U.S. patent application number 17/692481 was filed with the patent office on 2022-09-15 for pressure enhanced frac plug.
The applicant listed for this patent is DOWNHOLE INNOVATIONS, LLC. Invention is credited to Henry Joe JORDAN, JR., Wesley PRITCHETT, Rockni VAN CLIEF.
Application Number | 20220290517 17/692481 |
Document ID | / |
Family ID | 1000006228062 |
Filed Date | 2022-09-15 |
United States Patent
Application |
20220290517 |
Kind Code |
A1 |
JORDAN, JR.; Henry Joe ; et
al. |
September 15, 2022 |
PRESSURE ENHANCED FRAC PLUG
Abstract
The disclosure relates to a frac plug having an uphole side and
a downhole side and having a first cone, wherein the first cone
defines one or more chambers within the first cone; one or more
pistons each partially inserted into the one or more chambers at a
first end of the one or more pistons; a second cone connected to a
second end of each of the one or more pistons; a slip barrel
surrounding the first cone and the second cone.
Inventors: |
JORDAN, JR.; Henry Joe;
(Willis, TX) ; PRITCHETT; Wesley; (Liberty,
TX) ; VAN CLIEF; Rockni; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DOWNHOLE INNOVATIONS, LLC |
Houston |
TX |
US |
|
|
Family ID: |
1000006228062 |
Appl. No.: |
17/692481 |
Filed: |
March 11, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63161029 |
Mar 15, 2021 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/129 20130101;
E21B 23/01 20130101 |
International
Class: |
E21B 23/01 20060101
E21B023/01; E21B 33/129 20060101 E21B033/129 |
Claims
1. A frac plug having an uphole side and a downhole side,
comprising a first cone, wherein the first cone defines one or more
chambers within the first cone; one or more pistons each partially
inserted into the one or more chambers at a first end of the one or
more pistons; a second cone connected to a second end of each of
the one or more pistons; a slip barrel surrounding the first cone
and the second cone.
2. The frac plug of claim 1, wherein the one or more pistons each
include a shear tab configured to resist further insertion of the
one or more pistons into the one or more chambers up to a
predetermined amount of force.
3. The frac plug of claim 2, wherein each of the one or more
chambers are initially set at atmospheric pressure.
4. The frac plug of claim 3, wherein the frac plug comprises a
dissolvable material.
5. The frac plug of claim 4, further comprising a plurality of slip
buttons, wherein each of the plurality of slip buttons is embedded
in the slip barrel at a first non-perpendicular angle.
6. The frac plug of claim 5, wherein the plurality of slip buttons
comprise a first group of slip buttons proximate the uphole side of
the frac plug, and a second group of slip buttons proximate the
downhole side of the frac plug; and further wherein the first group
of slip buttons are embedded at the first non-perpendicular angle,
and the second group of slip buttons are embedded at a second
non-perpendicular angle.
7. A method of running and setting a frac plug at a desired
location in a casing within a wellbore, comprising the steps of:
providing a first cone and a second cone of the frac plug situated
at a distance from each other; wherein the first cone comprises one
or more chambers defined within the first cone, and wherein the
second cone comprises one or more pistons partially inserted into
the one or more chambers; setting each of the one or more chambers
at a predetermined pressure; preventing the one or more pistons
from further engaging with the one or more chambers via a shear tab
on each of the one or more pistons; and providing a slip barrel
surrounding the first cone and the second cone.
8. The method of claim 7, further comprising the steps of:
actuating a setting tool connected to the frac plug; shearing the
shear tab of each of the one or more pistons; decreasing the
distance between the first cone and the second cone; and driving
the one or more pistons further into the one or more chambers after
shearing the shear tab of each of the one or more pistons.
9. The method of claim 8 further comprising the step of: anchoring
the frac plug into the casing via the slip barrel.
10. The method of claim 9, further comprising the steps of driving
the one or more pistons further into the one or more chambers via a
hydrostatic pressure of the wellbore, wherein the hydrostatic
pressure is greater than the predetermined pressure of the one or
more chambers; further decreasing the distance between the first
cone and the second cone; and boosting the anchoring of the frac
plug into the casing; wherein the steps of driving the one or more
pistons further into the one or more chambers, further decreasing
the distance between the first cone and the second cone, and
boosting the anchoring of the frac plug into the casing occur after
the step of actuating the setting tool.
11. The method of claim 10, further comprising the steps of
dissolving the frac plug with a dissolving media; and accelerating
the step of dissolving the frac plug via exposing an increased
surface area of each of the one or more chambers to the dissolving
media.
12. The method of claim 11, further comprising the steps of:
creating an isolation zone via a sealing element connected to the
slip barrel, wherein the sealing element seals against the
casing.
13. The method of claim 9, further comprising the steps of:
releasing a ball of the frac plug; and retrieving the ball from the
wellbore while preventing the frac plug from releasing from the
casing via the slip barrel anchored into the casing.
14. A method of running and setting a frac plug at a desired
location in a casing within a wellbore, comprising the steps of:
setting a frac plug within the casing; and after the frac plug is
set, boosting a retention of the frac plug by enabling relative
motion to occur between a first cone and a second cone.
15. The method of claim 14 wherein the first cone defines at least
one chamber and the second cone comprises at least one piston
extending from the second cone; and further comprising the step of
inserting the at least one piston into the at least one
chamber.
16. The method of claim 15, wherein the at least one piston
comprises a shoulder and comprising the step of preventing the
insertion of the at least one piston past the shoulder up to a
predetermined pressure.
17. The method of claim 16, wherein the wellbore further comprises
a hydrostatic pressure and wherein the at least one chamber
comprises a chamber pressure; and further comprising the step of
setting the chamber pressure lower than the hydrostatic
pressure.
18. The method of claim 17, wherein the step of setting the frac
plug comprises the steps of: stroking a setting tool connected to
the frac plug; overcoming the shoulder of the at least one piston
and inserting the at least one piston past the shoulder into the at
least one chamber; and anchoring the frac plug into the casing.
19. The method of claim 18, wherein the difference between the
hydrostatic pressure and the chamber pressure drive the at least
one piston further into the at least one chamber.
20. A frac plug having an uphole side and a downhole side,
comprising a first frustoconical cone and a second frustoconical
cone of the frac plug, wherein each frustoconical cone defines a
top surface, and the top surface of the first frustoconical cone is
situated facing the top surface of the second frustoconical cone,
and wherein the top surface of the first frustoconical cone and the
top surface of the second frustoconical cone are separated at a
distance during a run-in position of the frac plug; a plurality of
chambers defined in the first frustoconical cone; a plurality of
pistons extending from the top surface of the second frustoconical
cone, wherein each of the plurality of pistons is partially
inserted into each of the plurality of chambers of the first
frustoconical cone during the run-in position of the frac plug; a
slip barrel surrounding the first frustoconical cone and the second
frustoconical cone.
21. The frac plug of claim 20, wherein each of the plurality of
pistons comprises a shoulder along each of the plurality of
pistons, wherein each of the plurality of pistons is partially
inserted into each of the plurality of chambers up to the shoulder
during the run-in position of the frac plug.
22. The frac plug of claim 21, further comprising a first set
position of the frac plug, wherein the first set position of the
frac plug comprises each of the plurality of the pistons inserted
further into each of the plurality of chambers beyond the shoulder
of each of the plurality of pistons.
23. The frac plug of claim 22, further comprising a second set
position of the frac plug, wherein the distance between the first
frustoconical cone and the second frustoconical cone is decreased;
and further wherein the second set position of the frac plug
comprises the plurality of pistons inserted even further into each
of the plurality of chambers as compared with the plurality of
pistons in the first set position of the frac plug.
24. The frac plug of claim 20, further comprising a second
plurality of pistons extending from the top surface of the first
frustoconical cone; and a second plurality of chambers defined in
the second frustoconical cone; wherein each of the second plurality
of pistons is partially inserted into each of the second plurality
of chambers during the run-in position of the frac plug.
Description
STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
[0001] Not Applicable.
NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0002] Not Applicable.
BACKGROUND
[0003] Unconventional Well Completions involve many different
operations. Stimulation or fracturing of the well formation to
provide increased production of hydrocarbon is typically required
and is a time consuming and costly operation. One of the most
popular means of isolating the individual zones or stages of the
well during the stimulation process is the utilization of either a
composite frac plug or a self-dissolving (dissolvable) frac plug.
The composite or dissolvable frac plug is generally pumped down the
well as part of a bottom hole assembly (hereinafter, also referred
to as "BHA") that includes the plug, a setting adapter with setting
tool, and a series of one or more perforating guns. This BHA is
attached to an electric line (also referred to as "E-line") which
is spooled off as the BHA is pumped down the well and out into the
well's horizontal section. Once the BHA is located at the correct
position within the well, an electric current is sent down the
wireline to actuate the setting tool and causes the frac plug to be
actuated or set in the well casing to create an isolation seal. The
plug further releases itself from the BHA. In the process of
setting the composite or dissolvable frac plug, an anchoring means
typically called a slip is imbedded into the casing to hold the
plug in its position within the well casing. Once the plug has been
set in place, the further operation of perforating the casing above
the plug is continued until all of the perforating guns on the BHA
are spent, then the BHA is removed from the well. Typically, a ball
is located on top of the frac plug to completely isolate the upper
zone above the plug from the lower zone below the plug when the
stimulation or frac pressure is applied down the well bore. Other
techniques are also used to create this same isolation effect,
including flappers, poppets, etc. Once these operations have been
complete, the frac pressure is applied to the well bore to create a
high-pressure and high-flow rate at the perforations and cause the
well formation to break-down or fracture, thus creating many
fractured paths that will eventually allow for the movement of
hydrocarbon to escape the formation and travel up the well
bore.
[0004] Normally this process is repeated numerous times at
progressive locations within the well with all of the plugs
remaining in the well following the full stimulation job. Once the
stimulation job (or frac job) has been completed on the full well,
the composite plugs or dissolvable plugs need to be removed from
the well so that the zones below it can be produced. The removal
process is different for a composite frac plug than for a
dissolvable frac plug.
[0005] For composite frac plugs, the plugs are typically removed
with a mill assembly run in the well on threaded pipe or coiled
tubing. The tubing is installed in the well from the surface to the
depth of the first bridge plug. The mill drills or grinds up the
plug leaving small debris in the well to be removed by fluid
circulation. This process continues until all the plugs are
removed.
[0006] For dissolvable frac plugs, the plugs will degrade, and the
material of the plugs will dissolve over a given time to cause the
plugs to disappear or go away from the well on their own. When
using these plugs, typically the operator does not have to mill
them up and will only run into the well to perform a clean-out or
fluid circulation run to verify the plugs are all gone.
[0007] The traditional composite or dissolvable plug is set in the
well casing with a setting tool that applies a high setting force
to cause the plug to anchor in the casing and to create a seal
against the casing. However, this is a `one-time` applied setting
force through the use of the setting tool and integrity of this
force retainment in the plug is typically maintained by a ratchet
type mechanical locking mechanism designed as part of the plug
itself. These mechanisms are designed only to retain the initial
setting force applied to the plug. A first known problem with
currently available frac plugs is that the plugs can become loose
due to rubber extrusion or back-lash in the locking mechanism, and
the plug can lose its initial setting force allowing the plug to
release its grip on the casing and potentially move in the well
bore when frac pressure is applied to it. This is a major problem
for the operator if the plug moves when they are applying the
stimulation or frac pressure to the top of the plug. This can
create an incomplete or bad stimulation/frac job.
[0008] In a similar fashion, and relating to a second known problem
with currently available frac plugs, sometimes the perforating guns
do not perform correctly, and the operator is required to back-flow
the well to remove the ball that is sitting on top of the frac plug
so that they can perform a new BHA pump-down operation. This
process causes a high-pressure differential across the frac plug
due to flow and pressure drops across the plug from below and can
cause the plug to move up the well bore. Most frac plugs are not
designed to take these high loads from below, but only from above
where the frac pressure is applied. In the event a plug moves
upwards under this condition, this will create an expensive problem
for the operator to have to remove the plug before continuing
normal operations.
[0009] Another issue related to only the currently available
dissolvable frac plugs is the rate of degradation that the frac
plug may experience based on the conditions within the well bore.
Dissolvable plugs are designed to start degrading the moment they
come into contact with the activating fluid which is typically
water. This means that even before the plug is set in the casing,
the plug begins the process of degrading. Once a plug is set and
anchored in the casing, the plug is still continually degrading
before the perforating operations are complete and before the frac
pressure is applied. This degradation process may cause the frac
plug to lose some of its anchoring or sealing integrity before the
plug sees the full load from the high differential frac pressure
that is applied to it.
[0010] Under this situation, the plug could move within the
wellbore due to significant material loss once the frac pressure is
applied, again resulting in a poor frac job. This can be a major
problem for the operator if the plug moves when they are applying
the stimulation or frac pressure to the top of the plug. This can
create an incomplete or bad stimulation/frac job.
[0011] The present disclosure is intended to capture several novel
concepts and solve at least the several known problems as described
above.
BRIEF SUMMARY
[0012] The disclosure relates to a frac plug having an uphole side
and a downhole side and having a first cone, wherein the first cone
defines one or more chambers within the first cone; one or more
pistons each partially inserted into the one or more chambers at a
first end of the one or more pistons; a second cone connected to a
second end of each of the one or more pistons; a slip barrel
surrounding the first cone and the second cone.
[0013] As used herein, the terms "frac" or "frack" also includes
encompasses the terms "fracture", "fracturing", "fracking",
"fracing", or "fraccing" or "hydraulic fracturing" as commonly
understood in the petrochemical field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The exemplary embodiments may be better understood, and
numerous objects, features, and advantages made apparent to those
skilled in the art by referencing the accompanying drawings. These
drawings are used to illustrate only exemplary embodiments and are
not to be considered limiting of its scope, for the disclosure may
admit to other equally effective exemplary embodiments. The figures
are not necessarily to scale and certain features and certain views
of the figures may be shown exaggerated in scale or in schematic in
the interest of clarity and conciseness.
[0015] FIG. 1 depicts a cross-section view of an exemplary
embodiment of a bottom hole assembly including a setting tool and a
frac plug.
[0016] FIG. 2 depicts a front view of an exemplary embodiment of a
frac plug.
[0017] FIG. 3 depicts a cross-section view of an exemplary
embodiment of a frac plug in its run-in position.
[0018] FIG. 4 depicts a cross-section view of an exemplary
embodiment of a frac plug within and set into a casing.
[0019] FIG. 5 depicts a partially cut-away perspective view of an
exemplary embodiment a frac plug.
[0020] FIG. 6A depicts a front view of an exemplary embodiment of
an upper cone of a frac plug.
[0021] FIG. 6B depicts a top view of the exemplary embodiment of
the upper cone of the frac plug in FIG. 6A.
[0022] FIG. 7A depicts a top view of an exemplary embodiment of a
lower cone of a frac plug.
[0023] FIG. 7B depicts a front view of the exemplary embodiment of
the lower cone of the frac plug in FIG. 7A.
[0024] FIG. 8A depicts a front view of an exemplary embodiment of a
slip barrel of a frac plug.
[0025] FIG. 8B depicts a top view of the exemplary embodiment of
the slip barrel of the frac plug in FIG. 8A.
[0026] FIG. 9 depicts a front view of an exemplary embodiment of a
piston of a frac plug.
[0027] FIG. 10A depicts a front view of an exemplary embodiment of
a seal ring of a bottom hole assembly.
[0028] FIG. 10B depicts a top view of the exemplary embodiment of
the seal ring of the bottom hole assembly in FIG. 10A.
DESCRIPTION OF EMBODIMENT(s)
[0029] The description that follows includes exemplary apparatus,
methods, techniques, and instruction sequences that embody
techniques of the inventive subject matter. However, it is
understood that the described embodiments may be practiced without
these specific details.
[0030] FIG. 1 depicts a cross-section view of an exemplary
embodiment of a bottom hole assembly 10 including a setting tool 20
and a frac plug 30, as being maneuvered or pumped into a wellbore
and connected to the surface via an electric line 14. A first end,
in relation to the wellbore, is defined as being the uphole end 11
or closer towards the surface, and a second opposite end, in
relation to the wellbore, is defined as being the downhole end 12,
as being farther away from the surface. These ends 11, 12 are also
present in a horizontal wellbore, wherein the downhole end 12 is
further within the wellbore in contrast to the uphole end 11.
[0031] The setting tool 20 includes a setting tool adapter tool kit
21, outer setting sleeves 22, a retention device 23, a shear ring
24 on the retention device 23, a solid stem 25 inserted through the
frac plug 30, and a ball 26 as the BHA 10 is being run into the
casing 13 or wellbore. The setting tool adapter kit 21, outer
setting sleeves 22, retention device 23, shear ring 24, and solid
stem 25 may all be connected during the run-in phase of the
wellbore operation.
[0032] A front view and a cross-section view of the plug or frac
plug 30 in an unset or run-in position 70 is provided for in FIGS.
2 and 3, respectively. FIG. 5 depicts a partially cut-away
perspective view of an exemplary embodiment the frac plug 30 in the
unset or run-in position 70. The frac plug 30 includes a top, or
upper frustoconical cone 31a; a bottom, or lower frustoconical cone
31b; and a slip barrel or collar 50. The upper cone 31a may define
an inclined or angled exterior surface 33a which connects a top
surface 34a of the upper cone 31a to the bottom surface 38a of the
upper cone 31a; and the lower cone 31b may define an inclined or
angled exterior surface 33b which connects a top surface 34b of the
lower cone 31b to the bottom surface 38b of the lower cone 31b (see
e.g. FIG. 4). The bottom surface 38a of the upper cone 31a may also
define a ball seat 27 against which the ball 26 is engaged when the
frac plug 30 is in a set position 72 in the casing 13. In the
exemplary embodiments as depicted in FIGS. 1-5, the top surface 34a
of the upper cone 31a may be oriented towards the downhole
direction 12, and the bottom surface 38a of the upper cone 31a may
be oriented towards the uphole direction 11. Further in the
exemplary embodiments as shown, the top surface 34b of the lower
cone 31b may be oriented towards the uphole direction 11, and the
bottom surface 38b of the lower cone 31b may be oriented towards
the downhole direction 12. The top surfaces 34a, 34b may have or
define a smaller diameter than the corresponding bottom surfaces
38a, 38b (see e.g. FIGS. 6A-7B). This disclosure will apply to
plugs 30 made of both composite and dissolvable materials.
[0033] The upper cone 31a includes one or more holes 32a used in
conjunction with pistons 40 to create chambers 32 defined within
the interior of the upper cone 31a through the top surface 34a and
not through the bottom surface 38a. The chambers 32 may be
optionally evenly distributed in a circular pattern about the top
surface 34a, although other patterns are considered within the
scope of the disclosure. By way of example only, referring at least
to FIGS. 6A-6B, there may be six chambers 32 defined within the
upper cone 31a, although any number of chambers 32 is considered
within the scope of this disclosure. The chambers 32 may be set at
atmospheric pressure during the run-in process. The chambers 32 may
take the form of a tube-like cavity, duct or hole and have a
substantially complimentary shape and length to engage the pins or
pistons 40. The lower cone 31b is connected to one or more pins,
rods, or pistons 40 via threading 35 on the cone 31b and threading
42 on the pistons 40 at one end 43 of the pistons 40. FIGS. 7A-7B
depict an enlarged view of the lower cone 31b prior to the
assembly, attachment or connection of the pistons 40. The pistons
40 extend from the top surface 34b of the lower cone 31b, and
arranged in a similar pattern to the chambers 32 so as to be able
to engage or insert into the chambers 32 at the other end 44 of the
piston 40. The pistons 40 for each particular embodiment are equal
in number to the number of chambers 32 in cone 31a and are
partially inserted into the chambers 32 up to a shoulder 41 when
the frac plug 30 is assembled and run-in. Each piston 40 includes
an extended shoulder or shear tab 41 abutting the top surface 34a
of the cone 31a to prevent inadvertent setting of the frac plug 30
during the run-in operation, via preventing the piston 40 from
further insertion into the corresponding atmospheric chambers 32
(see e.g., FIG. 9 for an enlarged view of the piston 40 including
the shoulder or shear tab 41). The top of each of the upper cone
31a and the lower cone 31b are facing each other in the run-in
position, held at a distance 37 between each respective top surface
34a, 34b of each cone 31a, 31b. After setting of the frac plug 30,
as depicted in FIG. 4, in an anchored or set position 72 of the
plug 30, a greater or increased length of the pistons 40 may be
further inserted into the chambers 32 past the shear tabs 41, as
compared with the length of the pistons 40 inserted into the
chambers 32 in the run-in or unset position 70.
[0034] In alternative exemplary embodiments, the chambers 32 (or
holes 32a) may instead all be defined on the lower cone 31b, and
the pistons 40 may instead all be attached to the upper cone 31a.
In further alternative exemplary embodiments, the upper cone 31a
may contain a combination of chambers 32 (or holes 32a) and pistons
40; in this particular further alternative exemplary embodiment,
the lower cone 31b would contain a complementary or mating pattern
of chambers 32 (or holes 32a) and pistons 40 so that the upper cone
31a can complementarily engage with or insert into the lower cone
31b. By way of example only, in an exemplary embodiment, the upper
cone 31a may contain two chambers 32 and two pistons 40, and the
lower cone may contain two pistons 40 that correspondingly engage
with the upper cone 31a's chambers 32 or holes 32a; and the lower
cone may further define two chambers 32 or holes 32a that
correspondingly engage with the upper cone 31a's pistons 40.
[0035] The slip or slip barrel, or anchoring mechanism 50 has a
substantially cylindrical ring-like or collar-like shape having an
outer surface 51 and an inner surface 52. The inner surface 52 of
the slip 50 further defines a first inclined surface 53a, and a
second inclined surface 53b. The inclined surfaces 53a and 53b
slidably engage with the angled exterior surface 33a of the upper
cone 31a, and the angled exterior surface 33b of the lower cone
31b, respectively. As can be best seen in the enlarged FIGS. 8A-8B,
the slip 50 also includes a pattern of slots, cavities, slits,
reliefs, or gaps 57 defined through the slip 50 which allows the
slip 50 to be adjustable, such as to extend/expand or retract, in
size, as the slip 50 moves over exterior angled surfaces 33a,33b of
the cones 31a,31b.
[0036] The outer surface 51 of the slip 50 also defines a number of
depressions 58 for the attachment or mounting of slip buttons 55.
These slip buttons 55 in certain exemplary embodiments may be made
of a ceramic material that is harder than the material of the
casing 13; the slip buttons 55 may in alternative exemplary
embodiments be made of other materials such as carbide or cast iron
or any other material as known to one of ordinary skill in the art.
The surface of each slip button 55 are positioned at an angle 56
within the slip 50, which may be an askew or non-perpendicular
angle. These slip buttons 55a and 55b may also be described to be
"back-facing" (e.g. the exterior surface of top slip buttons 55a
are tilted or angled towards the top 30a of the plug 30, and the
exterior surface of bottom slip buttons 55b are tilted or angled
towards the bottom 30b of the plug 30). By way of example only,
slip buttons 55a situated nearer or proximate to upper cone 31a may
engage the casing 13 via a gripping corner, sharp edge, square
edge, or right angle 59 at the downhole side 12 of the same button
55; and slip buttons 55b situated nearer or proximate to the lower
cone 31b may engage the casing 13 via a gripping corner, sharp
edge, square edge, or right angle 59 at the uphole side 11 of said
button 55. The angle 56 of the slip buttons 55a may be opposite or
opposing angles to angle 56 of slip buttons 55b. Slip buttons 55
may be one example of an anchoring mechanism 16 for `biting`,
anchoring, or engaging the casing 13. Other techniques or
mechanisms 16 beyond slip buttons 55 that provide for ability of
the slip 50 to anchor, bite, engage, or grip into the casing 13, as
known to one of ordinary skill in the art, are considered within
the scope of the present disclosure. By way of example only, one
such anchoring mechanism 16 in place of the buttons 55 may be to
machine or manufacture the profile of `teeth`, peaks, or sharp
points on the exterior of the slip 50 body itself so that the
anchoring mechanism 16 will bite, anchor, grip, or otherwise engage
with the case 13 when the slip 50 body is expanded.
[0037] The slip 50 may further include a sealing system, element or
mechanism 62 having a seal ring 60 and a seal 61 at an uphole end
11 of the slip 50. Please refer to FIGS. 10A and 10b for an
enlarged depiction of the seal ring 60. The deformable elastomeric
seal 61 is seated within the seal ring 60 (which may be made of
metal). The elastomeric seal 61 engages and seals against the
casing 13 when the frac plug 30 is set. The seal ring 60 and the
seal 61 may be the primary seal for the frac plug 30 for creating
an isolation zone and may assist with preventing the ball 26 and/or
plug 30 from leaking. The sealing ring 60 and elastomeric seal 61
may be one example of a sealing system, element, or mechanism 62
for the plug 30. In further alternative exemplary embodiments, a
rubber seal may be utilized in place of the expansion ring 60 and
an elastomeric seal 61 for the purposes of providing a primary seal
for the frac plug 30; in a further alternative exemplary
embodiment, the sealing system 62 may be a single or unitary piece
elastomeric packing element. Other traditional elastomeric sealing
systems 62 as known to one of ordinary skill in the art is
considered within the scope of the disclosure.
[0038] When the frac plug 30 is at the desired location within the
casing 13 in the wellbore (see e.g. FIG. 4 depicting one anchored
or `set` position 72 of the frac plug 30), setting tool 20 is fired
or stroked via the electric line 14 to set the frac plug 30,
creating by way of example only, 30,000 lbs of pressure applied to
the shear ring 24 and overcoming the shear tabs 41 on the pistons
40. The outer setting sleeves 22 and shear ring 24 are pulled which
releases the setting tool 20 and allows the setting tool 20,
including the setting tool adapter kit 21, outer sleeves 22,
retention device 23 and solid stem 25 to be retrieved from the
wellbore. The stroking of the setting tool 20 also pushes down on
the top 30a of the frac plug 30 and pushes against the bottom 30b
of the frac plug 30, thus driving the slip barrel 50 to engage with
the casing 13 via slip buttons 55 gripping into the casing 13. The
ball 26 is also released during this process and the deformable
elastomeric seal 61, or sealing system 62, seals against casing 13
as the plug 30 is set by the wireline 14. Media pumped into the
casing 13 will seat the ball 26 into the ball seat 27. In the event
that the ball 26 needs to be retrieved, the back-facing slip
buttons 55 will prevent the plug 30 from releasing from the casing
13. After setting, in a second or additional set or anchored
position 72 after the initial set or anchored position 72, the
wellbore hydrostatic pressure 15 surrounding the frac plug 30 also
continuously drives or forces the upper cone 31a and the lower cone
31b together, decreasing or maintaining the shortened distance 37
between the cones 31a,31b, and also drives the pistons 40 into the
chambers 32, which may be, by way of example only, at atmospheric
pressure. The chambers 32 may be at other pressures when the plug
30 is at the desired location in the casing 13, but the chambers 32
are generally at a different and lower pressure as compared to the
hydrostatic pressure 15 in the wellbore. There may be multiple set
or anchored positions 72 of the frac plug 30 ranging from the
initial actuation or stroking of the setting tool 20 setting the
frac plug 30 in a first set position 72 and as the hydrostatic
pressure 15 increases or boosts the anchoring, retention, or hold
of the frac plug 30 into the casing 13 in further set positions 72
of the frac plug 30.
[0039] As depicted in at least FIG. 4, the frac plug 30 allows for
pressure 15 from the surrounding well to boost or enhance the
initial setting force on the sealing and gripping mechanisms
(including at least the sealing system 62, the seal ring 60,
deformable elastomeric seal 61, the slip 50 and the slip buttons 55
in an exemplary embodiment) of the frac plug 30. Because of the
setting depth of the frac plug 30 within a well bore, there is a
natural high hydrostatic pressure 15 surrounding the plug 30. This
disclosure utilizes this natural high hydrostatic pressure 15 to
act against one or more atmospheric piston chambers 32 to
continually boost or enhance the forces 36 acting on the plug 30 to
cause continued cinching or tightening of the plug 30 beyond the
initial setting force applied through the wireline 14.
[0040] As described above, the frac plug 30 allows the continued
use of the well's surrounding hydrostatic pressure 15 to apply a
continued tightening force 36 on the seal, (by way of example, and
not to be limited to, the sealing system 62 having the sealing ring
60, and deformable elastomeric seal 61 in one exemplary embodiment)
and on the gripping mechanism (by way of example, and not to be
limited to, the slip 50 and the slip buttons 55). This prevents the
plug 30 from loosening its grip from the casing 13 as it maintains
a strong and positive anchoring force until the plug 30 is
removed.
[0041] Because this frac plug 30 responds to pressure, once the
surface frac pressure is applied to create a higher pressure down
in the well to perform the stimulation job or frac job, this higher
applied pressure will combine with the existing hydrostatic
pressure 15 around the plug 30 to cause even a greater tightening
force 36 on the plug 30.
[0042] Also because the piston rods 40 and the atmospheric chambers
32 are defined on opposingly situated and separate cones 31a,31b at
the top 30a and bottom 30b, respectively, of the plug 30, the
forces (which may include hydrostatic pressure 15 of the wellbore,
as well as applied surface frac pressure to the plug 30) that are
generated across these pistons 40 and chambers 32 act to drive the
upper cone 31a and lower cone 31b together, thus driving the seal
60 or sealing system 62 and the slip 50 to create a greater or
tighter engagement with the casing 13. This load creates the same
high engagement forces at the top 30a of the plug 30 and the bottom
30b of the plug 30. This creates a situation where the plug 30 will
have the same resistance to any load coming from above/uphole 11 or
below/downhole 12 the plug 30, so in the case of flow-back the frac
plug 30 will be more resistant than conventional plugs.
[0043] Further this hydraulically boosting frac plug 30 can be made
composed of either composite material or dissolvable material (e.g.
, but not limited to, magnesium). It is a notable feature that as
the dissolvable plug 30 begins to degrade and lose material from
the plug 30, the hydraulic boosting effect will cause the plug 30
to tighten and maintain its pressure and anchoring integrity for a
longer period of time than a traditional or conventional
dissolvable plug that will become loose more quickly when it has
structural material loss. Conventional or traditional plugs do not
allow further tightening of the plug into to casing once the plug
is set by the wireline. In the instant plug 30, even as the
material from the dissolvable plug 30 is degrading, the pistons 40
will continue to further insert into the chambers 32 after
disconnection with the setting tool 20 and the electric line 14,
thus maintaining the anchoring or engagement integrity with the
casing 13.
[0044] An additional feature of this improved frac plug 30 is that
the atmospheric piston chambers 32 are only initially protected
from contact with the dissolving media in the well. Once a
dissolvable plug 30 has performed its primary function of allowing
the frac job to be complete, the plug 30 then will begin to
dissolve over time and go away. With this design, once the
atmospheric chambers 32 are breached by the dissolution process,
the amount of surface area exposed to the dissolution media within
the upper cone 31a mass increases dramatically and thereby the
dissolution or dissolving process for the entire dissolvable frac
plug 30 accelerates, making this a desirable feature to cause the
plug 30 to go away faster once it has completed its job
downhole.
[0045] According to the methodology described herein after the frac
plug 30 is set, relative motion between the cones 31a and 32b may
continue to occur. The radial travel of the slip(s) 50 may vary
according to the surrounding inner diameter of the hole of the
casing and the diameter of the frac plug 30.
[0046] The present disclosure encompasses at least: a plug 30 of
any material (dissolvable or non-dissolvable) that uses one or more
atmospheric chambers 32 and pistons 40 to boost or continually
enhance the forces required to seal or grip the casing 13; the
combined use of applied surface frac pressure and existing downhole
hydrostatic pressure 15 that will continually act to increase the
forces of sealing and gripping of the plug 30 against the casing 13
after actuating a setting tool and setting the frac plug 30;
increased gripping forces which are bi-directional (from
above/uphole 11 and below/downhole 12 the plug 30) causing the
resistance to movement of the plug 30 to be increased from both
directions in the event of frac pressure loading or back-flow
loading; the use of atmospheric pistons 40 and chambers 32 allows
for continual tightening of a dissolvable frac plug 30 as the
material begins to degrade and there is substantial material loss;
and the rate of normal material degradation of a dissolvable plug
30 is proportional to the exposed material surface area, and the
dissolution rate of the plug 30 will increase as the atmospheric
chambers 32 are breached during the material degradation process,
thus making the dissolvable plug 30 go away faster.
[0047] While the embodiments are described with reference to
various implementations and exploitations, it will be understood
that these embodiments are illustrative and that the scope of the
inventive subject matter is not limited to them. Many variations,
modifications, additions, and improvements are possible.
[0048] Plural instances may be provided for components, operations
or structures described herein as a single instance. In general,
structures and functionality presented as separate components in
the exemplary configurations may be implemented as a combined
structure or component. Similarly, structures and functionality
presented as a single component may be implemented as separate
components. These and other variations, modifications, additions,
and improvements may fall within the scope of the inventive subject
matter.
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