Abstract:
A remotely deployed untethered device for actuation of a downhole application. The device may be equipped with inductive measurement capacity for interaction with a downhole well architecture. Such capacity affords the ability to trigger an actuation remotely at a site specific location in the well without further intervention relative surface equipment.

Description:
BACKGROUND 
       [0001]    Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming, and ultimately very expensive endeavors. As a result, well completions and architecture design are directed at enhancing overall recovery. In particular, efforts have increased related to minimizing all costly and time consuming endeavors related to installation and subsequent interventional management. For example, over the course of well completions and later management a host of interventions may be performed ranging from installation of hardware, detection of well conditions, follow-on isolations, shifting of sliding sleeves, and so on. Many of these interventions are equipment-heavy, time consuming and invasive operations. In the case of sliding sleeves, such as to open up a new region of production, ongoing operations are halted and a shifting tool inserted up to several thousand feet into the well for the sake of opening the sleeve. 
         [0002]    Dedicated interventions of this nature are not only time consuming, but generally include a substantial amount of rig-up equipment at the oilfield surface. For example, coiled tubing or other conveyance equipment utilized for the shifting application is set up and broken back down again before production operations are resumed. Thus, the overall time lost and cost associated with an otherwise fairly straight forward sleeve shifting, becomes discouraging. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a schematic overview of a remote downhole actuation device traversing well in advance of reaching a series of potential triggering engagements. 
           [0004]      FIG. 2  is a schematic view of an embodiment of the remote sensor element of the downhole actuation device passing through a portion of the well of  FIG. 1  and performing inductive measurements. 
           [0005]      FIG. 3  is a block diagram of the downhole actuation device of  FIG. 1 . 
           [0006]      FIG. 4  illustrates the sensor element of the remote actuation device of  FIG. 1  within a sleeve having notches therein to influence the magnetic flux lines and an inductive signature generated by the sensor element due to the notches. 
           [0007]      FIG. 5  is a flowchart illustrating an example method of operation for the remote actuation device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    A device is described for use in triggering downhole actuations. In one embodiment, the device may take the form of a remote actuation device that includes a main body configured for untethered deployment through a well. An inductive measurement device that is able to identify specific features of the well may be incorporated into the body for the triggering at a location in the well during the deployment. 
         [0009]    Some example embodiments described herein include certain types of remote actuations directed from surface via an untethered device. The embodiments make use of a remote actuation device deployable through a well for selective triggering of sliding sleeves at a well wall. However, a variety of other actuations and/or operations may implement the remote actuation device as detailed herein. Some embodiments include an untethered configuration relative to an oilfield surface in combination with inductive capacity built into the device for triggering a remote actuation as the device traverses past an actuation site. 
         [0010]    One embodiment may take the form of a multi-zone fracturing system in which a number of sliding sleeves are run during the completion of a reservoir. The sliding sleeves are positioned at determined intervals corresponding to fracture zones. The embodiment may include a method for identifying the sliding sleeves. In particular, the sliding sleeves may be identified by a device that is moving past the sliding sleeves in the wellbore, typically at an unknown velocity. The identification of the sliding sleeves may be used as a trigger for downhole actuation of the device. In some embodiments, the actuation may be autonomous. 
         [0011]    Some embodiments may include an autonomous dart that is pumped down the wellbore. Once the autonomous dart identifies a selected sliding sleeve, either by counting the number of sleeves passed or identifying a unique signature of the selected sleeve, the dart is actuated. The actuation of the dart may include at least one of a variety of suitable state changes. In one embodiment, the actuation may include a radial expansion of an outer diameter of the dart so that it engages an interior wall of the well bore, a tubular or a sliding sleeve, for example. 
         [0012]    The identification of the sliding sleeves includes changes in electro-magnetic coupling or inductive coupling between transmitting and receiving coils in the dart due to the differences in attributes in the wellbore and/or of downhole device (e.g., the sliding sleeves). These attributes include, but are not limited to, the geometry and material of the device being identified. By measuring the changes in electro-magnetic coupling a unique signature of the device can be generated. This signature can be a result of either the response of the unmodified device or the response to specific features added to the device being identified. For example, grooves on the inner diameter or outer diameter of the device may be used to intentionally generate a response or signature that can be recognized. 
         [0013]    In some embodiments, the sliding sleeves are interrogated by a device. The device may be a balanced coil that is sensitive to changes in the metal and shape of the sliding sleeve. In addition, grooves may be added to the inner diameter of the sliding sleeve so the balanced coil will generate a unique signature that will distinguish the sliding sleeve from the other equipment installed in the wellbore. 
         [0014]    A series of sliding sleeves are run in the wellbore as part of the casing string upon completion of an oil or gas reservoir. After completion of the reservoir, the decision is made on which sliding sleeve(s) is opened to allow hydraulic communication between the inside of the casing and the formation in the fracture zone(s) of interest. The sliding sleeve is opened by pumping an element or dart down the wellbore that can identify the sliding sleeves. The dart measures the unique signature using a balanced coil based sensing system and when it detects the sleeve of interest, either by counting the sleeves as if flows past them or by identifying a sleeve using a unique signature, the dart will initiate an action(s). In this application, the action is enabling a mechanism to open the sliding sleeve of interest. The dart was programmed at the surface on what sliding sleeve to open. 
         [0015]    A mechanism for identifying a wellbore element can have many other applications in the downhole environment. For example, whenever selective activation or selective communication with one or a series of devices is desired, embodiments as detailed herein may be utilized. 
         [0016]    Turning to the drawings and referring initially to  FIG. 1 , a remote actuation device  110  is shown traversing a well  105  in advance of reaching a series of potential triggering engagements  160 . The triggering engagements  160  may take any suitable form, as discussed further herein below. For the present example, a wellbore  140  with multiple sliding sleeves  120  having triggering engagements  160  installed is depicted with a sensing dart (e.g., the remote actuation device)  110  being pumped from the surface. The wellbore  140  may traverse one or more formations (hydrocarbon bearing formations, for example). In general, the wellbore  140  may extend through one or multiple zones or stages of the well  105 . 
         [0017]    The remote actuation device  110  may generally take the form of an untethered object (e.g., an object that travels at least some distance in a well passageway without being attached to a conveyance mechanism such as a slickline, wireline, coiled tubing sting and so forth). As specific examples, the untethered object may be a dart, a ball or a bar. However, it should be appreciated that the remote actuation device  110  may take any suitable form that may be pumped into the well  105 , although pumping may not be employed to move the device in the well, in accordance with further implementations. 
         [0018]    Turning to  FIG. 2  magnetic flux lines  100  of a sensor element  200  of the remote actuation device  110 , are depicted relative to a sliding sleeve  120 . More specifically,  FIG. 2  is a schematic view of an embodiment of a remote downhole actuation device  110  passing through a portion of a well and taking inductive measurements. It should be appreciated, that although the present examples are presented with reference to inductive or electro-magnetic coupling, other parameters may be measured such as conductance, impedance, capacitance, and so forth. 
         [0019]    In the illustrated embodiment, the remote actuation device  110  includes multiple coils. Specifically, the remote actuation device  110  includes a transmission coil  130 , and two receiver coils  140 . The two receiver coils  140  may be disposed on either side of the transmission coil  130 . That is, one receiver coil  140 A may be disposed on an uphole side  150  of the transmission coil  130  and the other receiver coil  140 B may be disposed on a downhole side  160  of the transmission coil. Each of the coils may be formed by winding a conductor, such as copper wire about a spool. The coils may be wound about a common spool or separate spools. It should be appreciated that some embodiments may include more or fewer coils. For example, one embodiment may include two coils, while another may include only the transmission coil  130 . That is, in one embodiment, a single coil may be implemented as an inductive sensor to sense changes in a coupling between the coil and the casing or sliding sleeve as the sensor passes therethrough. 
         [0020]    As illustrated, in some embodiments, the transmission coil  130  may include more windings than the receiver coils  140 . Additionally, the transmission coil  130  may be coupled to a power source, such as a battery, for example, so that an electrical current flows through the transmission coils to create the magnetic flux lines  100 . As such, the remote actuation device  110  may take the form of an active device. In other embodiments, the remote actuation device  110  may take the form of a passive device (e.g., one in which no battery or power is provided to the coils). 
         [0021]    The remote actuation device  110  may be configured to sense changes in a coupling between the coils  130 ,  140  as the remote actuation device moves in proximity to elements that influence the magnetic flux lines  100 . For example, as the remote actuation device  110  travels downhole, the magnetic flux lines may be altered by changes in a sliding sleeve and, thereby, changing the coupling between the transmission coil  130  and the receiver coils  140 . For example, notches or recesses on the interior or exterior of the sliding sleeve may be sensed, as well as protrusions, as the magnetic flux lines will be influenced by the different features. An on-board processor may process information gathered by the sensor and determine if a set criteria has been met to trigger and actuation. 
         [0022]    The operating frequency of the signal transmitted between the coils can be varied in order to change the depth of penetration into the metal to eliminate features of no interest. For example by increasing the frequency, the casing couplings that are located outside the casing will not be detected or produce unwanted responses. 
         [0023]      FIG. 3  is a block diagram of the remote actuation device  110 . The remote actuation device  110  may include a sensor element  200 , which may take the form of the inductive sensor with the coils  130 ,  140  described above or any other suitable sensor device, a processor  210  communicatively coupled to the sensor element, and an actuator  220  communicatively coupled to processor. A battery  230  may be provided to power the sensor element  200 , the processor  210  and the actuator  220 . As such, the battery  230  may be coupled to each of the noted devices. 
         [0024]    Generally, the processor  210  may take any suitable form and, in some embodiments, may take the form of a controller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a CPU, or other suitable processing device. In some embodiments, the processor  210  may take the form of a counting circuit that keeps track of a number of changes in the magnetic flux lines. In particular, a count may increase upon a change in the magnetic flux lines that exceeds a determined threshold (e.g., a threshold voltage or voltage change produced by the receiving coils) as the remote actuation device  110  travels downhole. In other embodiments, the processor  210  may have on-board memory which may store particular patterns or signatures that may be used as reference to determine if a sensed change in a magnetic flux should trigger an actuation. In some embodiments, the processor  210  may be configured to determine if a particular change in magnetic flux lines should register a count. In other embodiments, rather than depending upon keeping count, the processor  210  may be configured to determine if a determined triggering signature has been found. 
         [0025]    Upon reaching a desired count, or finding the determined triggering signature, the processor  210  may trigger the actuator  220  to actuate. In some embodiments, actuation of the actuator  220  may result in the stopping of the remote actuation device  110  in the casing. For example, a portion of the remote actuation device  110  may radially expand and engage an interior wall of the casing. An operation may be performed while the remote actuation device  110  is stopped within the casing creating a diversion or stoppage. In one embodiment, a shifting sleeve may be shifted. In another embodiment, a fracing operation may be performed. 
         [0026]      FIG. 4  illustrates the sensor element  200  of the remote actuation device of  FIG. 1  within a portion of a sleeve  300  having attributes to change the magnetic flux lines  100  of the sensor element. Specifically, the sleeve  300  includes notches  310 ,  320 ,  330  to influence the magnetic flux lines  100  and generate an inductive signature. Generally, the remote actuation device  110  traveling through the sliding sleeve  300  while transmitting from the transmission coil  130  to the two receiver coils  140  will generate a signature response based on the dimensions of the notches  310 ,  320 ,  330 . The signature or measured response will change based on the change in coupling between the coils caused by attribute changes in the sliding sleeve. Further, the signature may deviate more than a threshold amount from an average steady state of the magnetic flux lines  100  of the sensor element  200  as the device  110  travels through the wellbore  140 . 
         [0027]    The notches or grooves  310 ,  320 ,  330  have been added to the inner diameter of sleeve  300 , but in other embodiments, the notches may be formed on an outer diameter of the sleeve. Additionally, a protrusion may extend from the sleeve and influence the magnetic flux lines. In the illustrated example, the notches  310 ,  320 ,  330  influence the magnetic flux lines in a manner that results in a pre-established signature unique to the sliding sleeve for reliably identifying the sliding sleeve. It should be appreciated that the size and spacing of the notches, as well as other attributes, each may influence the magnetic flux lines and, hence, help create the unique signature for the sleeve. 
         [0028]    An example signature  340  is illustrated in  FIG. 4 . The example signature  340  includes three distinct peaks  350 ,  360 ,  370 , each with a width A, B, C and a relative spacing D, E between the peaks. Each of the various features of the signature  340  may be used alone or in combination with other features for determining if a particular marker has been passed and/or for identifying a device. Additionally, the unique signature can be modified to increase the uniqueness with the respect to the other components in the wellbore by changing some attributes, such as (but not limited to) geometry and material of the component. For example, a component may be made with a larger or smaller thickness and/or made of a plastic, composite, alloy, or other material that is different from other components to help differentiate the signature of the component from other components. 
         [0029]      FIG. 5  is a flowchart illustrating a method  500  of operating the remote actuation device  110  in accordance with an example embodiment. The method  500  includes deploying the remote actuation device downhole (Block  510 ). As the remote actuation device  110  moves downhole, the magnetic flux lines are sensed (Block  520 ). A determination is made if there have been changes in the flux lines (Block  530 ). If there are no changes in the flux lines, then the magnetic flux lines continue to be sensed (Block  520 ). If there is a change in the flux lines, a count is increased (Block  540 ). A determination may then be made as to whether a threshold count has been exceeded (Block  550 ). If a threshold has been exceeded, the actuator is triggered (Block  570 ). If the threshold has not been exceeded, the magnetic flux lines continue to be sensed (Block  520 ). 
         [0030]    In another embodiment, signatures may be sensed. Specifically, when there is a change in the flux lines (Block  530 ), the change may be compared against stored signatures to check for a match (Block  560 ). If there is no match, the magnetic flux lines continue to be sensed (Block  520 ). If there is a match, the actuator may be triggered (Block  570 ). 
         [0031]    It should be appreciated that other methods may be implemented in certain embodiments. For example, in some embodiments, a signature may be matched to increase a count and a threshold number of signatures may be matched before triggering the actuator. Further, in some embodiments, a failure to match a signature may result in a triggering event. 
         [0032]    Embodiments detailed hereinabove provide a device configured for untethered remote triggering of downhole actuations. Thus, costs associated with more expensive and time consuming interventions may be largely avoided. 
         [0033]    The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Furthermore, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.