Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MUD PULSE LANDING ASSEMBLY FOR
USE IN DIRECTIONAL DRILLING
FIELD OF THE INVENTION
This invention relates to a mud pulse landing assembly having a
removable mud pulse generator for use in drill strings, particularly
directional
oil well drilling systems.
BACKGROUND OF THE INVENTION
Communicating with the instrumented end of a drill string inside a well
bore, deep within the Earth presents unique challenges. The development of
real time communications for use in well bores has revolutionized the drilling
industry; this is especially evident in measurement-while-drilling (MWD)
technologies. Various wireless communication methods have been
developed for MWD operations including mud pulse telemetry as well as
electromagnetic-based systems. In traditional mud pulse systems, an orifice
~5 works in concert with a reciprocating piston to vaiy the drilling mud
pressure
riear the bottom end of the drill string, thereby forming pulses that transmit
through the mud to the surface. Using this system, digitally encoded
messages ca.n be sent via mud pulses, said pulses being received and
interpreted by telemetry devices located at the surface. In some designs, the
20 orifice represents the bore terminus of the tool string since previous
designs
have the orifice permanently fixed in position. 'As a result, it has been
previously impossible to pass tools beyond this point, without first removing
the entire drill string, a costly and time consuming task. Another design is
presented in U.S. 4,636,995 where a flow constrictor and throttling member is
25 provided as an integrated retrievable unit. The unit, however, cannot be
displaced and moved downwards past its terminal seat or stop. In addition,
the unit positions the pulsar unit at the top of the assembly, subjecting the
mechanics of the mud pulsar to the extreme flow turbulence that is
experienced during drilling operations. Additionally, this prior art design
does
so not incorporate a retainer.
There is therefore a significant need for an alternate mud pulse
telemetry system that does not obstruct passage of sensing devices through
the drill string. A means to remove the obstruction, and an object of the
present invention, is to have a mud pulse orifice incorporated into the
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removable mud pulse generator. This eliminates the obstruction and the
limitation of previous mud pulse telemetry systems: A further object is to
provide a retainer system in a mud pulse landing assembly that engages the
removable mud pulse generator to prevent spatial and rotational movement.
Another object is to provide a modular mud pulse generator system that
allows for replacement of only those parts that have failed. A removable
system must have the ability to self align, should be self seating and be
removable~in either the upward or downward direction from the normal
operating position.
1o SUMMARY OF THE INVENTION
The mud pulse landing assembly, in accordance with an aspect of this
invention, allows for the removal of the mud pulse generator containing the
mud pulse orifice, thus creating an unobstructed passageway for any device
that may need to be passed through the drill string. The retainer of the mud
pulse landing assembly also provides a universal mount for engaging
alternate tools oi- instrumentation for use in analyzing the borehole geology.
The mud pulse landing assembly comprises a mud pulse landing sub
having a longitudinal bore, contained with the longitudinal bore is positioned
a
stationary retainer to which a removable mud pulse generator can be
2o releasably connected. The mud pulse orifice and MDW tool containing the
piston actuator are housed within the removable mud pulse generator. The
removable mud pulse generator can be remotely detached from the stationary
latching subassembly by either applying downward pressure to drive the
removable mud pulse generator further down the drill string, or it may be
detached by applying an upward force to pull the removable mud pulse
generator up the drill string. Provided is a means for releasably connecting
the removable mud pulse generator to the stationary latch subassembly,
where the removable mud pulse generator is self seating and self aligning.
According to an aspect of the present invention, provided is a mud
3o pulse assembly for producing mud pulses for communicating during
directional drilling data telemetry, the improvement comprises:
a removable mud pulse generator for positioning in a landing sub body,
said removable mud pulse generator having' a outlet end, and
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a retainer for releasably engaging said removable mud pulse generator in
said landing sub body, said retainer engaging said mud pulse generator at or
upstream of said outlet end,
said retainer being remotely operable to release said removable mud
pulse generator from said mud pulse assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of an embodiment of the mud pulse
landing assembly.
Figure 2 is a side elevation of the embodiment shown in Figure 1.
Figure 3 is an exploded perspective view of the embodiment shown in
Figure 1.
Figure 4A is an exploded view of the compact muleshoe (shown in side
elevation view) and the anti-rotation latch receiver and thru-bore latch
receiver
~5 (shown in sectional view) of the embodiment hown in Figure 1.
Figure 4B is a perspective view of the embodiment shown in Figure 1,
showing engagement of the splines with the compact muleshoe.
Figure 4C is a perspective view of the embodiment shown in Figure 1,
showing engagement of the detent or ridge with the compact muleshoe.
2o Figure 5A, 5B and 5C are sectional views showing the insertion of the
removable mud pulse generator into the retainer of the mud pulse landing
assembly.
Figure 6A is a side view of an alternate embodiment showing a ball
detent retainer.
25 Figure 6B is a cross-sectional view of an alternate embodiment
showing non-circular keyed mating surfaces of the mud pulse generator and
landing sub body to prevent rotational movement.
Figures 6C (side view) and 6D (cross-section view) show another
alternate embodiment having a detent system designed to maintain both
3o spatial and rotational position.
Figure 6E is a cross-sectional view showing another embodiment
having a detent system configured with a spline.
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Figure 6F is a side view of another embodiment showing a detent
actuator and receiver system for refiaining the mud pulse generator in the
landing sub body.
Figure 7A Is a sectional view of the retainer with the removable mud
pulse generator in operational position and the piston in a retracted
position.
Figure 7B is a sectional view of the retainer with removable mud pulse
generator in position, where the piston is in close proximity to the orifice.
Figure 8 is a section view of a spear point assembly and retriever tool
for wireline retrieval of the tool string.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The mud pulse landing assembly of the present invention is used in
drill strings, particularly directional oil well drilling strings. The mud
pulse
landing assembly generally comprises a landing sub body, a retainer and a
removable mud pulse generator. Figure 1 shows an embodiment of a mud
pulse landing assembly (10). Mud pulse landing assembly (10) comprises a
landing sub body (11 ), a longitudinal bore (12), a retainer (14) and a
removable mud pulse generator (16). The invention provides a mud pulse
landing assembly (10) that is capable of remote release of the removable mud
2o pulse generator, providing clear unobstructed passage of any device that
may
be required to pass through the drill string. The removable mud pulse
generator can be displaced in either the forward or reverse direction relative
to the mud pulse landing assembly. The assembly (10) further comprises two
ends, a first end (18) being adapted to connect to a first drill string
component,
and a second end (20) being adapted to connect to a second drill string
component. The mud pulse landing assembly (10) is circular in cross-section.
Shown in Figure 2 is a partial sectional view of the mud pulse landing
assembly (10). The longitudinal bore (12) consists of a first region (22) and
a
second region (24), each being immediately adjacent to each other and
3o concentric with.reference to the longitudinal axis (26) of the assembly.
The
first region (22), with reference to the second region (24) is of a smaller
diameter, thereby defining shoulder (28). The first region (22) of the
longitudinal bore (12) remains clear and unobstructed in the assembled mud
pulse landing assembly (10). In the second region (24), immediately adjacent
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to the shoulder (28) is a compact flow diverter (30) positioned so that the
inside tapered diameter (shown in dot) of the compact flow diverter (30)
tapers inwards in a direction facing the second end (20). Immediately
adjacent the compact flow diverter (30) moving in a direction towards the
s second end (20) is bumper ring (32), and retainer (14), the retainer
comprising
an anti-rotation latch receiver (34), a latch spacer (36) and a thru-bore
latch
receiver (38). Continuing towards the second end (20), there is a second
bumper ring (40) and a second compact flow diverter (42), positioned so that
the inside tapered diameter (shown in dot) tapers outwards towards the
second-end (20). To retain the above elements in place within the second
region (24) of the longitudinal bore (12), a retaining ring (44) is positioned
immediately adjacent the second compact flow diverter (42), the retaining ring
(44) being positioned within a circumferential box-shaped groove (46) located
on the inside surface of the mud pulse landing subassembly (11 ). To
maintain the anti-rotation latch receiver (34) in radial alignment, a key
slider
(48) is positioned within a recess (50) in the anti-rotation latch receiver
(34),
the key slider (48) being fixed in place by a first bolt (52) and a second
bolt
(54) that threadably engages the key slider (48). The first and second bolts
(52, 54) are accessible from the exterior of the mud pulse landing assembly
20 (10) by means of a first hole (56), through which the first bolt (52)
passes, and
a second hole (58), through the second bolt (54) passes. By means of first
and second bolts (52, 54) and key slider (48), the anti-rotation latch
receiver is
maintained in radial alignment, thus preventing rotational movement of the
mud pulse generator that is ultimately retained by the retainer. The recess
25 (50) of the anti-rotation latch receiver (34) is longer than the key slider
(48) to
accommodate vibrational movement in a direction parallel to the longitudinal
axis (26).' Although the ability to accommodate certain vibrational movement
and stress is configured into the means by which the key slider (48) and anti-
rotation latch receiver (34) engage, the first and second bumper rings (32,
40)
so further serve to reduce the various stresses that are commonly associated
with directional drilling applications.
Shown in Fig. 3 is an exploded view of the retainer (14) and removable
mud pulse generator (16). As was explained above, the retainer comprises
the anti-rotation latch receiver (34), the latch spacer (36), and the thru-
bore
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latch receiver (38). The removable mud pulse generator, is of modular design
and comprises a compact muleshoe body (60), first, second and third
muleshoe legs (62, 64; third leg not shown) and an MWD tool (66) in a
spaced-apart relationship from said compact muleshoe. The muleshoe legs
are attached to the MWD tool (66) by bolts or screws (68) or alternate
suitable
means. Each muleshoe leg, on the end mating with the MWD tool (66), has
an elevated step (70) that is received by a corresponding receptacle (72) on
the MWD tool (66). Similarly, with respect to each muleshoe leg, on the end
mating with the compact muleshoe body (60), each muleshoe leg has an
angled step (74) that corresponds to a receiving receptacle (76) on the
compact muleshoe body (60). The interaction of the steps on each muleshoe
leg with the corresponding receptacles on the receiving structures ensures
there is no movement of the compact muleshoe body (60) with reference to
the MWD tool (66). It can be appreciated that while the present embodiment
uses three legs to attach the MWD tool (66) to the compact muleshoe (60),
one skilled in the art may choose to either increase or decrease the number of
legs used, as required: In addition, while the present embodiment shows
legs that are separate structures that are ultimately attached to the compact
muleshoe (60), one skilled in the art may choose to use a compact muleshoe
20 of unitary structure where the legs are integral with the muleshoe body.
The modular design of the mud pulse generator and the compactness of the
compact muleshoe body (containing the orifice) offers particular advantages
to the present invention. By bridging the space between the muleshoe and
the MWD tool using legs, instead of a solid enclosure surrounding the MWD
25 tool, and by positioning the MWD tool upstream of the compact muleshoe,
destructive forces due to flow turbulence upon the MWD tool is reduced. With
this configuration, the mud flowing downwards through the drill string does
not
enter the muleshoe until after passing the MWD tool, thus restricting the
turbulence to the region of the compact muleshoe and the region
so downstream. Damage resulting from this tubulance can be fixed by merely
replacing the compact muleshoe without having to replace the MWD tool.
In an assembled mud pulse landing assembly (10), the removable
mud pulse generator (16) is maintained in a fixed spatial and rotation
position
with respect to the retainer by means of a plurality of~anti-rotation latch
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receiver fingers (78) and a plurality of thru bore latch fingers (80), where
the
anti-rotation latch receiver fingers (78) and the thru-bore latch fingers (80)
are
adapted to engage the compact muleshoe body (60). In the assembled
position, the anti-rotation latch receiver fingers (78) and the thru bore
latch
fingers (80) interdigitate within the region (81 ) defined by the latch spacer
(36). Located on one end of the latch spacer (36) are a first set of tongue
extensions (83) that fit within corresponding channels (85) on the anti-
rotation
latch receiver (34). Similarly, on the other end of the latch spacer (36) are
a
second set of tongue extensions (87) that fit within corresponding channels
(89) on the thru-bore latch receiver (38). In the assembled position, the anti-
rotation latch receiver (34) and the thru-bore latch receiver (38) remain
spatially fixed due to the engagement between the tongue extensions (83, 87)
of the latch spacer (36) and the corresponding channels (85, 89) on the anti-
rotation latch receiver (34) and the thru-bore latch receiver (38). Since the
~5 anti-rotation latch receiver (34) is maintained in a fixed position by
means of
the key slider (48) and first and second bolts (52, 54; see Figure 2), it
follows
that by means of the latch spacer (36), the thru-bore latch receiver (38) is
also
maintained in a fixed position. With respect to the fingers engaging the
compact muleshoe body (60), as shown in Figure 4A, the anti-rotation latch
20 .receiver fingers (78) have located on the inside surface of the terminal
ends a
plurality of elongated longitudinally-oriented engagement splines (82) that
engage the compact muleshoe body (60) at receiving elongated radial splines
(84) located on the outside surface of the compact muleshoe body (60), as
shown in Fig. 4B. This serves to prevent rotational movement of the compact
25 muleshoe body relative to the landing sub body. Similarly, the thru-bore
latch
fingers (80) have located on the inside surface of the terminal ends a detent
or ridge (86) that engages a receiving groove (88) located on the outside
surface of the compact muleshoe body (60), as shown in Fig. 4C. The ridge
or detent serves to engage the compact muleshoe to maintain it in fixed
3o spatial relationship relative to the landing sub body. The need to maintain
the
various elements in a fixed position resides in the fact that in some
applications, the internal electronics of the MWD tool require positioning at
precise, accurate, known angles. By maintaining a fixed internal
arrangement, the required angle of the MWD tool can be accurately set.
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Furthermore, to allow for accurate guidance of the drill, the MWD tool must be
fixed with respect to the bend in the drill motor.
The releasable self seating connecting means of the mud pulse landing
assembly (10) will be explained by making reference to Figures 5A, 5B and
s 5C. With the retainer (14) in position within the mud pulse landing sub (11
),
the removable mud pulse generator (16) can be inserted into place. Shown
in Figure 5A is the insertion of the mud pulse generator (16) into the mud
pulse landing sub (11 ) from the second end (20). To facilitate insertion of
the
mud pulse generator (16) into the mud pulse landing sub (11 ), the leading end
(90) of the mud pulse generator (16) has been configured with a tapered edge
(92). As the mud pulse generator (16) is moved through the longitudinal bore
(12), the tapered edge (92) of the mud pulse generator encounters the
elongated engagement splines (82) of the anti-rotation latch receiver fingers
(78). To accommodate movement of the mud pulse generator (16) beyond
the elongated engagement splines (82) of the anti-rotation latch receiver
fingers (78) in a direction towards fihe first end (18; see Figure 2), the
anti-
rotation latch receiver fingers (78) have been adapted to flex outwardly thus
permitting movement of the mud pulse generator (16) through the longitudinal
bore (12). To accommodate this outward flex of the anti-rotation latch
2o receiver fingers (78), the latch spacer (36) has a series of openings (91;
see
Figure 3) in positions corresponding to the terminal ends of each anti-
rotation
latch receiver finger (78). To further facilitate passage of the mud pulse .
generator (16) beyond the anti-rotation latch receiver fingers (78), the
elongated longitudinally-oriented engagement splines (82) are configured with
25 a first angled side (94) and a second angled side (96; refer to Figure 4 to
see
angled sides) to allow for outward deflection of anti-rotation receiver
fingers
(78). As the mud pulse generator (16) is moved further through the
longitudinal bore (12) towards the first end (18; see Figure 2), the tapered
edge (92) of the mud pulse generator (16) encounters the ridge (86) on the
so inside surface of the terminal ends of the thru-bore latch fingers (80). To
allow for passage of the mud pulse generator (16) beyond the ridge (86), the
thru-hold latch fingers (80) are adapted to flex outwardly. To accommodate
this outward flex of the thru-bore latch receiver fingers (80), the latch
spacer
(36) has a series of openings (93; see Figure 3) in positions corresponding to
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the terminal ends of each thru-bore latch receiver finger (80). To further
facilitate movement of the mud pulse generator (16) beyond the ridge (86),
the ridge is tapered at a first side (98) and a second side (100; refer to
Figure
4 to see angled sides) to allow for outward deflection of the thru-bore latch
receiver fingers (80), as shown in Figure 5B. As the mud pulse generator (16)
is positioned into operational position, as shown in Figure 5C, the elongated
splines (82) of the anti-rotation latch receiver fingers (78) engage the
elongated radial splines (84) of the compact muleshoe body (60), thus
preventing rotation about the longitudinal axis (refer to Fig. 4B).
Concurrently,
1o the ridge (86) on the thru-bore latch receiver fingers (80) position within
the
receiving groove (88) thereby locking the mud pulse generator (16) in place
within the retainer (14) (See Fig. 4C).
The insertion or removal of the removable mud pulse generator can be
performed or operated remotely. For example, pressure can be applied to the
tool string fio push and disengage the removable mud pulse generator from
the retainer in the downward direction. Alternately, a wireline can be lowered
into the string to engage the removable mud pulse generator, such that a
pulling force on the wireline disengages the removable mud pulse generator
in the upward direction. For example, the tool string can be fitted with a
spear
2o point assembly comprising a spear point housing (162) and spear point (164)
to which a "J-Latch" or "overshot" device can be attached at end (166),
allowing the tool string to be retrieved to the surface (See Figure 8). The
retainer and removable mud pulse generator allow for the initiating activity
to
be remote relative to the location of the mud pulse landing assembly.
25 Movement of the mud pulse generator in either direction is facilitated and
self
aligned by incorporating into the construction various tapers to eliminate the
abutment of opposing shoulders. As previously mentioned, the elongated
splines (82) of the anti-rotation latch receiver fingers (78) are dual tapered
as
are the ridges (86) of the thru-bore latch receiver fingers (80). To further
3o facilitate movement in either direction, the compact muleshoe body (60)
also
incorporates various tapers. As shown in Figure 4A, the receiving groove (88)
of the compact muleshoe body (60) has a first outwardly tapering edge (95)
and a second outwardly tapering edge (97). Similarly, in the region of the
elongated radial splines (84) of the compact muleshoe body (60), there is a
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first outwardly tapering edge (99) and a second outwardly tapering edge
(102). An additional taper (104) is incorporated into the design of the
compact
muleshoe body (60) to further facilitate movement, especially when directing
the mud pulse generator upwards through the drill string.
Figure 6A shows an alternate embodiment of a mud pulse landing
assembly, where the retainer (120) comprises a detest for retaining the
removable mud pulse generator ('122) in place within the landing sub body
(124). The removable mud pulse generator is correspondingly adapted with a
receptacle (126) to receive the detest. An example of a detest that can be
used is a spring-actuated ball detest (as shown in Fig. 6A). To prevent
rotation of the mud pulse generator, the refiainer further comprises a coupler
for registering the mud pulse generator in a fixed rotational position
relative to
the landing sub body. The coupler may comprise at least one spline (128) for
registering the mud pulse generator in a fixed rotational position relative to
the
landing sub body. The splines for registering the mud pulse generator in
place are machined on at least a portion of adjacent surfaces of the
removable mud pulse generator (122) and the landing sub body (124).
Alternatively, removable mud pulse generator (129) may be registered in a
fixed rotational position relative to the landing sub body (131 ) by means of
a
2o coupler comprising non-circular keyed mating surfaces (130; i.e. a hex fit)
as
shown in Fig. 6B. Alternatively, the detest may be configured with a means
for locking the mud pulse generator in fixed rotational position. For example,
as shown in Figures 6C and 6D, the detest (132) could be configured with a
tapered front edge (134) and a tapered rear edge (136), to facilitate
engagement and disengagement from the mud pulse generator (138), but
with non-tapered side walls (140) that engage side walls (142) configured into
the detest receptacle on the mud pulse generator (138). Additionally, as
shown in Fig. 6E, the means for locking could comprise at feast one
longitudinal spline (144) on the detest (146), the removable mud pulse
3o generator (148) being adapted to receive both the detest, as well as
registering the splined detest in a corresponding splined receptacle (150).
r
Another alternative, as shown in Fig. 6F is a retainer comprising a retainer
actuator (152) and a receiver (154), where the retainer is remotely activated
by means of a actuating signal. The receiver (154), on receiving and
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actuating signal acts to actuate the retainer actuator (152), disengaging the
detent (156), thereby releasing the removable mud pulse generator (158) from
the landing sub body (160). While the embodiment shown in Fig. 6F has an
additional spline to maintain the mud~pulse generator (158) in fixed
rotational
s position relative to the landing sub body (160), an alternate means as
discussed above may also be implemented.
The retainer of the present invention presents certain advantages over
the prior designs. The retainer of the present invention is positioned between
the mud pulse generator and the landing sub body at a location that is either
at or upstream of the outlet end of the compact muleshoe. By placing the
retainer between the mud pulse generator and the landing sub body, the
retainer is separated from the mud flow which can be highly abrasive and,
destructive. The retainer is effectively shielded or protected from the mud
flow, thus improving overall reliability. In addition, by placing the retainer
in
15 this protected position, the area downstream of the compact muleshoe
remains unobstructed as a seat or stop for receiving a forward shoulder of the
muleshoe is not necessary. A stop or seat in the area downstream of the
muleshoe would be subjected to extreme flow turbulence and abrasiveness,
ultimately leading to problems in reliability. The present invention overcomes
2o these problems by protecting the retainer from the turbulent and abrasive
mud
flow.
The use of a retainer to maintain the mud pulse generator in fixed
spatial and rotational relationship with the landing sub body ensures proper
positioning of the MWD components. In addition, it serves to prevent the
25 mud pulse generator from displacing upwards in the event of sudden
backflow. Furthermore, vibrational forces are experienced during drilling and
the retainer system of the present invention serves to maintain the mud pulse
generator in position under extreme conditions. The retainer or detent serves
to engage the mud pulse generator, where prior designs merely provide a
30 seat.
The retainer may also be used as a universal mount to retain alternate
tools or instrumentation for use in analyzing the borehole geology. For
example, a tool could be lowered into the,drill string, engaged by the
retainer,
and subsequently released in either a downward or upward direction
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depending on the analytical operation to be performed. It may be possible to
set up a series of tools in tandem, where the retainer is used to releasably
retain the tandem assembly in a series of positions corresponding to the
series of tools in the tandem string.
In order for the mud pulse landing assembly to generate
communicative mud pulses that can be measured at the surface (i.e. mud
pulse telemetry), a system well known in the art for producing such pulses
must be present which includes an orifice and a reciprocating piston. In
traditional mud pulse telemetry, the orifice is a fixed element in the
construction. In an effort to allow for passage of various devices through the
drill string without obstruction by the orifice, the present invention allows
for
removal of the orifice due to its incorporation into the removable mud pulse
generator. As shown in Figure 7A, the compact muleshoe body (60) has a
longitudinal bore (105) that contains a mud pulse orifice (106) that has one
face positioned against a formed shoulder (108) on the inside surface of the
compact muleshoe body (60). The mud pulse orifice (106) is retained in
position by a suitable means, shown in the figure as a retaining ring (110).
To produce a mud pulse, a piston actuator~(112), housed within the MWD tool
is activated, bringing into close proximity to the mud pulse orifice (106) a
2o piston (114) that results in higher mud pressure (See Fig. 7B). The
activation of the piston is controlled by various means well known in the art.
Although preferred embodiments of the invention have been
described herein in detail, it will be understood by those skilled in the art
that
variations may be made thereto without departing from the spirit of the
invention, as described herein.
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