Patent Description:
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.

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.

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 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. <CIT>, entitled "Indexing Dart System and Method for Wellbore Fluid Treatment," discloses a wellbore dart comprising a body conveyable through a tubing string, the body defining a central flow bore to allow circulation of fluid from a tool through the wellbore dart; an internal valve to seal the central flow bore; a valve actuator; a collapsible annular protrusion; and a control mechanism configured to register a dart seat count responsive to dart seat contact and switch the dart between a run in configuration and landing configuration responsive to registering a target number of counts.

In accordance with an aspect of the present disclosure, there is provided an actuation device according to claim <NUM>.

In one embodiment, the sensor comprises a shock sensor. In another embodiment, the sensor is an accelerometer.

In another aspect of the present disclosure, there is provided a method according to claim <NUM>.

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.

In the figures, which illustrate, by way of example only, embodiments of the present disclosure,.

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 seating 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 seating 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.

<FIG> and <FIG> show schematically an actuation dart <NUM>, according to an example embodiment of the actuation device. Dart <NUM> has two states, an inactive state as illustrated in <FIG> and an activated state as illustrated in <FIG>.

Dart <NUM> has a housing <NUM> defining an external surface <NUM> and having an uphole end <NUM> and a downhole end <NUM>. Housing <NUM> may have an elongate, cylindrical shape.

Housing <NUM> may define a fluid conduit <NUM>. Fluid conduit <NUM> may be a cylindrical conduit that passes through the center of housing <NUM>. Fluid conduit <NUM> allows fluid to flow through housing <NUM> to avoid fluid pressure from building up when dart <NUM> is deployed.

Fluid conduit <NUM> may also have one or more protruding members <NUM> at downhole end <NUM>. Protruding members <NUM> extend longitudinally past the end of fluid conduit <NUM>, so that fluid can flow through the sides of dart <NUM>. Thus, should the downhole end <NUM> of dart <NUM> be blocked, fluid can still flow through the sides of dart <NUM>.

Housing <NUM> may have a first cut-out <NUM> on a surface thereof. Cut-out <NUM> mayhouse a controller such as control circuit <NUM> (<FIG>, and <FIG>). Cut-out <NUM> may be filled with a waterproof and thermally insulating material to encase control circuit <NUM>, such as a rubber, a waterproof resin, or an epoxy material. The waterproof and thermally insulating material may protect control circuit <NUM> from the harsh environment within the wellbore through which dart <NUM> is placed.

Housing <NUM> may also have a second cut-out <NUM> on a second surface thereof. Second cut-out <NUM> may house one or more elements of the control circuit <NUM>. In one example, cut-out <NUM> houses an actuator <NUM> (<FIG>, and <FIG>). Cut-out <NUM> may also be filled with a waterproof and thermally insulating material to encase those elements of control circuit <NUM>, such as a rubber, a waterproof resin, or an epoxy material.

As illustrated schematically in <FIG>, actuator <NUM> may be connected using wires <NUM>, <NUM> to one or more elements of control circuit <NUM> housed within cut-out <NUM>.

Housing <NUM> may have a number of grooves <NUM> for retaining seals (not shown) in between the surface <NUM> of housing <NUM> and surface structure <NUM>. The seals may be retained due to the pressure and friction between housing <NUM> and surface structure <NUM>. The seals may further protect control circuit <NUM> from the harsh environmental conditions which dart <NUM> 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 O-rings or D-shaped seals.

In one example embodiment, the waterproof and thermally insulating material and the seals work together to keep control circuit <NUM> dry and at a suitable operating temperature, for example, less than <NUM> ° C.

Housing <NUM> may have a ridge <NUM> for retaining a foil <NUM>. Foil <NUM> has a first end attached to housing <NUM>, in proximity to downhole end <NUM>. The first end may be glued to housing <NUM>, or alternatively may be moulded in place. Foil <NUM> also has an unsecured second end, which extends outwardly from housing <NUM>. In one example, foil <NUM> is angled such that the second end of foil <NUM> points towards uphole end <NUM>. In one example, foil <NUM> is annular in shape, extending around housing <NUM>. Foil <NUM> may be made of soft rubber material suitable for use with fracking fluids, such as Viton™, hydrogenated nitrile butadiene rubber (HNBR), or a nitrile rubber (NBR). In one example embodiment, foil <NUM> may be slightly larger in diameter than housing <NUM>.

Dart <NUM> has a surface structure <NUM> on external surface <NUM> of housing <NUM>. Surface structure <NUM> may include a movable structure that is moveable on the external surface, such as a sleeve <NUM> as depicted, which is movably mounted on the external surface <NUM> of housing <NUM> and surrounds a portion of external surface <NUM>. One or more fingers <NUM> may be provided and extend longitudinally from an end of sleeve <NUM>. Sleeve <NUM> may be made from the same material used to make housing <NUM>, although a different material may be used.

Each finger <NUM> may have a bendable terminal tip <NUM> and a protrusion <NUM> extending therefrom to expand the diameter of dart <NUM>. Each finger <NUM> has an edge <NUM> at an end thereof.

In an initial position (<FIG>), fingers <NUM> may be cantilevered from the end of sleeve <NUM> to project around and above external surface <NUM>, leaving a gap between terminal tips <NUM> and external surface <NUM>. Terminal tips <NUM> are thus unsupported by the housing <NUM> in this initial position. Fingers <NUM> may be made of a resilient material so that the terminal tips <NUM> of fingers <NUM> can bend under pressure towards the housing when unsupported, thus allowing dart <NUM> to pass through restrictions in the tubing through which dart <NUM> travels. In this initial position dart <NUM> is in the inactive state so that dart <NUM> can pass through restrictions in the tubing.

Sleeve <NUM> may be slidable from the initial (first) position to a second position where the terminal tips <NUM> are supported by a portion of housing <NUM>, particularly ridge <NUM>, and thus can no longer bend towards the housing surface. Housing <NUM> may also include locking mechanisms to secure sleeve <NUM> in each position. When the sleeve <NUM> is in the second position, it is in the activated state as dart <NUM> can no longer pass through a selected seat, as will be further discussed below.

To lock the sleeve <NUM> in the initial position, sleeve <NUM> may include a bore <NUM>' and housing <NUM> may include a corresponding counterbore <NUM> at downhole end <NUM> (<FIG>), for receiving a shear screw <NUM> to secure sleeve <NUM> to housing <NUM> at the initial position, corresponding to the inactive state. Shear screw <NUM> may be made of a frangible, breakable material to allow sleeve <NUM> to be released from the initial position to activate dart <NUM>. Shear screw <NUM> may be made of bronze, steel, or hard plastic. Bore <NUM>' and counterbore <NUM> have internal threads and are aligned for receiving and thread engagement with shear screws <NUM> when the sleeve <NUM> is in the initial position.

In some embodiments, a number of shear screws <NUM> may be positioned around the circumference of housing <NUM> to secure sleeve <NUM>. In the embodiment as depicted in the drawings, four shear screws are used to secure sleeve <NUM>. Each shear screw may require a head breaking torque in the range of <NUM> to <NUM>, such as <NUM>, to break or shear off the screw head. In different embodiments, the number and positions of bores <NUM>' and counterbores <NUM> may be varied. Further, the counterbores <NUM> may be replaced with a groove extending along the circumference of housing <NUM>.

With counterbores <NUM>, when shear screws <NUM> are threadably engaged with bores <NUM>' and counterbores <NUM>, sleeve <NUM> is prevented from sliding axially and rotating about its central axis. If the counterbores are replaced with a groove, the sleeve <NUM> is still prevented from sliding axially but may be able to rotate about its axis.

In other embodiments, sleeve <NUM> may be secured in the first position using one or more pins (not shown) or an annular rim (not shown).

Dart <NUM> may also include a locking mechanism <NUM> for locking sleeve <NUM> in the second position, corresponding to the activated state. Locking mechanism <NUM> is positioned in proximity to uphole end <NUM> and includes a ridge <NUM> and a bevelled surface <NUM> that matches the shape of the edge <NUM> of terminal tips <NUM>. Terminal tips <NUM> may have a notch <NUM> that matches the shape of ridge <NUM> and oriented to engage ridge <NUM>. When sleeve <NUM> is in the second position, ridge <NUM> props up the terminal tips <NUM> by abutting notch <NUM> to prevent fingers <NUM> from bending towards the surface <NUM> of the dart <NUM>, and edge <NUM> of the tips <NUM> abuts the bevelled surface <NUM> to prevent fingers <NUM> from bending away from the surface <NUM> (as shown in <FIG>), thus preventing unlocking of the terminal tips <NUM>. Thus, in the activated state, fingers <NUM> are prevented from bending under pressure or on impact, and the surface structure is non-collapsible.

In addition, locking mechanism <NUM> also prevents fingers <NUM> from moving longitudinally. This is because ridge <NUM> blocks the side walls <NUM>, <NUM> of notch <NUM> from moving laterally relative to the surface <NUM>.

Housing <NUM> may include one or more ridge structures <NUM>, which may be used to retain seals (not shown), which seal fluid to one side of a tubing through which dart <NUM> may travel.

Dart <NUM> may also have a removable cap <NUM> at either end thereof. Cap <NUM> may be wider in diameter than housing <NUM>. Cap <NUM> may be removed to slide sleeve <NUM> into position surrounding external surface <NUM> of housing <NUM>. Cap <NUM> is removably fixed at uphole end <NUM> using arms <NUM> which latch onto external surface <NUM>. External surface <NUM> may have grooves <NUM> that correspond to the position of arms <NUM> to provide cap <NUM> with a surface to latch onto.

Cap <NUM> may also include a receptacle <NUM>. Receptacle <NUM> has an enlarged opening, which may be cone-shaped as depicted in the drawings, to receive and retain a ball <NUM>. In one embodiment, the opening has a wider diameter than the diameter of housing <NUM>. Ball <NUM>, when retained in receptacle <NUM>, blocks fluid flow through fluid conduit <NUM>. In some embodiments, receptacle <NUM> may include a retaining clip (not shown), pin (not shown), or other mechanical mechanism to retain ball <NUM>.

Dart <NUM> includes a control circuit <NUM> for activating surface structure <NUM> to seat at a selected seat structure within the wellbore.

A first example embodiment of control circuit <NUM> is schematically shown in block diagram form in <FIG>. Control circuit <NUM> may include a processor <NUM> in communication with an impact sensor <NUM>, actuator <NUM>, I/O interface <NUM>, and memory <NUM>.

Memory <NUM> is a processor-readable medium and stores processor executable instructions, including activation code <NUM> for activating dart <NUM>. When executed, activation code <NUM> may cause processor <NUM> to implement a method <NUM>, as discussed in detail below.

Memory <NUM> also stores variables for use by activation code <NUM>, including a count <NUM> indicating the number of impacts experienced by dart <NUM> within the wellbore that exceeds a threshold level, and settings <NUM> defining operational parameters of dart <NUM> (for example, defining a selection of seat structures for seating).

Impact sensor <NUM> generates a signal in response to an acceleration of dart <NUM> resulting from a physical impact experienced by dart <NUM> as dart <NUM> travels within the wellbore.

Impact sensor <NUM> may be selected from shock sensors, accelerometers, gyroscopes, strain gauge sensors, proximity sensors, piezoelectric sensors, piezo-resistive sensors, capacitive sensors, and acoustic sensors.

An acoustic sensor, such as a microphone, can detect sound or other acoustic waves generated by the physical impact of dart <NUM> contacting a seat structure <NUM>. 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 <NUM> has passed through a seat structure <NUM>. Processor <NUM> may, in some embodiments, analyze the detected acoustic signal to determine whether detected acoustic signal indicates a physical impact between dart <NUM> and the seat structure <NUM>. For example, the amplitude of the detected acoustic signal may be correlated to the level of physical impact experienced by dart <NUM>.

In one example embodiment, more than one sensor (of the same type or of different types) may be used in combination.

In one example embodiment, sensor <NUM> may be configured to measure an impact causing dart <NUM> to experience a gravitational force (g-force) in the range of <NUM> to <NUM>.

In one embodiment, sensor <NUM> may be a SignalQuest™ SQ-ASA series shock sensor, which has a sensitivity range of <NUM> to <NUM> and has a response time of under <NUM> micro seconds. The SignalQuest™ SQ-ASA series shock sensor provides an analog voltage pulse output (in the range of <NUM> to <NUM> Volts) upon detecting a shock that exceeds a threshold level. The SignalQuest™ SQ-ASA series shock sensor is cylindrical in shape and is approximately <NUM> long and <NUM> in diameter and may be coupled to a printed circuit board ('PCB').

The SignalQuest™ SQ-ASA series shock sensor is suitable for operation at temperatures ranging from -<NUM> to +<NUM>. As previously discussed, the operating temperature of the sensor may be maintained at a suitable operating temperature by isolating control circuit <NUM> using a waterproof and thermally insulating material.

In another embodiment, sensor <NUM> may be a Murata™ shock sensor.

Impact sensor <NUM> may be a "go/no-go" sensor which only generates and sends a signal to processor <NUM> 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 <NUM> only when the level of impact exceeds the selected threshold value.

Alternatively, impact sensor <NUM> may be an impact level sensor. An impact level sensor can generate a signal indicating a quantitative level of impact experienced by dart <NUM> over a period of time (i.e. a sampling period).

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 <NUM> 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 <NUM>,<NUM> to <NUM>,<NUM> 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 <NUM>.

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 <NUM>,<NUM> to <NUM>,<NUM> times per second.

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 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.

Processor <NUM> is configured to receive signals from sensor <NUM> and updates, based on the signals received from sensor <NUM>, the count <NUM> in memory <NUM>. Accordingly, the count <NUM> in memory <NUM> is indicative of physical impacts experienced by dart <NUM> with impact levels exceeding a pre-determined threshold level.

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 <NUM> is configured to increment count <NUM> in response to any signal from a "go/no-go" sensor.

On the other hand, the pre-determined threshold level of an impact level sensor may be stored in settings <NUM>. Processor <NUM> increments count <NUM> when a signal from an impact level sensor indicates that a physical impact experienced by dart <NUM> has an impact level that exceeds the pre-determined threshold level, as stored in settings <NUM>.

Settings <NUM> may be configured via I/O interface <NUM>, which provides a communication link between control circuit <NUM> and external devices. I/O interface <NUM> may be a wireless communication interface, thereby ensuring that control circuit <NUM> remains in a sealed enclosure. Alternatively, I/O interface <NUM> may be a wired interface, and may optionally have a communication port protected using a removable seal (not shown).

Processor <NUM> may provide an activation signal to activate actuator <NUM> when count <NUM> reaches the pre-selected value, as stored in settings <NUM>. Actuator <NUM> may be electrically coupled to battery <NUM>, via a switch <NUM> that operates under control of processor <NUM>. Switch <NUM> may receive an activation signal from processor <NUM>. In response to receiving the activation signal, switch <NUM> may connect battery <NUM> to actuator <NUM>, thereby causing actuator <NUM> to activate dart <NUM>. The activation signal may be an analog voltage or current pulse that causes switch <NUM> to open, thereby allowing current to flow from battery <NUM> to actuator <NUM>. Alternatively, switch <NUM> may be controlled using a digital signal from processor <NUM>.

To activate dart <NUM>, actuator <NUM> may provide a force sufficient to release sleeve <NUM> from shear screw <NUM>, thereby causing sleeve <NUM> to slide towards uphole end <NUM>, engage locking mechanism <NUM>, and lock in the activated position. As previously explained, once locked in the activated position, sleeve <NUM> is prevented from collapsing.

In one example embodiment, actuator <NUM> may include a micro gas generator. The force to release sleeve <NUM> from sear screws <NUM> may be provided by the micro gas generator, thereby causing sleeve <NUM> to slide towards uphole end <NUM>. 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 <NUM> may provide the electric charge to ignite the initiator when switch <NUM> is opened in response to the activation signal. The size and response time (which is typically in the range of <NUM> to <NUM> milliseconds) of the micro gas generator may be selected so that the micro gas generator is suitable for use in dart <NUM>.

In another example embodiment, the actuation force to release sleeve <NUM> from shear screws <NUM> may be provided by an electric actuator, such as a motor, which may be powered using a power source, such as a battery.

In another embodiment, the actuation pressure for actuating sleeve <NUM> 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 <NUM> may be provided using hydraulic pressure, for example, by allowing fluids to flow into a cavity of dart <NUM>.

Control circuit <NUM> may also include a power source, such as a battery <NUM>, to power the modules of control circuit <NUM>.

As illustrated schematically in <FIG>, sensor <NUM>, I/O interface <NUM>, processor <NUM>, and memory <NUM> may be mounted to a PCB <NUM> and thereby connected to one another. PCB <NUM>, switch <NUM>, and battery <NUM> (or other suitable power source) may be physically secured in cut-out <NUM> on dart <NUM>. Actuator <NUM> may be physically secured in cut-out <NUM> on dart <NUM>. Alternatively, actuator <NUM> may also be physically secured in cut-out <NUM>.

PCB <NUM> may include negative and positive terminals <NUM>, <NUM> for connecting the PCB to battery <NUM>. The terminals of the battery <NUM> may be connected to wires <NUM>, <NUM> which are then connected to the terminals <NUM>, <NUM> of the PCB. The PCB may route power from battery <NUM> to the modules mounted thereon.

The battery <NUM> may also be connected, using a wire <NUM> to actuator <NUM>, and using a wire <NUM> to switch <NUM>. Switch <NUM> may also be connected to actuator <NUM> using a wire <NUM>. Processor <NUM> may also be connected using switch <NUM> to a wire <NUM> to send the activation signal.

Control circuit <NUM>', shown schematically in block diagram form in <FIG>, provides a second example embodiment of control circuit <NUM>. Control circuit <NUM>' may thus replace control circuit <NUM>. Control circuit <NUM>' includes "go/no-go" sensor <NUM>', a counter <NUM>', a power source, such as battery <NUM>, and an actuator <NUM>. Actuator <NUM> is electrically coupled to battery <NUM> via a switch <NUM>.

"Go/no-go" sensor <NUM>' is powered by battery <NUM> and generates an analog voltage or current pulse output when a physical impact experienced by dart <NUM> exceeds a threshold level. Counter <NUM>' may be a mechanical or electronic counter that is configured to increment its count upon receiving the pulse output from "go/no-go" sensor <NUM>'. Accordingly, counter <NUM>' increments its count when the physical impact experienced by dart <NUM> exceeds the threshold level of "go/no-go" sensor <NUM>'. Counter <NUM>' is also configured to provide an output indicative of its count, which may be an electronic signal or a physical change (for example, counter <NUM>' may cause a mechanical dial to rotate). In the case where counter <NUM>' is an electronic counter, it may also be powered by battery <NUM>.

Counter <NUM>' may include an input interface <NUM>' to allow counter <NUM>' to receive a pre-selected value and counter <NUM>' may actuate actuator <NUM> when the count reaches the pre-selected value. Input interface <NUM>' may be an electronic interface or a mechanical interface, such as a push-pin interface or a mechanical dial.

As illustrated in <FIG>, when the count is equal to the value selected using the input interface <NUM>', counter <NUM>' triggers actuator <NUM> by generating an analog voltage or current pulse that causes switch <NUM> to open, thereby allowing current to flow from battery <NUM> to actuator <NUM>. In an alternative embodiment, when the count is equal to the value selected using the input interface <NUM>', counter <NUM>'may generate a physical change that causes switch <NUM> to open instead of generating the pulse.

<FIG> shows a schematic view of a well system <NUM> from a side elevation view. Well system <NUM> may include a wellbore <NUM> extending therefrom and penetrating a subterranean earth formation <NUM>. Well system <NUM> may also include an oil and gas rig <NUM> at the Earth's surface. Rig <NUM> may include derrick <NUM> and rig floor <NUM>.

A completion assembly <NUM> may be deployed within a lateral portion of wellbore <NUM>. Completion assembly <NUM> includes a well tubing <NUM> supported by packers <NUM> or other wellbore isolation devices. Fracking fluid can be pumped downhole through tubing <NUM> at a controlled pump / flow rate.

Packers <NUM> may seal off an annulus <NUM> defined between completion assembly <NUM> and an inner wall of wellbore <NUM>. Thus, subterranean formation <NUM> may be effectively divided into multiple regions <NUM> (shown as regions 528a, 528b, and 528c) which may be stimulated and produced independently. While only three regions 528a-c are shown in <FIG>, any number of regions <NUM> may be defined or otherwise used in the well system <NUM>.

Each region <NUM> may include one or more sliding sleeves <NUM> (shown as sliding sleeves 300a, 300b, and 300c) arranged in, coupled to, or otherwise forming integral parts of tubing <NUM>. Each sliding sleeve 300a-c is movable within tubing <NUM> to open one or more ports <NUM> (shown as ports 232a, 232b, and 232c) defined in tubing <NUM>. Once opened, the ports 232a-c allow fluid communication between the annulus <NUM> and the interior of tubing <NUM>. Pressurized fracking fluid <NUM> may then be released to fracture formation <NUM>.

Each sliding sleeve 300a-c also includes a seat structure <NUM> (shown as seat structures 350a, 350b, and 350c). Seat structures 350a-c provide a restriction in tubing <NUM> for seating dart <NUM>. The seat structures 350a, 350b, and 350c are placed along tubing <NUM>, with each seat structure being placed at least <NUM> meters away from the next seat structure.

In order to move a sliding sleeve 300a-c to its open position, and thereby open the corresponding ports 232a-c, dart <NUM> (not shown) may be conveyed into tubing <NUM>. Dart <NUM> then travels through tubing <NUM> until dart <NUM> seats at the seat structure 350a-c of the selected sliding sleeve 300a-c. Dart <NUM> may be pumped through tubing <NUM>, along with fracking fluids.

Dart <NUM> may be conveyed into tubing <NUM> in the inactive state. Dart <NUM> 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 <NUM> 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 <NUM> 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 <NUM>), then dart <NUM> may be conveyed into tubing <NUM> in the activated state.

Once conveyed into tubing <NUM>, dart <NUM> travels at a speed in the range of <NUM>-<NUM>/s. At such a speed, the dart <NUM> can travel <NUM> meters in about <NUM> to about <NUM> seconds. Conveniently, the time required to activate dart <NUM> may be in the range of <NUM> to <NUM> milliseconds. As can be understood by those skilled in the art, <NUM> is a typical distance between two adjacent downhole tools, such as seat structures <NUM>.

The speed of dart <NUM> 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 <NUM> to <NUM><NUM> per minute.

When dart <NUM> travels through tubing <NUM> at the above-noted speeds, dart <NUM> is configured to experience a physical impact having an impact level exceeding the threshold level of sensor <NUM> when passing through each one of seat structures <NUM> in the inactive state. Thus, sensor <NUM> detects an impact each time dart <NUM> is impacted when contacting a seat structure <NUM> in the inactive state with an impact level exceeding the threshold level, and generates a signal. In response to the signal, processor <NUM> increments count <NUM> (or counter <NUM>' increments its count). Accordingly, the count indicates the number of physical impacts experienced by dart <NUM> that exceeds the threshold level (which may be indicative of the seat structures <NUM> that dart <NUM> has travelled through).

As dart <NUM> travels through tubing <NUM>, dart <NUM> may also experiences other impacts. For example, impacts with the walls of tubing <NUM> or other structures in tubing <NUM>. The threshold level of physical impact for incrementing count <NUM> is therefore set to be substantially higher than the floor level. In one embodiment, the threshold level of shock may be <NUM> times greater than the floor level.

In one example embodiment, the floor level may be <NUM>, the threshold level of shock may be <NUM>, and surface structure <NUM> may be configured such that dart <NUM> experiences a physical impact having an impact level of <NUM> when passing through seat structures <NUM> in tubing <NUM>.

However, the level of physical impact experienced by dart <NUM> may vary based on any one of the following factors: the speed at which dart <NUM> is conveyed through tubing <NUM>, the flow / pump rate of the fracking fluids, the weight of dart <NUM>, the materials used to make fingers <NUM>, the number of fingers <NUM>, the thickness of fingers <NUM> (particularly at the point of attachment to sleeve <NUM>), the shape of terminal tips <NUM>, the angle and shape of seat structures <NUM>, amongst others. Accordingly, in different embodiments, the threshold level of shock may be set in dependence on more than one factor.

In one example embodiment, sensor <NUM> may be configured to detect the force of impact on dart <NUM> in only one direction, and particularly, along the longitudinal axis of dart <NUM> and tubing <NUM> (axis l, as shown in <FIG>). The impact of dart <NUM> with seat structures <NUM> may result in a force direction predominantly along the longitudinal axis of dart <NUM>. 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.

Accordingly, dart <NUM> is configured to experience a level of impact that exceeds the threshold level upon impact with a seat structure <NUM> and to experience levels of impact that are significantly lower than the threshold level upon impact with other structures in tubing <NUM>. Since count <NUM> 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.

<FIG> are examples of well tubing <NUM>, sleeve <NUM>, and seat structure <NUM> in more detail.

<FIG> shows in isolation a section of an example well tubing <NUM> for use with well system <NUM>. Each section of tubing <NUM> may have an outer housing <NUM>, one or more ports <NUM>, and upper and lower connection elements <NUM>, <NUM> to connect multiple sections of tubing to form well tubing <NUM>.

The section of well tubing <NUM> may also have pins <NUM> which extend inwardly from outer housing <NUM> to engage with sleeve <NUM>. Pins <NUM> may be partially threaded so that the pin <NUM> can be secured to bore holes in tubing <NUM>. In one example, pins <NUM> have an upper threaded portion and a lower unthreaded shaft.

The section of well tubing <NUM> may also have shear pins <NUM> which extend inwardly from outer housing <NUM> to engage with sleeve <NUM>. Pins <NUM> may be partially threaded so that the pin <NUM> can threadly engage internal threads in pin holes <NUM>. In one example, pins <NUM> have an upper threaded portion and a lower unthreaded shaft.

As can be seen in <FIG>, tubing <NUM> also has an internal groove <NUM>, the function of which will be discussed below.

A slidable sleeve <NUM>, as shown in isolation in <FIG>, may be mounted inside internal bore <NUM> of tubing <NUM> (as shown in <FIG>) to selectively block ports <NUM> of an interval 528a-c. Sleeve <NUM> may be slid into tubing <NUM> to open ports <NUM> (as shown in <FIG>).

Sleeve <NUM> may have one or more longitudinal slots <NUM> in an outer surface thereof, each to receive a pin <NUM> of tubing <NUM>. In one example, the lower unthreaded shaft of a pin <NUM> engages a longitudinal slot <NUM>. The movement of the sleeve <NUM> is thereby limited by the pins <NUM>, as pins <NUM> collide with the sides of the longitudinal slots <NUM>. Pins <NUM> may therefore guide the movement of sleeve <NUM> along the length of tubing <NUM>. Pins <NUM> may also prevent sleeve <NUM> from rotating / spinning inside tubing <NUM>.

Sleeve <NUM> may also have counterbores <NUM>. Shear pins <NUM> may be positioned in pin holes <NUM> in tubing <NUM> and in counterbores <NUM> in sleeve <NUM> so as to retain sleeve <NUM>. Shear pins <NUM> may break when a sufficient pressure is applied on sleeve <NUM> by dart <NUM>, thereby allowing sleeve <NUM> to slide open.

Sleeve <NUM> may have an annular groove <NUM> around the outer surface of the sleeve. A C-ring <NUM> may be attached to annular groove <NUM>. C-ring <NUM> may be made of a metal, such as steel. C-ring <NUM> may be sized and configured to fit around annular groove <NUM> but in its natural state protrudes above the external surface of sleeve <NUM>. C-ring <NUM> is resilient and can be compressed inward to fit within groove <NUM>, so that when sleeve <NUM> is inserted into tubing <NUM> with C-ring <NUM> mounted thereon, C-ring <NUM> pushes against the inner wall of tubing <NUM> but allows sleeve <NUM> to slide within tubing <NUM> before sleeve <NUM> reaches the position where groove <NUM> is aligned with internal groove <NUM> on tubing <NUM> (this position is referred to herein as the open position as when sleeve <NUM> is at this position ports <NUM> are "open"). When sleeve <NUM> is moved to the open position, the space provided by groove <NUM> allows C-ring <NUM> to spring back to its natural state and protrude above groove <NUM>, therefore functioning as a stopper for locking sleeve in the open position. Thus, once sleeve <NUM> is in the open position, C-ring <NUM> can engage both groove <NUM> and groove <NUM> in the inner wall of tubing <NUM> to secure sleeve <NUM> in the open position (<FIG>).

Sleeve <NUM> also includes a seat structure <NUM> (<FIG>) mounted therein. Seat structure <NUM> may have a wall <NUM> that defines an inner opening (not shown) through which dart <NUM> may pass through when in the inactive state but cannot pass through when in the activated state. In the inactive state, protrusions <NUM> of fingers <NUM> can contact wall <NUM> and cause dart <NUM> to experience an impact exceeding the threshold level. Terminal tips <NUM> of fingers <NUM> however can bend by the force of the impact, thus allowing dart <NUM> to pass through seat structure <NUM>. However, the inner opening of the seat structure <NUM> is sized and shaped so as to prevent dart <NUM> from passing through if terminal tips <NUM> of fingers <NUM> cannot bend inwardly towards the housing wall. Thus, when in the activated state (i.e. when fingers <NUM> are non-collapsible), dart <NUM> will engage and seat at seat structure <NUM>. In effect, seat structure <NUM> provides a narrow inner opening through which dart <NUM> is allowed to pass through only when dart <NUM> is in the inactive state.

Wall <NUM> and inner opening of seat structure <NUM> may also be shaped to interact with terminal tips <NUM> to cause dart <NUM> to experience a physical impact having an impact level exceeding the threshold level when passing through.

<FIG> shows a flow-chart of a method <NUM> for using dart <NUM> in the operation of a multi-interval wellbore, such as wellbore <NUM> of well system <NUM> (<FIG>).

At <NUM>, operational parameters of dart <NUM> are configured. Example operational parameters that may be configured include the threshold level of sensor <NUM> and the count at which dart <NUM> is activated. In one example, one of multiple sliding sleeves <NUM> is selected for actuation and dart <NUM> is configured to target the selected sliding sleeve <NUM> 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 <NUM> / counter <NUM>' receives a pre-selected value corresponding to a number of impacts exceeding a threshold level which dart <NUM> is configured to detect prior to activation. For example, in the depicted configuration shown in <FIG>, to target sliding sleeve 300c, the pre-selected value may be set to <NUM>, because dart <NUM> needs to pass through two (<NUM>) uphole sleeves 300a and 300b before reaching sleeve 300c.

Processor <NUM> (<FIG>) may receive the pre-selected value via I/O interface <NUM>, and the value may be stored in settings <NUM>. Similarly, counter <NUM>' (<FIG>) may receive the pre-selected value via input interface <NUM>'.

Optionally, at <NUM>, the threshold level of sensor <NUM> may also be set and stored in settings <NUM>.

Once the operational parameters are configured, dart <NUM> is released into well tubing <NUM>, which may be filled with a fracking fluid, at <NUM>, to actuate the selected sliding sleeve <NUM>. For example, to actuate sliding sleeve 300c, once released, dart <NUM> travels through well tubing <NUM> through sliding sleeve 300a and seat structure 350a (<FIG>), through sliding sleeve 300b and seat structure 350b (<FIG>) until it reaches sliding sleeve 300c and seat structure 350c (<FIG>). The fracking fluid in well tubing <NUM> interacts with foil <NUM> (<FIG>) to generate a force which propels dart <NUM> forward through well tubing <NUM>.

As dart <NUM> travels within well tubing <NUM>, dart <NUM> performs the steps of method <NUM>. Method <NUM> illustrates an example method for activating dart <NUM> as it travels through tubing <NUM>. Steps of method <NUM> may be performed by processor <NUM> of control circuit <NUM> of <FIG> or by control circuit <NUM>' of <FIG>.

As dart <NUM> travels within well tubing <NUM>, dart <NUM> 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 <NUM> or other structures in the well tubing <NUM>, due to contact of terminal tips <NUM> with seat structures <NUM> within well tubing <NUM>, and so forth). When dart <NUM> contacts internal components in tubing <NUM>, the impact may detected by sensor <NUM>.

When method <NUM> is implemented by control circuit <NUM> (<FIG>), after an impact, at <NUM>, processor <NUM> receives a signal from sensor <NUM>. If sensor <NUM> is an impact level sensor, in response to receiving the signal from sensor <NUM>, processor <NUM> determines, at <NUM>, if the level of impact detected is greater than or equal to the threshold impact level. If so, the impact count is incremented at <NUM>. On the other hand, when sensor <NUM> is a "go/no-go" sensor, processor <NUM> increments the count at <NUM> (i.e. skipping <NUM>) in response to receiving each signal from sensor <NUM>, 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 <NUM>, processor <NUM> determines if the count is equal to the pre-selected value corresponding to the number of impacts exceeding the threshold level which dart <NUM> is configured to detect prior to activation. If so, processor <NUM> triggers actuator <NUM> at <NUM>, thereby activating dart <NUM>. If not, method <NUM> returns to <NUM>.

When method <NUM> is implemented by control circuit <NUM>' (<FIG>), after an impact, at <NUM>, counter <NUM>' receives a signal from "go/no-go" sensor <NUM>' and increments the count at <NUM> (i.e. skipping <NUM>) in response to receiving the signal from sensor <NUM>'. At <NUM>, if the count is equal to the pre-selected value, method <NUM> proceeds to <NUM>, and control circuit <NUM>' triggers actuator <NUM>, thereby activating dart <NUM>. If not, method <NUM> returns to <NUM>.

In one embodiment, triggering actuator <NUM> causes sleeve <NUM> to slide towards uphole end of dart <NUM>, thereby locking sleeve <NUM> in the activated position. In the activated position, fingers <NUM> engage locking mechanism <NUM> which supports sleeve <NUM> in a protruded position, and can no longer bend inward so dart <NUM> cannot pass through the seating structure in the next target sleeve 300c.

Before dart <NUM> contacts seat structure 350a (<FIG>), the impact count is initially set to <NUM> and dart <NUM> 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 <NUM> detects the impact and provides a signal to processor <NUM> or counter <NUM>', and the processor <NUM> / counter <NUM>' in response increments the impact count <NUM> from <NUM> to <NUM>. As <NUM> is less than <NUM>, the dart <NUM> is still in the inactive state when it contacts seat structure 350b (<FIG>), so dart <NUM> can also pass through seat structure 350b. The impact caused by dart <NUM> contacting seat structure 350b will exceed the threshold level so the impact count is incremented from <NUM> to <NUM>. At this point, dart <NUM> is activated. Impacts with seat structure 350a and with seat structure 350b may cause dart <NUM> to slow down.

As can be appreciated by those skilled in art. terminal tips <NUM> of fingers <NUM> are squeezed upon impact with seat structure 350a and with seat structure 350b (<FIG>), and can bend inward as they are not supported and there is a gap between the terminal tips <NUM> and the housing <NUM>, thereby permitting dart <NUM> to pass through seat structures 350a, 350b. A component of the force of impact of terminal tips <NUM> with seat structure <NUM> is along the longitudinal axis of dart <NUM> and tubing <NUM> (axis l). Since terminal tips <NUM> are allowed to bend inward generally along the radial direction of dart <NUM> and tubing <NUM> (axis r), a component of the force in the radial direction causes terminal tips <NUM> to bend towards external surface <NUM> of housing <NUM>. Such bending provides the needed clearance for dart <NUM> to continue traveling within tubing <NUM> in the inactive state (see <FIG>).

As noted, after the impact count <NUM> reaches the selected threshold value, "<NUM>" in the depicted example, dart <NUM> is activated. That is, dart <NUM> is activated after passing through sleeve 300b so that dart <NUM> reaches sleeve 300c in the activated state (<FIG>).

Since terminal tips <NUM> are prevented from bending inward in the activated state, dart <NUM> cannot pass through and will seat at the selected seat structure 350c (see <FIG> and <FIG>). As better illustrated in <FIG>, terminal tips <NUM> are supported in the protruded position by sliding sleeve <NUM> to uphole end <NUM> of dart <NUM> and locking sleeve <NUM> in that position. Sleeve <NUM> is moved into the locked position by actuator <NUM>, which is in turn triggered by the controller such as control circuit <NUM> when the impact count reaches the threshold value of <NUM>.

Returning to method <NUM>, once seated, dart <NUM> may be used to actuate and slide the selected sleeve 350c to the open position at <NUM> (<FIG>). Foil <NUM> interacts with the walls of tubing <NUM> to create a seal which at least partially blocks fluid from flowing around the housing <NUM> when dart <NUM> is seated and increases the fluid pressure at uphole end <NUM>. In some embodiments, foil <NUM> may be made of flexible material, such as a rubber, which allows foil <NUM> to bend towards the inner walls of tubing <NUM> in response to increased fluid pressure, thereby creating a tighter seal with the inner walls of tubing <NUM>. Furthermore, dart <NUM> may have seals attached to ridge structures <NUM> to improve the seal.

In an embodiment, the force of impact produced by the dart <NUM> on contact with the seat structure 350c and the increased fluid pressure due to the seal created by foil <NUM> together may be sufficient to cause the sleeve 300c to slide to the open position, thus opening ports <NUM> (for example, by breaking shear pins <NUM> shown in <FIG>).

In other embodiments, a ball <NUM> may be conveyed through tubing <NUM> to contact the dart <NUM> thereby generating the needed force for opening the sleeve 300c. When ball <NUM> reaches dart <NUM>, dart <NUM> receives and retains ball <NUM> at the receptacle <NUM>. Ball <NUM> may be retained by receptacle <NUM> because the fluid pressure and fluid flow may exert a force pushing ball <NUM> into and against receptacle <NUM>. Ball <NUM> once seated in the receptacle <NUM> can block fluid flow through fluid conduit <NUM>, thereby causing an increase in fluid pressure which, along with the increased pressure created by foil <NUM>, may cause sleeve 300c to slide to the open position. In some cases, the impact generated the ball <NUM> contacting dart <NUM> may be sufficient for actuating the sleeve 300c.

In other embodiments, ball <NUM> may be attached to dart <NUM> when the dart <NUM> is released into the tubing <NUM>, and travel with dart <NUM> through tubing <NUM>. Once seated at seat 350c, the resulting increased fluid pressure then causes sleeve 300c to slide to the open position.

At <NUM>, the region 528c corresponding to the selected sleeve 300c may be stimulated. Stimulation of the interval may include pumping fracking fluid <NUM> at a high pressure through the open ports of that interval to fracture the rock formation <NUM> (<FIG> and <FIG>).

At <NUM>, it is determined whether another region from the regions 528a-c is to be stimulated. If so, at <NUM>, the previous region is plugged (i.e. region 528c). The region 528c may be plugged by conveying ball <NUM> to dart <NUM> at sleeve 300c, thereby plugging fluid conduit <NUM> of dart <NUM>. Step <NUM> may be skipped if ball <NUM> is attached to dart <NUM> and travels with dart <NUM> through tubing <NUM>.

Method <NUM> then proceeds to <NUM>, where a new dart <NUM> is configured and released into wellbore <NUM> to open ports <NUM> associated with region 528b. Method <NUM> may be repeated once more to target region 528a. As shown in <FIG>, 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.

Downhole operations may therefore be conducted in stages by conveying successive pre-configured darts <NUM>, each targeting a sleeve <NUM> at a different region <NUM>. After all regions 528a-528c are stimulated, darts 100a-100c and balls 136a-136c may be removed at <NUM> to allow for the hydrocarbon extraction process to commence at <NUM>.

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 <NUM> to dissolve darts 100a-100c.

Alternatively, housing <NUM> may be made of drillable material, such as ductile iron of grade <NUM>-<NUM>-<NUM>. After stimulating regions 528a-528c, a drill may be used to drill through darts 100a-100c.

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 <NUM> 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.

Dart <NUM> therefore includes a sensor <NUM> for detecting a level of shock experienced by the dart as it travels through the well tubing. When inactive, dart <NUM> impacts seat structures <NUM> in well tubing <NUM>, and upon impact with each seat structure <NUM> experiences an impact having a level of impact exceeding a threshold level. Sensor <NUM> provides a signal indicating that dart <NUM> has experienced an impact having the level of impact exceeding a threshold level, thereby causing dart <NUM> to increment a count of the number of seat structures <NUM> it has traversed. Once dart <NUM> determines that it has traversed a pre-selected number of seat structures <NUM>, dart <NUM> is activated. Once activated, dart <NUM> can no longer pass through seat structures <NUM> in well tubing <NUM>, and seats at the next seat structure <NUM> it encounters.

Count <NUM> is not incremented unless the dart experiences an impact level exceeding a threshold level. To avoid incrementing count <NUM> unless dart <NUM> has impacted a seat structure <NUM>, the threshold level of impact for incrementing count <NUM> 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.

Dart <NUM> also does not rely on detecting any external stimuli; sensor <NUM> measures the movement of dart <NUM> as it travels within the tubing. In contrast, a sensor that is responsive to an external stimuli within tubing <NUM> or to control signals from rig <NUM> 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 <NUM>. Thus, sensor <NUM> is less prone to failure of detecting that dart <NUM> has traversed a seat structure <NUM> within tubing <NUM>.

Dart <NUM> also operates autonomously without communicating with other devices as it travels through tubing <NUM>. For example, dart <NUM> does not require control signals from external devices while dart <NUM> is in tubing <NUM>. Communication with other devices may be unpredictable due to the harsh environmental conditions in the tubing. Thus, by operating autonomously, dart <NUM> eliminates the point of failure associated with communicating with external devices and may be more reliable.

The structure of dart <NUM> may be modified in various embodiments. Dart <NUM> has a protrusion <NUM> on a surface structure thereof which impacts a restriction in tubing <NUM>. Different techniques may be used to configure dart <NUM> to experience an impact having an impact level that exceeds the threshold level. Protrusion <NUM> is further configured to collapse upon impact with the restriction when dart <NUM> is inactive, thereby allowing dart <NUM> to pass through the restriction in tubing <NUM>. Different techniques may be used to collapse protrusion <NUM> upon impact with the restriction in tubing <NUM> when dart <NUM> is inactive.

Protrusion <NUM> is further configured to remain in a protruding position upon impact when dart <NUM> is activated, thereby causing dart <NUM> to seat at the restriction and to actuate a tool at the restriction. Different techniques may be used to support protrusion <NUM> in a protruding position upon impact with the restriction in tubing <NUM> when dart <NUM> is activated.

In one example embodiment, housing <NUM> of dart <NUM> may have a diameter in the range of <NUM> to <NUM> centimeters, a length in the range of <NUM> to <NUM> centimeters, and a weight in the range of <NUM> to <NUM>. In one embodiment, fluid conduit <NUM> may have a diameter of <NUM> to <NUM> centimeters near uphole end <NUM>. In one embodiment, fluid conduit <NUM> may be wider at downhole end <NUM> than at uphole end <NUM>. In one embodiment, cut-out <NUM> is approximately <NUM> to <NUM> centimeters long, <NUM> to <NUM> centimeters wide, and <NUM> to <NUM> centimeters in thickness.

In one embodiment, each finger <NUM> may be <NUM> to <NUM> centimeters wide and <NUM> to <NUM> centimeters long. In example embodiments, the number of fingers <NUM> may range from <NUM> to <NUM> fingers. The number of fingers <NUM> chosen may vary in dependence on the diameter of housing <NUM> and the width of each finger.

Selected Embodiments of the present invention may be used in a variety of fields and applications.

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.

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.

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.

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.

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.

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.

Claim 1:
An actuation device (<NUM>) comprising:
a housing (<NUM>) configured to travel within a well tubing (<NUM>), wherein a plurality of seat structures (<NUM>) are mounted in the well tubing, each one of the seat structures comprising a seat (<NUM>) to seat the device (<NUM>) thereon;
a surface structure (<NUM>) on an external surface (<NUM>) of the housing (<NUM>), having an inactive state and an activated state, and being configured to (i) allow the device (<NUM>) to travel through the seat structures (<NUM>) when the surface structure (<NUM>) is in the inactive state or (ii) to seat in a selected one of the seats (<NUM>) in the well tubing (<NUM>) when the surface structure (<NUM>) is in the activated state,
characterized in that,
the device (<NUM>) 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 (<NUM>), and further comprises:
a sensor (<NUM>, <NUM>') enclosed in the housing (<NUM>), configured to generate a signal in response to the physical impact experienced by the device (<NUM>);
a controller (<NUM>, <NUM>', <NUM>) housed in the housing (<NUM>) and in communication with the sensor (<NUM>) to receive the signal from the sensor (<NUM>), wherein the controller (<NUM>) is configured to determine, based on signals received from the sensor (<NUM>), a number of seat structures (<NUM>) traversed by the device (<NUM>), and to activate the surface structure (<NUM>) when the number of seat structures (<NUM>) traversed by the device reaches a pre-selected value.