Patent Publication Number: US-2020291743-A1

Title: Sleeve control valve for high temperature drilling applications

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. patent application Ser. No. 15/066,389 filed Mar. 10, 2016, the contents of which are hereby incorporated in their entirety. 
    
    
     BACKGROUND 
     Downhole operations often include a downhole string that extends from an uphole system into a formation. The uphole system may include a platform, pumps, and other systems that support drilling operation, resource exploration, development, and extraction. In some instances, fluids may be passed from the uphole system into the formation through the downhole string. In other instances, fluid may pass from the formation through the downhole string to the uphole system. The downhole string may include various sensors that detect downhole parameters including formation parameters and parameters associated with the downhole string. 
     It is desirable to communicate information from downhole sensors to the uphole system. Communication may take place through wired, optical, or acoustical systems. Acoustical systems rely upon passage of pressure pulses generated downhole by a mud pulser to an uphole receiver. The pressure pulses are created by moving a piston into a choke valve in order to create an additional temporarily pressure increase at the pump system on the surface. The generated pressure pulse travels to the surface. The uphole receiver converts the pressure pulses to data indicative of sensed parameters. The pressure pulses provide useful information to uphole operators. 
     During drilling, a typical mud pulser substantially continuously generates pressure pulses over long time periods, often several days. In addition, a number of wellbores are currently drilled in formations having temperatures that are above 300° F. (149° C.). A majority of currently utilized mud pulsers include oil fillings, elastomers and/or electrical high pressure connectors, all of which tend to deteriorate over time and thus are not suitable for use in high temperature environments. The disclosure herein provides pulsers that are suitable for high temperature environments while also being made without oil fillings, elastomers or electrical high pressure connectors. 
     SUMMARY 
     Disclosed is a control valve assembly for use in a downhole tool in a wellbore including a body having a fluid passage including a fluid inlet and a fluid outlet. A portion of the body is formed from a first magnetic material. A sleeve slidingly mounted to the body. The sleeve selectively slides from a first position covering one of the fluid outlet and the fluid inlet to a second position exposing one of the fluid outlet and the fluid inlet. At least a portion of the sleeve is formed from a second magnetic material. A magnetic circuit having a gap is defined within the control valve assembly. The portion of the body formed from the first magnetic material defines a first portion of the magnetic circuit and the portion of the sleeve formed from the second magnetic material forms another portion of the magnetic circuit. A biasing member is in operable communication with the sleeve. A solenoid is mounted to the body about at least a portion of the first magnetic material of the body. The solenoid is selectively activated to create a magnetic field across the gap in the magnetic circuit. The magnetic circuit causes the sleeve to slide, narrowing the gap and sliding from the first position to the second position to produce a pressure pulse in the wellbore, wherein the biasing member biases the sleeve back to the first position. 
     Also disclosed a resource recovery and exploration system including an uphole system, and a downhole system including a downhole string extending into a wellbore operatively connected to the uphole system. The downhole string includes a pulser alternator generator having a main valve assembly, an alternator, and a control valve assembly operatively connected to the main valve assembly and the alternator. The control valve assembly includes a body having a fluid passage including a fluid inlet and a fluid outlet. A portion of the body is formed from a first magnetic material. A sleeve slidingly mounted to the body. The sleeve selectively slides from a first position covering one of the fluid outlet and the fluid inlet to a second position exposing one of the fluid outlet and the fluid inlet. At least a portion of the sleeve is formed from a second magnetic material. A magnetic circuit having a gap is defined within the control valve assembly. The portion of the body formed from the first magnetic material defines a first portion of the magnetic circuit and the portion of the sleeve formed from the second magnetic material forms another portion of the magnetic circuit. A biasing member is in operable communication with the sleeve. A solenoid is mounted to the body about at least a portion of the first magnetic material of the body. The solenoid is selectively activated to create a magnetic field across the gap in the magnetic circuit. The magnetic circuit causes the sleeve to slide, narrowing the gap and sliding from the first position to the second position to produce a pressure pulse in the wellbore, wherein the biasing member biases the sleeve back to the first position. 
     Further disclosed is a method of operating a control valve assembly in a wellbore including activating a solenoid to create a magnetic field in a magnetic circuit having a gap, passing the magnetic field across the gap in the magnetic circuit, and sliding a sleeve with the magnetic field thereby narrowing the gap, the sleeve sliding from a first position covering one of a fluid inlet and a fluid outlet to a second position uncovering one of the fluid inlet and the fluid outlet to produces a pressure pulse in the wellbore, wherein the sleeve in made from a magnetic material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
         FIG. 1  depicts a resource exploration system having an uphole system operatively connected to a downhole string including a pulser alternator generator (PAG) having a sleeve control valve assembly, in accordance with an exemplary embodiment; 
         FIG. 2  depicts a partial cross-sectional view of the PAG of  FIG. 1 ; 
         FIG. 3  depicts a sleeve control valve assembly, in accordance with an aspect of an exemplary embodiment; and 
         FIG. 4  depicts a sleeve control valve assembly, in accordance with another aspect of an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A drilling system (e.g. a resource exploration and/or recovery system), in accordance with an exemplary embodiment, is indicated generally at  2 , in  FIG. 1 . Drilling system  2  should be understood to include well drilling operations, resource extraction and recovery, CO 2  sequestration, and the like. Drilling system  2  may include an uphole system  4  operatively connected to a downhole system  6 . Uphole system  4  may include pumps  8  that aid in completion and/or extraction processes as well as fluid storage  10 . Fluid storage  10  may contain a gravel pack fluid or slurry (not shown) that is introduced into downhole system  6 . 
     Downhole system  6  may include a downhole string  20  that is extended into a wellbore  21  formed in formation  22 . Downhole string  20  may include a number of connected downhole tools or tubulars  24 . One of tubulars  24  may include a pulser alternator generator (PAG) assembly  28 . PAG assembly  28  may receive signals from one or more sensors (not shown) indicating one or more of formation parameters, downhole fluid parameters, tool condition parameters and the like. PAG assembly  28  creates one or more pressure pulses that are received at uphole system  4 . The one or more pressure pulses define a code that may contain information regarding data received by the sensors. In accordance with an exemplary embodiment, PAG assembly  28  creates pressure pulses by selectively stopping a flow of pressurized fluid such as downhole fluid or drilling mud as will be detailed more fully below. 
     In accordance with an exemplary embodiment illustrated in  FIG. 2 , PAG assembly  28  includes a body portion  30  having an outer surface portion  32  and an inner portion  34 . An inner housing  36  is arranged within inner portion  34 . Inner housing  36  includes an outer surface  38  and an inner surface  40  that defines an interior portion  42 . Interior portion  42  houses an alternator assembly  46 , a control valve assembly (CVA)  48 , and a main valve assembly (MVA)  50  having a mud flow inlet portion (not separately labeled) and a mud flow outlet portion (also not separately labeled). As will be detailed more fully below, alternator assembly  46  provides signals to CVA  48  that allow fluid or drilling mud to flow through MVA  50  and created pressure pulses in the drilling mud according to the signals. CVA  48  creates pressure pulses in the mud flow that provide downhole data from sensors or one or more processors in the downhole string (not shown) operatively coupled to alternator assembly  46  to uphole operators. In this disclosure the terms “mud flow” or “mud” is used synonymously with the term “fluid” or “flowing fluid. 
     As shown in  FIG. 3 , CVA  48  includes a body  60  including a first body portion  62  and a second body portion  64 . A mud flow passage  66  extends through first body portion  62  and second body portion  64 . In the exemplary embodiment shown, mud flow passage  66  includes a first passage portion  67  that extends through first body portion  62 , a second passage portion  68 , and a third passage portion  69 . Both second passage portion  68  and third passage portion  69  extend through second body portion  64 . Third passage portion  69  may extend at an angle relative to a longitudinal axis (not separately labeled) of CVA  48 . 
     In accordance with an aspect of an exemplary embodiment, third passage portion  69  may extend at an angle of between about 20° and about 80° relative to a longitudinal axis (not separately labeled) of CVA  48 . In accordance with another aspect, third passage portion  69  may extend at an angle of about 60° relative to the longitudinal axis. In this manner, impact forces associated with pulses of mud passing from third passage portion onto inner surface  40  may be reduced over those which would be realized if third passage portion  69  were perpendicular to the longitudinal axis. Mud flow passage  66  includes a mud flow inlet  70  arranged in first body portion  62  and a mud flow outlet  72  provided in second body portion  64 . Mud flow inlet is fluidically connected with first passage portion  67  and mud flow outlet  72  is fluidically connected with third passage portion  69 . First body portion  62  is joined to second body portion  64  through a pressure sleeve  74  that facilitates alignment of first passage portion  67  with second passage portion  68 . Joining first and second body portion may be achieved for example through a press fit, a threaded connection or a joining process such a welding. In further accordance with an aspect of an exemplary embodiment, first and second body portions  62  and  64  as well as pressure sleeve  74  are formed from soft magnetic material. At this point, it should be understood that first and second body portions  62  and  64  and pressure sleeve  74  may be formed from substantially similar magnetic material or they may be formed from different magnetic materials depending upon desired performance characteristics. 
     In still further accordance with an exemplary embodiment, second body portion  64  includes an annular recessed portion  80  having a first section  82 , a second section  84  and a third section  86 . A solenoid  89  is positioned at first section  82  of recessed portion  80 . Solenoid  89  is operatively coupled to alternator assembly  46  through a conductor (not shown) extending through a conductor passage  92 . Alternator  46  provides signals to selectively activate, e.g., energize through an application of electric energy, solenoid  89 , creating a magnetic flux or field in a magnetic circuit including a gap  94 . A solenoid housing  96  which may take the form of a pressure sleeve is provided in second section  84  of annular recessed portion  80 . Solenoid housing  96  extends about and protects solenoid  89  from downhole fluids passing through CVA  48  as well as from high downhole pressure. That is, housing  96  may be formed from a corrosion resistant high strength non-magnetic material such as Inconel to provide protection from corrosive high pressured downhole fluids. 
     In yet still further accordance with an exemplary aspect, CVA  48  includes a sleeve  100  slideably arranged in third section  86  of annular recessed portion  80 . Sleeve  100  includes a first end portion  104 , a second end portion  105  and a blocking portion  106  extending therebetween. Blocking portion  106  includes an opening  110  that selectively registers with fluid outlet  72 . In embodiments opening  110  may register with a fluid inlet. In the embodiment shown, gap  94  exists between first end portion  104  and housing  60 . 
     A biasing member, such as first spring  114  applies a biasing force onto sleeve  100  and is arranged between first end portion  104  and an annular surface of first body portion  62 , also referred to as first wall portion of the first body portion (not separately labeled). A second spring  115  is arranged between second end portion  105  and another annular surface of third section  86 , also referred to as second wall portion of the second body portion (also not separately labeled). It is to be mentioned that the term annular refers to the longitudinal axis of CVA  48 . First and second springs  114  and  115  cooperate to maintain sleeve  100  in a first position wherein opening  110  exposes fluid (mud flow) outlet  72 . Fluid outlet  72  is exposed when solenoid  100  is deactivated. When solenoid  100  is deactivated spring  114  will bias sleeve  100  in the first position. Spring  115  is dimensioned to be weaker (spring rate of spring  115  is smaller than spring rate of spring  114 ). In embodiments sleeve  100  may be functional with only the first spring  114 . Spring  115  is good for supporting the sliding movement of sleeve  100  when solenoid  89  is activated. However, the magnetic forces initiated by activating solenoid  89  are sufficient to shift sleeve  100  without the additional force provided by spring  115 . 
     In alternative embodiments hydraulic forces are used to drive the biasing member. The kinetic energy of the fluid flowing through the CVA  48  is used to push the sleeve back to the first position after the solenoid was deactivated. Sleeve  100  may include a structural feature which interferes with the flow path of the flowing fluid and creates a barrier onto which the flowing fluid applies a force which pushes the sleeve back towards the first position when the solenoid is deactivated. Applying a hydraulic force on the structural feature included in the sleeve works similar to a hydraulically driven piston. 
     With this arrangement, alternator assembly  46  provides signals to selectively activate solenoid  89  which, in turn, selectively shifts sleeve  100  between the first position ( FIG. 3 ) and a second position. In the second position blocking portion  106  of sleeve  100  covers fluid (mud flow) outlet  72 . In the first position fluid outlet register with opening  110  ( FIG. 3 ), mud may flow through fluid outlet  72 . When sleeve  100  is operated rapidly (activation, deactivation of solenoid  89 ) and is moved between the first position and the second position, pulses of mud pass from fluid outlet  72  and contact inner surface  40  of inner housing  36 . Mud pulses travel through downhole string  20 . An uphole receiver (not separately labeled) captures pressure waves created by the pulses of mud. The pressure pulses are presented in a pattern dictated by signals received from one or more sensors (formation parameters) or one or more processors in the downhole string  20 . The pressure pulses may be decrypted to provide data regarding one or more downhole parameters to uphole operators. In embodiments opening  110  may register with the fluid outlet  72  when the solenoid  89  is activated and blocking portion  106  may cover fluid outlet  72  when solenoid  89  is deactivated (not shown). In alternative embodiments opening  110  may register with fluid outlet  72  when solenoid  89  is deactivated and blocking portion  106  may cover fluid outlet  72  when solenoid  89  is activated. 
     In accordance with an exemplary embodiment, a continuous flow of mud passes through CVA  48  and the mud pulse is created when the solenoid is activated to cover (close) the fluid outlet. Activating solenoid  89  closes a magnetic circuit in CVA  48  and narrows gap  94 . Deactivating solenoid  89  allows the magnetic circuit to open (not separately labeled) by cutting off a magnetic flux or magnetic field  120  which was holding sleeve  100  in the second position. Gap  94  is opening. At this point, it should be understood that the term “magnetic circuit” defines a pathway of material within CVA  48  through which magnetic flux  120  will flow, because the magnetic reluctance of the material is low. The magnetic circuit, in the embodiment shown, may include first body portion  62 , second body portion  64 , pressure sleeve  74 , and sleeve  100 . Consequently, the magnetic flux  120  may flow through first body portion  62 , second body portion  64 , pressure sleeve  74 , and sleeve  100 . A magnetic field will arise across the gap  94  defined between sleeve  100  and first body portion  62  at first end  104 . The magnetic field creates a magnetic force (attraction) that acts across the gap  94  causing sleeve  100  to slide towards first body portion  62 . Sleeve  100  slides along a longitudinal axis of the body narrowing the gap  94 . Gap  94  need not fully close in order to cover fluid outlet  72  and to close the control valve. The gap  94  need only close so far as to at least partially cover fluid outlet  72  to block at least partially the flowing fluid to reduce the flow rate of the mud flow through fluid outlet  72  and to generate the pressure pulse. Solenoid  89  may then be deactivated widening gap  94  and opening (interrupting) the magnetic circuit cutting off magnetic flux  120  allowing spring  114  to bias sleeve  100  back to the first position, opening the control valve. In the first position the width of gap  94  is larger than the width of gap  94  in the second position. The first position is also referred to as a gap open position, the second position is also referred to as a gap closed position. The gap closed position does not require that the gap to be fully closed. 
     In accordance with an aspect of an exemplary embodiment, sleeve  100 , first body portion  62 , second body portion  64 , and pressure sleeve  74  may be formed from a magnetic material, such as a soft magnetic material, e.g., Vacoflux® 9CR from Vacuumschmelze GmbH and Co. Magnetic and soft-magnetic materials are defined as having a magnetic permeability μ that is greater than about 1.26*10 −4  N/A 2  (ferromagnetic or ferrimagnetic material). The magnetic or soft-magnetic material may also be corrosion resistant. At this point, it should be understood that the term magnetic material includes any suitable material that may form part of a magnetic circuit including soft magnetic material. In alternative embodiments only portions of sleeve  100 , first body portion  62 , second body portion  64 , and pressure sleeve  74  may be formed from a magnetic material, such as a soft magnetic material. Sleeve  100 , first body portion  62 , second body portion  64 , and pressure sleeve  74  may be made from a magnetic material that is also corrosion resistant. Sleeve  100 , first body portion  62 , second body portion  64 , and pressure sleeve  74  may be made from substantially similar magnetic materials or different magnetic materials depending upon desired performance characteristics. 
     In accordance with another aspect of an exemplary embodiment, sleeve  100  is formed from diamond coated soft magnetic material. In this manner, sleeve  100  may withstand corrosive and abrasive properties of downhole fluids such as downhole mud or fluid passing through CVA  48  at high downhole temperatures. Solenoid housing  96  is formed from high-strength, non-magnetic material such as Inconel. The particular materials are chosen to provide corrosion resistance to downhole fluids. Other materials that may also resist corrosion may also be employed. 
     In the embodiment of control valve  48 , the solenoid  89  may be placed in a sealed and clean 1-bar environment. In the embodiment of the device  48  in  FIG. 3 , sleeve  100  moves when the solenoid in the control valve  48  is energized. Sleeve  100  slides in an environment that is flooded with fluid (mud). The presence of mud allows sleeve  100  to slide back and forth (from first position to second position and vice versa) with relative low friction. Reference will now follow to  FIG. 4  in describing a CVA  128  in accordance with another aspect of an exemplary embodiment. CVA  128  includes a body  130  having a first body portion  132  that is mechanically linked to a second body portion  134 . First body portion  132  and second body portion  134  may be formed from soft magnetic material. A plate member  136  is arranged between first and second body portions  132  and  134 . Plate member  136  may be formed from soft magnetic material and may include a first annular recess  137 . A mud flow passage  140  extends through body  140 . Mudflow passage  130  includes a first passage portion  141  extending through first body portion  132  and a second passage portion  142  extending through second body portion  134 . A third passage portion  143  extends substantially perpendicularly from second passage portion  142 . In embodiments third passage  143  may extend at an angle substantially different to 90. Mudflow passage  140  includes a mud flow inlet  144  fluidically connected to first passage portion  141  and a mud flow outlet  145  fluidically connected to third passage portion  143 . Second body portion  134  also includes a conductor passage  148  extending therethrough. 
     In accordance with an aspect of an exemplary embodiment, second body portion  134  also includes an annular recessed portion  150  having a first section  154 , a second section  156  and a third section  158 . A solenoid  162  is arranged in first section  154  of annular recessed portion  150 . Solenoid  162  is electrically connected to alternator assembly  46  via a conductor (not shown) extending through conductor passage  148 . A pressure sleeve  164  is arranged in second section  156  of annular recessed portion  150 . A housing which may take form of a pressure sleeve or solenoid housing  164  extends about and provides protection for solenoid  162 . Solenoid housing  164  is, in accordance with an aspect of an exemplary embodiment, is formed from magnetic material and may include an annular recess  165 . 
     In further accordance with an aspect of an exemplary embodiment, CVA  128  includes a sleeve  166  arranged in third section  158  of annular recessed portion  150 . Sleeve  166  is mechanically linked with solenoid housing  164  and may be formed from a soft magnetic material as will be detailed herein. Sleeve  166 , together with solenoid housing  164  are selectively shiftable between a first position ( FIG. 4 ) wherein mud flow outlet  145  is exposed and a second position (not shown) wherein mud flow outlet  145  is at least partially closed. Closed in this context refers to covered by sleeve  166 . A return spring  170  biases sleeve  166  and solenoid housing  164  in the first position. Return spring  170  nests within first and second annular recesses  137  and  165 . Solenoid housing may be formed from a corrosion resistant magnetic material to provide protection from corrosive high pressured downhole fluids. 
     In accordance with an aspect of an exemplary embodiment, sleeve  166 , first body portion  132 , second body portion  134 , solenoid housing  164 , and plate member  136  may be formed from a magnetic material, such as a soft magnetic material, e.g., Vacoflux® 9CR from Vacuumschmelze GmbH and Co. Magnetic and soft-magnetic materials are defined as having a magnetic permeability μ that is greater than about 1.26*10 −4  N/A 2  (ferromagnetic or ferrimagnetic material). The magnetic or soft-magnetic material may also be corrosion resistant. At this point, it should be understood that the term magnetic material includes any suitable material that may form part of a magnetic circuit including soft magnetic material. In alternative embodiments only portions of sleeve  166 , first body portion  132 , second body portion  134 , solenoid housing  164 , and plate member  136  may be formed from a magnetic material. Further, it should be understood that sleeve  166 , first body portion  132 , second body portion  134 , solenoid housing  164 , and plate member  136  may be formed from substantially similar magnetic materials or they may be formed from different magnetic materials depending upon desired performance characteristics. 
     With this arrangement, alternator assembly  46  provides signals to selectively activate solenoid  162  which, in turn, shifts sleeve  166  from the first position to the second position. In the first position, mud may flow through fluid (mud flow) outlet  145 . Activating solenoid  162  closes a magnetic circuit in CVA  48  and covers mud flow outlet  145 . Deactivating solenoid  162  allows the magnetic circuit to open by cutting off the magnetic flux or magnetic field  180 , which were holding sleeve  166  in the second position. When solenoid  162  is energized, magnetic field  180  crosses a gap  183  defined between sleeve  166  and plate member  136 . At this point, it should be understood that the term “magnetic circuit” defines a pathway of material within CVA  48  through which magnetic flux  180  will flow. The magnetic circuit, in the embodiment shown, may include first body portion  132 , second body portion  134 , plate member  136 , pressure sleeve  164 , and sleeve  166 . 
     When sleeve  166  is operated rapidly (activation, deactivation of solenoid  162 ) and is moved between the first position and the second position, pulses of mud pass from mud flow outlet  145  and contact inner surface  40  of inner housing  36 . An uphole receiver (not separately labeled) captures pressure waves created by the pulses of mud. The pressure pulses are presented in a pattern dictated by signals received from one or more sensors or one or more processors in the downhole string  20 . The pressure pulses may be decrypted to provide data regarding one or more downhole parameters to uphole operators. Gap  183  need not fully close in order to cover mud flow outlet  145  and to close the control valve. The gap  183  need only close so far as to at least partially cover mud flow outlet  145  to block at least partially the flowing fluid (mud) to reduce the flow rate of the mud flow through mud flow outlet  145  and to generate the pressure pulse. 
     Set forth below are some embodiments of the foregoing disclosure: 
     Embodiment 1. A control valve assembly for use in a downhole tool in a wellbore comprising: a body including a fluid passage having a fluid inlet and a fluid outlet, wherein at least a portion of the body is formed from a first magnetic material; a sleeve slidingly mounted to the body, the sleeve selectively sliding from a first position covering one of the fluid outlet and the fluid inlet to a second position exposing one of the fluid outlet and the fluid inlet, wherein at least a portion of the sleeve is formed from a second magnetic material; a magnetic circuit having a gap defined within the control valve assembly, wherein the portion of the body formed from the first magnetic material defines a first portion of the magnetic circuit and the portion of the sleeve formed from the second magnetic material forms another portion of the magnetic circuit; a biasing member in operable communication with the sleeve; and a solenoid mounted to the body about at least a portion of the first magnetic material of the body, the solenoid being selectively activated to create a magnetic field across the gap in the magnetic circuit, the magnetic circuit causing the sleeve to slide, narrowing the gap and sliding from the first position to the second position to produce a pressure pulse in the wellbore, wherein the biasing member biases the sleeve back to the first position. 
     Embodiment 2. The control valve assembly according to any prior embodiment, wherein the sleeve includes an opening that selectively registers with one of the fluid outlet and the fluid inlet in the first position. 
     Embodiment 3. The control valve assembly according to any prior embodiment, wherein the body includes a sleeve receiving recess including at least one wall portion, the sleeve including a first end portion, a second end portion and a blocking portion nesting within the sleeve receiving recess. 
     Embodiment 4. The control valve assembly according to any prior embodiment, further comprising: a spring arranged between the at least one wall portion and one of the first and second end portions of the sleeve. 
     Embodiment 5. The control valve assembly according to any prior embodiment, wherein the body includes a first body portion operatively coupled to a second body portion, the sleeve receiving recess being formed between the first and second body portions. 
     Embodiment 6. The control valve assembly according to any prior embodiment, wherein the at least one wall portion includes a first wall portion defined by the first body portion and a second wall portion defined by the second body portion, the biasing member comprising a spring arranged between the first wall portion and the first end portion of the sleeve. 
     Embodiment 7. The control valve assembly according to any prior embodiment, wherein the first magnetic material is substantially similar to the second magnetic material. 
     Embodiment 8. The control valve assembly according to any prior embodiment, wherein at least a portion of the sleeve is formed from a soft magnetic material. 
     Embodiment 9. The control valve assembly according to any prior embodiment, wherein at least a portion of the sleeve is formed from a diamond coated soft magnetic material. 
     Embodiment 10. A resource recovery and exploration system comprising: an uphole system; and a downhole system including a downhole string extending into a wellbore operatively connected to the uphole system, the downhole string including a pulser alternator generator having a main valve assembly, an alternator, and a control valve assembly operatively connected to the main valve assembly and the alternator, the control valve assembly comprising: a body including a fluid passage having a fluid inlet and a fluid outlet, wherein at least a portion of the body is formed from a first magnetic material; a sleeve slidingly mounted to the body, the sleeve selectively sliding from a first position covering one of the fluid outlet and the fluid inlet to a second position exposing one of the fluid outlet and the fluid inlet, wherein at least a portion of the sleeve is formed from a second magnetic material; a magnetic circuit having a gap defined within the control valve assembly, wherein the portion of the body formed from the first magnetic material defines a first portion of the magnetic circuit and the portion of the sleeve formed from the second magnetic material forms another portion of the magnetic circuit; a biasing member in operable communication with the sleeve; and a solenoid mounted to the body about at least a portion of the first magnetic material of the body, the solenoid being selectively activated to create a magnetic field across the gap in the magnetic circuit, the magnetic circuit causing the sleeve to slide, narrowing the gap and sliding from the first position to the second position to produce a pressure pulse in the wellbore, wherein the biasing member biases the sleeve back to the first position. 
     Embodiment 11. The resource recovery and exploration system according to any prior embodiment, wherein the sleeve includes an opening that selectively registers with one of the fluid outlet and the fluid inlet in the first position. 
     Embodiment 12. The resource recovery and exploration system according to any prior embodiment, wherein the body includes a sleeve receiving recess including at least one wall portion, the sleeve including a first end portion, a second end portion and a blocking portion nesting within the sleeve receiving recess. 
     Embodiment 13. The resource recovery and exploration system according to any prior embodiment, further comprising: a spring arranged between the at least one wall portion and one of the first and second end portions of the sleeve. 
     Embodiment 14. The resource recovery and exploration system according to any prior embodiment, wherein the body includes a first body portion operatively coupled to a second body portion, the sleeve receiving recess being formed between the first and second body portions. 
     Embodiment 15. The resource recovery and exploration system according to any prior embodiment, wherein the at least one wall portion includes a first wall portion defined by the first body portion and a second wall portion defined by the second body portion, the biasing member comprising a spring arranged between the first wall portion and the first end portion of the sleeve. 
     Embodiment 16. The resource recovery and exploration system according to any prior embodiment, wherein the first magnetic material is substantially similar to the second magnetic material. 
     Embodiment 17. The resource recovery and exploration system according to any prior embodiment, wherein at least a portion of the sleeve is formed from a soft magnetic material. 
     Embodiment 18. The resource recovery and exploration system according to any prior embodiment, wherein at least a portion of the sleeve is formed from a diamond coated soft magnetic material. 
     Embodiment 19. A method of operating a control valve assembly in a wellbore comprising: activating a solenoid to create a magnetic field in a magnetic circuit having a gap; passing the magnetic field across the gap in the magnetic circuit; and sliding a sleeve with the magnetic field thereby narrowing the gap, the sleeve sliding from a first position covering one of a fluid inlet and a fluid outlet to a second position uncovering one of the fluid inlet and the fluid outlet to produce a pressure pulse in the wellbore, wherein at least a portion of the sleeve is made from a magnetic material. 
     Embodiment 20. The method according to any prior embodiment, further comprising: biasing the sleeve back to the first position. 
     The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value. 
     While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.