Note: Descriptions are shown in the official language in which they were submitted.
DEVICE AND METHOD FOR ACTUATING DOWNHOLE TOOL
FIELD
[0001] The present disclosure relates generally to downhole tool operations
and, more
particularly, to actuation devices and methods for selectively actuating
downhole tools in
different sections of a wellbore.
BACKGROUND
[0002] To produce hydrocarbons from subterranean hydrocarbon reservoirs such
as bitumen
formations, one or more wells may be drilled into the formation, and a
treatment fluid may be
injected into the formation through a well to facilitate or enhance
hydrocarbon production.
For example, a fracturing fluid may be selectively injected through different
sections of a
wellbore to treat corresponding zones in the formation. In a typical
fracturing operation, a
perforated tubing is introduced into the wellbore and the treatment fluid is
pumped into the
tubing and applied to the surrounding formation via the perforations, to open
or enlarge
drainage channels in the formation.
[0003] It is sometimes desirable to perform staged treatment of the wellbores
and the
surrounding formations in multiple isolated zones or sections along the
tubing. For this
purpose, sliding sleeves may be provided on the tubing to selectively open and
close the
respective sections of perforations and the sliding sleeves may be actuated
with a ball or a
dart.
[0004] For example, a proposed actuation dart for actuating a target tool in a
tubing string
includes a body conveyable through the tubing string to reach a target sleeve,
a control
module configured to respond to contact with a sleeve in the tubing string to
locate the target
sleeve, and an actuation mechanism for actuating the target sleeve when it is
located. The
control module includes a switch that is depressed by a seat of the sleeve as
the dart passes
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Date Recue/Date Received 2021-02-02
the seat. In response to being depressed, the switch generates an output
signal to allow the
dart to register and count passing of the seat.
SUMMARY
[0005] In accordance with an aspect of the present disclosure, there is
provided a device
comprising: a housing configured to travel within a well tubing, wherein a
plurality of seat
structures are mounted in the well tubing, each one of the seat structures
comprising a seat to
seat the device thereon; a surface structure on an external surface of the
housing, having an
inactive state and an activated state, and being configured to (i) allow the
device to travel
through the seat structures when the surface structure is in the inactive
state or (ii) to seat in a
selected one of the seats in the well tubing when the surface structure is in
the activated state,
wherein the device is configured to experience a physical impact having an
impact level
exceeding a threshold level when passing through each one of the plurality of
seat structures;
a sensor enclosed in the housing, configured to generate a signal in response
to the physical
impact experienced by the device; a controller housed in the housing and in
communication
with the sensor to receive the signal from the sensor, wherein the controller
is configured to
determine, based on signals received from the sensor, a number of physical
impacts
experienced by the device with impact levels exceeding the threshold level,
and to activate
the surface structure when the number of physical impacts reaches a pre-
selected value.
[0006] In one embodiment, the sensor comprises a shock sensor. In another
embodiment, the
sensor is an accelerometer.
[0007] In another aspect of the present disclosure, there is provided a method
comprising:
detecting a physical impact experienced by an actuation device while the
device is traveling
downhole in a well tubing, wherein the actuation device is seatable in a
downhole seat in the
well tubing; determining a number of physical impacts experienced by the
actuation device
wherein each of the physical impacts has an impact level that exceeds a
selected threshold
level of impact; and seating the actuation device in the downhole seat if the
number of
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Date Recue/Date Received 2021-02-02
physical impacts has reached a pre-selected value, or passing the actuation
device through the
downhole seat if the number of physical impacts is less than the pre-selected
value.
[0008] In a further aspect of the present disclosure, there is provided a
device comprising a
housing configured to travel within a well tubing, wherein a plurality of seat
structures are
mounted in the well tubing, each one of the seat structures comprising a seat
to seat the
device thereon; a surface structure on an external surface of the housing,
having an inactive
state and an activated state, and being configured to (i) allow the device to
travel through the
seat structures when the surface structure is in the inactive state or (ii) to
seat in a selected
one of the seats in the well tubing when the surface structure is in the
activated state, wherein
the device is configured to experience a physical impact having an impact
level exceeding a
threshold level when passing through each one of the plurality of seat
structures; a sensor
enclosed in the housing, configured to generate a signal in response to the
physical impact
experienced by the device; and a controller housed in the housing and in
communication with
the sensor to receive the signal from the sensor, wherein the controller is
configured to:
monitor, based on signals received from the sensor, physical impacts
experienced by the
device with impact levels exceeding the threshold level, and activate the
surface structure
when the monitored physical impacts indicate that the device is next reaching
a target seat
structure.
[0009] Other aspects, features, and embodiments of the present disclosure will
become
apparent to those of ordinary skill in the art upon review of the following
description of
specific embodiments in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF DRAWINGS
[0010] In the figures, which illustrate, by way of example only, embodiments
of the present
disclosure,
[0011] FIG. 1A is a schematic perspective view of an example actuation device
according to
an embodiment of the disclosure, shown in an inactive state;
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Date Recue/Date Received 2021-02-02
[0012] FIG. 1B is a schematic front side view of the device of FIG. 1A;
[0013] FIG. 1C is a schematic rear side view of the device of FIG. 1A;
[0014] FIG. 1D is a schematic cross-section view of the device of FIG. 1A;
[0015] FIG. lE is a schematic perspective cross-section view of the device of
FIG. 1A;
[0016] FIG. 2A is a schematic cross-section perspective view of the device of
FIG. 1, in an
activated state;
[0017] FIG. 2B is a schematic cross-section view of the device of FIG. 2A;
[0018] FIG. 2C is a schematic perspective cross-section view of the device of
FIG. 2A;
[0019] FIG. 3 is a schematic block diagram illustrating a control circuit for
use in the device
of FIG. 1;
[0020] FIG. 4A is a schematic block diagram illustrating a first example
control circuit for
use in the device of FIG. 1;
[0021] FIG. 4B is a schematic block diagram illustrating a second example
control circuit for
use in the device of FIG. 1;
[0022] FIG. 5 shows a schematic cross-section view of an example well system;
[0023] FIG. 6 is a top-perspective view of a section of the well tubing in the
well system of
FIG. 5;
[0024] FIG. 7 is a top-perspective view of a sleeve in the section of the well
tubing of FIG. 6;
[0025] FIG. 8 shows a cross-section view of the well tubing section of FIG. 6,
where the
sleeve is moved to the closed position;
[0026] FIG. 9 shows a cross-section view of the well tubing section of FIG. 6,
where the
sleeve is moved to the open position;
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Date Recue/Date Received 2021-02-02
[0027] FIG. 10 is a flowchart illustrating a method for operating the device
of FIG. 1 in the
well system of FIG. 5;
[0028] FIG. 11A-11E shows a schematic cross-section view of the device of FIG.
1 in the
well system of FIG. 5;
[0029] FIGS. 12 and 13 are schematic cross-section views illustrating passing
of the device
of FIG. 1 through a non-targeted sleeve in the well system of FIG. 5, when the
device is in
the inactive state;
[0030] FIGS. 14 and 15 are cross-section views illustrating seating of the
device of FIG. 1 in
a target sleeve in the well system of FIG. 5, and actuation of the target
sleeve from the closed
position to the open position, when the device is in the activated state;
[0031] FIGS. 16A and 16B are cross-section views of a sleeve having a seat
structure,
according to an alternative embodiment, wherein the seat structure is at
respective positions;
and
[0032] FIG. 17 is a cross-section view of another seat structure, according to
a further
alternative embodiment.
DETAILED DESCRIPTION
[0033] In an embodiment, disclosed here is a device, such as an actuation
dart, for selectively
actuating a selected one of downhole tools in a well tubing. For example, each
of the
downhole tools may have corresponding seat structures for seating the
actuation device
therein so that the seated device can be used to actuate the downhole tool.
The actuation
device is configured to locate and seat in the target seat structure in the
well tubing based on
the number of physical impacts the device experiences when traversing the well
tubing,
where each of the physical impacts exceeds a threshold impact level, such as a
shock level or
gravitational force ('g-force') level. A sensor is provided within the housing
of the actuation
device to detect such physical impacts.
Date Recue/Date Received 2021-02-02
[0034] FIGS. lA to lE and FIGS. 2A to 2C show schematically an actuation dart
100,
according to an example embodiment of the actuation device. Dart 100 has two
states, an
inactive state as illustrated in FIGS. 1A-1E and an activated state as
illustrated in FIGS. 2A-
2C.
[0035] Dart 100 has a housing 117 defining an external surface 112 and having
an uphole
end 150 and a downhole end 152. Housing 117 may have an elongate, cylindrical
shape.
[0036] Housing 117 may define a fluid conduit 138. Fluid conduit 138 may be a
cylindrical
conduit that passes through the center of housing 117. Fluid conduit 138
allows fluid to flow
through housing 117 to avoid fluid pressure from building up when dart 100 is
deployed.
[0037] Fluid conduit 138 may also have one or more protruding members 154 at
downhole
end 152. Protruding members 154 extend longitudinally past the end of fluid
conduit 138, so
that fluid can flow through the sides of dart 100. Thus, should the downhole
end 152 of dart
100 be blocked, fluid can still flow through the sides of dart 100.
[0038] Housing 117 may have a first cut-out 160 on a surface thereof. Cut-out
160 may
house a controller such as control circuit 114 (FIGS. 3, and 4A-4B). Cut-out
160 may be
filled with a waterproof and thermally insulating material to encase control
circuit 114, such
as a rubber, a waterproof resin, or an epoxy material. The waterproof and
thermally
insulating material may protect control circuit 114 from the harsh environment
within the
wellbore through which dart 100 is placed.
[0039] Housing 117 may also have a second cut-out 161 on a second surface
thereof.
Second cut-out 161 may house one or more elements of the control circuit 114.
In one
example, cut-out 161 houses an actuator 126 (FIGS. 3, and 4A-4B). Cut-out 161
may also be
filled with a waterproof and thermally insulating material to encase those
elements of control
circuit 114, such as a rubber, a waterproof resin, or an epoxy material.
[0040] As illustrated schematically in FIG. 3, actuator 126 may be connected
using wires
310, 311 to one or more elements of control circuit 114 housed within cut-out
160.
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Date Recue/Date Received 2021-02-02
[0041] Housing 117 may have a number of grooves 158 for retaining seals (not
shown) in
between the surface 112 of housing 117 and surface structure 110. The seals
may be retained
due to the pressure and friction between housing 117 and surface structure
110. The seals
may further protect control circuit 114 from the harsh environmental
conditions which dart
100 is expected to be exposed to, including high temperature, high pressure,
and corrosive
fluids. The seals may be made of any number of elastomers, for example, a
rubber material.
Seals may be shaped in any number of shapes, for example, as 0-rings or D-
shaped seals.
[0042] In one example embodiment, the waterproof and thermally insulating
material and the
seals work together to keep control circuit 114 dry and at a suitable
operating temperature,
for example, less than 85 C.
[0043] Housing 117 may have a ridge 155 for retaining a foil 156. Foil 156 has
a first end
attached to housing 117, in proximity to downhole end 152. The first end may
be glued to
housing 117, or alternatively may be moulded in place. Foil 156 also has an
unsecured
second end, which extends outwardly from housing 117. In one example, foil 156
is angled
such that the second end of foil 156 points towards uphole end 150. In one
example, foil 156
is annular in shape, extending around housing 117. Foil 156 may be made of
soft rubber
material suitable for use with fracking fluids, such as VitonTM, hydrogenated
nitrile butadiene
rubber (HNBR), or a nitrile rubber (NBR). In one example embodiment, foil 156
may be
slightly larger in diameter than housing 117.
[0044] Dart 100 has a surface structure 110 on external surface 112 of housing
117. Surface
structure 110 may include a movable structure that is moveable on the external
surface, such
as a sleeve 118 as depicted, which is movably mounted on the external surface
112 of
housing 117 and surrounds a portion of external surface 112. One or more
fingers 115 may
be provided and extend longitudinally from an end of sleeve 118. Sleeve 118
may be made
from the same material used to make housing 117, although a different material
may be used.
[0045] Each finger 115 may have a bendable terminal tip 116 and a protrusion
111 extending
therefrom to expand the diameter of dart 100. Each finger 115 has an edge 171
at an end
thereof.
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Date Recue/Date Received 2021-02-02
[0046] In an initial position (FIG. 1), fingers 115 may be cantilevered from
the end of sleeve
118 to project around and above external surface 112, leaving a gap between
terminal tips
116 and external surface 112. Terminal tips 116 are thus unsupported by the
housing 117 in
this initial position. Fingers 115 may be made of a resilient material so that
the terminal tips
116 of fingers 115 can bend under pressure towards the housing when
unsupported, thus
allowing dart 100 to pass through restrictions in the tubing through which
dart 100 travels.
In this initial position dart 100 is in the inactive state so that dart 100
can pass through
restrictions in the tubing.
[0047] Sleeve 118 may be slidable from the initial (first) position to a
second position where
the terminal tips 116 are supported by a portion of housing 117, particularly
ridge 134, and
thus can no longer bend towards the housing surface. Housing 117 may also
include locking
mechanisms to secure sleeve 118 in each position. When the sleeve 118 is in
the second
position, it is in the activated state as dart 100 can no longer pass through
a selected seat, as
will be further discussed below.
[0048] To lock the sleeve 118 in the initial position, sleeve 118 may include
a bore 131' and
housing 117 may include a corresponding counterbore 131 at downhole end 152
(FIGS. 2A-
2C), for receiving a shear screw 132 to secure sleeve 118 to housing 117 at
the initial
position, corresponding to the inactive state. Shear screw 132 may be made of
a frangible,
breakable material to allow sleeve 118 to be released from the initial
position to activate dart
100. Shear screw 132 may be made of bronze, steel, or hard plastic. Bore 131'
and
counterbore 131 have internal threads and are aligned for receiving and thread
engagement
with shear screws 132 when the sleeve 118 is in the initial position.
[0049] In some embodiments, a number of shear screws 132 may be positioned
around the
circumference of housing 117 to secure sleeve 118. In the embodiment as
depicted in the
drawings, four shear screws are used to secure sleeve 118. Each shear screw
may require a
head breaking torque in the range of 450 to 550 kg, such as 500 kg, to break
or shear off the
screw head. In different embodiments, the number and positions of bores 131'
and
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Date Recue/Date Received 2021-02-02
counterbores 131 may be varied. Further, the counterbores 131 may be replaced
with a
groove extending along the circumference of housing 117.
[0050] With counterbores 131, when shear screws 132 are threadably engaged
with bores
131' and counterbores 131, sleeve 118 is prevented from sliding axially and
rotating about its
central axis. If the counterbores are replaced with a groove, the sleeve 118
is still prevented
from sliding axially but may be able to rotate about its axis.
[0051] In other embodiments, sleeve 118 may be secured in the first position
using one or
more pins (not shown) or an annular rim (not shown).
[0052] Dart 100 may also include a locking mechanism 130 for locking sleeve
118 in the
second position, corresponding to the activated state. Locking mechanism 130
is positioned
in proximity to uphole end 150 and includes a ridge 134 and a bevelled surface
173 that
matches the shape of the edge 171 of terminal tips 116. Terminal tips 116 may
have a notch
113 that matches the shape of ridge 134 and oriented to engage ridge 134. When
sleeve 118
is in the second position, ridge 134 props up the terminal tips 116 by
abutting notch 113 to
prevent fingers 115 from bending towards the surface 112 of the dart 100, and
edge 171 of
the tips 116 abuts the bevelled surface 173 to prevent fingers 115 from
bending away from
the surface 112 (as shown in FIG. 2B), thus preventing unlocking of the
terminal tips 116.
Thus, in the activated state, fingers 115 are prevented from bending under
pressure or on
impact, and the surface structure is non-collapsible.
[0053] In addition, locking mechanism 130 also prevents fingers 115 from
moving
longitudinally. This is because ridge 134 blocks the side walls 175, 177 of
notch 113 from
moving laterally relative to the surface 112.
[0054] Housing 117 may include one or more ridge structures 162, which may be
used to
retain seals (not shown), which seal fluid to one side of a tubing through
which dart 100 may
travel.
[0055] Dart 100 may also have a removable cap 164 at either end thereof. Cap
164 may be
wider in diameter than housing 117. Cap 164 may be removed to slide sleeve 118
into
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Date Recue/Date Received 2021-02-02
position surrounding external surface 112 of housing 117. Cap 164 is removably
fixed at
uphole end 150 using arms 165 which latch onto external surface 112. External
surface 112
may have grooves 167 that correspond to the position of arms 165 to provide
cap 164 with a
surface to latch onto.
[0056] Cap 164 may also include a receptacle 166. Receptacle 166 has an
enlarged opening,
which may be cone-shaped as depicted in the drawings, to receive and retain a
ball 136. In
one embodiment, the opening has a wider diameter than the diameter of housing
117. Ball
136, when retained in receptacle 166, blocks fluid flow through fluid conduit
138. In some
embodiments, receptacle 166 may include a retaining clip (not shown), pin (not
shown), or
other mechanical mechanism to retain ball 136.
[0057] Dart 100 includes a control circuit 114 for activating surface
structure 110 to seat at a
selected seat structure within the wellbore.
[0058] A first example embodiment of control circuit 114 is schematically
shown in block
diagram form in FIG. 4A. Control circuit 114 may include a processor 122 in
communication with an impact sensor 120, actuator 126, I/0 interface 124, and
memory 128.
[0059] Memory 128 is a processor-readable medium and stores processor
executable
instructions, including activation code 142 for activating dart 100. When
executed,
activation code 142 may cause processor 122 to implement a method 400, as
discussed in
detail below.
[0060] Memory 128 also stores variables for use by activation code 142,
including a count
140 indicating the number of impacts experienced by dart 100 within the
wellbore that
exceeds a threshold level, and settings 144 defining operational parameters of
dart 100 (for
example, defining a selection of seat structures for seating).
[0061] Impact sensor 120 generates a signal in response to an acceleration of
dart 100
resulting from a physical impact experienced by dart 100 as dart 100 travels
within the
wellbore.
Date Recue/Date Received 2021-02-02
[0062] Impact sensor 120 may be selected from shock sensors, accelerometers,
gyroscopes,
strain gauge sensors, proximity sensors, piezoelectric sensors, piezo-
resistive sensors,
capacitive sensors, and acoustic sensors.
[0063] An acoustic sensor, such as a microphone, can detect sound or other
acoustic waves
generated by the physical impact of dart 100 contacting a seat structure 350.
The acoustic
wave generated by such impact may have identifiable characteristics, such as
signature
frequencies or amplitudes, which can be used by the control unit to determine
if dart 100 has
passed through a seat structure 350. Processor 122 may, in some embodiments,
analyze the
detected acoustic signal to determine whether detected acoustic signal
indicates a physical
impact between dart 100 and the seat structure 350. For example, the amplitude
of the
detected acoustic signal may be correlated to the level of physical impact
experienced by dart
100.
[0064] In one example embodiment, more than one sensor (of the same type or of
different
types) may be used in combination.
[0065] In one example embodiment, sensor 120 may be configured to measure an
impact
causing dart 100 to experience a gravitational force (g-force) in the range of
400 G to 1000
G.
[0066] In one embodiment, sensor 120 may be a SignalQuestTM SQ-ASA series
shock
sensor, which has a sensitivity range of 100 G to 2000 G and has a response
time of under
100 micro seconds. The SignalQuestTM SQ-ASA series shock sensor provides an
analog
voltage pulse output (in the range of 3 to 4 Volts) upon detecting a shock
that exceeds a
threshold level. The SignalQuestTM SQ-ASA series shock sensor is cylindrical
in shape and
is approximately 7 mm long and 3 mm in diameter and may be coupled to a
printed circuit
board ('PCB').
[0067] The SignalQuestTM SQ-ASA series shock sensor is suitable for operation
at
temperatures ranging from -40 to +85 C. As previously discussed, the
operating temperature
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Date Recue/Date Received 2021-02-02
of the sensor may be maintained at a suitable operating temperature by
isolating control
circuit 114 using a waterproof and thermally insulating material.
[0068] In another embodiment, sensor 120 may be a MurataTM shock sensor.
[0069] Impact sensor 120 may be a "go/no-go" sensor which only generates and
sends a
signal to processor 122 when the level of impact exceeds a pre-determined
threshold level of
impact. A "go/no-go" sensor may be suited to detect sudden and transient
impacts and
changes in motion, as a "go/no-go" sensor generates an output signal (for
example, in the
form of a voltage or current pulse) to processor 122 only when the level of
impact exceeds
the selected threshold value.
[0070] Alternatively, impact sensor 120 may be an impact level sensor. An
impact level
sensor can generate a signal indicating a quantitative level of impact
experienced by dart 100
over a period of time (i.e. a sampling period).
[0071] The output of the impact level sensor may be an analog voltage or
current output that
has an amplitude indicative of the level of impact detected. Processor 122 may
sample the
analog output of the impact level sensor. A sampling rate of the impact level
sensor may be
selected to ensure that a sudden and transient impact or change in motion is
detected by
impact level sensor. In one embodiment, the sampling rate is in the range of
15,000 to
25,000 samples per second. An additional analog-to-digital convertor (not
shown) may
convert the analog voltage or current output to a digital format, and provide
the digital format
to processor 122.
[0072] Alternatively, the output of the impact level sensor may be a digital
output that
represents the level of impact detected in a digital format (e.g. using a
binary code). The
impact level sensor may update the digital output at a predefined number of
times per second,
which may range from 15,000 to 25,000 times per second.
[0073] However, due to the sampling required to detect sudden and transient
impacts or
changes in motion, an impact level sensor may consume more power compared to a
"go/no-
go" sensor. Further, a more powerful or more complicated processing circuit or
processor
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Date Recue/Date Received 2021-02-02
may be required to process the signals from an impact level sensor compared to
a "go/no-go"
sensor, as more signals need to be processed and more processing steps may be
required.
[0074] Processor 122 is configured to receive signals from sensor 120 and
updates, based on
the signals received from sensor 120, the count 140 in memory 128.
Accordingly, the count
140 in memory 128 is indicative of physical impacts experienced by dart 100
with impact
levels exceeding a pre-determined threshold level.
[0075] The pre-determined threshold level of a "go/no-go" sensor is determined
by selection
of a "go/no-go" sensor that is triggered only when the impact level detected
exceeds the
threshold level. Thus, processor 122 is configured to increment count 140 in
response to any
signal from a "go/no-go" sensor.
[0076] On the other hand, the pre-determined threshold level of an impact
level sensor may
be stored in settings 144. Processor 122 increments count 140 when a signal
from an impact
level sensor indicates that a physical impact experienced by dart 100 has an
impact level that
exceeds the pre-determined threshold level, as stored in settings 144.
[0077] Settings 144 may be configured via I/0 interface 124, which provides a
communication link between control circuit 114 and external devices. I/0
interface 124 may
be a wireless communication interface, thereby ensuring that control circuit
114 remains in a
sealed enclosure. Alternatively, I/0 interface 124 may be a wired interface,
and may
optionally have a communication port protected using a removable seal (not
shown).
[0078] Processor 122 may provide an activation signal to activate actuator 126
when count
140 reaches the pre-selected value, as stored in settings 144. Actuator 126
may be
electrically coupled to battery 127, via a switch 125 that operates under
control of processor
122. Switch 125 may receive an activation signal from processor 122. In
response to
receiving the activation signal, switch 125 may connect battery 127 to
actuator 126, thereby
causing actuator 126 to activate dart 100. The activation signal may be an
analog voltage or
current pulse that causes switch 125 to open, thereby allowing current to flow
from battery
13
Date Recue/Date Received 2021-02-02
127 to actuator 126. Alternatively, switch 125 may be controlled using a
digital signal from
processor 122.
[0079] To activate dart 100, actuator 126 may provide a force sufficient to
release sleeve 118
from shear screw 132, thereby causing sleeve 118 to slide towards uphole end
150, engage
locking mechanism 130, and lock in the activated position. As previously
explained, once
locked in the activated position, sleeve 118 is prevented from collapsing.
[0080] In one example embodiment, actuator 126 may include a micro gas
generator. The
force to release sleeve 118 from sear screws 132 may be provided by the micro
gas
generator, thereby causing sleeve 118 to slide towards uphole end 150. The
micro gas
generator may be selected from any number of commercially available micro gas
generators.
As is known to a person skilled in the art, the micro gas generator may
include an initiator
charge and a gas generating composition. The initiator charge ignites the gas
generating
composition upon receiving an electric charge. Battery 127 may provide the
electric charge
to ignite the initiator when switch 125 is opened in response to the
activation signal. The size
and response time (which is typically in the range of 2 to 4 milliseconds) of
the micro gas
generator may be selected so that the micro gas generator is suitable for use
in dart 100.
[0081] In another example embodiment, the actuation force to release sleeve
118 from shear
screws 132 may be provided by an electric actuator, such as a motor, which may
be powered
using a power source, such as a battery.
[0082] In another embodiment, the actuation pressure for actuating sleeve 118
may be
provided by, or result from, a chemical reaction with or without combustion,
or generation of
gases. For example, two or more chemicals may be mixed to generate a gas. In
yet another
embodiment, the force to release sleeve 118 may be provided using hydraulic
pressure, for
example, by allowing fluids to flow into a cavity of dart 100.
[0083] Control circuit 114 may also include a power source, such as a battery
127, to power
the modules of control circuit 114.
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Date Recue/Date Received 2021-02-02
[0084] As illustrated schematically in FIG. 3, sensor 120, I/0 interface 124,
processor 122,
and memory 128 may be mounted to a PCB 312 and thereby connected to one
another. PCB
312, switch 125, and battery 127 (or other suitable power source) may be
physically secured
in cut-out 160 on dart 100. Actuator 126 may be physically secured in cut-out
161 on dart
100. Alternatively, actuator 126 may also be physically secured in cut-out
160.
[0085] PCB 312 may include negative and positive terminals 318, 316 for
connecting the
PCB to battery 127. The terminals of the battery 127 may be connected to wires
317, 319
which are then connected to the terminals 318, 316 of the PCB. The PCB may
route power
from battery 127 to the modules mounted thereon.
[0086] The battery 127 may also be connected, using a wire 310 to actuator
126, and using a
wire 320 to switch 125. Switch 125 may also be connected to actuator 126 using
a wire 311.
Processor 122 may also be connected using switch 125 to a wire 214 to send the
activation
signal.
[0087] Control circuit 114', shown schematically in block diagram form in FIG.
4B,
provides a second example embodiment of control circuit 114. Control circuit
114' may thus
replace control circuit 114. Control circuit 114' includes "go/no-go" sensor
120', a counter
140', a power source, such as battery 127, and an actuator 126. Actuator 126
is electrically
coupled to battery 127 via a switch 125.
[0088] "Go/no-go" sensor 120' is powered by battery 127 and generates an
analog voltage or
current pulse output when a physical impact experienced by dart 100 exceeds a
threshold
level. Counter 140' may be a mechanical or electronic counter that is
configured to
increment its count upon receiving the pulse output from "go/no-go" sensor
120'.
Accordingly, counter 140' increments its count when the physical impact
experienced by dart
100 exceeds the threshold level of "go/no-go" sensor 120'. Counter 140' is
also configured
to provide an output indicative of its count, which may be an electronic
signal or a physical
change (for example, counter 140' may cause a mechanical dial to rotate). In
the case where
counter 140' is an electronic counter, it may also be powered by battery 127.
Date Recue/Date Received 2021-02-02
[0089] Counter 140' may include an input interface 124' to allow counter 140'
to receive a
pre-selected value and counter 140' may actuate actuator 126 when the count
reaches the pre-
selected value. Input interface 124' may be an electronic interface or a
mechanical interface,
such as a push-pin interface or a mechanical dial.
[0090] As illustrated in FIG. 4B, when the count is equal to the value
selected using the input
interface 124', counter 140' triggers actuator 126 by generating an analog
voltage or current
pulse that causes switch 125 to open, thereby allowing current to flow from
battery 127 to
actuator 126. In an alternative embodiment, when the count is equal to the
value selected
using the input interface 124', counter 140'may generate a physical change
that causes
switch 125 to open instead of generating the pulse.
[0091] FIG. 5 shows a schematic view of a well system 500 from a side
elevation view.
Well system 500 may include a wellbore 506 extending therefrom and penetrating
a
subterranean earth formation 508. Well system 500 may also include an oil and
gas rig 502
at the Earth's surface. Rig 502 may include derrick 510 and rig floor 512.
[0092] A completion assembly 520 may be deployed within a lateral portion of
wellbore 506.
Completion assembly 520 includes a well tubing 200 supported by packers 524 or
other
wellbore isolation devices. Fracking fluid can be pumped downhole through
tubing 200 at a
controlled pump / flow rate.
[0093] Packers 524 may seal off an annulus 526 defined between completion
assembly 520
and an inner wall of wellbore 506. Thus, subterranean formation 508 may be
effectively
divided into multiple regions 528 (shown as regions 528a, 528b, and 528c)
which may be
stimulated and produced independently. While only three regions 528a-c are
shown in FIG.
5, any number of regions 528 may be defined or otherwise used in the well
system 500.
[0094] Each region 528 may include one or more sliding sleeves 300 (shown as
sliding
sleeves 300a, 300b, and 300c) arranged in, coupled to, or otherwise forming
integral parts of
tubing 200. Each sliding sleeve 300a-c is movable within tubing 200 to open
one or more
ports 232 (shown as ports 232a, 232b, and 232c) defined in tubing 200. Once
opened, the
16
Date Recue/Date Received 2021-02-02
ports 232a-c allow fluid communication between the annulus 526 and the
interior of tubing
200. Pressurized fracking fluid 518 may then be released to fracture formation
508.
[0095] Each sliding sleeve 300a-c also includes a seat structure 350 (shown as
seat structures
350a, 350b, and 350c). Seat structures 350a-c provide a restriction in tubing
200 for seating
dart 100. The seat structures 350a, 350b, and 350c are placed along tubing
200, with each
seat structure being placed at least 10 meters away from the next seat
structure.
[0096] In order to move a sliding sleeve 300a-c to its open position, and
thereby open the
corresponding ports 232a-c, dart 100 (not shown) may be conveyed into tubing
200. Dart
100 then travels through tubing 200 until dart 100 seats at the seat structure
350a-c of the
selected sliding sleeve 300a-c. Dart 100 may be pumped through tubing 200,
along with
fracking fluids.
[0097] Dart 100 may be conveyed into tubing 200 in the inactive state. Dart
100 activates
prior to reaching the selected sliding sleeve 300a-c and after passing through
the previous
sliding sleeve 300a-c, to thereby seat at that selected sliding sleeve 300a-c.
For example, if
the selected sliding sleeve is 300c, then dart 100 is activated after passing
through sliding
sleeve 300b and prior to reaching sliding sleeve 300c. In another example, if
the selected
sliding sleeve is 300b, then dart 100 activates after passing through sliding
sleeve 300a and
prior to reaching sliding sleeve 300b. In yet another example, if the selected
sliding sleeve is
300a (i.e. the first sliding sleeve 300), then dart 100 may be conveyed into
tubing 200 in the
activated state.
[0098] Once conveyed into tubing 200, dart 100 travels at a speed in the range
of 2.5-12 m/s.
At such a speed, the dart 100 can travel 10 meters in about 0.8 to about 4
seconds.
Conveniently, the time required to activate dart 100 may be in the range of 2
to 4
milliseconds. As can be understood by those skilled in the art, 10 m is a
typical distance
between two adjacent downhole tools, such as seat structures 350.
17
Date Recue/Date Received 2021-02-02
[0099] The speed of dart 100 may be controlled by controlling the flow / pump
rate of the
fracking fluids. In one example, the flow rate is set to be in the range of 2
to 8 m3 per
minute.
[00100] When dart 100 travels through tubing 200 at the above-noted
speeds, dart 100
is configured to experience a physical impact having an impact level exceeding
the threshold
level of sensor 120 when passing through each one of seat structures 350 in
the inactive state.
Thus, sensor 120 detects an impact each time dart 100 is impacted when
contacting a seat
structure 350 in the inactive state with an impact level exceeding the
threshold level, and
generates a signal. In response to the signal, processor 122 increments count
140 (or counter
140' increments its count). Accordingly, the count indicates the number of
physical impacts
experienced by dart 100 that exceeds the threshold level (which may be
indicative of the seat
structures 350 that dart 100 has travelled through).
[00101] As dart 100 travels through tubing 200, dart 100 may also
experiences other
impacts. For example, impacts with the walls of tubing 200 or other structures
in tubing 200.
The threshold level of physical impact for incrementing count 140 is therefore
set to be
substantially higher than the floor level. In one embodiment, the threshold
level of shock
may be 4 times greater than the floor level.
[00102] In one example embodiment, the floor level may be 200 G, the
threshold level
of shock may be 500 G, and surface structure 110 may be configured such that
dart 100
experiences a physical impact having an impact level of 800 G when passing
through seat
structures 350 in tubing 200.
[00103] However, the level of physical impact experienced by dart 100
may vary
based on any one of the following factors: the speed at which dart 100 is
conveyed through
tubing 200, the flow / pump rate of the fracking fluids, the weight of dart
100, the materials
used to make fingers 115, the number of fingers 115, the thickness of fingers
115
(particularly at the point of attachment to sleeve 118), the shape of terminal
tips 116, the
angle and shape of seat structures 350, amongst others. Accordingly, in
different
18
Date Recue/Date Received 2021-02-02
embodiments, the threshold level of shock may be set in dependence on more
than one
factor.
[00104] In one example embodiment, sensor 120 may be configured to
detect the force
of impact on dart 100 in only one direction, and particularly, along the
longitudinal axis of
dart 100 and tubing 200 (axis /, as shown in FIGS. 12-15). The impact of dart
100 with seat
structures 350 may result in a force direction predominantly along the
longitudinal axis of
dart 100. Accordingly, a sensor configured to detect the force of impact in
only one direction
is less likely to detect other impacts, and therefore less prone to false
positive signals.
[00105] Accordingly, dart 100 is configured to experience a level of
impact that
exceeds the threshold level upon impact with a seat structure 350 and to
experience levels of
impact that are significantly lower than the threshold level upon impact with
other structures
in tubing 200. Since count 140 is not incremented unless the impact level is
greater than the
threshold level of impact, such other impacts will not be counted, and can be
avoided.
[00106] FIGS. 6-9 are examples of well tubing 200, sleeve 300, and seat
structure 350
in more detail.
[00107] FIG. 6 shows in isolation a section of an example well tubing
200 for use with
well system 500. Each section of tubing 200 may have an outer housing 210, one
or more
ports 232, and upper and lower connection elements 222, 220 to connect
multiple sections of
tubing to form well tubing 200.
[00108] The section of well tubing 200 may also have pins 226 which
extend inwardly
from outer housing 210 to engage with sleeve 300. Pins 226 may be partially
threaded so
that the pin 226 can be secured to bore holes in tubing 200. In one example,
pins 226 have
an upper threaded portion and a lower unthreaded shaft.
[00109] The section of well tubing 200 may also have shear pins 228
which extend
inwardly from outer housing 210 to engage with sleeve 300. Pins 228 may be
partially
threaded so that the pin 228 can threadly engage internal threads in pin holes
227. In one
example, pins 228 have an upper threaded portion and a lower unthreaded shaft.
19
Date Recue/Date Received 2021-02-02
[00110] As can be seen in FIGS. 8 and 9, tubing 200 also has an internal
groove 242,
the function of which will be discussed below.
[00111] A slidable sleeve 300, as shown in isolation in FIG. 7, may be
mounted inside
internal bore 202 of tubing 200 (as shown in FIG. 8) to selectively block
ports 232 of an
interval 528a-c. Sleeve 300 may be slid into tubing 200 to open ports 232 (as
shown in
FIG. 9).
[00112] Sleeve 300 may have one or more longitudinal slots 328 in an
outer surface
thereof, each to receive a pin 226 of tubing 200. In one example, the lower
unthreaded shaft
of a pin 226 engages a longitudinal slot 328. The movement of the sleeve 300
is thereby
limited by the pins 226, as pins 226 collide with the sides of the
longitudinal slots 328. Pins
226 may therefore guide the movement of sleeve 300 along the length of tubing
200. Pins
226 may also prevent sleeve 300 from rotating / spinning inside tubing 200.
[00113] Sleeve 300 may also have counterbores 327. Shear pins 228 may be
positioned in pin holes 227 in tubing 200 and in counterbores 327 in sleeve
300 so as to
retain sleeve 300. Shear pins 228 may break when a sufficient pressure is
applied on sleeve
300 by dart 100, thereby allowing sleeve 300 to slide open.
[00114] Sleeve 300 may have an annular groove 342 around the outer
surface of the
sleeve. A C-ring 340 may be attached to annular groove 342. C-ring 340 may be
made of a
metal, such as steel. C-ring 340 may be sized and configured to fit around
annular groove
342 but in its natural state protrudes above the external surface of sleeve
300. C-ring 340 is
resilient and can be compressed inward to fit within groove 342, so that when
sleeve 300 is
inserted into tubing 200 with C-ring 340 mounted thereon, C-ring 340 pushes
against the
inner wall of tubing 200 but allows sleeve 300 to slide within tubing 200
before sleeve 300
reaches the position where groove 342 is aligned with internal groove 242 on
tubing 200 (this
position is referred to herein as the open position as when sleeve 300 is at
this position ports
232 are "open"). When sleeve 300 is moved to the open position, the space
provided by
groove 242 allows C-ring 340 to spring back to its natural state and protrude
above groove
342, therefore functioning as a stopper for locking sleeve in the open
position. Thus, once
Date Recue/Date Received 2021-02-02
sleeve 300 is in the open position, C-ring 340 can engage both groove 342 and
groove 242 in
the inner wall of tubing 200 to secure sleeve 300 in the open position (FIG.
9).
[00115] Sleeve 300 also includes a seat structure 350 (FIGS. 8-9)
mounted therein.
Seat structure 350 may have a wall 314 that defines an inner opening through
which dart 100
may pass through when in the inactive state but cannot pass through when in
the activated
state. In the inactive state, protrusions 111 of fingers 115 can contact wall
314 and cause dart
100 to experience an impact exceeding the threshold level. Terminal tips 116
of fingers 115
however can bend by the force of the impact, thus allowing dart 100 to pass
through seat
structure 350. However, the inner opening of the seat structure 350 is sized
and shaped so as
to prevent dart 100 from passing through if terminal tips 116 of fingers 115
cannot bend
inwardly towards the housing wall. Thus, when in the activated state (i.e.
when fingers 115
are non-collapsible), dart 100 will engage and seat at seat structure 350. In
effect, seat
structure 350 provides a narrow inner opening through which dart 100 is
allowed to pass
through only when dart 100 is in the inactive state.
[00116] Wall 314 and inner opening of seat structure 350 may also be
shaped to
interact with terminal tips 116 to cause dart 100 to experience a physical
impact having an
impact level exceeding the threshold level when passing through.
[00117] FIG. 10 shows a flow-chart of a method 1200 for using dart 100
in the
operation of a multi-interval wellbore, such as wellbore 506 of well system
500 (FIG. 5).
[00118] At 1206, operational parameters of dart 100 are configured.
Example
operational parameters that may be configured include the threshold level of
sensor 120 and
the count at which dart 100 is activated. In one example, one of multiple
sliding sleeves 300
is selected for actuation and dart 100 is configured to target the selected
sliding sleeve 300
for actuation. In one embodiment, the downhole most sliding sleeve 300c is
selected for
actuation first followed by the next downhole-most sliding sleeve 300b, until
the uphole-
most sliding sleeve 300a is reached. In this regard, processor 122 / counter
140' receives a
pre-selected value corresponding to a number of impacts exceeding a threshold
level which
dart 100 is configured to detect prior to activation. For example, in the
depicted
21
Date Recue/Date Received 2021-02-02
configuration shown in FIGS. 11A-11C, to target sliding sleeve 300c, the pre-
selected value
may be set to 2, because dart 100 needs to pass through two (2) uphole sleeves
300a and
300b before reaching sleeve 300c.
[00119] Processor 122 (FIG. 4A) may receive the pre-selected value via
1/0 interface
124, and the value may be stored in settings 144. Similarly, counter 140'
(FIG. 4B) may
receive the pre-selected value via input interface 124'.
[00120] Optionally, at 1206, the threshold level of sensor 120 may also
be set and
stored in settings 144.
[00121] Once the operational parameters are configured, dart 100 is
released into well
tubing 200, which may be filled with a fracking fluid, at 1208, to actuate the
selected sliding
sleeve 300. For example, to actuate sliding sleeve 300c, once released, dart
100 travels
through well tubing 200 through sliding sleeve 300a and seat structure 350a
(FIG. 11A),
through sliding sleeve 300b and seat structure 350b (FIG. 11B) until it
reaches sliding sleeve
300c and seat structure 350c (FIG. 11C). The fracking fluid in well tubing 200
interacts with
foil 156 (FIG. 1) to generate a force which propels dart 100 forward through
well tubing 200.
[00122] As dart 100 travels within well tubing 200, dart 100 performs
the steps of
method 400. Method 400 illustrates an example method for activating dart 100
as it travels
through tubing 200. Steps of method 400 may be performed by processor 122 of
control
circuit 114 of FIG. 4A or by control circuit 114' of FIG. 4B.
[00123] As dart 100 travels within well tubing 200, dart 100 will
experience varying
levels of physical impacts, such as shocks (for example, due to changes in
fluid pressure, due
to contact with the inner walls of well tubing 200 or other structures in the
well tubing 200,
due to contact of terminal tips 116 with seat structures 350 within well
tubing 200, and so
forth). When dart 100 contacts internal components in tubing 200, the impact
may be
detected by sensor 120.
[00124] When method 400 is implemented by control circuit 114 (FIG. 4A),
after an
impact, at 404, processor 122 receives a signal from sensor 120. If sensor 120
is an impact
22
Date Recue/Date Received 2021-02-02
level sensor, in response to receiving the signal from sensor 120, processor
122 determines,
at 406, if the level of impact detected is greater than or equal to the
threshold impact level. If
so, the impact count is incremented at 408. On the other hand, when sensor 120
is a "go/no-
go" sensor, processor 122 increments the count at 408 (i.e. skipping 406) in
response to
receiving each signal from sensor 120, as "go/no-go" sensor only provides a
signal when the
level of impact is greater than or equal to the threshold impact level. At
410, processor 122
determines if the count is equal to the pre-selected value corresponding to
the number of
impacts exceeding the threshold level which dart 100 is configured to detect
prior to
activation. If so, processor 122 triggers actuator 126 at 412, thereby
activating dart 100. If
not, method 400 returns to 404.
[00125] When method 400 is implemented by control circuit 114' (FIG.
4B), after an
impact, at 404, counter 140' receives a signal from "go/no-go" sensor 120' and
increments
the count at 408 (i.e. skipping 406) in response to receiving the signal from
sensor 120'. At
410, if the count is equal to the pre-selected value, method 400 proceeds to
410, and control
circuit 114' triggers actuator 126, thereby activating dart 100. If not,
method 400 returns to
404.
[00126] In one embodiment, triggering actuator 126 causes sleeve 118 to
slide towards
uphole end of dart 100, thereby locking sleeve 118 in the activated position.
In the activated
position, fingers 115 engage locking mechanism 130 which supports sleeve 118
in a
protruded position, and can no longer bend inward so dart 100 cannot pass
through the seat
structure in the next target sleeve 300c.
[00127] Before dart 100 contacts seat structure 350a (FIG. 11A), the
impact count is
initially set to 0 and dart 100 is in the inactive state and will pass through
seat structure 350a.
The contact with seat structure 350a will produce a physical impact that
exceeds the pre-
selected threshold impact level, thus sensor 120 detects the impact and
provides a signal to
processor 122 or counter 140', and the processor 122 / counter 140' in
response increments
the impact count 140 from 0 to 1. As 1 is less than 2, the dart 100 is still
in the inactive state
when it contacts seat structure 350b (FIG. 11B), so dart 100 can also pass
through seat
23
Date Recue/Date Received 2021-02-02
structure 350b. The impact caused by dart 100 contacting seat structure 350b
will exceed the
threshold level so the impact count is incremented from 1 to 2. At this point,
dart 100 is
activated. Impacts with seat structure 350a and with seat structure 350b may
cause dart 100
to slow down.
[00128] As can be appreciated by those skilled in art. terminal tips 116
of fingers 115
are squeezed upon impact with seat structure 350a and with seat structure 350b
(FIG. 13),
and can bend inward as they are not supported and there is a gap between the
terminal tips
116 and the housing 117, thereby permitting dart 100 to pass through seat
structures 350a,
350b. A component of the force of impact of terminal tips 116 with seat
structure 350 is
along the longitudinal axis of dart 100 and tubing 200 (axis /). Since
terminal tips 116 are
allowed to bend inward generally along the radial direction of dart 100 and
tubing 200 (axis
r), a component of the force in the radial direction causes terminal tips 116
to bend towards
external surface 112 of housing 117. Such bending provides the needed
clearance for dart
100 to continue traveling within tubing 200 in the inactive state (see FIGS.
12 and 13).
[00129] As noted, after the impact count 140 reaches the selected
threshold value, "2"
in the depicted example, dart 100 is activated. That is, dart 100 is activated
after passing
through sleeve 300b so that dart 100 reaches sleeve 300c in the activated
state (FIG. 11C).
[00130] Since terminal tips 116 are prevented from bending inward in the
activated
state, dart 100 cannot pass through and will seat at the selected seat
structure 350c (see FIGS.
11C and FIG. 14). As better illustrated in FIG. 14, terminal tips 116 are
supported in the
protruded position by sliding sleeve 118 to uphole end 150 of dart 100 and
locking sleeve
118 in that position. Sleeve 118 is moved into the locked position by actuator
126, which is
in turn triggered by the controller such as control circuit 114 when the
impact count reaches
the threshold value of 2.
[00131] Returning to method 1200, once seated, dart 100 may be used to
actuate and
slide the selected sleeve 350c to the open position at 1210 (FIG. 15). Foil
156 interacts with
the walls of tubing 200 to create a seal which at least partially blocks fluid
from flowing
around the housing 117 when dart 100 is seated and increases the fluid
pressure at uphole end
24
Date Recue/Date Received 2021-02-02
150. In some embodiments, foil 156 may be made of flexible material, such as a
rubber,
which allows foil 156 to bend towards the inner walls of tubing 200 in
response to increased
fluid pressure, thereby creating a tighter seal with the inner walls of tubing
200.
Furthermore, dart 100 may have seals attached to ridge structures 162 to
improve the seal.
[00132] In an embodiment, the force of impact produced by the dart 100
on contact
with the seat structure 350c and the increased fluid pressure due to the seal
created by foil
156 together may be sufficient to cause the sleeve 300c to slide to the open
position, thus
opening ports 232 (for example, by breaking shear pins 228 shown in FIG. 6).
[00133] In other embodiments, a ball 136 may be conveyed through tubing
200 to
contact the dart 100 thereby generating the needed force for opening the
sleeve 300c. When
ball 136 reaches dart 100, dart 100 receives and retains ball 136 at the
receptacle 166. Ball
136 may be retained by receptacle 166 because the fluid pressure and fluid
flow may exert a
force pushing ball 136 into and against receptacle 166. Ball 136 once seated
in the receptacle
166 can block fluid flow through fluid conduit 138, thereby causing an
increase in fluid
pressure which, along with the increased pressure created by foil 156, may
cause sleeve 300c
to slide to the open position. In some cases, the impact generated the ball
136 contacting dart
100 may be sufficient for actuating the sleeve 300c.
[00134] In other embodiments, ball 136 may be attached to dart 100 when
the dart 100
is released into the tubing 200, and travel with dart 100 through tubing 200.
Once seated at
seat 350c, the resulting increased fluid pressure then causes sleeve 300c to
slide to the open
position.
[00135] At 1212, the region 528c corresponding to the selected sleeve
300c may be
stimulated. Stimulation of the interval may include pumping fracking fluid 518
at a high
pressure through the open ports of that interval to fracture the rock
formation 508 (FIGS.
11D and 15).
[00136] At 1214, it is determined whether another region from the
regions 528a-c is to
be stimulated. If so, at 1216, the previous region is plugged (i.e. region
528c). The region
Date Recue/Date Received 2021-02-02
528c may be plugged by conveying ball 136 to dart 100 at sleeve 300c, thereby
plugging
fluid conduit 138 of dart 100. Step 1216 may be skipped if ball 136 is
attached to dart 100
and travels with dart 100 through tubing 200.
[00137] Method 1200 then proceeds to 1206, where a new dart 100 is
configured and
released into wellbore 506 to open ports 232 associated with region 528b.
Method 1200 may
be repeated once more to target region 528a. As shown in FIG. 11E, once
regions 528a-528c
are stimulated, darts 100a-100c and balls 136a-136c remain seated at seats
350a-350c due to
protrusions 111a-111b of the darts being supported and unbendable.
[00138] Downhole operations may therefore be conducted in stages by
conveying
successive pre-configured darts 100, each targeting a sleeve 300 at a
different region 528.
After all regions 528a-528c are stimulated, darts 100a-100c and balls 136a-
136c may be
removed at 1217 to allow for the hydrocarbon extraction process to commence at
1218.
[00139] To allow for easy removal of the darts 100a-100c, the housing of
darts 100a-
100c may be made of a material that degrades or dissolves upon contact with
dissolving
fluids. Examples of such materials include magnesium-based alloys and aluminum-
based
alloys. Thus, after stimulating regions 528a-528c, dissolving fluids may be
pumped down
tubing 200 to dissolve darts 100a-100c.
[00140] Alternatively, housing 117 may be made of drillable material,
such as ductile
iron of grade 80-55-06. After stimulating regions 528a-528c, a drill may be
used to drill
through darts 100a-100c.
[00141] Alternatively, darts 100a-100c and balls 136a-136c may be pumped
up to the
surface along with a fluid. Balls 136a-136c may become detached from darts
100a-100c and
flow up separately from the darts. Protruding members 154 at the downhole end
of each dart
prevent the balls from blocking the flow of fluids. For example, while ball
136c may detach
from dart 100c and seat at protruding members 154b of dart 100b, fluid can
still flow through
the sides of dart 100b, 100c.
26
Date Recue/Date Received 2021-02-02
[00142] Dart 100 therefore includes a sensor 120 for detecting a level
of shock
experienced by the dart as it travels through the well tubing. When inactive,
dart 100 impacts
seat structures 350 in well tubing 200, and upon impact with each seat
structure 350
experiences an impact having a level of impact exceeding a threshold level.
Sensor 120
provides a signal indicating that dart 100 has experienced an impact having
the level of
impact exceeding a threshold level, thereby causing dart 100 to increment a
count of the
number of seat structures 350 it has traversed. Once dart 100 determines that
it has traversed
a pre-selected number of seat structures 350, dart 100 is activated. Once
activated, dart 350
can no longer pass through seat structures 350 in well tubing 200, and seats
at the next seat
structure 350 it encounters.
[00143] Count 140 is not incremented unless the dart experiences an
impact level
exceeding a threshold level. To avoid incrementing count 140 unless dart 100
has impacted a
seat structure 350, the threshold level of impact for incrementing count 140
may be
maintained at a higher level than the level of impact between the dart and
other structures in
the tubing. Thus, false positives may be avoided.
[00144] Dart 100 also does not rely on detecting any external stimuli;
sensor 120
measures the movement of dart 100 as it travels within the tubing. In
contrast, a sensor that
is responsive to an external stimuli within tubing 200 or to control signals
from rig 502 may
fail to detect the external stimuli or control signals due to the fast pace of
movement of the
dart and the harsh environmental conditions in tubing 200. Thus, sensor 120 is
less prone to
failure of detecting that dart 100 has traversed a seat structure 350 within
tubing 200.
[00145] Dart 100 also operates autonomously without communicating with
other
devices as it travels through tubing 200. For example, dart 100 does not
require control
signals from external devices while dart 100 is in tubing 200. Communication
with other
devices may be unpredictable due to the harsh environmental conditions in the
tubing. Thus,
by operating autonomously, dart 100 eliminates the point of failure associated
with
communicating with external devices and may be more reliable.
27
Date Recue/Date Received 2021-02-02
[00146] The structure of dart 100 may be modified in various
embodiments. Dart 100
has a protrusion 111 on a surface structure thereof which impacts a
restriction in tubing 200.
Different techniques may be used to configure dart 100 to experience an impact
having an
impact level that exceeds the threshold level. Protrusion 111 is further
configured to collapse
upon impact with the restriction when dart 100 is inactive, thereby allowing
dart 100 to pass
through the restriction in tubing 200. Different techniques may be used to
collapse
protrusion 111 upon impact with the restriction in tubing 200 when dart 100 is
inactive.
[00147] Protrusion 111 is further configured to remain in a protruding
position upon
impact when dart 100 is activated, thereby causing dart 100 to seat at the
restriction and to
actuate a tool at the restriction. Different techniques may be used to support
protrusion 111
in a protruding position upon impact with the restriction in tubing 200 when
dart 100 is
activated.
[00148] In one example embodiment, housing 117 of dart 100 may have a
diameter in
the range of 6 to 12 centimeters, a length in the range of 30 to 40
centimeters, and a weight in
the range of 3 to 7 kg. In one embodiment, fluid conduit 138 may have a
diameter of 2 to 5
centimeters near uphole end 150. In one embodiment, fluid conduit 138 may be
wider at
downhole end 152 than at uphole end 150. In one embodiment, cut-out 160 is
approximately
to 8 centimeters long, 2 to 3 centimeters wide, and 1 to 2 centimeters in
thickness.
[00149] In one embodiment, each finger 115 may be 1 to 3 centimeters
wide and 5 to 8
centimeters long. In example embodiments, the number of fingers 115 may range
from 8 to
fingers. The number of fingers 115 chosen may vary in dependence on the
diameter of
housing 115 and the width of each finger.
[00150] In some embodiments, the controller such as control circuit 114
may be
configured to monitor the physical impacts experienced by the dart 100, and
activate the
surface structure 110 when the monitored physical impacts indicate that the
dart 100 is next
reaching the target seat structure in the target sleeve or target tool. For
example, in selected
embodiments, each seat structure 350 may be configured to generate one or more
physical
impacts with an identifiable impact profile when the dart 100 passes through
the seat
28
Date Recue/Date Received 2021-02-02
structure 350. The control circuit 114 may be configured to monitor the
position of the dart
100 in the well tubing 200 based on the impact profiles of the seat structures
350 already
passed by the dart 100 and determine if the dart 100 is next reaching the
target seat structure
based on the position of the dart 100.
[00151] In some embodiments, the impact profile of each seat structure
350 may
comprise two or more peaks exceeding the threshold level. For example, the
wall 314 and
inner opening of a seat structure 350 may be shaped to provide two or more
separate but
closely adjacent restriction points (impact points) which interact with
terminal tips 116 of the
dart 100 to cause dart 100 to experience two separate physical impacts each
having an impact
level exceeding the threshold level when passing through. If all of the seat
structures 350
have the same number of restriction points (thus same number of impact peaks
in the impact
profiles), the control circuit 114 may determine the number of seat structures
passed by the
dart 100 by dividing the total number of detected physical impacts exceeding
the threshold
level by the known number of restriction points. As can be appreciated by
those skilled in the
art, when the seat structures 350 produce two or more impact peaks exceeding
the threshold
level within a short time period, it helps to identify the passing of the seat
structure and
reduce the possibility of false positive, thus improving the accuracy of the
count or
identification of the seat structures 350 that have been passed by the dart
100. In this case,
the control circuit 114 can increment the count of passed seat structures or
physical impacts
only when there are a pre-determined number of consecutive physical impacts
exceeding the
threshold level within a selected time interval and increment the count by
only one for the
predetermined number of consecutive physical impacts. For example, if each
seat structure
350 generates 2 physical impact peaks over the threshold level, the seat count
may be
incremented by only one for every two physical impacts detected by the sensor
114.
[00152] For example, an integrated sleeve-seat structure 350' mounted in
a well tubing
200' is illustrated in FIGS. 16A and 16B, where the integrated sleeve-seat
structure 350' is at
the closed position in FIG. 16A and at the open position in FIG. 16B. Tubing
200' is similar
to tubing 200 as described above. Integrated sleeve-seat structure 350' is
similar to sleeve
300 with seat structure 350 except the differences discussed next. Instead of
providing one
29
Date Recue/Date Received 2021-02-02
restriction (impact point) as with seat structure 350 in sleeve 300, the
tubular wall 314' of the
integrated sleeve-seat structure 350' is configured to provide two impact
points 352 and 354.
In the depicted example, the first impact point 352 may be sized and shaped as
the impact
point in the seat structure 350 as illustrated in FIGS. 8 and 9, and the
second impact point
354 is provided by an enlarged section 356 in the inner opening of the
integrated sleeve-seat
structure 350'. As can be understood, when the dart 100 is not activated, it
can pass through
the first impact point 352 and will experience an impact upon contacting the
wall 314' at
impact point 352. The terminal tips 116 of fingers 115 of the dart 100 however
can
subsequently expand in the enlarged section 356 and thus the dart 100 will
experience
another physical impact when contacting the second impact point 354. The
impact level or
profile of the impact at the second impact point 354 may be adjusted by
changing the size of
the inner opening at the impact point 354, or the length and size (inner
diameter) of the
enlarged section 356, or any combination of these features. When the dart 100
is activated
before reaching the seat structure 350', it will seat in the seat structure
350' at the first impact
point 352.
[00153] In different embodiments, the two impact points 352 and 354 may
be sized to
provide different physical impacts with different impact levels or
characteristics. For
example, the first impact point 352 may provide a slightly lower or higher
physical impact
than the second impact point 354. The seat structure 350' may also be
configured to seat the
dart 100 at the second impact point 354 when the dart 100 is activated.
[00154] Thus, the integrated sleeve-seat structure 350' may be sized and
shaped to
interact with terminal tips 116 of the dart 100 to cause dart 100 to
experience two physical
impacts each having an impact level exceeding the threshold level when passing
through.
[00155] FIG. 17 illustrates another embodiment of an integrated sleeve-
seat structure
350" with three impact points 360, 362, 364, and two enlarged sections 366,
368. Integrated
sleeve-seat structure 350" is similar to sleeve-seat structure 350' but with
an additional
impact point, thus providing a different impact profile. In alternative
embodiments, a seat
structure may have more than three impact points.
Date Recue/Date Received 2021-02-02
[00156] In some embodiments, each seat structure 350, 350', 350" may be
configured
to have a unique identifiable impact profile and different seat structures
350, 350', 350" may
have different impact profiles, so that the seat structure just passed by the
dart 100 can be
identified by the controller such as control circuit 114 based on the impact
profile of the seat
structure. For example, the impact profile of each seat structure may have a
different number
of impact peaks, such as 2, 3, 4, 5, ... and so on. By determining the number
of impact peaks
in the impact profile, the controller can determine the particular seat
structure just passed by
the dart 100 and thus the position of the dart 100 in the well tubing 200, and
its relative
position to the target seat structure 350. As can be appreciated, it is not
necessary to
determine the precise location of the dart 100 in the well tubing 350; it
would be sufficient to
know that the dart 100 is at a position to reach the target seat structure
next (i.e. there is no
other seat structure downstream of the dart 100 between the dart 100 and the
target seat
structure) before activating the surface structure 110 of dart 100.
[00157] In other words, each seat structure 350 may be configured to
produce a
signature impact profile and can be identified based on the signature impact
profile. When
the seat structures 350 have uniquely identifiable or signature impact
profiles, it is not
necessary to count the number of physical impacts. Instead, the controller
such as control
circuit 114 may process and analyze the signals received from the sensor 120
to determine if
the monitored physical impacts have impact profiles, such as certain impact
characteristics or
features, that match impact profiles of the seat structures 350 of interests
such as the seat
structure 350 that is just before the target seat structure 350. When there is
a match, it can be
determined that the dart 100 has just passed the corresponding seat structure.
[00158] The impact profiles or data representative of the impact
profiles of the seat
structures 350 may be pre-stored stored in a memory on the dart 100. The
impact profile
may be a full profile indicating the time dependence of the impact level over
a time period.
The impact profile may also be represented by data indicative of the
characteristics of the
physical impact, such as the peak amplitude, the time interval between
adjacent peaks, and
other features and characteristics of the physical impact as discussed
elsewhere in this
disclosure or can be understood by those skilled in the art.
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Date Recue/Date Received 2021-02-02
[00159] An integrated sleeve-seat structure such as the examples
illustrated herein can
also be sized to provide an inner passage channel that has a similar size or
diameter to the
inner diameter of the well tubing such as tubing 200 or 200', as illustrated
in FIGS. 8, 9, and
16A-16B. For example, as depicted in the figures, an integrated sleeve-seat
structure may be
configured so that the inner opening in the integrated sleeve-seat structure
may be generally
flush with the inner channel of the well tubing. Conveniently, such a
configuration of the
integrated sleeve-seat structure can reduce the restriction on fluid flow
through the sleeve-
seat structure and the well tubing when the dart 100 is not seated at the seat
structure. In
comparison, a conventional seat such as a ball seat for seating a ball in a
conventional sleeve
in a well tubing typically has an inner fluid path sized much smaller than the
fluid path in the
well tubing, and thus substantially restricts or impedes the fluid flow
through the ball seat
due to the narrower opening at the ball seat.
CONCLUDING REMARKS
[00160] Selected Embodiments of the present invention may be used in a
variety of
fields and applications.
[00161] Other features, modifications, and applications of the
embodiments described
here may be understood by those skilled in the art in view of the disclosure
herein.
[00162] It will be understood that any range of values herein is
intended to specifically
include any intermediate value or sub-range within the given range, and all
such intermediate
values and sub-ranges are individually and specifically disclosed.
[00163] The word "include" or its variations such as "includes" or
"including" will be
understood to imply the inclusion of a stated integer or groups of integers
but not the
exclusion of any other integer or group of integers.
[00164] It will also be understood that the word "a" or "an" is intended
to mean "one
or more" or "at least one", and any singular form is intended to include
plurals herein.
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Date Recue/Date Received 2021-02-02
[00165] It will be further understood that the term "comprise",
including any variation
thereof, is intended to be open-ended and means "include, but not limited to,"
unless
otherwise specifically indicated to the contrary.
[00166] When a list of items is given herein with an "or" before the
last item, any one
of the listed items or any suitable combination of two or more of the listed
items may be
selected and used.
[00167] Of course, the above described embodiments of the present
disclosure are
intended to be illustrative only and in no way limiting. The described
embodiments are
susceptible to many modifications of form, arrangement of parts, details and
order of
operation. The invention, rather, is intended to encompass all such
modification within its
scope, as defined by the claims.
33
Date Recue/Date Received 2021-02-02
