Patent Publication Number: US-2022235615-A1

Title: Downhole inductive coupler with ingot

Description:
RELATED APPLICATIONS 
     The present application presents an alteration and modification of U.S. Pat. No. 8,519,865, to Hall et al., entitled Downhole Coils, issued Aug. 27, 2013, which is incorporated herein by this reference. 
     U.S. Pat. No. 6,670,880, to Hall et al., entitled Downhole Data Transmission System, issued Dec. 30, 2003, is incorporated herein by this reference. 
    
    
     BACKGROUND 
     The present invention relates to downhole drilling, and more particularly, to systems and methods for transmitting power and data to components of a downhole tool string. Downhole sensors, tools, telemetry components and other electronic components continue to increase in both number and complexity in downhole drilling systems. Because these components require power to operate, the need for a reliable energy source to power these downhole components is becoming increasingly important. Constraints imposed by downhole tools and the harsh downhole environment significantly limit options for delivering power and data to downhole components. 
     As downhole instrumentation and tools have become increasingly more complex in their composition and versatile in their functionality, the need to transmit power and/or data through tubular tool string components is becoming ever more significant. Real-time logging tools located at a drill bit and/or throughout a tool string require power to operate. Providing power downhole is challenging, but if accomplished it may greatly increase the efficiency of drilling. Data collected by logging tools are even more valuable when they are received at the surface real time. 
     BRIEF SUMMARY 
     The application presents an alteration and modification to the &#39;865 reference above. A large portion of the summary and detailed description are taken from said reference in relation to the prior art figures. The following portion of the summary relates to  FIGS. 1-5  of the present application. The teachings of the &#39;865 reference are applicable to this application except to the extent they are altered or modified by  FIGS. 1-5  and related text, abstract and claims. 
     This application discloses an inductive coupler and a method for producing the inductive coupler for use in a downhole tool such as a drillpipe or bottom hole assembly. The inductive coupler may comprise an annular magnetically conductive electrically insulating (MCEI) U-shaped single piece trough or mold comprising an annular channel. The annular channel may comprise a first perforation and one or more second perforations. Typically, inductive couplers for use in downhole applications may be comprised of multiple MCEI trough segments arranged end for end to form an annular ring-like structure. See (Prior Art)  FIG. 15 . The MCEI segments may be composed of a ferrite composition. Ferrite may be hard and brittle and susceptible to breakage. The use of segments may enable construction and handling of the MCEI coupler and reduce breakage of the ferrite ring. In this application, a solid ferrite ring may be used. The ferrite trough or MCEI ring may be used as a mold and an annular electrically conducting molten ingot may be cast within the annular channel of the mold. A molten metal comprising metal or a metal alloy may be cast into the MCEI mold producing the electrically conducting ingot. Ferrite segments may be used as a mold, also, by lining the channel with a thin refractory liner, such as a ceramic liner or a titanium, or other metal foil, to prevent molten metal leakage between the segments. 
     The ingot may comprise a first end and a second end. A first socket may be cast in the ingot adjacent the first end. One or more second sockets may be cast in the ingot adjacent the second end. The sockets may be cast when the ingot is cast in the channel or the sockets may be formed after the ingot is cast by machining. A first perforation and one or more second perforations may be formed in the bottom of the annular channel. The perforations may be formed by machining after the ingot is cast into the channel of the mold. The first perforation may be aligned with the first socket and the one or more second perforations may be aligned with the one or more second sockets. The respective sockets may house electrical connections. The first socket may house an electrical connection to a ground pin in the downhole tool. The one or more second sockets may house electrical connections to cables within the downhole tools. The cables may be connected to electronic equipment in the drill string or downhole tool. One or more cables may be attached to a similarly configured inductive coupler at the opposite end of the drill pipe or within the downhole tool. The alignment of the perforations with the respective sockets allows for cable access through the MCEI mold to the make an electrical connection with the ingot. 
     The channel in the MCEI mold may comprise one or more cleats projecting into the ingot thereby securing the ingot within the channel. The ingot may comprise one or more cleats projecting into the channel as a means of securing the ingot within the channel. The ingot may comprise annular flutes and the channel also may comprise annular flutes. The annular flutes of the ingot may couple with the annular flutes of the channel. The annular flutes may assist in securing the ingot within the annular channel. Also, the annular flutes may increase the surface area of the ingot thereby increasing the strength of the electromagnetic field between adjacent inductive couplers. The ingot may comprise an annular internal passageway within the ingot. The passageway may contribute resiliency to the ingot. Also, the passageway may promote rigidity in the ingot. An electrical cable may run through the passageway. 
     A nonelectrically conductive seal may enclose the ingot within the channel. A seal seat may be provided in the wall of the channel to seal the ingot from downhole fluids and to fix the seal over the ingot. The seal may act as a channel filler protecting the ingot from contamination from the downhole environment. Also, seals may be provided for the respective sockets and electrical connections, sealing the ingot and the respective sockets and electrical connections against downhole contamination. 
     The inductive coupler may be produced by providing an annular MCEI U-shaped mold comprising an annular channel and casting an electrically conductive molten metal or metal alloy into the channel, thereby producing an annular electrically conducting ingot. 
     The ingot may have a first end and a second end. A first socket may be formed proximate the first end and a second socket may be formed proximate the second end. The respective sockets may be formed when the molten metal is cast into the channel, or the respective sockets may be formed by machining after the ingot is cooled. The ingot may comprise one or more second sockets. The sockets may provide a housing for electrical connections to the ingot. 
     A first perforation and one or more second perforations may be formed in the channel by machining. The respective perforations may be aligned with the respective sockets. The perforations allow cables within the downhole tool or drill string to access electrical connections in the ingot. The first electrical connection may be to a ground pin within the downhole tool. The one or more electrical connections may be to cables connecting the ingot to a similarly configured ingot at the opposite of the drill pipe. And, the cables may connect the ingot to electronics and electrical equipment within the downhole tool. 
     Seals may be provided to protect the ingot and electrical connections within the channel. A seal may be provided to cover the ingot within the channel. The channel seal may be partially disposed within annular seal seats formed in the walls of the channel. The respective sockets may be provided with seals to prevent contamination from downhole fluids and debris. 
     The ingot may be provided with an annular passageway formed within the ingot placing a tubular form in the channel prior to casting in the molten metal. The tubular form may be electrically conductive and remain within the ingot or it may be nonelectrically conductive and consumed in the process. 
     Cleats and flutes may be formed in the channel and in the ingot. The cleats and flutes may be formed in the channel before it is sintered or machined in after sintering. Also, the flutes and cleats may be formed in the ingot when the ingot is cast into the channel by providing a form in the channel comprising the flutes and cleats. The form may be permanent or may be a consumable. 
     The following portion of the summary is taken from the &#39;865 reference and applies to the prior art figures incorporated herein. The teachings of the remainder of the summary are applicable to the present application except when altered or modified by the teachings of the  FIGS. 1-5  and related text, claims, and abstract. 
     In one aspect of the invention, a downhole tool string component comprises a tubular body with at least one end adapted for threaded connection to an adjacent tool string component. The at least one end comprises at least one shoulder adapted to abut an adjacent shoulder of an adjacent end of the adjacent tool string component. An annular inductive coupler is disposed within an annular recess formed in the at least one shoulder, and the inductive coupler comprises a coil in electrical communication with an electrical conductor that is in electrical communication with an electronic device secured to the tubular body. The coil comprises a plurality of windings of wire strands that are electrically isolated from one another and which are disposed in an annular trough of magnetic material secured within the annular recess. 
     The coil wire may comprise a gauge of between 36 and 40 AWG, and may comprise between 1 and 15 coil turns. The coil wire may comprise between 5 and 40 wire strands. The wire strands may be interwoven. The coil may comprise the characteristic of increasing less than 35.degree. Celsius when 160 watts are passed through the coil. In some embodiments the coil may comprise the characteristic of increasing less than 20.degree. C. when 160 watts are passed through the coil. 
     The adjacent shoulder of the adjacent downhole tool string may comprise an adjacent inductive coupler configured similar to the inductive coupler. These couplers may be adapted to couple together when the downhole components are connected together at their ends. The inductive coupler and the adjacent inductive coupler may then be adapted to induce magnetic fields in each other when their coils are electrically energized. In such embodiments the inductive coupler may comprise a characteristic of transferring at least 85% energy from the inductive coupler to the adjacent inductive coupler when 160 watts are passed through the coil. 
     The electronic device that is secured to the tubular body may be a power source. The power source may comprise a battery, generator, capacitor, motor, or combinations thereof. In some embodiments the electronic device may be a sensor, drill instrument, logging-while-drilling tool, measuring-while-drilling tool, computational board, or combinations thereof. 
     The magnetic material may comprise a material selected from the group consisting of ferrite, a nickel alloy, a zinc alloy, a manganese alloy, soft iron, a silicon iron alloy, a cobalt iron alloy, a mu-metal, a laminated mu-metal, barium, strontium, carbonate, samarium, cobalt, neodymium, boron, a metal oxide, rare earth metals, and combinations thereof. The magnetic material may comprise a relative magnetic permeability of between 100 and 20000. 
     In another aspect of the invention, a method of transferring power from a downhole tool string component to an adjacent tool string component comprises a step of providing a downhole tool string component and an adjacent tool string component. The components respectively comprise an annular inductive coupler and an adjacent annular inductive coupler disposed in an annular recess in a shoulder of an end of the component. The method further comprises adapting the shoulders of the downhole tool string component and the adjacent tool string component to abut one another when the ends of the components are mechanically connected to one another. The method also comprises a step of mechanically connecting the ends of the components to one another and a step of driving an alternating electrical current through the inductive coupler at a frequency of between 10 and 100 kHz. In some embodiments the frequency may be between 50 and 79 kHz. In some embodiments a square wave may be used. The square wave may be a 170-190 volt square wave. 
     The inductive coupler and the adjacent inductive coupler may be respectively disposed within annular troughs of magnetic material that are disposed within the respective annular recess of the downhole and adjacent components. At least one of the inductive coupler and adjacent inductive coupler may comprise a coil that comprises a plurality of windings of wire strands, the wire strands each being electrically isolated from one another. At least 85% of the energy comprised by the alternating electrical current being driven through the annular inductive coupler may be inductively transferred to the adjacent inductive coupler when 160 watts are passed through the coil. In some embodiments at least 95% of the energy comprised by the alternating electrical current being driven through the annular inductive coupler may be inductively transferred to the adjacent inductive coupler when 160 watts are passed through the coil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a half section of an annular mold and ingot of the present invention. 
         FIG. 2  is a diagram of an end portion of an annular mold and ingot of the present invention. 
         FIG. 3  is a diagram of an interior of a half section of an annular mold and ingot of the present invention. 
         FIG. 4  is a diagram of a half section of an annular mold and ingot depicting cleats. 
         FIG. 5  is a diagram of a half section of an annular mold and ingot depicting flutes and annular internal passageway. 
       (Prior Art)  FIG. 6  is a cross-sectional view of a formation disclosing an orthogonal view of a tool string. 
       (Prior Art)  FIG. 7  is a cross-sectional diagram of an embodiment of tool string component. 
       (Prior Art)  FIG. 8  is a cross-sectional diagram of another embodiment of a tool string component. 
       (Prior Art)  FIG. 8A  is an electrical schematic of an embodiment of an electrical circuit. 
       (Prior Art)  FIG. 9  is a perspective diagram of an embodiment of an inductive coupler. 
       (Prior Art)  FIG. 10  is an exploded diagram of an embodiment of an inductive coupler. 
       (Prior Art)  FIG. 11  is a cross-sectional diagram of an embodiment of an inductive coupler disposed in a tool string component. 
       (Prior Art)  FIG. 12  is a perspective diagram of an embodiment of a coil comprising a plurality of electrically isolated wire strands. 
       (Prior Art)  FIG. 13  is a perspective diagram of another embodiment of a coil comprising a plurality of electrically isolated wire strands. 
       (Prior Art)  FIG. 14  is a cross-sectional diagram of a tool string component having an embodiment of an electronic device. 
       (Prior Art)  FIG. 15  is a perspective diagram of an embodiment of an inductive coupler. 
       (Prior Art)  FIG. 16  is a cross-sectional diagram of an embodiment of a tool string component connected to an adjacent tool string component. 
       (Prior Art)  FIG. 17  is a cross-sectional diagram of a formation showing a tool string having a downhole network. 
       (Prior Art)  FIG. 18  is a cross-sectional diagram of an embodiment of a tool string component having an embodiment of an electronic device. 
       (Prior Art)  FIG. 19  is a flowchart disclosing an embodiment of a method of transferring power between tool string components. 
     
    
    
     DETAILED DESCRIPTION 
     Relative to  FIGS. 1 through 5 , this application discloses an inductive coupler trough or mold  1500  and a method for producing the inductive coupler mold or trough  1500  for use in a downhole tool such as a drillpipe or bottom hole assembly. See (Prior Art)  FIG. 6 . The mold  1500  may comprise an annular magnetically conductive electrically insulating (MCEI) U-shaped single piece trough or mold  1500  comprising an annular channel comprising side walls  1540  and a bottom wall  1555 . The MCEI mold comprises inner diameter  1535  and an outer diameter  1520  and inner and outer top surfaces  1530  and  1525 , respectively. The annular channel  1540 / 1555  may comprise a first perforation  1640  and one or more second perforations  1580 . Typically, inductive couplers for use in downhole applications may be comprised of multiple MCEI trough segments arranged end for end to form an annular ring-like structure. See (Prior Art)  FIG. 15 . The MCEI segments may be composed of a ferrite composition. Ferrite may be hard and brittle and susceptible to breakage. The use of segments may enable construction and handling of the MCEI coupler and reduce breakage of the ferrite ring. In this application, a solid MCEI ferrite ring  1500  may be used, a half section of which, between section surfaces  1505  and  1550  is diagramed in  FIGS. 1-5 , at  1500 . The ferrite trough or mold  1500  may comprise an annular channel  1540 / 1555 . The ferrite trough or MCEI ring  1500  may be used as a mold and an annular electrically conducting molten ingot  1515  may be cast within the annular channel  1540 / 1555  of the mold  1500 . The ingot  1515  may produce an electromagnetic field when energized suitable for transmitting data to an electromagnetic field produced by a similarly configured nearby ingot. A molten metal comprising an electrically conducting metal or a metal alloy may be cast into the MCEI mold  1500  producing the electrically conducting ingot  1515 . Ferrite segments may be used as a mold, also, by lining the channel with a thin refractory liner, such as a ceramic liner or a titanium or other metal foil, to prevent molten metal leakage between the segments. 
     The ingot  1515  may comprise a first end  1590  and a second end  1585 , as diagramed through cut away  1595 . A first socket  1570  may be cast in the ingot  1515  adjacent the first end  1590 . One or more second sockets  1635  may be cast in the ingot  1515  adjacent the second end  1585 . The sockets  1635 / 1570  may be cast when the ingot  1515  is cast in the channel or the sockets may be formed after the ingot is cast by machining. A first perforation  1640  and one or more second perforations  1580  may be formed in the bottom  1555  of the annular channel. The perforations  1640 / 1580  may be formed by machining after the ingot  1515  is cast into the channel of the mold  1500 . The first perforation  1640  may be aligned with the first socket  1570  and the one or more second perforations  1580  may be aligned with the one or more second sockets  1635 . The respective sockets may house electrical connections  1565 . The first socket  1570  may house an electrical connection to a ground pin  1600  in the downhole tool. The one or more second sockets  1635  may house electrical connections  1565  to cables within the downhole tools. The cables may be connected to electronic equipment in the drill string or downhole tool. One or more cables may be attached to a similarly configured inductive coupler at the opposite end of the drill pipe or within the downhole tool. The alignment of the perforations  1640 / 1580  with the respective sockets allows for cable access through the MCEI mold to the make an electrical connection with the ingot  1515 . 
     The channel  1540 / 1555  in the MCEI mold  1500  may comprise one or more cleats  1615  projecting into the ingot  1555  thereby securing the ingot within the channel. The ingot  1555  may comprise one or more cleats  1605  projecting into the channel as a means of securing the ingot within the channel. The ingot  1515  may comprise annular flutes  1620  and the channel also may comprise annular flutes  1625 . The annular flutes of the ingot  1620  may couple with the annular flutes of the channel  1625 . The annular flutes may assist in securing the ingot within the annular channel. Also, the annular flutes may increase the surface area of the ingot thereby increasing the strength of the electromagnetic field between adjacent inductive couplers. The ingot  1515  may comprise an annular internal passageway  1630  within the ingot  1515 . The passageway  1630  may contribute resiliency to the ingot. Also, the passageway  1630  may promote rigidity in the ingot. An electrical cable, not shown, may run through the passageway  1630 . 
     A nonelectrically conductive seal  1545  may enclose the ingot  1515  within the channel. A seal seat  1560  may be provided in the wall  1540  of the channel to seal the ingot  1515  from downhole fluids and other contamination and to fix the seal  1545  over the ingot. The seal  1545  may act as a channel filler protecting the ingot  1515  from contamination from the downhole environment. Also, seals  1575  may be provided for the respective sockets and electrical connections, sealing the ingot and the respective sockets and electrical connections against downhole contamination. 
     The inductive coupler may be produced by providing an annular MCEI U-shaped mold  1500  comprising an annular channel  1540 / 1555  and casting an electrically conductive molten metal or metal alloy into the channel, thereby producing an annular electrically conducting ingot  1515 . 
     The ingot  1515  may have a first end  1590  and a second end  1585 . A first socket  1570  may be formed proximate the first end and a second socket  1635  may be formed proximate the second end. The respective sockets may be formed when the molten metal is cast into the channel, or the respective sockets may be formed by machining after the ingot has cooled. The ingot may comprise one or more second sockets  1635 . The sockets may provide a housing for electrical connections to the ingot  1515 . 
     A first perforation  1640  and one or more second perforations  1580  may be formed in the channel by machining. The respective perforations may be aligned with the respective sockets. The perforations allow cables within the downhole tool or drill string to access electrical connections in the ingot. The first electrical connection  1600  may be to a ground pin within the downhole tool. The one or more second electrical connections  1565  may be to cables connecting the ingot to a similarly configured ingot at the opposite of the drill pipe, and the cables may connect the ingot  1515  to electronics and electrical equipment within the downhole tool. 
     Seals may be provided to protect the ingot and electrical connections within the channel. A seal  1545  may be provided to cover the ingot within the channel. The channel seal  1545  may be partially disposed within annular seal seats  1560  formed in the walls  1540  of the channel. The respective sockets may be provided with seals  1575  to prevent contamination from downhole fluids and debris. 
     The ingot  1515  may be provided with an annular passageway  1630  that may be formed within the ingot by placing a tubular form, not shown, in the channel prior to casting in the molten metal. The tubular form may be electrically conductive and remain within the ingot or it may be nonelectrically conductive and consumed in the process. 
     Cleats  1605 / 1615  and flutes  1620 / 1625  may be formed in the channel and in the ingot, respectively. The cleats and flutes may be formed in the channel before it is sintered or machined in after sintering. Also, the flutes and cleats may be formed in the ingot when the ingot is cast into the channel by providing a form in the channel comprising the flutes and cleats. The form may be permanent or may be a consumable. 
     The remainder of the detailed description relates to the prior art figures of the &#39;865 reference. The teachings of the prior art figures are applicable to this disclosure except when modified by this disclosure. 
     Referring to (Prior Art)  FIG. 6 , one embodiment of a downhole drilling system  10  for use with the present invention includes a tool string  12  having multiple sections of drill pipe and other downhole tools. The tool string  12  is typically rotated by a drill rig  14  to turn a drill bit  16  that is loaded against a formation  18  to form a borehole  20 . Rotation of the drill bit  16  may alternatively be provided by other downhole tools such as drill motors or drill turbines located adjacent to the drill bit  16 . 
     The tool string  12  includes a bottom-hole assembly  22  which may include the drill bit  16  as well as sensors and other downhole tools such as logging-while-drilling (“LWD”) tools, measurement-while-drilling (“MWD”) tools, diagnostic-while-drilling (“DWD”) tools, or the like. The bottom-hole assembly  22  may also include other downhole tools such as heavyweight drill pipe, drill collar, crossovers, mud motors, directional drilling equipment, stabilizers, hole openers, sub-assemblies, under-reamers, drilling jars, drilling shock absorbers, and other specialized devices. 
     While drilling, a drilling fluid is typically supplied under pressure at the drill rig  14  through the tool string  12 . The drilling fluid typically flows downhole through a central bore of the tool string  12  and then returns up-hole to the drill rig  14  through an annulus  20  about the tool string  12 . Pressurized drilling fluid is circulated around the drill bit  16  to provide a flushing action to carry cuttings to the surface. 
     To transmit information at high speeds along the tool string  12 , a telemetry network comprising multiple network nodes  24  may be integrated into the tool string  12 . These network nodes  24  may be used as repeaters to boost a data signal at regular intervals as the signal travels along the tool string  12 . The nodes  24  may also be used to interface with various types of sensors to provide points for data collection along the tool string  12 . The telemetry network may include a top-hole server  26 , also acting as a network node, which may interface with the tool string  12  using a swivel device  28  for transmitting data between the tool string  12  and the server  26 . The top-hole server  26  may be used to transfer data and tool commands to and from multiple local and remote users in real time. To transmit data between each of the nodes  24  and the server  26 , data couplers and high-speed data cable may be incorporated into the drill pipe and other downhole tools making up the tool string  12 . In selected embodiments, the data couplers may be used to transmit data across the tool joint interfaces by induction and without requiring direct electrical contact between the couplers. 
     One embodiment of a downhole telemetry network is described in U.S. Pat. No. 6,670,880 entitled Downhole Data Transmission System, having common inventors with the present invention, which this specification incorporates by reference. The telemetry network described in the above-named application enables high-speed bi-directional data transmission along the tool string  12  in real-time. This provides various benefits including but not limited to the ability to control downhole equipment, such as rotary steerable systems, instantaneously from the surface. The network also enables transmission of full seismic waveforms and logging-while-drilling images to the surface in real time and communication with complex logging tools integrated into the tool string  12  without the need for wireline cables. The network further enables control of downhole tools with precision and in real time, access to downhole data even during loss of circulation events, and monitoring of pressure conditions, hole stability, solids movement, and influx migration in real time. The use of the abovementioned equipment may require the ability of passing power between segments of the tool string  12 . 
     Referring now to (Prior Art)  FIG. 7 , a downhole tool string component  200  of the tool string  12  of (Prior Art)  FIG. 6  comprises a tubular body  201 A with a box end  202 A and a pin end  203 A, with each end  202 A,  203 A being adapted for threaded connection to an adjacent tool string component (not shown). Both ends  202 A,  203 A have a shoulder  204 A that is adapted to abut an adjacent shoulder of an adjacent end of the adjacent tool string component. The downhole tool string component  200 A may have a plurality of pockets  205 A. The pockets  205 A may be formed by a plurality of flanges  206 A disposed around the downhole tool string component  200 A at different axial locations and covered by individual sleeves  207 A disposed between and around the flanges  206 A. A pocket  205 A may be formed around an outer surface of the tubular body  201 A by a sleeve  207 A disposed around the tubular body  201 A such that opposite ends of the sleeve  207 A fit around at least a portion of a first flange  206 A and a second flange  206 A. The sleeves  207 A may be interlocked or keyed together near the flanges  206 A for extra torsional support. At least one sleeve  207 A may be made of a non-magnetic material, which may be useful in embodiments using magnetic sensors or other electronics. The pockets  205 A may be sealed by a sleeve  207 A. 
     Electronic equipment may be disposed within at least one of the pockets  205 A of the downhole tool string component  200 A. The electronics may be in electrical communication with the aforementioned telemetry system, or they may be part of a closed-loop system downhole. An electronic device  210 A is secured to the tubular body  201 A and may be disposed within at least one of the pockets  205 A, which may protect the device  210 A from downhole conditions. The electronic device  210 A may comprise sensors for monitoring downhole conditions. The sensors may include pressure sensors, strain sensors, flow sensors, acoustic sensors, temperature sensors, torque sensors, position sensors, vibration sensors, geophones, hydrophones, electrical potential sensors, nuclear sensors, or any combination thereof. In some embodiments of the invention the electronic device  210 A may be a sensor, drill instrument, logging-while drilling tool, measuring-while drilling too, computational board, or combinations thereof. Information gathered from the sensors may be used either by an operator at the surface or by the closed-loop system downhole for modifications during the drilling process. If electronics are disposed in more than one pocket  205 A, the pockets  205 A may be in electrical communication, which may be through an electrically conductive conduit disposed within the flange separating them. The information may be sent directly to the surface without any computations taking place downhole. In some embodiments the electronic device may be a sonic tool. The sonic tool may comprise multiple poles and may be integrated directly into the tool string. Sending all of the gathered information from the sonic tool directly to the surface without downhole computations may eliminate the need for downhole electronics which may be expensive. The surface equipment may in some cases by able to process the data quicker since the electronics up-hole is not being processed in a high temperature, high pressure environment. 
     Referring now to (Prior Art)  FIG. 8  and (Prior Art)  FIG. 8A , (Prior Art)  FIG. 8  discloses a pin end  203 B of an embodiment of a downhole tool string component  200 B having a plurality of annular recesses  301 B formed in a shoulder  204 B. In some embodiments the shoulder  204 B may comprise a single recess  301 B. An annular inductive coupler  302  is disposed within each recess  301 B and comprises a coil  303 B. A first inductive coupler  304 B may be optimized for the transfer of power and a second inductive coupler  305 B may be optimized for the transfer of data. Referring to the coil  303 B disposed in the first coupler  304 B, the coil  303 B is in electrical communication with the electronic device  210 B via an electrical conductor  306 B. An electrical circuit  307 B comprises the electronic device  210 B, the annular coil  303 B disposed in the first coupler  304 B, and two electrical conductors  306 B that are disposed intermediate, or between, the electronic device  210 B and the coil  303 B and which are in electrical communication with both the electronic device  210 B and the coil  303 B. A portion  308 B of the electrical circuit  307 B comprises the coil  303 B and the two electrical conductors  306 B, and in some embodiments may not comprise the electronic device  210 B. The portion  308 B is electrically isolated from the tubular body  201 B of the component  200 B. 
     (Prior Art)  FIGS. 9 and 10  respectively disclose a perspective view and an exploded view of an embodiment of an inductive coupler  302 C. The inductive coupler  302 C comprises a housing ring  401 C, a first lead  402 C and a second lead  403 C. The housing ring  401 C may comprise a durable material such as steel. In the present embodiment the first lead  402 C and the second lead  403 C are proximate one another. The first lead  402 C and the second lead  403 C are adapted to electrically communicate with electrical conductors such as the two electrical conductors  306 B disclosed in (Prior Art)  FIG. 8 . In the embodiments of (Prior Art)  FIGS. 9 and 10 , the leads  402 C,  403 C and their corresponding electrical conductors are disposed proximate one another. The inductive coupler  302 C also comprises a coil  303 C and an annular trough  404 C made of magnetic material. The magnetic material may comprise a composition selected from the group consisting of ferrite, a nickel alloy, a zinc alloy, a manganese alloy, soft iron, a silicon iron alloy, a cobalt iron alloy, a mu-metal, a laminated mu-metal, barium, strongtium, carbonate, samarium, cobalt, neodymium, boron, a metal oxide, rare earth metals, Fe, Cu, Mo, Cr, V, C, Si, molypermalloys, metallic powder suspended in an electrically insulating material, and combinations thereof. The magnetic material may comprise a relative magnetic permeability of between 100 and 20000. The coil  303 C may comprise an electrically conductive material such as copper. When an alternating electrical current is passed through the coil  303 C an inductive signal may be generated. The coil  303 C may comprise a characteristic of increasing less than 35 degrees Celsius (.degree. C.) when 160 watts of power are passed through the coil  303 . In some embodiments the coil  303  may increase less than 20.degree. C. when 160 watts are passed through it. 
     Referring now to (Prior Art)  FIGS. 11-13 , inductive coupler  302 D comprises a coil  303 D having a plurality of windings  601 D of wire strands  602 D that are each electrically isolated from one another. The wire strands  602 D are disposed in the annular trough  404 D of magnetic material that is secured within the annular recess  301 D. As disclosed in (Prior Art)  FIGS. 12 and 13 , the wire strands  602 D may be interwoven. In some embodiments each coil  303 D may comprise between 5 and 40 wire strands  602 D and between 1 and 15 coil turns. In the present application, windings  601 D and coil turns may be used interchangeably. The coil  303 D may comprise a gauge between 36 and 40 American Wire Gauge (AWG). In the present embodiment a first lead  402  and a second lead  403  of the inductive coupler  302 D and their corresponding electrical conductors are disposed on opposite sides of the inductive coupler  302 D. In some embodiments, the wire strands  602 D are collectively wrapped with an insulator and in some embodiments, no insulator is required. A filler material such as Teflon®, (i.e. polytetrafluoroethlyene, fluoropolymer, and other fluoropolymers) or an epoxy may be used to fill the gaps in the inductive couplers  302 D, such as the gaps between the coil  303 D and the annular trough  404 D, and the annular trough  404 D and the annular recess  301 D, and so forth. 
     (Prior Art)  FIG. 14  discloses an embodiment of a downhole drill string component  200 E in which an electronic device  210 E is a computational board  901 E. The computational board  901 E is in electrical communication with both a first lead  402 E and a second lead  403 E of the inductive coupler  302 E through an electrical conductor  306 E. The computational board  901 E may send and receive electrical signals to and from other electrical equipment associated with the drilling operation through the downhole network. 
     (Prior Art)  FIG. 15  is a perspective diagram of an inductive coupler  302 F in which a first lead  402 F and a second lead  403 F are proximate one another. (Prior Art)  FIG. 15  also shows an embodiment in which an annular trough  404 F of magnetic material comprises a plurality of segments  1001 F of magnetic material that are each disposed intermediate, or between, the coil  303 F and the ring housing  401 F. 
     Referring now to (Prior Art)  FIG. 16 , an embodiment is shown in which a downhole component  200 G is connected at its box end  202 G to a pin end  203 G of an adjacent tool string component  1101 G. The adjacent tool string component  1101 G comprises an adjacent inductive coupler  1102 G that is configured similar to the inductive coupler  302 G of the downhole tool string component  200 G. The inductive couplers  302 G,  1102 G are adapted to couple when the components  200 G,  1101 G are connected together at their ends  202 G,  203 G. The inductive couplers  302 G,  1102 G are adapted to induce magnetic fields in each other when their coils  303 G are electrically energized. Specifically, passing an alternating electrical current through the coil  303 G of either inductive coupler  302 G,  1102 G, induces a magnetic field in the other coupler  1102 G,  302 G. This induced magnetic field is believed to induce an alternating electrical current in the induced coil  303 G. In some embodiments, when 160 watts are passed through one of the couplers  302 G,  1102 G, at least 136 watts are induced in other coupler  1102 G,  302 G. In other words, the inductive coupler  302 G may comprise a characteristic of transferring at least 85% of its energy input into the adjacent coupler  1102 G. In some embodiments the inductive coupler  302 G may transfer at least 95% of its input energy into the adjacent coupler  1102 G. 
     (Prior Art)  FIG. 16  also discloses tool string components  200 G,  1101 G comprising both primary and secondary shoulders  1103 G,  1004 G. In the present embodiment an inductive coupler  302 G is disposed in each of the primary and secondary shoulders  1103 G,  1004 G. In some embodiments only the primary shoulder  1103 G or only the secondary shoulder  1104 G may comprise a inductive coupler  302 G. In embodiments where each of the primary and secondary shoulders  1103 G,  1004 G comprises a inductive coupler  302 G, each inductive coupler  302 G may transfer energy at a different optimal frequency. This may be accomplished by providing the first and second coils  303 G with different geometries which may differ in the number of windings  601 G, diameter, type of material, surface area, length, or combinations thereof. The annular troughs  404 G of the couplers  302 G,  1102 G may also comprise different geometries as well. The inductive couplers  302 G,  1102 G may act as band pass filters due to their inherent inductance, capacitance and resistance such that a first frequency is allowed to pass at a first resonant frequency, and a second frequency is allowed to pass at a second resonant frequency. Preferably, the signals transmitting through the electrical conductors  306 G may have frequencies at or about at the resonant frequencies of the band pass filters. By configuring the signals to have different frequencies, each at one of the resonant frequencies of the couplers  302 G, the signals may be transmitted through one or more tool string components and still be distinguished from one another. In (Prior Art)  FIG. 16 , the coils  303 G disposed in the inductive couplers  302 G in the primary and secondary shoulders  1103 G,  1104 G of the tool string component each comprise a single winding  601 G, while the coils  303 G disposed in the adjacent inductive couplers  1102 G in the primary and secondary shoulders  1103 G,  1004 G of the adjacent component  1101 G each comprise three windings  601 G. Other numbers and combinations of windings  601 G may be consistent with the present invention. 
     Referring now to (Prior Art)  FIG. 17 , an embodiment of a downhole network  17 H in accordance with embodiment of the invention is disclosed comprising various electronic devices  210 H spaced at selected intervals along the network  17 H. Each of the electronic devices  210 H may be in operable communication with a bottom-hole assembly  22 H based on power and/or data transfer to the electronic devices  210 H. As power or data signals travel up and down the network  17 H, transmission elements  86 Ha- 86 He may be used to transmit signals across tool joints of a tool string  12 H. Transmission elements  86 Ha- 86 He may comprise an inductive coupler  302 H coupled with an adjacent inductive coupler  1102 H. Thus, a direct electrical contact is not needed across a tool joint to provide effective power coupling. In selected embodiments, when using transmission elements  86 Ha- 86 He, consistent spacing should be provided between each transmission element  86 Ha- 86 He to provide consistent impedance or matching across each tool joint. This may help to prevent excessive power loss caused by signal reflections or signal dispersion at the tool joint. 
     (Prior Art)  FIG. 18  discloses an embodiment in which the electronic device  210 J is a power source  1301 J. In (Prior Art)  FIG. 18  the power source  1301 J is a battery  1302 J. The battery  1302 J may store chemical potential energy within it. Because downhole sensors, tools, telemetry and other electronic components require power to operate, a need exists for a reliable energy source to power downhole components. In some embodiments, the power source  1301 J may comprise a battery, generator, capacitor, motor, or combinations thereof. A downhole electric power generator may be used to provide power to downhole components. In certain embodiments, the generator may be a micro-generator mounted in the wall of a downhole tool to avoid obstructing the tool&#39;s central bore. 
     In general, a downhole generator in accordance with the invention may include a turbine mechanically coupled to an electrical generator. The turbine may receive a moving downhole fluid, such as drilling mud. This downhole fluid may turn blades of the turbine to produce rotational energy (e.g., by rotating a shaft, etc.). This rotational energy may be used to drive a generator to produce electricity. The electrical power produced by the generator may be used to power electrical equipment such as sensors, tools, telemetry components, and other electronic components. One example of a downhole generator which may be used with the present invention is described in U.S. Pat. No. 7,190,084 which is herein incorporated by reference in its entirety. Preferably, however, the turbine is disposed within the bore of the drill string. 
     Downhole generators may be AC generators that are configured to produce an alternating current with a frequency between about 100 Hz and 2 kHz. More typically, AC generators are configured to produce an alternating current with a frequency between about 300 Hz and 1 kHz. The frequency of the alternating current is proportional to the rotational velocity of the turbine and generator. In some embodiments of the invention, a frequency converter may alter the frequency from a range between 300 Hz and 1 kHz to a range between 10 kHz and 100 kHz. In certain embodiments, an alternating current with a frequency between about 10 kHz and 100 kHz may achieve more efficient power transmission across the tool joints. Thus, in selected embodiments, the frequency of the alternating current produced by the generator may be shifted to a higher frequency to achieve more efficient power transmission. 
     To achieve this, a rectifier may be used to convert the alternating current of the generator to direct current. An inverter may convert the direct current to an alternating current having a frequency between about 10 kHz and 100 kHz. The inverter may need to be a custom design since there may be few if any commercially available inverters designed to produce an AC signal between about 400 Hz and 1 MHz. The alternating current at the higher frequency may then be transmitted through electrical conductors  306  routed along the tool string  12 . The power signal may be transmitted across tool joints to other downhole tools by way of the transmission elements  86  discussed in the description of (Prior Art)  FIG. 17 . 
     In selected embodiments, a gear assembly may be provided between the turbine and the generator to increase the rotational speed of the generator relative to the turbine. For example, the gear assembly may be designed such that the generator rotates between about 1.5 and 10 times faster than the turbine. Such an increase in velocity may be used to increase the power generated by the generator as well as increase the frequency of the alternating current produced by the generator. One example of an axially mounted downhole generator that may be used with the present invention is described in patent application Ser. No. 11/611,310 and entitled, “System for steering a tool string,” which has common inventors with the present invention and which this specification incorporates by reference for all that it contains. 
     Referring now to (Prior Art)  FIG. 19 , a flowchart illustrates a method  1400  of transferring power from a downhole tool string component  200  to an adjacent tool string component  1101 . The method  1400  comprises a step  1401  of providing a downhole tool string component  200  and an adjacent tool string component  1101  respectively comprising an annular inductive coupler  302  and an adjacent annular inductive coupler  1102 . Each coupler  302 ,  1102  is disposed in an annular recess  301  in a shoulder  204  of an end  202 ,  203  of one of the components  200 ,  1101 . The method  1400  further comprises a step  1402  of adapting the shoulder  204  of each of the downhole tool string component  200  and the adjacent tool string component  1101  to abut one another when the ends  202 ,  203  of the components  200 ,  1101  are mechanically connected to one another. The method  140  further comprises a step  1403  of mechanically connecting the ends  202 ,  203  of the components  200 ,  1101  to one another, and a step  1404  of driving an alternating electrical current through the inductive coupler  302  at a frequency of between 10 and 100 kHz. In some embodiments, the alternating electrical current is a square wave. 
     In some embodiments the alternating electrical current may be driven at a frequency between 50 and 70 kHz. The inductive couplers  302 ,  1102  may each be disposed within an annular trough  404  of magnetic material. The troughs  404  may each be disposed within an annular recess  301  of the tool string components  200 ,  1101 . At least one of the inductive couplers  302 ,  1102  may comprise a coil  303  that comprises a plurality of windings  601  of wire strands  602 . The wire strands  602  may each be electrically isolated from each other. In some embodiments at least 85% of the energy comprised by the alternating electrical current being driven through the annular inductive coupler  302  may be inductively transferred to the adjacent inductive coupler  1102  when 160 watts are passed through the coil  303  of the inductive coupler  302 . In some embodiments at least 95% of the energy may be inductively transferred when 160 watts are passed through the coil  303 . 
     Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.