engage slip 104 at angled surface 104-1. It is noted
that an angle of angled surface 104-1 may correspond to a cone
angle .phi. shown in FIG. 2. In particular, internal button 222 is
visible in a location at angled surface 104-1 for engagement by
cone surface 106-1. Accordingly, internal button 222 may improve
the setting force that is applied to slip 104, such as by
increasing friction between slip 104 and cone 106. Because internal
button 222 may be formed from a material that has a higher
coefficient of friction than angled surface 104-1 when in contact
with setting cone 106, such as a hard metal, a ceramic, a glass, a
composite of non-metallic and metallic materials, or another
composite material (such as a fiber-reinforced ceramic), among
others, internal button 222 may enable an improved setting of the
downhole tool or assembly, and may improve stability in operation,
because of the increased frictional three that results from
internal button 222. As a result of this increased frictional force
enabled by internal button 222 at angled surface 104-1, the ability
of slip 104 to hold the downhole tool or assembly in place in
operation may be improved, including the ability to stay in place
at higher pressures or at higher flowrates in the wellbore. For
example, the downhole tool or assembly may be enabled to withstand
high pressure, such as pressures of up to 8 kpsi (about 55 MPa), up
to 10 kpsi (about 69 MPa), or up to 12 kpsi (about 83 MPa) within
the wellbore. Furthermore, the downhole tool or assembly may be
enabled to withstand high flow rates during production, such as
such as up to 80 million standard cubic feet per day (MMSCFD) of
gas or up to 4,000 barrels of oil per day (BOPD).
[0052] In some instances, internal button 222 may accordingly
enable a more compact design in a given downhole tool or assembly,
such as by enabling the use of a single set of cone 106/slips 104
instead of a plurality of sets, for example, to achieve the same
downhole slip performance (see also FIGS. 4A and 4B).
[0053] As shown, external buttons 110 and internal button 222 may
be formed as cylindrically shaped parts that are mounted in
corresponding holes formed in slip 104. Additionally, the exposed
surfaces of external buttons 110 or internal button 222 or both may
be non-parallel with their respective engaging surfaces, such that
external buttons 110 or internal button 222 have an edge that can
bite in the respective engaging surface when set to further
increase frictional force. It is noted that in various embodiments,
internal button 222 may cause at least some plastic deformation in
cone 106 when set, such as an indentation that corresponds to the
shape of internal button 222 and helps to hold internal button 222,
and also slip 104, in place when set. In some embodiments, cone 106
may be formed from a metal, such as steel, while internal button
222 may be formed from a hard material, such as a ceramic. It is
noted that a body of slip 104 may be formed from any of various
materials, including metals or rubbers, resin, epoxy, or other
polymers. In particular, the body of slip 104 may be a composite
material having a matrix phase as noted with an inclusion phase
that may include various inclusions, such as fibers, filaments, and
particles, or various combinations thereof.
[0054] In certain embodiments, slip 104 may be made using a
filament-reinforced composite material, such as an epoxy with glass
fiber filaments, among other types of composite matrix and
inclusion combinations. In particular embodiments, the glass fiber
is wound as a continuous filament on a mandrel from which
individual parts for slip 104 may be cut. One example of a
filament-reinforced slip part is disclosed in U.S. patent
application Ser. No. 15/981,592 titled "Filament Reinforced
Composite Material with Load-Aligned Filament Windings" filed on
May 16, 2018, which is hereby incorporated by reference.
[0055] Referring now to FIG. 3, a flow chart of selected elements
of an embodiment of a method 300 of using a slip with internal
buttons, as disclosed herein. It is noted that certain operations
described in method 300 may be optional or may be rearranged in
different embodiments. In various embodiments, method 300 may be
performed for various types of downhole tools, as described
herein.
[0056] Method 300 may begin at step 302 by running a downhole tool
to a depth in a wellbore, where the downhole tool comprises a
setting cone enabled to engage a plurality of slips located
circumferentially about the setting cone when the downhole tool is
set. At step 304, the downhole tool is set in the wellbore,
including causing the plurality of slips to engage the setting
cone, and where at least one of the slips is an inner button slip.
At step 306, the plurality of slips are forced against the setting
cone, including the at least one inner button slip, where the inner
button contacts the setting cone as the outer surface of the
plurality of slips engages the wellbore.
[0057] Referring now to FIGS. 4A and 4B, a frac plug 400 having
slips 404 is depicted in an external view and a sectional view,
respectively. FIGS. 4A and 4B are schematic diagrams for
descriptive purposes and are not drawn to scale or perspective. In
FIG. 4A, frac plug 400 is shown as a compact tool exhibiting a
relatively low ratio of tool length to tool diameter and includes a
frustoconical member 406, which may be similar to or analogous to
cone 106 described above with respect to FIGS. 1 and 2. Although
frustoconical member 406 is depicted in the drawings having
relatively smooth surfaces, it is noted that in different
embodiments, different surface roughness, surface geometries, or
surface texture may be used, such as in conjunction with a given
design or material choice of slips 404, for example. Frac plug 400
may operate to plug a wellbore, such as a cased wellbore having a
casing diameter of 3.5 inches, 4 inches, 4.5 inches, or 5.5 inches,
among other casing diameters. Frac plug 400 may be set in place by
compressing frac plug 400, such that slips 404 are engaged to
firmly hold frac plug 400 in a particular location in a
corresponding wellbore, such as within a casing of the wellbore.
Frac plug 400 may be compressed for setting in place by forcing
slips 404 against frustoconical member 406 in a direction given by
arrow 420. The frictional force of slips 404 pressing against the
interior surface of the wellbore (or the casing) holds frac plug
400 in place in the set or "plugged" condition. Accordingly, the
force that maintains frac plug 400 in the set or plugged condition
is achieved by virtue of the material strength of slips 404, as
well as the friction between slips 404 and frustoconical member
406. Also visible in FIGS. 4A and 4B are external buttons 410,
which are enabled to engage the casing when frac plug 400 is
set.
[0058] In FIG. 4A, a sectional line on frac plug 400-1 indicates a
sectional view 400-2 shown in FIG. 4B. In FIG. 4B showing the
sectional view 400-2, internal (or inner) buttons 422 and external
buttons 410 are visible. Specifically, internal buttons 422 are
shown embedded within slip 404 and protrude from slip 404. Also
visible in FIG. 4B is a slight non-parallel surface of internal
buttons 422, resulting in an edge to cylindrically shaped internal
buttons 422 that is enabled to engage with frustoconical member 406
when frac plug 400 is set (not shown), such as by biting into or
otherwise deforming at least a portion of frustoconical member
406.
[0059] The non-parallel surface of internal buttons 422 or external
buttons 410 may be realized using different methods. As shown in
FIG. 4B, internal buttons 422 are regular cylinders that are
embedded in a hole that is drilled at a non-perpendicular angle to
an inner surface 404-1 of slip 404 (see also inner surface 104-1 in
FIG. 1). In other embodiments, internal buttons 422 or external
buttons 410 may be cylindrical parts that are cut obliquely with a
non-perpendicular surface at least one end, while the holes drilled
in slip 404 are drilled perpendicular to inner surface 404-1. It is
noted that in certain implementations, external buttons 422 or
internal buttons 410 may be non-cylindrical in shape, such as
having shapes of triangular prisms, square prisms, rectangular
prisms, or other polygonal prisms (not shown).
[0060] In this manner, internal buttons 422 may increase the
frictional force by which slip 404 is held in place by
frustoconical member 406 when frac plug 400 is set, which may
enable the relatively low ratio of tool length to tool diameter,
such as by allowing frac plug 400 to have a single frustoconical
member 406, instead of a plurality of cones and a respective
plurality of sets of slips.
[0061] The above disclosed subject matter is to be considered
illustrative, and not restrictive, and the appended claims are
intended to include all such modifications, enhancements, and other
embodiments thereof which fall within the true spirit and scope of
the present disclosure.
* * * * *