Patent Publication Number: US-2019195051-A1

Title: Plugging packer shunt tubes using magnetically responsive particles

Description:
BACKGROUND 
     In oil and gas wells, an annular region exists around the production tubing. It is often desirable to isolate some portions of this annular region from other portions, e.g., to prevent fluid flow between different zones of a formation, or to force formation fluids from a completion zone to enter ports in the production tubing en route to the surface. Tools that isolate different annular regions by creating a seal around the production tubing are known as “packers.” 
     The fluids leaving a formation in a completion zone may be transporting sand, grit, and other solids that can accumulate inside the production tubing and create barriers to further fluid flow. To prevent such solids from entering the production tubing, engineers routinely equip the ports of the production tubing with screens, and pack the annular region outside the screen with gravel (i.e., a “gravel pack”) or similar materials that are transported into place by fluid flow from the surface. To facilitate this transport, one of the packers used to define the completion zone (i.e., the “gravel-pack packer”) is equipped with crossover, or “shunt”, tubes that, when open, enable fluid-transported gravel to flow from the annulus between the casing and screen or blank pipe into the shunt tubes to exit at a point lower in the screen interval. 
     Because the shunt tubes provide a bypass from one screen to another screen section, they must be closed during normal production operations to force all fluid flow through the screens. Mechanical valves, such as check valves, ball valves, and sliding sleeves, are often used. However, such valves are subject to sticking, erosion, and incomplete sealing in sandy environments such as those encountered in gravel pack operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Accordingly, systems and methods for preventing flow through shunt tubes using magnetically responsive particles are disclosed herein. In the following detailed description of the various disclosed embodiments, reference will be made to the accompanying drawings in which: 
         FIG. 1  is a contextual view of an illustrative drilling environment; 
         FIG. 2  is a cross-sectional view of an illustrative casing and cementing operation; 
         FIG. 3  is a cross-sectional view of an illustrative perforated borehole; 
         FIG. 4A  is downhole view of an illustrative gravel-packing assembly; 
         FIG. 4B  is a detail view of an illustrative configuration of shunt tubes on the screen assembly; 
         FIGS. 5 and 6  are cross-sectional views of illustrative fluid chambers and release assemblies for the magnetically responsive particles; 
         FIG. 7  is a cross-sectional view of an illustrative system for plugging shunt tubes using magnetically responsive particles; and 
         FIG. 8  is a flow diagram of an illustrative shunt tube plugging method using magnetically responsive particles. 
     
    
    
     It should be understood, however, that the specific embodiments given in the drawings and detailed description thereto do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims. 
     NOTATION AND NOMENCLATURE 
     Certain terms are used throughout the following description and claims to refer to particular system components and configurations. As one of ordinary skill will appreciate, companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or a direct electrical or physical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, through an indirect electrical connection via other devices and connections, through a direct physical connection, or through an indirect physical connection via other devices and connections in various embodiments. 
     DETAILED DESCRIPTION 
     The issues identified in the background are at least partly addressed by systems and methods for plugging shunt tubes using magnetically responsive particles. Shunt tubes are flow paths that enable gravel slurry to flow from inside the production tubing to the annular region outside the sand screens, bypassing the screens. Multiple shunt tubes may be disposed on the same gravel-pack assembly, and the tubes may have various lengths, diameters, and cross-sectional shapes. Larger tubes have relatively low friction, and therefore support higher flow rates. The shunt tubes may need to be plugged after use, and the disclosed systems and methods for plugging the shunt tubes enable a variety of sizes of shunt tubes to be plugged using the same equipment. Additionally, at least some of the disclosed systems and methods enable the shunt tubes to be easily unplugged and re-plugged. 
       FIG. 1  illustrates how a well may be formed. Specifically, a drilling platform  2  is equipped with a derrick  4  that supports a hoist  6 . In at least some embodiments, the platform  2  is located offshore for subsea drilling. Drilling of oil and gas wells is carried out by a string of drill pipes connected together by “tool” joints  7  so as to form a drill string  8 . The hoist  6  suspends a kelly  10  that lowers the drill string  8  through a rotary table  12 . Connected to the lower end of the drill string  8  is a drill bit  14 . The bit  14  is rotated and drilling of the borehole  20  is accomplished by rotating the drill string  8 , by use of a downhole motor near the drill bit, or by both methods. 
     Drilling fluid, termed mud, is pumped by mud recirculation equipment  16  through a supply pipe  18 , through the kelly  10 , and down through the drill string  8  at high pressures and volumes to emerge through nozzles or jets in the drill bit  14 . The mud then travels back up the hole via the annulus formed between the exterior of the drill string  8  and the borehole wall  20 , through a blowout preventer, and into a mud pit  24  on the surface. On the surface, the drilling mud is cleaned and then recirculated by recirculation equipment  16 . 
       FIG. 2  shows an illustrative borehole  202  that has been drilled into the earth. Such boreholes are routinely drilled to ten thousand feet or more in depth and can be steered horizontally for twice that distance. During the drilling process, the driller circulates a drilling fluid to clean cuttings from the bit and carry them out of the borehole. In addition, the drilling fluid is normally formulated to have a desired density and weight to approximately balance the pressure of native fluids in the formation. Thus the drilling fluid itself can at least temporarily stabilize the borehole and prevent blowouts. To provide a more permanent solution, the driller inserts a casing string  204  into the borehole  202 . The casing string  204  is normally formed from lengths of tubing joined by threaded tubing joints  206 . The driller connects the tubing lengths together as the casing string  204  is lowered into the borehole  202 . 
     The casing string  204  may be coupled to a measurement unit  214  that senses one or more parameters of the casing  204  including temperature, pressure, strain, acoustic (noise) spectra, acoustic coupling, chemical (e.g., hydrogen or hydroxyl) concentration, and the like. The measurement unit  214  may process each measurement and combine it with other measurements to obtain a high-resolution measurement of that parameter. Though  FIG. 2  shows a cable as the sensing element, alternative embodiments of the system variously employ an array of spaced-apart sensors that communicate measurement data via wired or wireless channels to the measurement unit  214 . A data processing system  216  may periodically retrieve the measurements as a function of position and establish a time record of those measurements. Software, represented by information storage media  218 , runs on the data processing system  216  to collect the measurement data and organize it in a file or database. The software further responds to user input via a keyboard or other input mechanism  222  to display the measurement data as an image or movie on a monitor or other output mechanism  220 . Some software embodiments may provide audible and/or visual alerts to the user. 
     To cement the casing  204 , the drilling crew injects a cement slurry  225  into the annular space (typically by pumping the slurry  225  through the casing  204  to the bottom of the borehole  202 , which then forces the slurry  225  to flow back up through the annular space around the casing  204 ). It is expected that the software and/or the crew will be able to monitor the measurement data in real time or near real time to observe the profile of the selected parameter (i.e., the value of the parameter as a function of depth) and to observe the evolution of the profile (i.e., the manner in which the profile changes as a function of time). 
       FIG. 3  is a cross-sectional view of an illustrative, perforated borehole  302 . The illustrative borehole  302  has been fully drilled, all drilling equipment has been removed, and the borehole  302  has been cased with casing  304  and cemented to sustain the structural integrity and stability of the borehole  302 . The borehole  302  is formed within the earth and, more precisely, through target formation  300 , which extends beyond the limited scope with which it is represented in  FIG. 3 . The target formation  300  may include multiple layers, each layer with a different type of rock formation, including the hydrocarbon-containing target formation within which the borehole may extend horizontally for some distance. The casing  304  contains multiple perforations  306 , which may be formed by a perforation gun. The perforation gun may be transported downhole on a perforation tool using a wireline. When the gun is aligned with the desired perforation location, the gun may emit a high energy charge in order to perforate the surrounding casing  304  and formation  300 . For example, the perforation tool may be aligned a certain distance  314  from the bottom of the borehole  302 , and the perforation gun may create perforations having a certain spacing  312 . 
     Once the borehole has been formed, cased, and cemented, the sump packer is run downhole using an electric line tool that locates the sump packer at the correct position in the well. The packer is set using a setting tool, after which the setting tool and electric line tool are retrieved. The borehole may then be equipped with a gravel-packing assembly.  FIG. 4A  is downhole view of an illustrative gravel-packing assembly  400  suitable for use in a cased-hole environment. A sump packer  402  may be used as a base on which the screen  404  rests. In addition to support, the sump packer  402  may be used to accurately place the screen  404  next to the perforations  406 . The sump packer  402  may be run into the well on an electric wireline before perforation, and may be set a specified distance (e.g., 5 to 10 ft.) below the lowest planned perforation. 
     On top of the sump packer  402 , the screen  404  creates an annulus between the screen  404  and the production casing  416 , and the screen  404  holds the gravel  410  in place during production. Near the top of the gravel-pack assembly is a gravel-pack packer  414  that creates a hydraulic seal against the production casing  416  in order to isolate the annulus below the gravel-pack packer  414 . For example, an expandable elastomeric element may be used to form the seal between the gravel-pack assembly  400  and the production casing  416 . The gravel-pack packer  414  may be permanent or retrievable. 
     The annulus is packed with natural or synthetic gravel  410  of a specific size designed to prevent the passage of formation sand but not the passage of hydrocarbons into the production tubing  418  for transport to the surface. A slurry of gravel and carrier fluid is pumped into the perforations  406  and the annulus between the screen  404  and the perforated casing. The gravel  410  is deposited as the carrier fluid is squeezed into the formation or as it circulates back to surface through the screen  404 . As such, the gravel  410  should be large enough to be held in place by the screen  404 . 
     The gravel-pack assembly  400  includes one or more shunt tubes  408 , internal or external to the outer pipe, that create a secondary path for slurry. Multiple shunt tubes  408  may be used in the same gravel packing operation and the shunt tubes  408  may be various sizes. Larger shunt tubes  408  have relatively low friction, and therefore support higher flow rates. The shunt tubes  408  may be mounted external to the screen  404  as illustrated in detail in  FIG. 4B . 
       FIG. 4B  is a detail view of one shunt tube configuration on the gravel-pack assembly  400 . Specifically, two shunt tubes  404  are external and parallel to the screen base pipe  401  and screen base jacket  403 . The shunt tubes  404  may be made of steel or a similar rigid material. Here, the shunt tubes  404  are of similar size, but in other embodiments the shunt tubes are different lengths and have different cross-sectional diameters. A shunt tube bulkhead  409  provides fluid communication between the tubes and the inside of the production tubing. 
     The gravel-pack assembly  400  also includes one or more magnetic field generators, which generate one or more magnetic fields. For example, the one or more magnetic fields may be generated by one or more magnets  405 , as shown here, positioned on the outer diameter of the screen base pipe  401 . In other embodiments, the magnets  405  are positioned on the inner diameter of the screen base pipe  401 , embedded in the screen base pipe  401 , run down on a separate tool, and the like. The magnets  405  may be attached or otherwise secured to the screen base pipe  401  via adhesives, welding, mechanical attachments, embedding the magnets within the tubing, and the like. Additionally, although one magnet  405  is shown for ease of reference, it should be understood that multiple magnets  405  may be used, and each may be ring-shaped and positioned around the circumference of tubing. The magnet  405  generates a magnetic field that arrests released fluid, including magnetically responsive particles, within the shunt tube  404  thus creating plugs  407  that may extend farther than the end of the shunt tubes  404  as shown. The fluid may be stored and released as shown in  FIGS. 5 and 6 , the description of which also describes the fluid in detail. The description of  FIG. 7  describes the arresting process in detail. 
       FIG. 5  is a cross-sectional view of a release assembly  501  including a fluid chamber  510 . The fluid chamber  510  stores fluid  507  including magnetically responsive particles  505 . For example, the fluid  507  may be a magnetorheological fluid, ferrofluid, and the like. The fluid  507  may additionally include a polymer precursor material or similar material that forms cross-links such as plastics, adhesives, thermoplastics, thermosetting resins, elastomeric materials, polymers, epoxies, silicones, sealants, oils, gels, glues, acids, thixotropic fluids, dilatant fluids, epoxies, and the like. If the polymer precursor is an epoxy, the epoxy may be a one-part epoxy (e.g., a silicone sealant) or a multi-part epoxy. 
     The polymer precursor may be a material that can carry the magnetically responsive particles  505  and cure or otherwise set given appropriate forces, environmental conditions, or time. The polymer precursor may also return to a flowing state given appropriate forces, environmental conditions, or time for ease of unplugging. The polymer precursor may be a material that can create a seal in order to plug the shunt tube entrances and exits, and the polymer precursor may be capable of being stored downhole without having to be activated for immediate use. Any other type of polymer precursor or other material that may act as a carrier for magnetically responsive particles, and that can cure to form a seal or otherwise act as a sealant, may also be used. 
     The magnetically responsive particles  505  (which may also be referred to herein as particles  505 ) may be units of a ferromagnetic material, such as iron, nickel, cobalt, any ferromagnetic, diamagnetic, or paramagnetic particles, any combination thereof, or any other particles that can respond to a magnetic field. The particles  505  may not be easily visible in the fluid  507  due to their size, and they have thus been exaggerated in the figures for ease of viewing. However, any suitable particle size can be used for the particles  505 . For example, the particles  505  may range from the nanometer size up to the micrometer size. In one example, the particles  505  are in the size range of about 100 nanometers to about 1000 nanometers. In another example, the particles  505  range into the micrometer size, e.g., up to about 100 microns. The particles  505  may also be any shape, non-limiting examples of which include spheres, spheroids, tubulars, corpusculars, fibers, oblate spheroids, or any other appropriate shape. Multiple shapes and multiple sizes may be combined in a single group of particles  505  in the fluid  507 . 
     The fluid chamber  510  includes a release assembly  501  that releases fluid  507  stored in the fluid chamber  510  into a line  502  coupled to the shunt tube (not shown). The release assembly  501  may include a piston  508  that forces the fluid  507  out of the fluid chamber  510  during release when pressure is applied to the fluid  507  via the piston  508 . The piston  508  may have a spring engagement  506  that causes movement of the piston  508  when activated. Alternatively, the piston  508  may be driven by hydraulic fluid or a motor-driven threaded rod. The spring is used to provide pressure by keeping the piston  508  in contact with the fluid  507 . The pressure is maintained by creating a seal between the fluid chamber  510  wall and the piston  508 . This may also prevent the fluid  507  from prematurely hardening by preventing air from contacting the fluid  507  within the fluid chamber  510 . 
     A burstable disk  504  may be provided to prevent premature injection of the fluid  507  into the line  502  and shunt tube. Pressure, when applied, may cause the fluid  507  to rupture or burst the burstable disk  504  and exit the fluid chamber  510  into the line  502  through the resultant opening. Specifically, the spring engagement  506  may exert a force on the piston  508  in the direction of the fluid  507 . The force exerted on the piston  508  may cause the piston  508  to exert a force on the fluid  507  in the direction of the burstable disk  504 . The burstable disk  504  may remain closed and exert a force on the fluid  507  in a direction opposite to the direction of the force exerted by the piston  508 . Once the force exerted on the fluid  507  by the piston  508  exceeds the force able to be exerted by the burstable disk  504 , the burstable disk  504  bursts. Such bursting removes the force exerted by the burstable disk  504  on the fluid  507 . This allows the fluid  507  to flow into the line  502  and shunt tube in response to the force exerted by the piston  508 . 
     The burstable disk  504  may be a piece of foil, metal, or other material. The burstable disk may also be implemented as a dissolvable barrier that dissolves upon a certain pH exposure, environmental exposure, or other pre-selected trigger. For example, the burstable disk  504  may be formed as a temperature-sensitive material or shape-memory material that dissolves upon a certain temperature, shrinks or enlarges at a certain environmental condition, or otherwise ceases to contain the fluid  507  in the fluid chamber  510  in response to a pre-selected trigger. 
     The release assembly  501  may include a sensor to sense a remotely-generated signal, the signal initiating release of the fluid when received by the sensor. For example, the burstable disk  504  may be coupled to an electronic circuit housed within the gravel-packer or system  500  to create electronic activation of the burstable disk  504  when desired. A wireless signal may be generated remotely, sent to the circuit, and received by the circuit. The signal may be based on the pressure rise from screen out of the gravel pack, tubing movement, pressure cycles, temperature changes, or any other activating event. Another implementation of the release assembly is shown in  FIG. 6 . 
       FIG. 6  is a cross-sectional view of a release assembly  606  including a fluid chamber  604 . The release assembly  606  may include a collapsible tube  603  that forces the fluid  605  out of the fluid chamber  604  (and the collapsible tube  603  itself) during release in response to pressure external to the collapsible tube  603  that collapses the collapsible tube  603 . For example, a hydraulic pump may generate the pressure within the fluid chamber  604  through a pressure line  602 . The release assembly  606  may also include a check valve  610  coupled to the fluid exit line  608  that enables the fluid  605  to exit the fluid chamber  604  (and collapsible tube  603 ). The check valve  610  may also prevent the fluid  605  from flowing back into the fluid chamber  510  or collapsible tube  603 . 
     In addition to containing magnetically responsive particles  607 , the fluid  605  may be viscous. The fluid  605  may have a minimum yield stress before it flows, such as Bingham plastic, and it may behave as a thixotropic material, such as a gel. The fluid  605  may remain in a moveable form until a magnetic field arrests the magnetically responsive particles  607  as described with respect to  FIG. 7 . 
       FIGS. 5 and 6  show an active deployment; specifically, the fluid is forced to exit the release assemblies. However, a passive deployment is also possible. For example, the fluid may be attracted toward the magnetic fields to allow the fluid to enter the shunt tube. 
       FIG. 7  is a top-view of an illustrative system  700  for plugging a shunt tube  706  using magnetically responsive particles. A magnetic field  714  is generated by a magnetic field generator, shown here as a magnet  708 . The magnet  708  may be a disk magnet, ring-shaped magnet, block magnet, or the like. Another type of magnetic field generator may include a sensor to sense a remotely-generated signal, the signal initiating generation of and/or extinguishing the magnetic field when received by the sensor. As shown, the magnet  708  is embedded in the screen jacket  712 , which is surrounding the screen base pipe  710 . However, the magnet  708  may be disposed radially outside of the screen jacket  712  or radially inside of the screen base pipe  710 . Also, multiple magnets  708  may be disposed on the gravel packer in various such configurations to produce a magnetic fields with a particular shape to optimize shunt tube plugging for multiple shunt tubes and multiple fluid chambers. 
     Fluid containing magnetically responsive particles flows from the fluid chamber  702 , through the line  704 , and into the shunt tube  706 . In the shunt tube  706 , passage of the fluid through the magnetic field  714  causes the magnetically responsive particles to align with the magnetic field  714 . Alignment of the particles with the magnetic field  714  causes the particles to hold the fluid in place, thereby plugging the shunt tube  706 . Subsequent movement of the fluid is limited due to arrangement of the particles. Specifically, the arrangement of the particles changes the shear strength of the fluid, decreasing its viscosity. 
     Once formed, the fluid may be allowed to cure, harden, or otherwise create a seal. Any polymer precursor material may begin to cross-link. For example, the passage of time, applied heat, and/or exposure to certain fluids or environments may cause the fluid to set to form a plug within the shunt tube  706 , thereby preventing any material from passing through the shunt tube  706 . In this way, the formation fluid is forced to pass into the production tubing via the screens. Plugging the shunt tubes provides a way to isolate sections at the producing interval from one another. Without isolation, the different zone layers may communicate, allowing water zones or gas zones to flow thus preventing preferable oil flow. 
       FIG. 8  is a flow diagram of an illustrative shunt tube plugging method using magnetically responsive particles. At  802 , a shunt tube diverts the gravel slurry to bypass blockages or bridges. For example, field operators pump a slurry of gravel and carrier fluid into the perforations and the annulus between the screen and the perforated casing. The pressure from blockages diverts the slurry into shunt tubes of different sizes and cross-sectional diameters disposed on the gravel packer. The gravel is deposited as the carrier fluid enters the formation or circulates back to surface through the screen. 
     At  804 , a sensor receives a signal generated by a remote source. The signal may be generated remotely, wirelessly sent to a circuit including the sensor on the gravel packer, and wirelessly received by the circuit. The signal may be based on the pressure rise from screen out of the gravel pack, tubing movement, pressure cycles, temperature changes, or any other activating event. 
     At  806 , in response to the received signal, fluid chambers release fluid, including magnetically responsive particles, into the shunt tubes. Multiple fluid chambers may be coupled to multiple shunt tubes in various configurations. For example, multiple fluid chambers may release fluid into a single shunt tube, one fluid chamber may release fluid into multiple shunt tubes, and the like. Burstable disks or check valves may be coupled to electronic circuits housed within the gravel packer to create electronic activation of the burstable disks or check valves when desired. The disks may burst and the check valves may open in response to the electronic activation. 
     At  808 , magnetic field generators generate magnetic fields to activate the magnetically responsive particles. Once activated, the fluids released into the shunt tubes are arrested, thereby plugging the shunt tubes. Specifically, passage of the fluids through the magnetic fields cause the magnetically responsive particles to align with the magnetic fields. Alignment of the particles with the magnetic fields causes the particles to hold the fluids in place because the arrangement of the particles changes the shear strength of the fluids, decreasing the viscosity. Once formed, the fluids may be allowed to cure, harden, or otherwise create a seal. Any polymer precursor material may begin to cross-link. For example, the passage of time, applied heat, and/or exposure to certain fluids or environments may cause the fluids to form plugs within the shunt tubes, thereby preventing any material from passing through the shunt tubes. In this way, the gravel packer may isolate a zone of the annulus without open shunt tubes. 
     In at least one embodiment, the gravel slurry may include a second set of magnetically responsive particles, and the method  800  may include arresting the gravel slurry by activating the second set of magnetically responsive particles using the one or more magnetic fields. 
     In at least one embodiment, a borehole packer includes a shunt tube and a fluid chamber coupled to the shunt tube. The fluid chamber includes a release assembly that releases fluid stored in the fluid chamber into the shunt tube. The fluid includes magnetically responsive particles. The packer also includes one or more magnetic field generators that generate one or more magnetic fields that arrest released fluid within the shunt tube by activating the magnetically responsive particles, thereby plugging the shunt tube. 
     In another embodiment, a method of performing a gravel packing operation within a borehole includes releasing fluid including magnetically responsive particles into a shunt tube. The method further includes plugging the shunt tube by activating the magnetically responsive particles to arrest the fluid released into the shunt tube. 
     The following features may be incorporated into the various embodiments described above, such features incorporated either individually in or conjunction with one or more of the other features. The one or more magnetic fields may be generated by one or more magnets. The release assembly may include a sensor to sense a remotely-generated signal, the signal initiating release of the fluid when received by the sensor. The one or more magnetic field generators may include a sensor to sense a remotely-generated signal, the signal initiating generation of the one or more magnetic fields when received by the sensor. The gravel slurry may include a second set of magnetically responsive particles, and the one or more magnetic fields may arrest the gravel slurry by activating the second set of magnetically responsive particles. The packer may also include a gravel screen, and the fluid chamber may be external to the screen. The release assembly may include a check valve that enables the fluid to exit the fluid chamber and prevents the fluid from entering the fluid chamber. The release assembly may include a piston that forces the fluid out of the fluid chamber during release. The release assembly may include a collapsible tube that forces the fluid out of the fluid chamber during release in response to pressure external to the collapsible tube that collapses the tube. A hydraulic pump may generate the pressure. The release assembly may include a burstable disk responsive to pressure within the fluid chamber that bursts the disk and enables fluid to exit the fluid chamber. The packer may include a second shunt tube. The fluid chamber may be coupled to the second shunt tube, and the release assembly may release the fluid into the second shunt tube. The one or more magnetic fields may arrest released fluid within the second shunt tube by activating the magnetically responsive particles, thereby plugging the second shunt tube. The packer may include a second fluid chamber sharing the release assembly with the fluid chamber. Releasing the fluid may include releasing the fluid after gravel transported by a gravel slurry is placed. Releasing the fluid may include releasing the fluid as a result of receiving a signal generated from a remote source. Plugging the shunt tube may include isolating a zone of an annulus of the borehole. Plugging the shunt tube may include generating one or more magnetic fields to activate the magnetically responsive particles. Generating the one or more magnetic fields may include generating the one or more magnetic fields as a result of receiving a signal generated from a remote source. The gravel slurry may include a second set of magnetically responsive particles, and the method may include arresting the gravel slurry by activating the second set of magnetically responsive particles using the one or more magnetic fields. 
     While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations.