Note: Descriptions are shown in the official language in which they were submitted.
DOVVNHOLE TOOL AND METHOD OF ASSEMBLY
FIELD OF THE INVENTION
[0001] The present invention relates to a downhole tool, such as those
used in oil and gas
wellbores.
BACKGROUND OF THE INVENTION
[0002] Oil and gas wells typically use subterranean wellbores lined with
a casing to add
strength to the wellbore. Downhole tools, such as bridge plugs, frac plugs, or
packers, are used
in the casing to isolate sections of the wellbore. Downhole tools are usually
constructed of
durable metals, with a sealing element being formed of a compressible material
that may also
expand radially outward to engage the casing and seal off a section of the
wellbore, thereby
allowing an operator to control the passage or flow of fluids. Typical
downhole tools are
disclosed, for example, in U.S. Patent Nos. 9,677,373, 9,334,703, and
8,915,305, the subject
matter of each of which is herein incorporated by reference.
[0003] In fracing, for example, a downhole tool, such as a frac plug, is
used in a wellbore
below or beyond a respective target zone, followed by pumping or injecting
high pressure frac
fluid into the zone. The frac operation results in fractures or "cracks" in
the formation that allow
hydrocarbons to be more readily extracted and produced by an operator, and may
be repeated as
desired or necessary until all target zones are fractured.
[0004] Problems often occur when setting and removing the downhole tool
from the
wellbore. Therefore, a need exists for an improved downhole tool that avoids
premature setting
of the tool in the wellbore casing during run-in and facilitates removal of
the tool from the
wellbore.
1
CA 2997084 2018-02-28
SUMMARY OF THE INVENTION
[0005] Accordingly, the present invention may provide a downhole tool
for a wellbore
that comprises a mandrel that has a stem portion and a hub portion at an end
of the stem portion,
a load member mounted on the stem portion of the mandrel, and at least one
compression
member mounted on the stem portion of the mandrel. The compression member has
a body with
a compression end configured to compress a sealing element. At least one slip
member is
mounted on the stem portion of the mandrel between one of the opposing ends of
the load
member and the body of the compression member. The slip member is configured
for axial
movement with respect to the mandrel. A bonding agent is disposed between an
outer surface of
the mandrel and an inner surface of the load member and disposed between an
outer surface of
the stem portion of the mandrel and an inner surface of the compression
member. The bonding
agent has a predetermined shear strength that fixes the load member and the
compression
member to the mandrel, thereby isolating and preventing axial movement of the
at least one slip
member with respect to the mandrel between the load member and the compression
member.
[0006] In some embodiments, a second compression member is mounted on
the stem
portion of the mandrel that has a body with a compression end configured to
compress the
sealing element; the bonding agent is disposed between an outer surface of the
stem portion of
the mandrel and an inner surface of the second compression member, thereby
fixing the second
compression member to the mandrel; the sealing element is expandable and no
bonding agent is
disposed between the sealing element and the mandrel; and/ or a second slip
member is mounted
on the stem portion of the mandrel between the body of the second compression
member and an
end cap installed on a distal end of the stem portion of the mandrel, the
second slip member
being configured for axial movement with respect to the mandrel, wherein the
second
compression member isolates and prevents axial movement with respect to the
mandrel of the
second slip member between the second compression member and the end cap.
[0007] In certain embodiments, the inner surface of the load member is
tapered to
correspond to a tapered shoulder of the outer surface of the mandrel with the
bonding agent
therebetween; the bonding agent is an adhesive or epoxy and the predetermined
shear strength
2
CA 2997084 2018-02-28
resists a shear force of greater than 1000psi; the load member is a load ring,
the compression
member is a compression cone, and the slip member has one or more inserts
configured to grab a
casing of the wellbore; the opposing ends of the load member include a
mounting end and an
interface end, the interface end has a first anti-rotation feature; the slip
member has an interface
end that generally faces the interface end of the load member, the interface
end of the slip
member has a second anti-rotation feature configured to engage the first ant-
rotation feature such
that engagement of the first and second anti-rotation features prevents
rotation of the load
member and the slip member with respect to one another; and/or the body of the
at least one
compression member has at least one outer planar face that tapers inwardly
from the
compression end towards the mandrel for aligning with and engaging at least
one corresponding
inner planar surface of the slip member that tapers outwardly away from the
mandrel to prevent
rotation of the compression member and the slip member with respect to one
another.
[0008] The
present invention may also provide a downhole tool that comprises a mandrel
that has a stem portion and a hub portion at an end of the stem portion; a
load member mounted
on the stem portion of the mandrel and that has opposing ends including a
mounting end and an
interface end with a first anti-rotation feature, and at least one slip member
mounted on the stem
portion of the mandrel, the slip member being configured for axial movement
with respect to the
mandrel, and the slip member has an interface end generally facing the
interface end of the load
member. The interface end of the slip member has a second anti-rotation
feature configured to
engage the first anti-rotation feature. Engagement of the first and second
anti-rotation features
prevents rotation of the load member and the slip member with respect to one
another.
[0009] In
one embodiment, the first anti-rotation feature is at least one protrusion and
at
least one detent sized to engage at least one corresponding detent and at
least one corresponding
protrusion, respectively, of the second anti-rotation feature. In
other embodiments, a
compression member is mounted on the stem portion of the mandrel such that the
slip member is
located between the load member and the compression member and the compression
member
has a body with a compression end for compressing a sealing element, the body
has at least one
outer planar face that tapers inwardly from the compression end towards the
mandrel for aligning
with and engaging at least one corresponding inner planar surface of a
receiving end of the slip
3
CA 2997084 2018-02-28
member that tapers outwardly away from the mandrel to prevent rotation of the
compression
member and the slip member with respect to one another; and/or a bonding agent
is disposed
between an outer surface of the mandrel and an inner surface of the load
member and disposed
between an outer surface of the stem portion of the mandrel and an inner
surface of the
compression member, wherein the bonding agent has a predetermined shear
strength that fixes
the load member and the compression member to the mandrel, thereby isolating
and preventing
axial movement of the at least one slip member with respect to the mandrel
between the load
member and the compression.
[0010] In an embodiment, the body of the compression member includes a
plurality of
outer planar surfaces that taper inwardly towards the mandrel, the plurality
of outer planar
surfaces define edge lines therebetween; and/ or the receiving end of the slip
member includes a
plurality of inner planar surfaces that taper outwardly away from the mandrel
configured to
engage each of the plurality of outer planar surfaces, respectively, the
plurality of inner planar
surfaces define edge lines configured to align with the edge lines of the body
of the compression
member.
[0011] In another embodiment, a second slip member and a second
compression member
are mounted on the stem portion of the mandrel such that the slip member is
located between the
second compression member and an end cap installed on a distal end of the stem
portion of the
mandrel, the second slip member being configured for axial movement with
respect to the
mandrel, the second slip member has an interface end generally facing an
interface end of the
end cap, the interface end of the second slip member having a third anti-
rotation feature
configured to engage a fourth anti-rotation feature on the interface end of
the end cap, thereby
preventing rotation of the second slip member and the end cap with respect to
one another. In
yet another embodiment, the second compression member has a body with a
compression end for
compressing the sealing element, the body of the second compression member has
at least one
outer planar face that tapers inwardly from the compression end thereof
towards the mandrel for
aligning with and engaging at least one corresponding inner planar surface of
a receiving end of
the second slip member that tapers outwardly away from the mandrel to prevent
rotation of the
second compression member and the second slip member with respect to one
another.
4
CA 2997084 2018-02-28
[0012] In a certain embodiment, the bonding agent is disposed between an
outer surface
of the stem portion of the mandrel and an inner surface of the second
compression member to
prevent movement of the second compression member with respect to the mandrel,
thereby
preventing axial movement of the second slip member with respect to the
mandrel between the
second compression member and the end cap. In one embodiment, the load member
is a load
ring and the slip member has one or more inserts configured to grip a casing
of a wellbore.
[0013] The present invention may further provide a method of assembly of
a downhole
tool, comprising the steps of mounting a load member on a mandrel; applying a
bonding agent
between an inner surface of the load member and an outer surface of the
mandrel; mounting a
first slip member on the mandrel, the first slip member being configured for
axial movement
with respect to the mandrel; aligning an anti-rotation feature of the first
slip member with an
anti-rotation feature of the load member, thereby preventing rotation of the
load member and the
first slip member with respect to one another; mounting a first compression
member on the
mandrel; and applying the bonding agent between an inner surface of the
compression member
and an outer surface of the mandrel, wherein the bonding agent has a
predetermined shear
strength that fixes the load member and the first compression member to the
mandrel, thereby
isolating and preventing axial movement of the first slip member with respect
to the mandrel
between the load member and the first compression member.
[0014] In some embodiments, the method may further comprise the steps of
installing an
expandable sealing element on the mandrel adjacent a compression end of the
first compression
member without applying adhesive between the sealing member and the mandrel;
mounting a
second compression member on the mandrel and applying the bonding agent
between an inner
surface of the second compression member and an outer surface of the mandrel;
mounting a
second slip member on the mandrel, the second slip member being configured to
move axially
with respect to the mandrel; aligning an anti-rotation feature of the second
slip member with an
anti-rotation feature of an end cap installed on a distal end of the mandrel,
thereby preventing
rotation of the second slip member and the end cap with respect to one
another; interlocking
protrusions and detents of the anti-rotation features of the load member and
the first slip member,
CA 2997084 2018-02-28
respectively; and/or interlocking protrusion and detents of the anti-rotation
features of the second
slip member and the end cap.
[0015] In
other embodiments, the second compression member used in the method
prevents axial movement of the second slip member with respect to the mandrel
between the
second compression member and the end cap; and/or the step of preventing axial
movement is
done without using pins to mount the load member, the first compression
member, or the second
compression member to the mandrel.
6
CA 2997084 2018-02-28
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] A more complete appreciation of the invention and many of the attendant
advantages
thereof will be readily obtained as the same becomes better understood by
reference to the
following detailed description when considered in connection with the
accompanying drawing
figures:
[0017] FIG. 1 is a perspective view of a downhole tool according to an
exemplary
embodiment of the present invention;
[0018] FIG. 2 is an exploded perspective view of the downhole tool illustrated
in FIG. 1;
[0019] FIG. 3 is an elevational view of the downhole tool illustrated in FIG.
1;
[0020] FIG. 4 is a partial cross-sectional side view of the downhole
illustrated in FIG. 1; and
[0021] FIGS. 5a ¨ 5f are sequential perspective views of the downhole tool
showing the
steps of the assembly of the downhole tool according to an exemplary
embodiment of the present
invention.
7
CA 2997084 2018-02-28
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0022] Referring to the figures, the present invention generally relates
to a downhole tool
100, such as a bridge plug, a frac plug, a packer, a caged-ball frac plug, a
drop-ball frac plug, or
the like, used to isolate sections of a wellbore. As best seen in FIGS. 1 and
2, downhole tool 100
may have a number of assembled components, including a mandrel 102 that
supports the
components. The components may include a load member 104, a first slip member
106, a first
compression member 108, a sealing element 110, a second compression member
112, a second
slip member 114, and an end member 116. Sealing element 110 may be any
expandable element
known in the art to seal a section of a wellbore.
[0023] In accordance with exemplary embodiments of the present invention,
a bonding
agent may be applied between mandrel 102 and certain of the above components
such that when
tool 100 is assembled, those components are fixed to mandrel 102. This
prevents premature
setting or pre-set of tool 100 during run-in that often occurs due to impact
with unforeseen
obstructions in the wellbore. The bonding agent of the present invention is
preferably an
adhesive or epoxy with a predetermined shear strength high enough to resist an
impact force
from an obstruction if the tool were to impact an obstacle in the wellbore
during run-in, such as
debris, sand, or pieces of a plug previously used in the wellbore. The shear
strength is
determined by the maximum load force needed to break the bond created by the
bonding agent.
In one embodiment, the bonding agent is an adhesive or epoxy with a
predetermined shear
strength high enough to resist a shear force of 1000psi or greater, preferably
resists a shear force
of between 1000psi and 2000psi, and more preferably resists a shear force of
about 1250psi.
[0024] Also in accordance with exemplary embodiments of the present
invention, certain
of the above components of tool 100 are designed with anti-rotation features
to engage one
another to prevent rotation therebetween when tool 100 is assembled. This
maximizes efficiency
of the tool when activated and facilitates removal of tool 100 during drill
out from the wellbore
by preventing the free spinning of the components.
[0025] Mandrel 102 generally includes a stem portion 120 and a hub
portion 122 at one
end of stem portion 102 where stem portion 102 has an outer diameter that is
smaller than hub
8
CA 2997084 2018-02-28
portion 122, thereby allowing mounting of the components of tool 100 thereon.
Hub portion 122
may include a shoulder 124 that transitions to stem portion 120.
[0026] Load member 104 is configured to be mounted on mandrel 102, as
seen in FIGS.
5a and 5b. Load member 104 may be a load ring that has a ring body 130 with
opposing ends,
including a mounting end 132 configured to abut hub portion 122 of mandrel 102
and an
interface end 134 configured to engage first slip member 106, and an opening
extending
therebetween that is sized to receive stem portion 120. An inner surface 136
of ring body 130
may be tapered to correspond to and engage the taper of shoulder 124 of the
mandrel's hub
portion 122 when load member 104 is mounted on mandrel 102.
[0027] In a preferred embodiment, the bonding agent of the present
invention is applied
between mandrel 102 and load member 104, such as between the outer surface of
shoulder 124
and the load member's inner surface 136, to prevent movement of load member
104 with respect
to mandrel 102. The bonding agent fixes load member 104 in place on mandrel
102 during run-
in of tool 100 until tool 100 is activated and compressed (such as by using a
setting tool) with
enough force to overcome the shear strength of the bonding agent therebetween.
[0028] Slip members 106 and 114 are designed to grip the wellbore casing
to hold
downhole tool 100 in place in the wellbore and prevent it from moving once in
the set position.
Both first and second slip members 106 and 114 are configured to be mounted on
the mandrel's
stem portion 120, as seen in FIGS. 5c and 5f, respectively. Slip members 106
and 114 are
mounted such that they are able to move axially with respect to mandrel 102
along the length of
stem portion 120 when downhole tool 100 is compressed and moves from its set
position to a
compressed position to activate the tool where slip members 106 and 114 and
sealing element
110 expand to seal or isolate a section of the wellbore. Each slip member 106
and 114 may
include one or more outer inserts 200, such as pins, buttons, teeth or the
like, for gripping the
wellbore casing, as is well known in the art.
[0029] First slip member 106 is mounted on the mandrel's stem portion
120 between
load member 104 and first compression member 108 and second slip member 114 is
mounted on
the mandrel's stem portion 120 between second compression member 112 and end
member 116
9
CA 2997084 2018-02-28
(such as an end cap). Each slip member 106 and 114 generally includes an
interface end 140a,
140b (FIG. 3) and a receiving end 142 and an opening extending therebetween
for receiving stem
portion 120. Interface end 140a of first slip member 106 generally faces
interface end 134 of
load member 104 when first slip member 106 is mounted on mandrel 102 and
interface end 140b
of second slip member 114 generally faces end member 116 when mounted. Each of
the slip
members' interface ends 140a, 140b may include an anti-rotation feature 144
that engages a
corresponding anti-rotation feature 146 of the load member's interface end 134
and of the end
member 116, respectively, as seen in FIG. 2. Anti-rotation features 144 and
146 are configured
to prevent rotation of load member 104 and first slip member 106 with respect
to one another
and rotation of second slip member 114 and end member 116. Anti-rotation
features 144 and
146 may be, for example, one or more interlocking detents and protrusions 148
and 150, as best
seen in FIG. 3. Any known type of interlocking may be used as the anti-
rotation features 144
and 146, as long as load member 104 and slip member 106 cannot rotate with
respect to one
another and slip member 114 and end member 116 cannot rotate with respect to
one another.
[0030] Receiving end 142 of each slip member 106 and 114 has an inner
surface defining
a receiving area 152 (FIG. 2) that is shaped and sized to receive an end of
first and second
compression members 108 and 112, respectively, when downhole tool 100 is moved
to its
compression position. One or more inner planar faces 154 may be provided in
receiving area
152 on the inner surface for engaging compression member 108. Inner planar
faces 154
preferably taper outwardly away from the mandrel's stem portion 120. Edge
lines 156 are
defined between adjacent individual planar faces 154, as best seen in FIG. 2.
[0031] Compression members 108 and 112 are designed to compress sealing
element 110
and also expand first and second slip members 106 and 114, respectively, when
tool 100 is in the
compressed position. First compression member 108 is mounted on the mandrel's
stem portion
120 between first slip element 106 and sealing element 110 and second
compression member
112 is mounted on stem portion 120 between sealing element 110 and second slip
member 114,
as seen in FIGS. 5d-5f. Each compression member 108 and 112 may be a cone with
a body
160a, 160b having an opening that receives stem portion 120 and a compression
end 162a, 162b
that generally abuts sealing member 110. When tool 100 is activated,
compression ends 162a
CA 2997084 2018-02-28
and 162b engage and compress opposing ends 164a and 164b of sealing element
110 to force
element 110 to expand. In a preferred embodiment, the bonding agent of the
present invention is
applied between mandrel 102 and each of the compression members 108 and 112,
respectively,
to prevent movement of compression members 108 and 112. For example, the
bonding agent
may be applied between an inner surface 166 (FIG. 2) of each compression
member 108 and 112
and a corresponding outer surface of the mandrel's stem portion 120. This
fixes compression
members 108 and 112 in place on mandrel 102 and isolates slip members 106 and
114 until tool
100 is activated in which the compression force of the setting tool overcomes
the shear strength
of the bonding agent. The bonding agent does not need to be applied between
sealing element
110 and mandrel 102.
[0032] One or more outer planar faces 168 may be provided on the body
160a, 160b of
each compression member 108 and 112 that correspond to inner planar faces 154
of first and
second slip members 106 and 114, respectively. Edge lines 170 (FIG. 2) are
defined between
adjacent individual planar faces 168 that can align with edge lines 156 of
slip members 106 and
114, respectively, when tool 100 is activated. This assists with alignment
between the respective
slip members 106 and 114 and the compression members 108 and 112 when tool 100
is
compressed upon activation. When compression body 160a, 160b of compression
members 108
and 112 are received in the receiving areas 156 of slip members 106 and 114,
respectively, inner
and outer planar faces 154 and 168 engage one another, such as in a friction
fit. This
engagement of planar surfaces 154 and 168 also assists with preventing
rotation of the
components with respect to one another.
[0033] FIGS. 5a-5f illustrate the steps of assembly of downhole tool 100.
To assemble
downhole tool 100, load member 104 is first mounted on mandrel 102, as seen in
FIG. 5b, such
that its inner surface 136 engages shoulder 124 of hub portion 122. The
bonding agent of the
present invention is preferably applied between inner surface 136 and shoulder
124 to fix load
member 104 to mandrel 102. Next, first slip member 106 is mounted on mandrel
102 next to
load member 104, as seen in FIG. Sc. Anti-rotation features 144 and 146 of
load member 104
and slip member 106 are aligned and engaged, thereby preventing rotation of
load member 104
and first slip member 106 with respect to one another. First compression
member 108 is then
11
CA 2997084 2018-02-28
mounted on mandrel 102 adjacent first slip member 106, as seen in FIG. 5d. The
bonding agent
of the present invention is preferably also applied between the inner surface
166 of first
compression member 108 and a corresponding outer surface of stem portion 102
to fix first
compression member 108 on mandrel 102. This isolates slip member 106 between
load member
104 and compression member 108 to prevent premature movement and expansion of
slip
member 106.
[0034] The expandable sealing element 110 and second compression member
112 may
then be installed on mandrel 102 such that sealing element 110 is disposed
between first and
second compression members 108 and 112, as seen in FIG. 5e. The bonding agent
of the present
invention is preferably again applied between the inner surface 166 of second
compression
member 112 and a corresponding outer surface of stem portion 120 to fix second
compression
member 112 on mandrel 102. No bonding agent is applied between sealing element
110 and
mandrel 102. Second slip member 114 may then be mounted on mandrel 102
adjacent second
compression member 112, as seen in FIG. 5f. Finally, end member 116 is mounted
on the end of
stem portion 120 adjacent to and aligned with second slip member 114, as seen
in FIG. 1. This
isolates slip member 114 between second compression member 112 and end member
116 to
prevent premature movement and activation of slip member 114. Anti-rotation
features 144 and
146 of slip member 114 and end member 116 are aligned and engaged, thereby
preventing
rotation of slip member 114 and end member 116 with respect to one another.
[0035] In operation, the downhole tool 100 is run into the wellbore
casing and lowered to
a set position. The use and application of the bonding agent with the
predetermined shear
strength of the present invention, which fixes load member 104, first
compression member 108,
and second compression member 112 on mandrel 102, prevents premature setting
or pre-set of
tool 100 during run-in of tool 100 because the slip members 106 and 114 are
not able to activate
or expand even if the tool 100 impacts an unforeseen obstruction in the
wellbore. That is, fixed
load member 104 and fixed first compression member 108 isolate and prevent
axial movement or
expansion of first slip member 106 positioned therebetween. Likewise, fixed
second
compression member 116 isolates and prevents axial movement or expansion of
second slip
member 114 between it and end member 116 (which may be secured to the end of
mandrel 102
12
CA 2997084 2018-02-28
in any known manner). The bonding agent of the present invention also provides
this protection
against pre-set without the need for pins to assemble and mount the components
of tool 100 to
mandrel 102. This is beneficial because use of the bonding agent instead of
pins is cost efficient
and the strength of the composite material of the components is maintained.
That is because the
need to drill holes in the components of tool 100 (to accept the pins), which
reduces the strength
of the composite material of the components, is avoided.
[0036] Once the tool is in the proper set position, tool 100 is ready for
activation. When
activated, the shear strength of the bonding agent is overcome by application
of a compression
force by the setting tool to release the bond between load member 104,
compression members
108 and 112, and mandrel 102. This allows the tool to be compressed so that
slip members 106
and 114 and sealing element 110 expand outwardly to respectively clamp the
tool to the casing
of the wellbore. Once operations are complete, tool 100 is removed from the
wellbore, typically
by drilling or machine milling the tool. Interlocking of anti-rotation
features 144 and 146 of the
present invention, which prevent rotation between load member 104 and first
slip member 106
and prevent rotation between second slip member 114 and end member 116,
assists with drilling
out of tool 100 to maximize removal efficiency of tool 100. That is, as the
drill bit is rotating
and drilling into tool 100, the anti-rotating features 144 and 146 keep the
components engaged
with one another with respect to the wellbore casing, thereby preventing free
spinning of the
components or one component from spinning within another component, as tool
100 is being
drilled out.
[0037] While particular embodiments have been chosen to illustrate the
invention, it will
be understood by those skilled in the art that various changes and
modifications can be made
therein without departing from the scope of the invention as defined in the
appended claims.
13
CA 2997084 2018-02-28
