Note: Descriptions are shown in the official language in which they were submitted.
CA 02698572 2010-03-31
DOWNHOLE APPARATUS
TECHNICAL FIELD
[0001] This application relates to downhole apparatuses, for example
double-acting
compounders for coil tubing jars.
BACKGROUND
[0002] A downhole apparatus may have contained therein a fluid chamber for
a
variety of purposes. For example, a compounder used in tandem with ajar may
use a fluid
chamber as an inner spring mechanism in order to store additional energy used
to enhance a
jar. US Patent No. 5,931,242 describes a double-acting compounder that
incorporates a
movable piston disposed within a fluid chamber between inner and outer
cylindrical
assemblies to provide compounding in either jarring direction.
SUMMARY
[0003] A double-acting compounder is disclosed, comprising: an outer
housing; an
inner mandrel at least partially disposed telescopically within the outer
housing to defme a
fluid chamber between the inner mandrel and the outer housing, the fluid
chamber
containing fluid and being sealed at an uphole end and a downhole end; an
equalizer between
the fluid chamber and an exterior of the outer housing for equalizing
pressure; a movable
seal assembly disposed within the fluid chamber and having a first end that
defmes the
uphole end or the downhole end of the fluid chamber; the inner mandrel having
an outer
shoulder for contacting a second end of the movable seal assembly to move the
movable seal
assembly with the inner mandrel when the inner mandrel moves in a first
direction relative to
the outer housing to compresses fluid within the fluid chamber; and the outer
housing having
an inner shoulder for contacting the second end of the movable seal assembly
to prevent the
movable seal assembly from moving with the inner mandrel when the inner
mandrel moves
in a second direction relative to the outer housing to compresses fluid within
the fluid
chamber.
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[0004] A downhole apparatus is also disclosed, comprising: an outer
housing; an
inner mandrel at least partially disposed telescopically within the outer
housing to define
a fluid chamber between the inner mandrel and the outer housing, the fluid
chamber
containing fluid and being sealed at an uphole end and a downhole end; an
equalizer
between the fluid chamber and an exterior of the outer housing for equalizing
pressure,
the equalizer having an extension from the outer housing into the fluid
chamber between
the downhole end and the uphole end to define a chamber between the extension
and the
outer housing, the chamber having a port to the wellbore, and an equalization
piston
disposed within the chamber between the fluid chamber and the port.
[0005] A double-acting compounder is also disclosed, comprising: an outer
housing; an inner mandrel at least partially disposed telescopically within
the outer
housing to define a fluid chamber between the inner mandrel and the outer
housing, the
fluid chamber containing fluid and being sealed at an uphole end and a
downhole end; a
movable seal assembly disposed within the fluid chamber and having a first end
that
defines the uphole end or the downhole end of the fluid chamber; the inner
mandrel
having an outer shoulder for contacting a second end of the movable seal
assembly to
move the movable seal assembly with the inner mandrel when the inner mandrel
moves
in a first direction relative to the outer housing to compresses fluid within
the fluid
chamber; the outer housing having an inner shoulder for contacting the second
end of the
movable seal assembly to prevent the movable seal assembly from moving with
the inner
mandrel when the inner mandrel moves in a second direction relative to the
outer housing
to compresses fluid within the fluid chamber; and in which the double-acting
compounder is configured to expose the second end of the movable seal assembly
to
toolbore pressure in use.
[0006] These and other aspects of the device and method are set out in the
claims.
BRIEF DESCRIPTION OF THE FIGURES
[0007] Embodiments will now be described with reference to the figures, in
which like reference characters denote like elements, by way of example, and
in which:
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[0008] Figs. la-c form an exploded side elevation view, in section and not
to scale,
of a double-acting compounder in a neutral position.
[0009] Figs. 2a-c form an exploded side elevation view, in section and not
to scale,
of a double-acting compounder extended.
[0010] Figs. 3a-c form an exploded side elevation view, in section and not
to scale,
of a double-acting compounder retracted.
[0011] Figs. 4 and 5 are side elevation views, in section and not to scale,
of the
movable seal assembly of the compounder of Figs. la-c, illustrating the
operation of the
locking mechanism.
[0012] Fig. 6 is a side elevation view, in section and not to scale, of the
movable
seal assembly of a double-acting compounder that incorporates a vacuum chamber
in use.
[0013] Fig. 7 is an end elevation view, in section and not to scale, of the
sealing
interfaces of the movable seal assembly with the sealing interface of the
other end of the
apparatus overlaid in dotted lines for clarity.
[0014] Fig. 8 is a graph of the pressure applied to the fluid chamber vs.
the stroke
distance from neutral for various compounder embodiments.
[0015] Fig. 9 is an end elevation view, in section and not to scale, of the
relative
cross-sectional areas of the movable seal assembly (denoted in solid lines)
and the
equalization piston (denoted in dotted lines). The inner mandrel and outer
housing are
omitted for clarity.
DETAILED DESCRIPTION
[0016] Immaterial modifications may be made to the embodiments described
here
without departing from what is covered by the claims.
[0017] Various components of conventional drill pipe, coil tubing or other
downhole
tools get stuck in the well bore at times. Jars are used in the oilfield
industry to deliver
jarring blows in order to free a stuck component, such as a stuck section of
pipe. Jars are
also used in fishing operations, in order to free an object stuck in a
downhole well. Under
these circumstances, repetitive upjarring or downjarring with a jarring tool
can be useful.
Double-acting jars exist that are capable of performing this function.
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[0018] Adapting ajar and compounder assembly to a coil tubing application
presents some challenges to overcome. A coil tubing operation may involve a
continuous
pipe or tubing, which is uncoiled from a reel as it is lowered into the well
bore, and can be
used in drilling or workover applications for example. However, coil tubing
presents a
number of working constraints to the design of a tool. First of all, due to
the limited strength
of the coil tubing, limited compressive loads can be placed on the tubing by
the rig operator.
Essentially, this means that downhole tools that require compressive force to
operate, such
as a jarring tool, must be capable of operating with the limited compressive
load capability
of coil tubing. In addition, in coil tubing applications the overall length of
the downhole tool
becomes significant since there is limited distance available at the wellhead,
for example
between the stuffing box and the blowout preventor, to accommodate the bottom
hole
assembly. A typical bottom hole assembly may include additional tools, for
example, a
quick disconnect, a sinker bar, a release tool of some type, and an overshot.
Thus, the length
of the jar or compounder itself becomes particularly significant since the
entire bottom hole
assembly may be required to fit within the limited distance between the
stuffing box and
blowout preventor to introduce it into a pressurized well. Furthermore, within
these
confines, the jar and compounder assembly may be required to have a large
enough internal
bore to permit pump-down tools to pass. Thus, coil tubing jar and compounder
assemblies
may have a limited overall wall thickness in view of limited outer diameter
conditions.
[0019] A double-acting compounder may be used with a double-acting jar, in
order
to compound the jarring force of the jar in both directions. The compounder
may be
connected, for example, either directly or indirectly to the jar in the tubing
string. By
applying a compressive or tensile force to the tubing string, the compounder
uses, for
example, a fluid or mechanical spring to allow additional force to be built up
prior to the
release of that force in either an up or a down jar. Compounders are useful
additions to, for
example, a coil tubing jarring operation, because they allow additional force
to be built up
and stored in the compounder to be transferred during a jarring operation,
without imposing
additional strain on the already limited stress of the tubing string itself.
[0020] Referring to Figs. la-c, a downhole apparatus 10 is illustrated,
comprising an
outer housing 12 and an inner mandrel 14. Inner mandrel 14 is at least
partially disposed
telescopically within outer housing 12 to define a fluid chamber 16 between
the inner
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mandrel 14 and the outer housing 12, the fluid chamber 16 containing fluid and
being sealed
at an uphole end 18 and a downhole end 20. Apparatus 10 may be a compounder,
for
example as shown. The fluid contained within fluid chamber 16 is compressible,
for
example hydraulic liquid such as compressible silicon fluid. In the case of a
compounder,
the fluid may create a fluid spring within chamber 16, in which compounding
energy may
be stored to enhance the jarring impact.
[0021] Referring to Figs. la-c, apparatus 10 may have an equalizer 21
between the
fluid chamber 16 and an exterior 23 of the outer housing 12 for equalizing
pressure.
Equalizer 21 may comprise an equalization piston 30, which is configured to be
exposed to
wellbore pressure on one side 27 and pressure from fluid chamber 16 on the
other side 29 so
that equalization between the two fluids can occur in the presence of a
pressure differential
across piston 30. Equalizer 21 may also comprise an extension 22 from outer
housing 12
into the fluid chamber 16 between the downhole end 20 and the uphole end 18.
Extension
22 defines a chamber 24 between the extension 22 and the outer housing 12, and
chamber
24 has a port 26 to the wellbore 28. Equalization piston 30 is disposed within
the chamber
24 between the fluid chamber 16 and the port 26. The piston 30 divides chamber
24 into an
equalization chamber 89 that connects to fluid chamber 16, and a hydrostatic
chamber 91
that connects to exterior 23. Thus, as apparatus 10 is lowered into the well
and well pressure
is exerted upon piston 30 through port 26, piston 30 may travel along
extension 22 in order
to equalize the pressure between the wellbore and fluid in fluid chamber 16.
Equalization
eliminates the risk of tool collapse downhole. More than one equalizer 21 may
provided
with apparatus 10. The provision of extension or nose 22 allows equalizer 21
to be
positioned at an intermediate location in fluid chamber 16 between uphole and
downhole
ends 18 and 20 and thus gives apparatus 10 an equalization function with less
tool required
length than if piston 30 was situated at one of ends 18 or 20 without
extension 22. This is
because if piston 30 is positioned at one of ends 18 and 20, the size of the
piston 30 is
restricted because of the O.D. of the inner mandrel 14 and thus piston 30 must
move a
greater distance to equalize than if piston 30 was positioned in chamber 24,
where a piston
30 with a larger surface area on the side 27 exposed to hydrostatic pressure
may be used.
Equalization in the context of a compounder also affords smoother operation,
which extends
seal life and also allows more efficient use of the compounder over the stroke
length. In
CA 02698572 2015-10-20
some embodiments, equalizer 21 may be positioned at one of ends 18 or 20, with
piston 30
situated between inner mandrel 14 and outer housing 12.
[0022] Referring to Figs. la-c, apparatus 10 may comprise a movable seal
assembly
34, for example a piston as shown, disposed within the fluid chamber 16.
Assembly 34 has a
first end 42 that defines the downhole end 20 of the fluid chamber 16. This
orientation may
be reversed so that first end 42 defines the uphole end 18. Referring to Figs.
2a-c and 3a-c,
inner mandrel 14 and outer housing 12 have an outer shoulder 36 and inner
shoulder 38,
respectively, for contacting a second end 40 of the assembly 34. Referring to
Figs. la-c,
outer shoulder 36 of inner mandrel 14 is designed to contact second end 40 to
move the
movable seal assembly 34 with the inner mandrel 14 when the inner mandrel 14
moves in a
first direction relative to the outer housing 12 to compresses fluid within
the fluid chamber
16. Relative movement in the first direction is demonstrated by envisioning
the apparatus 10
moving from the configuration of Figs. la-c to the configuration of Figs. 2a-
c. Similarly,
inner shoulder 38 of outer housing 12 is designed to contact second end 40 to
prevent the
movable seal assembly 34 from moving with inner mandrel 14 when the inner
mandrel 14
moves in a second direction relative to the outer housing 12 to compresses
fluid within the
fluid chamber 16. Relative movement in the second direction is demonstrated by
envisioning the apparatus 10 moving from the configuration of Figs. la-c to
the
configuration of Figs. 3a-c. Figs. 2a-c illustrate inner mandrel 14 being
extended upwardly
relative to outer housing 12 from neutral, in which case inner shoulder 36
moves assembly
34 with inner mandrel 14. Figs. 3a-c illustrate inner mandrel 14 being
retracted downwardly
relative to outer housing 12 from neutral, in which case outer shoulder 38
prevents assembly
34 from moving with inner mandrel 14. In both cases, fluid above first end 42
and in fluid
chamber 16 is compressed. Thus, compounding action occurs in both directions.
[0023] Referring to Figs. la-c the movable seal assembly 34 may define an
outer
sealing interface 74 with the outer housing 12 and an inner sealing interface
76 with the
inner mandrel 14. In addition, the uphole end 18 may comprise a sealing
interface 78
between the inner mandrel 14 and outer housing 12 that defines a cross-
sectional area that is
greater than the cross-sectional area defined by the inner sealing interface
76 and less than
the cross-sectional area defined by the outer sealing interface 74. In
embodiments where
movable seal assembly 34 is positioned at uphole end 18, sealing interface 78
is located at
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downhole end 20. Referring to Fig. 7, the interface 78 is conceptually
illustrated as overlaid
on interfaces 74, and 76 to demonstrate that interface 78 defines a cross-
sectional area that
is greater than the cross-sectional area defined by the inner sealing
interface 76 and less than
the cross-sectional area defined by the outer sealing interface 74. The cross-
sectional areas
are understood to be defined perpendicular to the central axis 80 of the
apparatus 10,
between the interface and the axis 80 itself. Referring to Figs. 3a-c, in the
context of an
annular fluid chamber 16, the relative differences between cross-sectional
areas of interfaces
74, 76, and 78 can be understood by reference to the lengths of respective
interface
diameters 75, 77, and 79 as shown. The relative arrangement of interfaces 74,
76, and 78
described above allows compression to occur in chamber 16 regardless of the
direction of
movement between mandrel 14 and housing 12 when movable seal assembly 34 is
incorporated.
[0024] Referring to Figs. la-c and 4, apparatus 10 may be configured to
expose the
second end 40 of the movable seal assembly 34 to toolbore pressure in use.
Toolbore
pressure is understood to be the fluid pressure in a longitudinal bore 35,
such as a central
bore as shown, of apparatus 10. In some cases toolbore pressure may equal
wellbore
pressure, which is understood to be the hydrostatic pressure of the wellbore
surrounding the
apparatus 10 in use. To expose second end 40 to toolbore pressure, no seals
may be
provided between second end 40 and bore 35. Referring to Fig. 6, in a
contrasting
embodiment, assembly 34 may be isolated within fluid chamber 16 between seals
at uphole
and downhole ends 18 and 20. The seal closest to the assembly 34 of such an
embodiment is
illustrated as seal 44. In this embodiment, when relative movement occurs from
neutral
between inner mandrel 14 and outer housing 12, a vacuum chamber (not shown)
develops
beyond second end 40 of assembly 34 and seal 44. In contrast, the embodiment
of Fig. 4
forms no such vacuum chamber in use, thus reducing the risk of tool collapse
under
downhole conditions.
[0025] Referring to Fig. 4, apparatus 10 may comprise a restrictor, such
as a lock 46,
for restricting initial movement of the movable seal assembly 34 from both the
inner
shoulder 38 and the outer shoulder 36 due to hydrostatic pressure when the
compounder is
in a neutral position. The restrictor allows the equalization piston 30 to be
displaced by
wellbore pressure before or instead of assembly 34. The restrictor may
comprise a type of
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mechanical lock 46 configured to release when a force above a lock threshold
force is
applied against the second end 40 of movable seal assembly 34 by one or more
of shoulders
36 and 38. Lock 46 may comprise a pin 48 biased towards engagement with an
indent 50
that is positioned to align and engage with the pin 48 at least when the
compounder is in a
neutral position, for example as shown in Fig. 4. Pin 48 may be mounted on the
assembly 34
and the indent 50 may be positioned on one or both of the inner mandrel 14 and
outer
housing 12. Indent 50 may be located in a surface 52, which may be located on
inner
mandrel 14 or outer housing 12. One or more of the indent 50 and pin 48 may be
beveled,
for example smoothly curved as shown, to facilitate disengagement upon
application of
above threshold force. Referring to Fig. 5, the lock 46 is illustrated in a
disengaged position,
which has resulted from inner shoulder 38 of outer housing 12 contacting
assembly 34 to
prevent assembly 34 from moving with inner mandrel 14 during downward movement
of
inner mandrel 14. As shown, lock 46 may comprise an extension of assembly 34.
Referring
to Figs. 4 and 5, pin 48 may be biased by a flat spring arm 54, although any
suitable biasing
mechanism may be used, such as a coil spring. Spring arm 54 may be held in
place by screw
56. Other suitable restrictors may be used, such as a restrictive tolerance
between assembly
34, mandrel 14, and housing 12 when apparatus 10 is in a neutral position. The
use of a
restrictor is advantageous as it restricts assembly 34 from being displaced by
large external
pressures, such as wellbore pressure, on second end 40 when apparatus 10 is in
a neutral
position. As disclosed the restrictor allows equalization piston 30 to be
displaced before or
instead of assembly 34 in order to equalize pressure and preserve the amount
of stroke as is
discussed below in further detail.
[0026] Referring to Figs. la-c, apparatus 10 may have a first fluid fill
port 58 into
the fluid chamber 16 and a second fluid fill port 59 into the fluid chamber
16. Port 58 is
illustrated as being located at uphole end 18. The extension 22 may be located
between the
first fluid port 58 and the second fluid port 59 as shown. The extension 22
may be
configured so that a fluid chamber end 60 of the chamber 24 opens into the
fluid chamber
16 in a direction facing the first fluid fill port 58. This allows fluid
applied into fluid
chamber 16 through second fluid fill port 59 to displace air bubbles from
equalization
chamber 89. This technique uses first fluid fill port 58 as a vent, and may be
carried out as
follows. First, the apparatus 10 is tilted so that first fluid fill port 58 is
oriented at the highest
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point in the fluid chamber 16. Next, fluid is applied into chamber 16 through
second fluid
fill port 59, for example using a hand pump threaded into port 59. When fluid
begins to
come out of port 58, the apparatus 10 is shaken or bumped with a hammer to
dislodge
residual air bubbles in chamber 16. Next, port 58 is sealed, for example by
threading in a
sealing plug (not shown). More fluid is then supplied through port 59, in
order to force
movable seal assembly 34 into the neutral position in contact with shoulders
36 and 38. At
this stage, equalization piston 30 will also be forced towards port end 84 of
chamber 24.
Thus, if it is desired to have piston 30 spaced from port end 84 at ambient
conditions, a tool
such as a wrench may be inserted into chamber 24 through port 26 in order to
hold piston 30
at the desired spacing from port end 84 while chamber 16 is filled. As
discussed below,
spacing piston 30 from port end 84 allows piston 30 to compensate for thermal
expansion of
fluid in chamber 16 in a hot downhole environment. When chamber 16 is filled,
port 59 is
then sealed. The apparatus 10 may then be tested for leaks and pressure
capacity.
[0027] Referring to Figs. la-c, 2a-c and 3a-c, the operation of an example
of
apparatus 10 as a double-acting compounder will now be described. Referring to
Figs. la-c,
apparatus 10 is shown in a neutral position, with shoulders 36 and 38 abutting
second end
40 of assembly 34. The wellbore pressure of a downhole environment has moved
piston 30
through chamber 24 into the position shown because piston 30 is unrestricted
to move in
response to wellbore pressure so as to equalize fluid chamber 16 pressure with
wellbore
pressure. The lock threshold force required to open lock 46 has not been
overcome by the
pressure in the wellbore, and thus assembly 34 remains abutted against
shoulders 36 and 38.
In some embodiments, apparatus 10 may be configured so that at ambient
temperature and
pressure conditions piston 30 is spaced at an intermediate location of travel
along chamber
24, for example in the location as shown. Thus, if apparatus 10 is then
disposed into a hot
downhole environment in which fluid in fluid chamber 16 expands, piston 30 can
travel in
the direction toward port end 84 of chamber 24 in order to prevent
overpressurization in
fluid chamber 16 in the neutral position. Thus, equalizer 21 allows fluid
chamber 16 to
equalize pressure with relatively lower or higher external pressures.
[0028] When an operator requires intensifying jarring action in the uphole
direction,
a tensile load is applied to the coil tubing string. As soon as relative
upward movement of
mandrel 14 occurs, outer shoulder 36 contacts and moves assembly 34 with the
inner
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mandrel 14 while fluid located above first end 42 of assembly 34 is
compressed. Referring
to Figs. 2a-c, this compression then causes equalization piston 30 to
gradually migrate along
extension 22 towards port 26, eventually reaching port end 84 of chamber 24.
As mandrel
14 extends relative to housing 12, pressure builds within fluid chamber 16,
until the built up
force is released by the action of the jar, and the mandrel 14 is biased back
into the neutral
position shown in Figs. la-c.
[0029] Referring to Figs. la-c, from neutral either an intensified upjar
or downjar
action can be carried out. If an intensified downjar is desired, a compressive
force is applied
to the coil tubing string, forcing mandrel 14 to retract into housing 12.
Referring to Figs. 3a-
c, the response of equalization piston 30 in an intensified downjar action is
analogous to the
response observed during an intensified upjar action, in that the piston 30 is
gradually
biased towards port end 84 of chamber 24. The lock threshold force of lock 46
must be
overcome by inner shoulder 38 in order to pop pin 48 out of engagement with
indent 50 to
allow shoulder 38 to prevent the assembly 34 from moving with the inner
mandrel 14 as
shown. As mandrel 14 retracts into housing 12, pressure builds within fluid
chamber 16
until the built up force is released again by the action of the jar. The
compounder is then
biased back into the neutral position shown in Figs. la-c. The compounder may
be designed
to ensure that movable seal assembly 34 always returns to neutral after an
intensifying jar
action has been carried out in which the assembly 34 has been unlocked.
Referring to Fig. 9,
this may be accomplished by providing equalizer piston 30 with a cross-
sectional area that
is smaller than the cross-sectional area of movable seal assembly 34. The
cross-sectional
area of the equalizer piston 30 is defined between the dotted lines, while the
cross-sectional
area of the movable seal assembly 34 is defined between the solid lines.
Referring to Figs.
la-c, another way of accomplishing this is to spring-bias equalizer piston 30
away from port
end 84 of chamber 24.
[0030] Referring to Fig. 8, a graph is provided for illustrating the
distinction
between compounders with and without equalizer 21. It should be noted that
hydrostatic
pressure P(hyd) will be different depending on the depth of apparatus 10 in
the well, among
other factors. With equalizer 21 present, fluid chamber 16 remains at
hydrostatic pressure
P(hyd) from stroke LO to Li, and then experiences a smooth pressure buildup
from LI to
the maximum stroke distance L(max). By contrast, with no equalizer 21 present,
a
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substantial distance L2 of stroke must be traveled before an abrupt
pressurization to P(hyd)
occurs. Referring to Figs. la-c, the effect of having no equalizer 21 can be
envisioned by
considering the forces that assembly 34 will be under in the absence of
equalizer 21. As
apparatus 10 descends into the well and wellbore pressure rises, a pressure
differential is
created across assembly 34 that displaces assembly 34 a distance away from
shoulders 36
and 38 in order to equalize the pressure. This separation must be bridged by
the respective
shoulder 36 or 38 in an intensifying jar action before substantial pressure
buildup can occur.
Referring to Fig. 8, once assembly 34 is contacted by shoulders 36 or 38 at
stroke distance
L2, rapid and abrupt pressure-up to the hydrostatic wellbore pressure occurs.
By contrast,
fitting the compounder with equalizer 21 affords greater length of power
stroke, by avoiding
losses from the effect of hydrostatic pressure on the movable seal assembly
34. The graph
also illustrates that a compounder with equalizer 21 may actually pressure up
at a shallower
rate of pressure increase over a longer stroke distance (Ll-L(max)) as opposed
to a
compounder without equalizer 21, which pressures up over a shorter stroke
distance (L2-
L(max)).
[0031] Referring to Figs. la-c, equalization piston 30 and chamber 22 may
be
annular in shape, although this is not required. Similarly, assembly 34 may be
annular in
shape although this is not required. in some embodiments, there may be one or
more fluid
chambers 16, each one operating according to the embodiments disclosed herein.
Plural
pistons 30 or 34 may also be employed. Either or both of inner mandrel 14 and
outer
housing 12 may be individually composed of, for example, one or more units
connected
together. Each unit may be, for example, threadably connected together as
illustrated in the
figures. For example, referring to Figs. la-c, outer housing 12 may further
comprise a first
sub 62 connected to a second sub 64. The first sub 62 may comprise the
extension 22, the
extension 22 may define an outwardly facing surface 66 of the chamber 24, and
the second
sub 64 may define an inwardly facing surface 68 of the chamber 24. The first
sub 62 may
also be a connector sub connected between second sub 64 and a third sub 65,
Thus, the
complex structure of equalizer 21 may be created by assembly of simpler
constituent parts.
A clearance 19 is provided between extension 22 and inner mandrel 14 that is
sufficient to
allow fluid to flow through, for example during filling of chamber 16 or
relative movement
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between mandrel 14 and housing 12. The size of clearance 19 may be selected in
order to
reduce restriction to fluid flow, with clearance 19 being greater than a close
tolerance fit.
[0032] Outer housing 12 and inner mandrel 14 may be, for example,
tubulars. In the
embodiment illustrated in Figs. la-c, in a downhole application, inner mandrel
14 may be
connected, directly or indirectly, to a coil tubing string (not shown),
whereas outer housing
12 may be connected, directly or indirectly, to, for example, a fishing tool
(not shown). This
orientation may be reversed. It should be understood that apparatus 10 can be
oriented
upside down in a well, and still carry out the intended function of the
apparatus. In addition,
in some embodiments extension 22 may be positioned on inner mandrel 14 with a
port (not
shown) to the toolbore.
[0033] As indicated above, the apparatus 10 disclosed herein may be used
with coil
tubing. The compounder shown is advantageous for coil tubing operations,
because it is
adapted to deliver compressive enhancements in either direction, within a tool
length that
may be shorter than other double-acting compounders. The apparatus 10 may be
part of a
jar.
[0034] Referring to Figs. la-c, splines 70 and 72 may be provided on
mandrel 14
and housing 12, respectively, in order to transmit torque by restricting
relative rotation
between mandrel 14 and housing 12. Floating seals (not shown) may be used to
seal one or
more of uphole and downhole ends 18 and 20 in apparatus 10. Referring to Fig.
6, a seal as
discussed in this application may be achieved by a suitable sealing mechanism,
such as a
seal composed of an annular groove 82 and a corresponding o-ring (not shown).
[0035] Apparatus 10 disclosed herein may be used in, for example, fishing
operations, drilling operations, coil tubing, and drill strings. The use of up
or down in this
document illustrates relative motions within apparatus 10, and is not intended
to be limited
to vertical motions, or upward and downward motions. It should be understood
that
apparatus
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CA 02698572 2010-03-31
may be used in any type of well, including, for example, vertical, deviated,
and horizontal
wells.
[0036] In the claims, the word "comprising" is used in its inclusive sense
and does
not exclude other elements being present. The indefinite article "a" before a
claim feature
does not exclude more than one of the feature being present. Each one of the
individual
features described here may be used in one or more embodiments and is not, by
virtue only
of being described here, to be construed as essential to all embodiments as
defmed by the
claims.
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