Note: Descriptions are shown in the official language in which they were submitted.
CA 02778745 2012-05-31
EUTECTIC SALT INFLATED WELLBORE TUBULAR PATCH
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates generally to arrangements used to patch breaches
in
wellbore casings or liners.
2. Description of the Related Art
[0002] During the lifetime of a well, points of weakness and sometimes
actual
breaches occur in the metallic casing which lines the wellbore. This problem
can
occur with wellbore liners and other tubular members used in the downhole
environment. Patch assemblies are known which include a patch sub and multiple
packers which are set between the patch sub and the damaged casing to retain
the
patch sub in place over the breach or point of weakness. Unfortunately, the
mechanical components of the packers require space, which necessitates the use
of
a patch sub of greatly reduced diameter. This results in a loss of useable
wellbore
area.
SUMMARY OF THE INVENTION
[0003] The present invention provides systems and methods for patching a
desired
section of wellbore casing or another tubular member. In a described
embodiment, a
patch assembly is provided which includes a tubular patch sub which is
radially
surrounded by an inflatable boot. The boot is preferably formed of a high-
temperature tolerant material, such as silicone-coated KEVLARO fiber, which is
sufficient to contain high-temperature eutectic material in liquid form.
[0004] A setting tool is used to set the patch assembly within the
casing. An
exemplary setting tool includes a heated barrel that contains eutectic
material in
CA 02778745 2014-01-03
liquid form. When actuated from the surface, eutectic material is flowed from
the setting
tool to the boot of the casing patch assembly. The eutectic material inflates
the boot to
secure the patch sub at a desired location within the wellbore. Once in the
boot, the
eutectic material will cool and assume solid form.
[0005] After the patch assembly has been set, the setting tool is separated
from the
patch assembly and then removed from the wellbore. In a described embodiment,
removal of the setting tool closes flow ports into the boot.
[0006] The use of a flexible boot and eutectic material permits patch
assemblies to
be employed which require a very small spacing between the patch sub and the
casing
ro being patched.
[0006a] Accordingly, in one aspect there is provided a patch assembly for
patching a
desired section of a wellbore tubular, the patch assembly comprising: a patch
sub; a
flexible boot radially surrounding the patch sub which is formed of a material
suitable for
retaining a liquid, eutectic material; a cavity defined between the patch sub
and boot to
is receive liquid, eutectic material; and a heating barrel associated with
the patch sub to
supply the liquid, eutectic material, the heating barrel having a heating
element that is
energized to heat the barrel to a temperature that is sufficient to maintain
eutectic
material within the heating barrel in a liquid state.
[0006b] According to another aspect there is provided a system for patching a
desired
20 section of a wellbore tubular, the system comprising: a patch assembly
comprising a
tubular patch sub and a flexible boot radially surrounding the patch sub to
define a cavity
therebetween; and a setting tool for setting the patch assembly within the
desired
section, the setting tool comprising: a heating barrel having a chamber
containing a
eutectic material and a heating element that is energized to heat the barrel
to a
25 temperature sufficient to maintain the eutectic material in a liquid
state; and a flow
mechanism to flow the eutectic material from the chamber to the cavity.
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[0006c] According to yet another aspect there is provided a method of patching
a
section of wellbore tubular comprising the steps of: disposing a patch
assembly and
setting tool into a wellbore until the patch assembly is located adjacent a
section of
wellbore tubular that it is desired to patch, wherein the patch assembly
comprises a
tubular patch sub and a flexible boot radially surrounding the patch sub to
define a cavity
therebetween and the setting tool comprises a barrel having a chamber
containing a
eutectic material, a heating element that is energizable to heat the barrel,
and a flow
mechanism to flow the eutectic material from the chamber to the cavity;
energizing the
heating element to heat the barrel to a temperature sufficient to maintain the
eutectic
o material in liquid form; and flowing the eutectic material from the
barrel chamber to the
cavity to set the patch sub within the wellbore tubular.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a thorough understanding of the present invention, reference
is made to
the following detailed description of the preferred embodiments, taken in
conjunction
is with the accompanying drawings, wherein like reference numerals
designate like or
similar elements throughout the several figures of the drawings and wherein:
[0008] Figure 1 is a side, cross-sectional view of an exemplary wellbore
with a
breached casing and having a patch assembly and setting tool being run in.
[0009] Figure 2 is an enlarged side, cross-sectional view of the patch
assembly and
20 setting tool shown in Figure 1 in a run-in configuration.
[0010] Figure 3 is an axial cross-section taken along lines 3-3 in
Figure 2.
[0011] Figure 4 is a side, cross-sectional view of the patch assembly
and setting tool
shown in Figure 2, prior to the patch assembly being set.
[0012] Figure 5 is a side, cross-sectional view of the patch assembly
and setting tool
25 shown in Figure 2 and 4, during setting of the patch assembly.
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[0013] Figure 6 is a side, cross-sectional view of the patch assembly
and setting
tool shown in Figure 2, 4 and 5, now with the patch assembly fully set in
place.
[0014] Figure 7 is an enlarged side, cross-sectional view of portions of
the patch
assembly following removal of the setting tool.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Figure 1 depicts an exemplary wellbore 10 which has been drilled
from the
surface 12 through the earth 14 down to a hydrocarbon-bearing formation 16.
The
wellbore 10 has been lined with metallic casing 18 of a type known in the art.
The
casing 18 has a breach within it, depicted at 20, which it is desired to
patch. The
term "breach", as used herein, need not require an actual opening within the
casing
18, but may also refer to an area of weakness which it is desired to patch.
[0016] A wireline, e-line, or similar running string 22 is disposed into
the wellbore
10 from the surface 12. A setting tool 24 is secured to the running string 22
and is
releasably secured to a patch assembly 26 which is constructed in accordance
with
the present invention.
[0017] The setting tool 24, which is better appreciated with reference to
Figures 2
and 3, includes an elongated heating barrel 28 which defines an interior
chamber 30.
The upper axial end of the heating barrel 28 is affixed to a top sub 32. Above
the top
sub 32 is an arrangement (not shown) known in the art by which the setting
tool 24 is
secured to the running string 22. A top plug 34 is threadedly secured within
the top
sub 32. A flow port 36 is formed through the top plug 34 and is in fluid
communication with fluid injection conduit 38. The fluid injection conduit 38
extends
from the setting tool 24 to a fluid supply which may be in the form of a high-
pressure
cylinder (not shown) which is attached to the setting tool 24 having an
electrically-
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operated valve which can be opened from the surface 12. Cylinders and valves
of
this type are well known in the art. Other suitable fluid supply arrangements
known
in the art may be used as well. In a current embodiment, the fluid provided by
the
fluid supply is nitrogen. A fill port 44 is disposed through the heating
barrel 28 and is
closed off by removable plug 46.
[0018]
Eutectic material 47 is located within the chamber 30 of the heating barrel
28, and may be flowed into the chamber 30 in its liquid state via the fill
port 44. In
one embodiment, the eutectic material comprises eutectic salts. Eutectic salts
are
sometimes referred to as "phase changing salts" or phase-changing material.
Eutectic materials are characterized by forming very regular crystalline
molecular
lattices in the solid phase. Eutectic materials are chemical compounds that
have the
physical characteristic of changing phase (melting or solidifying) at varying
temperatures: melting at one temperature and solidifying at another.
The
temperature range between which the melting or solidification occurs is
dependent
is on the composition of the eutectic material. When two or more of these
materials
are combined, the eutectic melting point is lower than the melting temperature
of any
of the composite compounds. The composite material is approximately twice as
dense as water, weighing approximately 120 pounds per cubic foot. Salt-based
eutectic material can be formulated to work at temperatures as low as 30 F and
as
high as 1100 F. Metal-based eutectic materials can operate at temperatures
exceeding 1900 F.
[0019]
In a current embodiment, the salt compound is a sodium nitrate and
potassium nitrate mixture which melts at approximately 610 F and solidifies at
approximately 500 F. The liquid salt compound exists as a superheated fluid,
and
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when it changes phase, it does so very rapidly, typically in just minutes.
When
solidified, the salt compound has a compressive strength of approximately 2700
psi.
[0020] A number of axial grooves 48 are formed in the outer radial surface of
the
heating barrel 28, and heating elements 50 are disposed within the grooves 48.
The
heating elements 50 are preferably shaped to reside within the grooves 48 and
are
preferably supplied with electric power for heating via wires (not shown) that
are
incorporated into the running string 22. The heating element 50 may be
energized to
heat the barrel 28 to a temperature that is sufficient to maintain the
eutectic material
47 in its liquid state.
[0021] The volume of eutectic material 47 within the barrel 28 is bounded
at its
upper end by a floating piston 52 and at its lower end by a lower piston 54.
The
floating piston 52 is slidably moveable within the chamber 30 and, when the
chamber
30 is filled with eutectic material 47, the floating piston 52 is proximate to
or in
abutting contact with the top plug 34.
[0022] The lower piston 54 is located radially within the lower end of the
barrel 28
and a fill mandrel 56, as best shown in Figure 4. The fill mandrel 56 is
affixed to the
lower end of the heating barrel 28 by threading 58. Fluid flow ports 60 are
disposed
through the fill mandrel 56 and are initially closed off by the lower piston
54, which is
retained in place by frangible shear pins 62. A bottom plug 64 is threaded
into the
lower end of the fill mandrel 56 and represents the lower end of the setting
tool 28.
A collapsible chamber 66 is defined between the lower piston 54 and the bottom
plug
64.
[0023] The patch assembly 26 includes a tubular patch sub 68 which
preferably
has a top sub 70 affixed to its upper end and a bottom sub 72 affixed to its
lower
end. Shear members 74 releasably affix the top sub 70 to the fill mandrel 56,
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thereby releasably securing the patch assembly 26 to the setting tool 24. An
annular, flexible boot 76 radially surrounds the patch sub 68, and a cavity 78
is
defined between the patch sub 68 and the boot 76. The boot 76 is preferably
formed
of a high-temperature tolerant material that is capable of containing the
eutectic
material 47 in its liquid, high-temperature state. In a current embodiment,
the boot
76 is formed of silicone-coated KEVLARO fiber. The boot 76 is secured to the
sub
68 at its upper and lower axial ends so that the cavity 78 is completely
enclosed.
[0024] Flow ports 80 (Figure 4) are disposed through the patch sub 68
and are
aligned with the flow ports 60 of the fill mandrel 56 when the casing patch
assembly
26 is affixed to the setting tool 24. A slidable sleeve 82 is located within
the upper
end of the patch sub 68 and is moveable between a lower position, shown in
Figure
4, and an upper position, shown in Figure 6. Openings 84 are disposed through
the
sleeve 82 and, when the sleeve 82 is in the lower position, these openings 84
are
aligned with the flow ports 60 and 80. Collets 86 extend axially upwardly from
the
sleeve 82 and are shaped and sized to engage a complimentary shoulder 88 that
is
formed on the outer radial surface of the fill mandrel 56.
[0025] In operation, the patch assembly 26 and setting tool 24 are lowered
into the
wellbore 10 by the running string 22 until the patch assembly 26 is positioned
adjacent the breach 20. At this point, fluid is flowed into the setting tool
24 via the
fluid conduit 28. The fluid flows through the flow port 36 of the top sub 34
and urges
the floating piston 36 axially downwardly within the chamber 30 of the heating
barrel
28. The lower piston 54 will be urged downwardly as a result of fluid pressure
within
the barrel 28, shearing frangible pins 62 and uncovering ports 60. The liquid
eutectic
material 47 that fills the chamber 36 of the heating barrel 28 can now flow
through
aligned ports and openings, 60, 84 and 80 to enter the cavity 78 within the
boot 76.
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Figure 5 illustrates the setting tool 24 in an intermediate condition wherein
the
floating piston 54 has been moved partially downward within the chamber 30,
and
the lower piston 54 having been moved downwardly, collapsing chamber 66, so as
to
be adjacent the bottom plug 64. As fluid flows into the cavity 78, it will
begin to fill
the cavity 78 and expand the boot 76. As the boot 76 expands, it secures the
patch
sub 68 and top and bottom subs 70, 72 in place within the casing 18. Figure 6
illustrates a further point in the setting process wherein the liquid eutectic
material 47
has been flowed out of the chamber 30 and into the boot 76. The floating
piston 52
has descended within the chamber 30 until it comes into contact with the lower
piston 54. After the liquid eutectic material 47 has been flowed out of the
heating
barrel 28 and into the boot 76, the material 47 will cool and solidify.
[0026] Once the patch assembly 26 has been set, the setting tool 24 is
separated
from the patch assembly 26 by pulling upwardly on the running string 22 to
shear the
shear members 74. As the setting tool 24 is moved upwardly through the
wellbore
10 by the running string 22, the shoulder 88 of the fill mandrel 56 will
contact and
engage the inwardly protruding portions of the collets 86 on the slidable
sleeve 82.
Due to this engagement, further upward movement of the setting tool 24 will
move
the slidable sleeve 82 from its lower position to its upper position. Figure 7
shows
details of the upper end of the casing patch assembly 26 after it has been set
and
the setting tool 24 has been removed. As can be seen in Figure 7, the openings
84
in the sleeve 82 are moved above the ports 80 in the patch sub 68, thereby
closing
the ports 80 against fluid flow therethrough. As the sleeve 82 reaches its
upper
position, the outwardly protruding portions of the collets 86 will retract
into an annular
recess 90 that is formed on the interior radial surface of the top sub 70.
This will
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_
release the engagement between the collets 86 and shoulder 88, allowing the
setting
tool 24 to be completely freed from the casing patch assembly 26.
[0027] The invention provides systems for patching a desired section of
wellbore
casing or another wellbore tubular member. An exemplary patching system
includes
a patch assembly 26 and a setting tool 24. The exemplary patch assembly 26
includes a tubular patch sub 68 and a flexible boot 76 which radially
surrounds the
patch sub 68 to form a cavity 78 therein. The exemplary setting tool includes
a
heating barrel 28 which contains eutectic material at a temperature sufficient
to
maintain the eutectic material 47 in a liquid state. In addition, a flow
mechanism is
provided to selectively flow eutectic material from the heating barrel 28 to
the cavity
78 of the patch assembly 26. In a described embodiment, the flow mechanism is
provided by a flow path (aligned flow ports 60, 84, 80) through which the
liquid
eutectic material can flow from the heating barrel 28 to the boot 76. In
particular
embodiments, the flow mechanism includes a piston, such as floating piston 52,
which is moveable within the chamber 36 of the heating barrel 28 to urge the
eutectic
material 47 out of the chamber 36 and into the boot 76.
[0028] Those of skill in the art will also understand that the
invention provides
methods for patching a desired section of a wellbore tubular. According to
exemplary methods, a patch assembly 26 and setting tool 24 are disposed into a
wellbore 10 until the patch assembly is located adjacent a section of tubular
that it is
desired to patch. The patch assembly 26 is then set by flowing liquid eutectic
material along a flow path from the setting tool 24 to the cavity 78. The
eutectic
material will then cool within the cavity 78 and solidify. The setting tool 24
is
detached from the patch assembly 26 and removed from the wellbore 10. In a
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further exemplary embodiment, the flow path is closed against fluid flow as
the
setting tool 24 is detached and removed.
[0029] The use of a flexible, fabric boot 76 and liquid eutectic material 47
permits
patch assemblies to be employed which require very small spacing between the
patch sub 68 and the casing being patched.
[0030] Those of skill in the art will recognize that numerous
modifications and
changes may be made to the exemplary designs and embodiments described
herein. The invention is limited only by the claims that follow and any
equivalents
thereof.
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