Patent Publication Number: US-2015068772-A1

Title: Downhole Ball Dropping Systems and Methods with Redundant Ball Dropping Capability

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119 of the filing date of International Application No. PCT/US2013/058952, filed Sep. 10, 2013. 
     TECHNICAL FIELD OF THE DISCLOSURE 
     This disclosure relates, in general, to equipment utilized in conjunction with operations performed in relation to subterranean wells and, in particular, to downhole systems and methods for the deployment and use of one or more balls for the actuation of downhole tools. 
     BACKGROUND OF THE DISCLOSURE 
     Without limiting the scope of the present disclosure, its background is described with reference to actuating a downhole tool responsive to tubing pressure applied against a ball disposed in a ball seat, as an example. 
     It is well known in the subterranean well drilling and completion art to locate a downhole tool string within a casing, liner or production tubing to perform desired operations. Such a tool string may incorporate a variety of tools including sliding sleeves, circulating subs, packers and the like. Once the tool string is properly positioned downhole, actuation of one or more of the downhole tools in the string may be desired. One method to actuate such downhole tools involves deployment of a ball operable to travel down the tool string and engage a ball seat within the downhole tool or an associated setting tool. Thereafter, tubing pressure may be applied to actuate the downhole tool. For example, in the case of a packer, the ball may engage a seat in a packer setting tool. The fluid pressure is then increased above a certain threshold to actuate the packer setting tool, which in turn sets the packer to engage the casing, liner or production tubing. 
     Typically, the ball used to actuate the downhole tool is deployed from the surface. The ball must then be gravity feed or pumped through the pipe string until it reaches the downhole seat. It has been found, however, that although such a method works in many circumstances, there are several drawbacks to this method. For example, deployment of a ball from the surface is a time-consuming and costly process. In addition, deployment of a ball from the surface may result in the ball becoming stuck or lost in the pipe string or otherwise never making it to the downhole seat. Further, to ensure that the ball can be displaced from the surface to the downhole seat, all of the tools and components in the pipe string above the downhole seat must be free from restrictions that would prevent the ball from passing therethrough. 
     Accordingly, a need has arisen for an improved system and method for deploying a ball for engagement with a ball seat to enable actuation of a downhole tool. A need has also arisen for such an improved system and method for deploying a ball that does not require gravity feeding or pumping the ball from the surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the features and advantages of the present disclosure, reference is now made to the detailed description of the disclosure along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which: 
         FIGS. 1A-1D  are schematic illustrations of a downhole ball dropping system according to an embodiment of the present disclosure in various operating configurations; 
         FIGS. 2A-2D  are schematic illustrations of a downhole ball dropping system according to an embodiment of the present disclosure in various operating configurations; 
         FIG. 3  is a process flow diagram of a downhole ball dropping method according to an embodiment of the present disclosure; 
         FIGS. 4A-4M  are schematic illustrations of various embodiments of actuators that are operable for use in downhole ball dropping systems according to the present disclosure; and 
         FIG. 5  is a perspective illustration of a ball release mechanism for use in a downhole ball dropping system according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     While various system, method and other embodiments are discussed in detail below, it should be appreciated that the present disclosure provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative, and do not delimit the scope of the present disclosure. 
     In one aspect, the present disclosure is directed to a downhole ball dropping system that is operable to be positioned in a well. The system includes a tool string having a flow path. First and second ball dropper assemblies are interconnected in the tool string. The first ball dropper assembly releasably retains a first ball and the second ball dropper assembly releasably retains a second ball. A sensor is operable to detect deployment of the first ball and is operable to generate a signal to prevent release of the second ball from the second ball dropper assembly. 
     In one embodiment, the second ball dropper assembly may be positioned downhole of the first ball dropper assembly. In another embodiment, the second ball dropper assembly may be circumferentially positioned relative to the first ball dropper assembly. In some embodiments, the sensor may be operable to detect the first ball passing through the flow path after release thereof by the first ball dropper assembly. For example, the first ball may be a magnetic device and the sensor may detect a change in a magnetic field. Alternatively, the first ball may include an RFID tag and the sensor may be an RFID reader. In certain embodiments, the sensor may be operable to detect release of the first ball from first ball dropper assembly. 
     In another aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path, a first ball dropper assembly interconnected in the tool string and releasably retaining a first ball and a second ball dropper assembly interconnected in the tool string and releasably retaining a second ball; sending a deployment signal to the first ball dropper assembly to release the first ball; detecting deployment of the first ball with a downhole sensor; and generating a deactivation signal from the downhole sensor to prevent release of the second ball from the second ball dropper assembly. 
     The method may also include sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof; detecting the first ball passing through the flow path after release thereof by the first ball dropper assembly; detecting a change in a magnetic field; detecting an RFID tag; detecting release of the first ball from the first ball dropper assembly; and/or sending a deployment signal from the downhole sensor to at least one of a surface controller and a downhole component. 
     In a further aspect, the present disclosure is directed to a downhole ball dropping system that is operable to be positioned in a well. The system includes a tool string having a flow path. A first ball dropper assembly is interconnected in the tool string. The first ball dropper assembly releasably retains a first ball. A first actuation assembly is operably associated with the first ball dropper assembly. The first actuation assembly is operated responsive to a deployment signal of a first type. A second ball dropper assembly is interconnected in the tool string. The second ball dropper assembly releasably retains a second ball. A second actuation assembly is operably associated with the second ball dropper assembly. The second actuation assembly is operated responsive to a deployment signal of a second type, wherein, the deployment signal of the second type is different from the deployment signal of the first type, thereby providing independent and redundant ball deployment capability. 
     In one embodiment, the second ball dropper assembly may be positioned downhole of the first ball dropper assembly. In another embodiment, the second ball dropper assembly may be circumferentially positioned relative to the first ball dropper assembly. In some embodiments, the deployment signal of the first type and the deployment signal of the second type may each be selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof. 
     In yet another aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path, a first ball dropper assembly interconnected in the tool string and releasably retaining a first ball and a second ball dropper assembly interconnected in the tool string and releasably retaining a second ball; sending a deployment signal of a first type to the first ball dropper assembly to release the first ball; determining deployment of the first ball failed with a downhole sensor; and sending a deployment signal of a second type to the second ball dropper assembly to release the second ball, wherein, the deployment signal of the second type is different from the deployment signal of the first type, thereby providing independent and redundant ball deployment capability. 
     The method may also include sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof; detecting the first ball has not passing through the flow path downhole of the first ball dropper assembly; detecting no a change in a magnetic field; detecting no RFID tag; detecting a failure to release the first ball from the first ball dropper assembly; and/or sending a deployment failure signal from the downhole sensor to at least one of a surface controller and a downhole component. 
     In an additional aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path and a ball dropper assembly interconnected in the tool string that releasably retains a ball; sending a deployment signal to the ball dropper assembly to release the ball; shifting a piston of a release assembly in the ball dropper assembly; pushing the ball out of the ball dropper assembly through a port with the release assembly; sensing operation of the release assembly and closing the port. 
     In another aspect, the present disclosure is directed to a downhole ball dropping system that is operable to be positioned in a well. The system includes a tool string having a flow path. A ball dropper assembly is interconnected in the tool string. The ball dropper assembly releasably retains a ball. An actuation assembly is operably associated with the ball dropper assembly. The actuation assembly is operated responsive to a deployment signal. A release assembly including a piston is disposed within the ball dropper assembly. A sensor is operably associated with the ball dropper assembly. Responsive to the deployment signal, the actuation assembly triggers operation of the release assembly, the release assembly pushes the ball into the flow path through a port of the ball dropper assembly, the sensor senses operation of the release assembly and the port of the ball dropper assembly is closed. 
     In a further aspect, the present disclosure is directed to a downhole ball dropping method. The method includes positioning a downhole ball dropping system in a well, the downhole ball dropping system including a tool string having a flow path and a ball dropper assembly interconnected in the tool string and releasably retaining a ball; sending a deployment signal to the ball dropper assembly to release the ball; determining whether the ball deployed from the ball dropper assembly with a downhole sensor; and sending a signal from the downhole sensor to at least one of a surface controller and a downhole component indicating whether the ball deployed. 
     The method may also include sending a deployment signal selected from the group consisting of a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal and combinations thereof; detecting whether the ball has passed through the flow path downhole of the ball dropper assembly; determining whether there is a change in a magnetic field; determining whether an RFID tag is detected; and/or detecting whether the ball was released from the ball dropper assembly. 
     Referring now to  FIGS. 1A-1D , a tool string is being positioned in an interval of a wellbore that is generally designated  10 . Tool string  12  is being run in wellbore  10  on a conveyance such as a string of jointed tubing, a string of drill pipe, a coiled tubing string or the like. Wellbore  10  extends through the various earth strata including formation  14 . A casing  16  is positioned within wellbore  10  and may be secured therein by cement. Casing  16  includes a plurality of perforations  18 . In the illustrated embodiment, tool string  12  has been stabbed into a sump packer  20 . Tool string  12  has a central fluid flow path  22  indicated in phantom lines. In the illustrated embodiment, tool string  12  includes a sand control screen assembly  24 , a ball seat assembly  26  including a ball seat  28  indicated in phantom lines, a crossover assembly  30 , a packer assembly  32 , a setting assembly  34  including a ball seat  36  indicated in phantom lines, a ball dropper assembly  38  including a ball  40 , an actuator  42  and a sensor assembly  44 , and a ball dropper assembly  46  including a ball  48 , an actuator  50  and a sensor assembly  52 . 
     Even though  FIG. 1  depicts the tool string of the present disclosure as having a particular arrangement of tools, it should be understood by those skill in the art that tool strings having other arrangements of a greater number or lesser number of tools as well as tool strings having different tools requiring ball activation or ball interaction may alternatively be used. Also, even though  FIG. 1  depicts the tool string of the present disclosure in a vertical wellbore, it should be understood by those skilled in the art that the tool string of the present disclosure is equally well suited for use in wellbores having other directional configurations including horizontal wellbores, deviated wellbores, slanted wells, lateral wells and the like. In such wells, in addition to or as an alternative to gravity feeding, the balls may be moved within the central fluid flow path by a moving fluid. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward, uphole, downhole and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction being toward the surface of the well and the downhole direction being toward the toe of the well. Further, even though the present description has referred to ball dropper assemblies, balls and ball seats, it is to be understood by those skilled in the art that the term “ball” as used herein will be inclusive of other flowable objects suitable for actuating downhole tools, which may or may not be spherical including, but not limited to, darts and plugs. In addition, the balls used in the systems may be made from a single material such as metal or may be formed from multiple materials such as a rubber exterior with a plastic or metal core. Alternatively or additionally, the balls may be formed from a material that dissolves over time including balls having nanosized elements therein. 
     Referring specifically to  FIG. 1B , therein is depicted a ball dropping operation of the present disclosure. It should be noted that ball  48  may be used to perform a variety of functions in the well such as plug the tubing to allow pressure build up to actuate a piston setting tool to set a packer, plug the tubing to allow tubing pressure build up to set a hydraulic packer or otherwise actuate a tool, plug the tubing to change a flow path therethrough, for example, to direct proppant flow out into the annulus between the casing and completion hardware, change or reconfigure the flow path of the service tool for a particular operation such as an acid treatment as well as other functions known to those skilled in the art. As illustrated, ball  48  has been deployed from ball dropper assembly  46  into wellbore  10  and ball seat  36 . As discussed in greater detail below, ball  48  is released from ball dropper assembly  46  responsive to operation of actuator  50 . Actuator  50  may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. More specifically, once tool string  10  has stabbed into sump packer  20  and it is desired to set packer assembly  32 , the deployment signal is sent to actuator  50  of ball dropper assembly  46 . The deployment signal causes actuation of actuator  50 , which in turn causes release of ball  48  into flow path  22 . Gravity, fluid flow or a combination thereof, then causes ball  48  to travel downhole and engage ball seat  36  of setting assembly  34 . Once ball  48  is positioned in ball seat  36 , fluid pressure acting on ball  48  may be used to set packer assembly  32 . 
     As best seen in  FIG. 1C , once packer assembly  32  has been set, additional pressure within flow path  22  may be used to cause ball  48  to pass through ball seat  36  and travel to ball seat  28  in ball seat assembly  26 . In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen  24  and perforations  18  through cross over assembly  30 . Thereafter, additional pressure within flow path  22  may be used to cause ball  48  to pass through ball seat  28  or return flow may be used to retrieve ball  48  to the surface or other secure location. 
     During the process of ball activation of downhole tools, it is important to know whether a ball has been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. For example, sensor  52  of ball dropper assembly  46  is operable to determine whether ball dropper assembly  46  has released ball  48  into flow path  22 . Sensor  52  may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying whether ball  48  is located within ball dropper assembly  46 , whether ball  48  has passed through a particular location of ball dropper assembly  46  or both. Regardless of the sensing means, if sensor  52  determines that ball  48  has been released into flow path  22 , sensor  52  is operable to provide a signal that indicates ball  48  has been released into flow path  22 . Depending upon the configuration of tool string  12 , this signal may be sent to a surface controller via a wellbore telemetry system or, as illustrated, the signal may be sent directly to ball dropper assembly  38  via a wired downhole communication network  54 . Alternatively, the signal may be sent from sensor  52  to ball dropper assembly  38  via a wireless downhole communication system such as via acoustic communication. 
     As illustrated, sensor  52  and actuator  50  of ball dropper assembly  46  and sensor  44  and actuator  42  of ball dropper assembly  38  are nodes in wired downhole communication network  54 . Preferably, the signal indicating ball  48  has been released into flow path  22  is received by sensor  44  and/or actuator  42  of ball dropper assembly  38 . Either or both of sensor  44  and actuator  42  may include a downhole processor operably to interpret the signal and cause deactivation of ball dropper assembly  38  such that ball  40  will not be released into flow path  22 . In this embodiment, the signal from sensor  52  indicating ball  48  has been released into flow path  22  may be referred to as a deactivation signal operable to prevent release a redundant ball; namely ball  40 , into flow path  22 . In this manner, proper deployment of ball  48  into flow path  22  prevents a subsequent unwanted deployment of ball  40  into flow path  22 . 
     Alternatively or additionally, sensor  44  of ball dropper assembly  38  may be operable to determine whether ball  48  of ball dropper assembly  46  has entered flow path  22  and traveled past sensor  44 . Sensor  44  may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying the passing of ball  48  in flow path  22  proximate sensor  44 . 
     In one embodiment, ball  48  may be a magnetic device that includes one or more permanent magnets disposed within or on the surface of ball  48 . In this embodiment, sensor  44  may be a giant magneto-resistive (GMR) sensor, a Hall-effect sensor, conductive coils or the like. Permanent magnets can be combined with sensor  44  in order to create a magnetic field that is disturbed by ball  48 . A change in the magnetic field can be detected by sensor  44  as an indication of the presence or in this case the passage of ball  48 . 
     Sensor  44  may include electronic circuitry which determines whether the sensor has detected a particular predetermined magnetic field, or pattern or combination of magnetic fields, or other magnetic properties of ball  48 . For example, the electronic circuitry could have the predetermined magnetic field(s) or other magnetic properties programmed into non-volatile memory for comparison to magnetic fields/properties detected by sensor  44 . The electronic circuitry could be supplied with electrical power via an on-board battery, a downhole generator, or any other electrical power source. 
     In one example, the electronic circuitry could include a capacitor, wherein an electrical resonance behavior between the capacitance of the capacitor and sensor  44  changes, depending on whether ball  48  is present. In another example, the electronic circuitry could include an adaptive magnetic field that adjusts to a baseline magnetic field of the surrounding environment such as the formation, the surrounding metallic structures or the like. The electronic circuitry could determine whether the measured magnetic fields exceed the adaptive magnetic field level. In a further example, sensor  44  could comprise an inductive sensor, which can detect the presence of a metallic device by, for example, detecting a change in a magnetic field. In this case, ball  48  need not contain a magnetic element or elements, however, ball  48  can still be considered a magnetic device, in the sense that it conducts a magnetic field and produces changes in a magnetic field, which can be detected by sensor  44 . 
     In another embodiment, ball  48  may contain an electrical circuit such as, but not limited to, a passive or active radio frequency identification (RFID) tag. In the case of ball  48  containing a passive RFID tag, sensor  44  may include a transmitter operable to transmit an alternating current electromagnetic signal into flow path  22 . As ball  48  passes sensor  44 , the electrical circuit of ball  44  generates an electromagnetic signal responsive to the alternating current electromagnetic signal. A receiver of sensor  44  is operable to receive the responsive signal from the electrical circuit. The passive tag circuits have no internal power source, such as a battery. They contain an electromagnetic or electronic coil that can be excited by a particular frequency of electromagnetic energy transmitted from the transmitter of sensor  44 . The electromagnetic energy transmitted from the transmitter to the coil momentarily excites the coil causing the electrical circuit to transmit the contents of its buffer, such as some stored value unique to that particular tag. The transmitted information is then detected by the receiver of sensor  44 . 
     In the case of ball  48  containing an active RFID tag, the electrical circuit carried by ball  48  generates and transmits an electromagnetic signal. In this case, sensor  44  requires only an RFID reader or receiver operable to receive the electromagnetic signal from the electrical circuit. The active tag circuits contain an internal power source, typically a long life battery. The active tag can have read and write capability, allowing its internal operating program and other information to be remotely updated or changed as required. The active tag&#39;s memory can store, for example, several kilobytes information for future recall such as serial numbers, lot numbers, build dates, expiration dates and the like. Additionally, an active tag can be designed to transmit without initiation or interrogation by a transmitter. In this manner, the active tag, under its own power and circuit design or programmed control can self-generate an identifying electromagnetic signal that is detected by the receiver of sensor  44 . 
     Regardless of the sensing means, if sensor  44  determines that ball  48  has traveled past ball dropper assembly  38 , sensor  44  is operable to provide a deactivation signal such that ball  40  will not be released into flow path  22 . In this manner, proper deployment of ball  48  into flow path  22  prevents a subsequent unwanted deployment of ball  40  into flow path  22 . 
     During the process of ball activation of downhole tools, it is important to know whether a ball has not been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. As described above, sensor  52  and/or sensor  44  are operable to determine whether ball  48  has been deployed from ball dropper assembly  46  into flow path  22 . In the event that the active sensor or sensors determine that ball  48  has not been deployed from ball dropper assembly  46  into flow path  22 , the present disclosure includes a second and redundant ball; namely ball  40 , in ball dropper assembly  38  that is operable for use in actuating downhole tools such as packer assembly  32  and cross over assembly  30 . In this case, ball  40  is released from ball dropper assembly  38  responsive to operation of actuator  42 . Actuator  42  may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. Preferably, actuator  42  and the required actuation signal for actuator  42  are different from actuator  50  and the required actuation signal for actuator  50 . This is preferred as the cause of the failure of ball deployment from ball dropper assembly  46  may also cause a failure in ball dropper assembly  38  if the same type of actuator and same type of actuation signal are used. 
     As illustrated in  FIG. 1D , if it is determine that ball  48  has not been deployed from ball dropper assembly  46  into flow path  22  by sensor  52  and/or sensor  44 , then ball dropper assembly  38  is sent a deployment signal and ball  40  is deployed from ball dropper assembly  38  into flow path  22 . Gravity, fluid flow or a combination thereof, then causes ball  40  to travel downhole and engage ball seat  36  of setting assembly  34 . Once ball  40  is positioned in ball seat  36 , fluid pressure acting on ball  40  may be used to set packer assembly  32 . Thereafter, additional pressure within flow path  22  may be used to cause ball  40  to pass through ball seat  36  and travel to ball seat  28  in ball seat assembly  26 . In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen  24  and perforations  18  through cross over assembly  30 . Thereafter, additional pressure within flow path  22  may be used to cause ball  40  to pass through ball seat  28  or return flow may be used to retrieve ball  40  to the surface or other secure location. It is noted that tool string  12  could have one or more additional and redundant ball dropper assemblies that could be used to deploy a redundant ball into flow path  22  in a manner similar to that of ball  40 . 
     Referring next  FIGS. 2A-2D , a tool string is being positioned in an interval of a wellbore that is generally designated  110 . Tool string  112  is being run in wellbore  110  on a conveyance such as a string of jointed tubing, a string of drill pipe, a coiled tubing string or the like. Wellbore  110  extends through the various earth strata including formation  114 . A casing  116  is positioned within wellbore  110  and may be secured therein by cement. Casing  116  includes a plurality of perforations  118 . In the illustrated embodiment, tool string  112  has been stabbed into a sump packer  120 . Tool string  112  has a central fluid flow path  122  indicated in phantom lines. In the illustrated embodiment, tool string  112  includes a sand control screen assembly  124 , a ball seat assembly  126  including a ball seat  128  indicated in phantom lines, a crossover assembly  130 , a packer assembly  132 , a setting assembly  134  including a ball seat  136  indicated in phantom lines, a ball dropper assembly  138  including two balls  140 ,  141 , two actuators  142 ,  143  and two sensor assemblies  144 ,  145  and a ball dropper assembly  146  including two balls  148 ,  149 , two actuators  150 ,  151  and two sensor assemblies  152 ,  153 . 
     Referring specifically to  FIG. 2B , therein is depicted a ball dropping operation of the present disclosure. As illustrated, ball  140  from ball dropper assembly  138  has been deployed in wellbore  110  to ball seat  136 . As discussed in greater detail below, ball  140  is released from ball dropper assembly  138  responsive to operation of actuator  142 . Actuator  142  may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof More specifically, once tool string  110  has stabbed into sump packer  120  and it is desired to set packer assembly  132 , the deployment signal is sent to actuator  142  of ball dropper assembly  138 . The deployment signal causes actuation of actuator  142 , which in turn causes release of ball  140  into flow path  122 . Gravity, fluid flow or a combination thereof, then causes ball  140  to travel downhole and engage ball seat  136  of setting assembly  134 . Once ball  140  is positioned in ball seat  136 , fluid pressure acting on ball  140  may be used to set packer assembly  132 . 
     During the process of ball activation of downhole tools, it is important to know whether a ball has been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. For example, sensor  144  of ball dropper assembly  138  is operable to determine whether ball dropper assembly  138  has released ball  140  into flow path  122 . Sensor  144  may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying whether ball  140  is located within ball dropper assembly  138 , whether ball  140  has passed through a particular location of ball dropper assembly  138 , whether ball  140  has passed through a particular location in flow path  122  or combinations thereof Regardless of the sensing means, if sensor  144  determines that ball  140  has been released into flow path  122 , sensor  144  is operable to provide a signal that indicates ball  140  has been released into flow path  122 . Depending upon the configuration of tool string  112 , this signal may be sent to the surface, sent to another downhole tool or, as illustrated, the signal can be processed by ball dropper assembly  138  to deactivate the portion of ball dropper assembly  138  responsible for release of ball  141  into flow path  122 . In this manner, proper deployment of ball  140  into flow path  122  prevents a subsequent unwanted deployment of ball  141  into flow path  122 . 
     During the process of ball activation of downhole tools, it is important to know whether a ball has not been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. As described above, sensor  144  is operable to determine whether ball  140  has been deployed from ball dropper assembly  138  into flow path  122 . In the event that sensor  144  determines that ball  140  has not been deployed from ball dropper assembly  138  into flow path  122 , the present disclosure includes a second and redundant ball; namely ball  141  in ball dropper assembly  138  that is operable for use in actuating downhole tools such as packer assembly  132 . In this case, ball  141  is released from ball dropper assembly  138  responsive to operation of actuator  143 . Actuator  143  may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. Preferably, actuator  143  and the required actuation signal for actuator  143  are different from actuator  142  and the required actuation signal for actuator  142 . This is preferred as the cause of the failure of deployment of ball  140  may also cause a failure of deployment of ball  141  if the same type of actuator and same type of actuation signal are used. 
     As illustrated in  FIG. 2C , if it is determine that ball  140  has not been deployed from ball dropper assembly  138  into flow path  122  by sensor  144 , then ball dropper assembly  138  is sent a deployment signal and ball  141  is deployed from ball dropper assembly  138  into flow path  122 . Gravity, fluid flow or a combination thereof, then causes ball  141  to travel downhole and engage ball seat  136  of setting assembly  134 . Once ball  141  is positioned in ball seat  136 , fluid pressure acting on ball  141  may be used to set packer assembly  132 . It is noted that ball dropper assembly  138  could have one or more additional and redundant balls which could be deployed into flow path  122  in a manner similar to that of ball  141 . In addition, it is noted that tool string  112  could have one or more additional and redundant ball dropper assemblies that could be used to deploy a redundant ball into flow path  122  in a manner similar to that of ball  141 . Even though ball dropper assembly  138  has been referred to as a single ball dropper assembly, ball dropper assembly  138  could alternatively be viewed as including two ball dropper assemblies, the first ball dropper assembly operable to retain and release ball  140  and the second ball dropper assembly operable to retain and release ball  141 . 
     Whether by ball  140  or ball  141 , once packer assembly  132  has been set, additional pressure within flow path  122  may be used to cause ball  140  or ball  141  to pass through ball seat  136  as well as ball seat  128  in ball seat assembly  126 , which requires a larger ball than ball  140  or ball  141 , in the illustrated embodiment. Alternatively, return flow may be used to retrieve ball  140  or ball  141  to the surface or other secure location. Thereafter, as best seen in  FIG. 2D , ball  148  may be deployed from ball dropper assembly  146  to ball seat  128 . Ball  148  is released from ball dropper assembly  146  responsive to operation of actuator  150 . Actuator  150  may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. The deployment signal causes actuation of actuator  150 , which in turn causes release of ball  148  into flow path  122 . Gravity, fluid flow or a combination thereof, then causes ball  148  to travel downhole and engage ball seat  128  of ball seat assembly  126 . In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen  124  and perforations  118  through cross over assembly  130 . Thereafter, additional pressure within flow path  122  may be used to cause ball  148  to pass through ball seat  128  or return flow may be used to retrieve ball  148  to the surface or other secure location. 
     During the process of ball activation of downhole tools, it is important to know whether a ball has been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. For example, sensor  152  of ball dropper assembly  146  is operable to determine whether ball dropper assembly  146  has released ball  148  into flow path  122 . Sensor  152  may be a mechanical sensor, an electrical sensor, an optical sensor, a magnetic sensor or the like that is capable of identifying whether ball  148  is located within ball dropper assembly  146 , whether ball  148  has passed through a particular location of ball dropper assembly  146 , whether ball  148  has passed through a particular location in flow path  122  or combinations thereof. Regardless of the sensing means, if sensor  152  determines that ball  148  has been released into flow path  122 , sensor  152  is operable to provide a signal that indicates ball  148  has been released into flow path  122 . Depending upon the configuration of tool string  112 , this signal may be sent to the surface, sent to another downhole tool or, as illustrated, the signal can be processed by ball dropper assembly  146  to deactivate the portion of ball dropper assembly  146  responsible for release of ball  149  into flow path  122 . In this manner, proper deployment of ball  148  into flow path  122  prevents a subsequent unwanted deployment of ball  149  into flow path  122 . 
     During the process of ball activation of downhole tools, it is important to know whether a ball has not been deployed into the flow path of the tool string. In the present disclosure, sensors and systems are incorporated into the tool string to accomplish this operation. As described above, sensor  152  is operable to determine whether ball  148  has been deployed from ball dropper assembly  146  into flow path  122 . In the event that sensor  152  determines that ball  148  has not been deployed from ball dropper assembly  146  into flow path  122 , the present disclosure includes a second and redundant ball; namely ball  149  in ball dropper assembly  146  that is operable for use in actuating downhole tools such as cross over assembly  130 . In this case, ball  149  is released from ball dropper assembly  146  responsive to operation of actuator  151 . Actuator  151  may be actuated responsive to a deployment signal sent from the surface or generated downhole such as a mechanical signal, a pressure signal, an acoustic signal, an optical signal, an electrical signal, a temperature signal, a displacement signal, a time delay signal or combinations thereof. Preferably, actuator  151  and the required actuation signal for actuator  151  are different from actuator  150  and the required actuation signal for actuator  150 . This is preferred as the cause of the failure of deployment of ball  148  may also cause a failure of deployment of ball  149  if the same type of actuator and same type of actuation signal are used. 
     If it is determine that ball  148  has not been deployed from ball dropper assembly  146  into flow path  122  by sensor  152 , then ball dropper assembly  146  is sent a deployment signal and ball  149  is deployed from ball dropper assembly  146  into flow path  122  (not pictured). Gravity, fluid flow or a combination thereof, then causes ball  149  to travel downhole and engage ball seat  128  of ball seat assembly  126 . In this position, a gravel pack operation may be performed to gravel pack the production interval associated with sand control screen  124  and perforations  118  through cross over assembly  130 . Thereafter, additional pressure within flow path  122  may be used to cause ball  149  to pass through ball seat  128  or return flow may be used to retrieve ball  149  to the surface or other secure location. It is noted that ball dropper assembly  146  could have one or more additional and redundant balls which could be deployed into flow path  122  in a manner similar to that of ball  149 . In addition, it is noted that tool string  112  could have one or more additional and redundant ball dropper assemblies that could be used to deploy a redundant ball into flow path  122  in a manner similar to that of ball  149 . 
     Referring next to  FIG. 3 , a process flow diagram generally designated  200 , depicts a method for actuating a downhole tool using a downhole ball dropping system according to an embodiment of the present disclosure. The process begins by positioning the downhole ball dropping system in a well at step  202 . Once properly positioned in the well and it is desired to operate a downhole tool that requires ball interaction, a deployment signal is sent to actuate an actuator to cause release of a ball by a ball dropper assembly into the flow path at step  204 . The deployment signal may be a sent from a surface controller or may be generated downhole as described above. One or more sensors then determine whether a ball has been properly deployed in decision  206 . If the sensor determines that a ball has been properly deployed, the sensor generates one or more deactivation signals to prevent release of any redundant balls from a ball dropper assembly into the flow path in step  208 . The deactivation signals may be sent directly to the appropriate ball dropper assembly or assemblies and may alternatively or additionally be sent to the surface controller. If the deactivation signal is first sent to the surface controller, the well operator may acknowledge the received signal and then send one or more deactivation signals to the appropriate ball dropper assembly or assemblies as required. The process then progresses to actuating the downhole tool with the deployed ball in step  210 . If in decision  206  the sensor determines that a ball has not been properly deployed, the sensor generates a signal indicative of this failure, which is preferably sent to the surface controller where it is determined whether a redundant ball is available in a ball dropper assembly in decision  212 . If the failure signal is sent to the surface controller, the well operator may acknowledge the received signal before moving to the next step. If no redundant ball is available, the process ends. If a redundant ball is available, a signal is sent, for example from the surface controller, to actuate an actuator to cause release of a redundant ball from a ball dropper assembly into the flow path at step  214 . The process then returns to decision  206  to determine whether a ball has been properly deployed and a single indicating whether the ball has been deployed may be sent to the surface controller. The process can continue until either, a redundant ball is properly deployed, a deactivation signal is sent and the downhole tool is actuated or no redundant balls are available. 
     Referring next to  FIGS. 4A-4M , therein are depicted schematic illustrations of various actuators that are operable for use in the downhole ball dropper assemblies of the present disclosure. In  FIG. 4A , actuator  300  includes an outer housing  302  and an inner sleeve  304  having a ball release opening  306 . Outer housing  302  and inner sleeve  304  are initially secured together with a shearable member depicted as shear screw  308  Inner sleeve  304  is threadably coupled to a lower connector  310 . In the illustrated embodiment, a cylindrical region  312  is formed between outer housing  302  and inner sleeve  304 . A ball ramp  314  is sealably positioned in cylindrical region  312  and is preferably secured to outer housing  302 . Ball ramp  314  includes a fluid passageway  316  having a metering valve circuit  318  positioned therein. A fluid chamber  320  is defined between the lower end of ball ramp  314 , outer housing  302  and inner sleeve  304 . A viscous fluid such as oil is contained within fluid chamber  320 . In addition, a return spring  322  is positioned within fluid chamber  320 . A mandrel  324  is securably coupled to outer housing  302 . Mandel  324  includes a spring loaded ball support member  326 . A ball  328  is initially coupled to ball support  326  by a magnetic coupling, a shearable member or the like. One or more sensors  330  are located in proximity to ball  328  and are operable to provide a signal that indicates ball  328  has or has not been released into the flow path as described above. 
     In operation, actuator  300  releases ball  328  responsive to a mechanical deployment signal. Specifically, when the tool string including actuator  300  is positioned in the well and it is desired to deploy ball  328  into the flow path of the tool string, weight is applied on mandrel  324 . When sufficient shear force is generated between outer housing  302  and inner sleeve  304 , shear screw  308  is broken. Thereafter, the outer housing  302 , ball ramp  314  and mandrel  324  are shiftable relative to inner sleeve  304 . The downward force on mandrel  304  now compresses spring  322  and is counteracted by the fluid moving through metering valve circuit  318  to require a predetermined amount of time for this operation. As outer housing  302 , ball ramp  314  and mandrel  324  move downwardly relative to inner sleeve  304 , ball  328  becomes aligned with ball release opening  306  of inner sleeve  304  and ball  328  is released from ball support member  326 , through ball release opening  306  and into the flow path of the tool string. After deployment of ball  328 , release of weight on mandrel  324  allows spring  322  to return outer housing  302 , ball ramp  314  and mandrel  324  substantially to their run in positions. 
     In  FIG. 4B , actuator  330  includes an outer housing  332  and an inner sleeve  334  having a ball release opening  336 . Outer housing  332  includes a fluid passageway  338  that is in fluid communication with the annulus when actuator  300  is positioned in the well. Outer housing  302  is threadably coupled to a lower connector  340 . In the illustrated embodiment, a cylindrical region  342  is formed between outer housing  332  and inner sleeve  334 . A ball ramp  344  is positioned in a lower portion of cylindrical region  342  and a ball release assembly  346  is positioned in an upper portion of cylindrical region  342 . Ball release assembly  346  has a cylindrical chamber  348  that is in fluid communication with fluid passageway  338 . A piston  350  is sealably disposed within cylindrical chamber  348  and is initially secured therein with a shearable member depicted as shear screw  352 . Below piston  350 , cylindrical chamber  348  contains a viscous fluid such as oil  354 . A fluid flow control element depicted as orifice  356  is positioned between oil  354  and a piston  358 . The lower end of piston  358  is proximate to or in contact with ball  360 , which is held in place by a resilient ball holder  362 . One or more sensors  364  are located in proximity to ball  360  and are operable to provide a signal that indicates ball  360  has or has not been released into the flow path as described above. 
     In operation, actuator  330  releases ball  360  responsive to a pressure deployment signal. Specifically, when the tool string including actuator  330  is positioned in the well and it is desired to deploy ball  360  into the flow path of the tool string, annulus pressure is increased to apply a downward force on piston  350 . When sufficient shear force is generated between piston  350  and ball release assembly  346 , shear screw  352  is broken. Thereafter, the piston  350  is shiftable relative to ball release assembly  346 . The downward force on piston  350  is counteracted by fluid  354  moving through orifice  356  to require a predetermined amount of time for this operation. As piston  350  moves downwardly, fluid  354  acts on piston  358 , which shifts piston  358  downwardly pushing ball  360  out of ball holder  362 . Ball  360  then contacts ball ramp  344  which is aligned with ball release opening  336  enabling ball  360  to enter the flow path of the tool string. It is noted that the pressure deployment signal could alternatively be generated by increasing the tubing pressure by porting cylindrical chamber  348  to the tubing side. 
     In  FIG. 4C , actuator  400  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  434  that is ported to the annulus and a fluid passageway  436 , which is ported to the flow path of the tool string. A piston  438  is sealably disposed within cylindrical chamber  430  and is initially secured therein with a shearable member depicted as shear screw  440 . One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. For example, when ball release assembly  410  is operated such that lower ramp element  422  of plunger member  420  slides into slot  418  of ball ramp  412 , this is an indication that ball  428  has been expelled into the tubing. The one or more sensors  442  may determine that the two parts have slide together, for example, by opening or closing an electronic circuit, by cutting an electrical wire or breaking an optical fiber, by actuating a pressure switch, by aligning a magnet with a Hall Sensor or the like. The signal that indicates whether ball  428  has or has not been released into the flow path may be sent to a surface control by a wellbore communication means including, but not limited to, a electric conductor, an optical fiber, acoustic or electromagnetic telemetry or other suitable means. Actuator  400  may also include a lock assembly  444  that interacts with a locking feature  446  of piston  438  when piston  438  is fully extended. 
     In operation, actuator  400  releases ball  428  responsive to a differential pressure deployment signal. Specifically, when the tool string including actuator  400  is positioned in the well and it is desired to deploy ball  428  into the flow path of the tool string, tubing pressure is increased to generate a differential pressure between the tubing pressure and the annulus pressure which applies a downward force on piston  438 . When sufficient shear force is generated, shear screw  440  is broken. Thereafter, piston  438  is shiftable relative to outer housing  402  and the downward force on piston  438  acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  may be fully extended such that locking feature  446  interacts with lock assembly  444  preventing retraction of piston  438 . In this configuration, ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  400  from abrasive fluid flow. 
     In  FIG. 4D , actuator  450  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  436 , which is ported to the flow path of the tool string. A piston  438  is sealably disposed within cylindrical chamber  430 . A rupture disk  452  is also disposed within cylindrical chamber  430  between fluid passageway  436  and piston  438 . One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, actuator  450  releases ball  428  responsive to a pressure deployment signal. Specifically, when the tool string including actuator  450  is positioned in the well and it is desired to deploy ball  428  into the flow path of the tool string, tubing pressure is increased which acts on rupture disk  452 . When the tubing pressure reaches a sufficient absolute pressure, rupture disk  452  will burst. Thereafter, the fluid pressure generates a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  450  from abrasive fluid flow. 
     In  FIG. 4E , actuator  460  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  434 , which is ported to the annulus. A piston  438  is sealably disposed within cylindrical chamber  430 . A lock assembly  462  is also disposed within cylindrical chamber  430 . Lock assembly  462  includes a lock ring  464 , a piston  466  and a retainer member  468 . Initially, movement of piston  466  and lock ring  464  is prevented by the secure connection between piston  466  and retainer member  468  depicted as a shear screw  470 . One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, actuator  460  releases ball  428  responsive to a pressure deployment signal. Specifically, when the tool string including actuator  460  is positioned in the well and it is desired to deploy ball  428  into the flow path of the tool string, annulus pressure is increased which acts on piston  466 . When sufficient shear force is generated, shear screw  470  is broken allowing piston  466  to shift upwardly releasing lock ring  464 . Thereafter, the fluid pressure generates a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  460  from abrasive fluid flow. 
     In  FIG. 4F , actuator  480  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  434  that is ported to the annulus and a fluid passageway  436 , which is ported to the flow path of the tool string. A dual piston assembly  482  is sealably disposed within cylindrical chamber  430 . Dual piston assembly  482  includes a lower piston  484  that has an outer surface operable to cooperate with ratchet keys  486  to allow relative downward movement of lower piston  484  but prevent relative upward movement of lower piston  484 . Dual piston assembly  482  also includes an upper piston  488  that has an outer surface operable to cooperate with ratchet keys  490  to allow relative upward movement of lower piston  488  but prevent relative downward movement of lower piston  488 . A biasing member depicted as a spiral wound compression spring  492  is positioned between upper piston  488  and a lock ring  494  that is secured within cylindrical chamber  430 . Spring  492  acts to separate upper piston  488  from lower piston  484 . One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, actuator  480  releases ball  428  responsive to a pressure deployment signal. Specifically, when the tool string including actuator  480  is positioned in the well and it is desired to deploy ball  428  into the flow path of the tool string, tubing pressure is increased which acts upper piston  488  compressing spring  492 . Downward movement of upper piston  488  downwardly shifts lower piston  484  downwardly via ratchet keys  490 . At the same time, lower piston  484  is able to move downwardly relative to ratchet keys  486 . When tubing pressure is released, the biasing force of spring  492  either alone or in combination with the fluid pressure force of the annular fluid via fluid passageway  434  acts to upwardly shift upper piston  488  which is able to move upwardly relative to ratchet keys  490 . At the same time, ratchet keys  486  prevent upward movement of lower piston  484 . The tubing pressure is then cycled up and down in a manner similar to that described above to further downwardly shift lower piston  484  in a stepwise fashion. This process continues as lower piston  484  and inner sleeve  404  move together and spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , further downward movement of inner sleeve  404  positions ball release opening  406  behind a lower portion of outer housing  402  to protect the inside components of actuator  480  from abrasive fluid flow. 
     In  FIG. 4G , actuator  500  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . 
     Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . An upper portion of cylindrical chamber  430  is in fluid communication with a fluid passageway  434 , which is ported to the annulus. A piston  438  is sealably disposed within cylindrical chamber  430 . A computer controlled lock assembly  502  is also disposed within cylindrical chamber  430 . Computer controlled lock assembly  502  may include a self contained power source such as one or more batteries, a processor, memory, instructions and a motor having a retractable arm with a lock ring  504  attached thereto. Computer controlled lock assembly  502  may receive external stimuli from one or more sensors  506 ,  508  such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, depending upon the configuration of computer controlled lock assembly  502 , actuator  500  releases ball  428  responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. For example, a pressure deployment signal may be detected by sensor  506 , sensor  508  or both. Alternatively or additionally, an acoustic deployment signal or a temperature deployment signal could be detected by sensor  506 , sensor  508  or both. As yet another alternative, an accelerometer and timer may work together to generate a deployment signal based upon actuator  500  remaining stationary for a predetermined time period. This deployment signal may be in addition to one of the exterior stimuli, i.e., pressure, temperature, acoustic, discussed above. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled lock assembly  502  verifies the deployment signal then triggers the motor to retract its arm along with lock ring  504  to release piston  438 . Thereafter, annular fluid pressure via fluid passageway  434  generates a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  500  from abrasive fluid flow. 
     In  FIG. 4H , actuator  510  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . A piston  438  is sealably disposed within cylindrical chamber  430 . A motor  512  having an extendable shaft  514  is also disposed within cylindrical chamber  430 . In the illustrated embodiment, motor  512  receives power and command signals via communication cable  516  including one or more electrical conductors and one or more optional optical conductors communicably linked to a surface controller or other downhole controller. One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, actuator  510  releases ball  428  responsive to one or more of an optical and an electrical deployment signal. Specifically, when the tool string including actuator  510  is positioned in the well and it is desired to deploy ball  428  into the flow path of the tool string, the surface controller sends the deployment signal and provides power to operate motor  512 . In the illustrated embodiment, the motor drives the extendable shaft  514  downward generating a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , further downward movement of inner sleeve  404  positions ball release opening  406  behind a lower portion of outer housing  402  to protect the inside components of actuator  510  from abrasive fluid flow. 
     In  FIG. 41 , actuator  520  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  434 , which is ported to the annulus. A piston  438  is sealably disposed within cylindrical chamber  430 . A computer controlled release assembly  522  is also disposed within cylindrical chamber  430 . Computer controlled release assembly  522  may include a self contained power source such as one or more batteries, a processor, memory, instructions and a motor having a retractable arm  524  that is sealable received within cylindrical chamber  430 . Computer controlled release assembly  502  may receive external stimuli from one or more sensors  526  such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, depending upon the configuration of computer controlled release assembly  522 , actuator  520  releases ball  428  responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly  522  verifies the deployment signal then triggers the motor to retract arm  524  which exposes cylindrical chamber  430  to annular pressure generating a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  520  from abrasive fluid flow. 
     In  FIG. 4J , actuator  530  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . 
     Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  434 , which is ported to the annulus. A piston  438  is sealably disposed within cylindrical chamber  430 . A computer controlled release assembly  532  is also disposed within cylindrical chamber  430 . Computer controlled release assembly  532  may include a self-contained power source such as one or more batteries, a processor, memory and instructions. Computer controlled release assembly  532  is operably coupled to a disappearing plug  534  disposed in fluid passageway  434  via wire  536 . Computer controlled release assembly  532  may receive external stimuli from one or more sensors  538  such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, depending upon the configuration of computer controlled release assembly  532 , actuator  530  releases ball  428  responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly  532  verifies the deployment signal then triggers a current flow to generate heat in wire  536  which melts or otherwise removes plug  534  and exposes cylindrical chamber  430  to annular pressure generating a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  530  from abrasive fluid flow. 
     In  FIG. 4K , actuator  540  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  436 , which is ported to the flow path of the tool string. A piston  438  is sealably disposed within cylindrical chamber  430 . A computer controlled release assembly  542  is also disposed within cylindrical chamber  430 . Computer controlled release assembly  542  may include a self-contained power source such as one or more batteries, a processor, memory and instructions. Computer controlled release assembly  542  is operably coupled to a disappearing plug  544  disposed in an orifice  546  via wire  548 . Computer controlled release assembly  542  may receive external stimuli from one or more sensors  550  such as pressure sensors, temperature sensors, hydrophones or the like. Also disposed within cylindrical chamber  430  is a piston  552 . A viscous fluid  554 , such as oil, is disposed between piston  552  and orifice  546 . One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, depending upon the configuration of computer controlled release assembly  542 , actuator  540  releases ball  428  responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly  542  verifies the deployment signal then triggers a current flow to generate heat in wire  548  which melts or otherwise removes plug  544 . Tubing pressure via fluid passageway  436  acts on piston  552  to move piston  552  downwardly. The downward force on piston  552  is counteracted by fluid  554  moving through orifice  546  to require a predetermined amount of time for this operation. After passing through orifice  546 , fluid  554  acts on piston  438 , which in turn acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  540  from abrasive fluid flow. 
     In  FIG. 4L , actuator  560  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 . A piston  438  is sealably disposed within cylindrical chamber  430 . A computer controlled release assembly  562  is also disposed within cylindrical chamber  430 . Computer controlled release assembly  562  may include a self-contained power source such as one or more batteries, a processor, memory and instructions. Computer controlled release assembly  562  is operably coupled to a fluid pump  564 . A fluid passageway  566  extends through outer housing  402  connecting a lower portion of cylindrical chamber  430  with an inlet of fluid pump  564 . A fluid  568  is disposed within cylindrical chamber  430  and is operably to be pumped therein. Computer controlled release assembly  562  may receive external stimuli from one or more sensors  570  such as pressure sensors, temperature sensors, hydrophones or the like. One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, depending upon the configuration of computer controlled release assembly  562 , actuator  560  releases ball  428  responsive to one or more of an acoustic deployment signal, a pressure deployment signal, a temperature deployment signal, a displacement deployment signal and a time delay deployment signal or combinations thereof. Regardless of the type or types of deployment signals used, once received, the processor of computer controlled release assembly  562  verifies the deployment signal then triggers operation of fluid pump  564  which circulates fluid through cylindrical chamber  430  creating a high pressure regions above and a low pressure region below piston  438 . This action generates a downward force on piston  438 , which acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , further downward movement of inner sleeve  404  positions ball release opening  406  behind a lower portion of outer housing  402  to protect the inside components of actuator  560  from abrasive fluid flow. 
     In  FIG. 4M , actuator  580  includes an outer housing  402  and an inner sleeve  404  having a ball release opening  406 . In the illustrated embodiment, inner sleeve  404  is slidably disposed within outer housing  402 . A lower cylindrical chamber  408  is defined between inner sleeve  404  and outer housing  402 . A ball release assembly  410  is positioned in cylindrical chamber  408 . Ball release assembly  410  includes a ball ramp  412  having a pair of ramp members  414 ,  416  with a slot  418  therebetween, as best seen in  FIG. 5 . Ball release assembly  410  also includes a plunger member  420  having a lower ramp element  422  that is operable to enter slot  418  of ball ramp  412 . Ball release assembly  410  further includes a biasing member depicted as spiral wound compression spring  424  that is disposed around an upper extension  426  of plunger member  420 . In certain embodiments, plunger member  420  may optionally be secured to outer housing  402  in the run in configuration. A ball  428  is positioned within cylindrical chamber  408  between ball ramp  412  and plunger member  420 . Ball  428  may initially be secured to ball ramp  412  and/or plunger member  420  magnetically, shearably or the like. Outer housing  402  includes a cylindrical chamber  430  located above an upper surface of platform  432  of inner sleeve  404 , the lower portion of which is an atmospheric chamber  448 . Cylindrical chamber  430  is in fluid communication with a fluid passageway  436 , which is ported to the flow path of the tool string. A piston  438  is sealably disposed within cylindrical chamber  430 . An electromagnet  582  is also disposed within cylindrical chamber  430 . Electromagnet  582  is powered via wire  584 , which is coupled to an electrical source located downhole or at the surface. Electromagnet  582  is operable to generate a magnetic field that acts on magneto-rheological fluid  586  to form a barrier within cylindrical chamber  430 . Also disposed within cylindrical chamber  430  is a piston  588 . One or more sensors  442  may be located in proximity to ball  428  and are operable to provide a signal that indicates ball  428  has or has not been released into the flow path as described above. 
     In operation, actuator  580  releases ball  428  responsive to an electrical deployment signal. Specifically, when the tool string including actuator  580  is positioned in the well and it is desired to deploy ball  428  into the flow path of the tool string, the electric power to electromagnet  582  is cut off. The magneto-rheological fluid  586  that previously formed a barrier not returns to its liquid state. Tubing pressure via fluid passageway  436  acts on piston  588  to move piston  588  downwardly causing fluid  586  to acts on piston  438  which in turn acts through inner sleeve  404  to compress spring  424 . Now, piston  438  and inner sleeve  404  move together until spring  424  is fully compressed or a lower surface of platform  432  of inner sleeve  404  contacts upper extension  426  of plunger member  420 . In this position, ball  428  is aligned with ball release opening  406 . Further downward movement of piston  438  and inner sleeve  404  now causes plunger member  420  to shift downwardly relative to ball ramp  412 . The combination of the downward movement of piston  438  and inner sleeve  404  together with the force generated by spring  424  between ball ramp  412  and plunger member  420  cause ball  428  to be expelled through ball release opening  406  and into the flow path of the tool string. After deployment of ball  428 , piston  438  preferably remains in its fully extended positioned wherein ball release opening  406  has moved behind a lower portion of outer housing  402  to protect the inside components of actuator  580  from abrasive fluid flow. 
     It should be understood by those skilled in the art that the illustrative embodiments described herein are not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments will be apparent to persons skilled in the art upon reference to this disclosure. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.