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BACKGROUND 
   This invention relates to a system and method for processing signals in a well, and, more particularly, for acquiring signals and transmitting the signals across, or through, a component located downhole in a well. 
   It is often desirable to provide one or more electronic data sources, such as sensors, actuators, control systems, and the like, on or near a component in a tubing string that is inserted in a well penetrating a subterranean formation for the purpose of recovering oil and/or gas from the formation. For example, the data source could be in the form of a sensor to sense leakage across a packer, or other sealing device, deployed in the well for the purpose of isolating one or more portions of the well for testing, treating, or producing the well. 
   However, to utilize a data source in the above manner, it is usually necessary to run electrical cables from the data source under or through the component, which often causes problems. For example, the cables take up valuable space and, if the component is a packer, the cables could create a fluid leakage path through the packer. 
   Therefore, what is needed is a system and method which permits the transmission of data across or through a component in a well, while eliminating the need for electrical cables. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a partial sectional, partial diagrammatic, view of an embodiment of the present invention. 
       FIGS. 2 and 3  are similar to  FIG. 1  but depict alternate embodiments of the present invention. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1  of the drawing, a downhole tool is referred to, in general, by the reference numeral  10  and is shown installed in a casing  12  disposed in a well. The tool  10  is lowered to a predetermined depth in the casing  12  as part of a tubing string, or the like, (not shown) which often includes other tools used to perform various oil recovery and completion operations. Since the tool  10  is conventional, it will not be described in detail. 
   The tool  10  includes a packer  14  and an annular slip  16  located downstream, and axially spaced, from the packer  14 . The packer  14  is located at a predetermined axial location in the casing  12  and is set, or activated, in a conventional manner which causes it to engage the inner surface of the casing  12  to seal against the flow of fluids and thus permit the isolation of certain zones in the well. The slip  16  functions to engage, or grip, the inner wall of the casing  12  and since it and the packer  14  are conventional, they will not be described in further detail. 
   A data source  20  is mounted on the lower surface of the packer  14 , as viewed in the drawing, and is attached, or secured, to the packer  14  in any conventional manner. The data source  20  can be in the form of a sensor, an actuator, a control unit, or other type of device that is used in connection with the packer  14  for various operations, and is adapted to output a corresponding signal. For example, the data source  20  can be in the form of a sensor for sensing a condition or function of the packer  14 , such as fluid leakage across the packer  14 , and outputting a corresponding signal, as disclosed in assignee&#39;s copending patent application Ser. No. 10/251,160, filed Sep. 20, 2002, the disclosure of which is incorporated herein by reference in its entirety. 
   A wireless electronic transmitter module  24  is mounted on the lower surface of the packer  14 , as viewed in the drawing and is adapted to broadcast, or transmit electrical signals. The transmitter module  24  can be in the form of an acoustic source such as a solid state transducer formed by a piezoelectric, ferroelectric, or magnetostrictive material, or it can be in the form of an electroactive polymer, or a voice coil. 
   An electronic receiver module  26  is mounted on the upper surface of the packer  14  and may be in the form of a solid-state transducer formed by a piezoelectric, ferroelectric, or magnetostrictive material or it can be in the form of an accelerometer, microphone, foil strain gage, or a voice coil. Thus, signals emitted by the transmitter module  24  can be received by the receiver module  26  without the use of conductors, cables, or wires. 
   A data communication cable  28  extends between, and is electrically connected to, the data source  20  and the transmitter module  24 . One end of a data communication cable  30  is electrically connected to the receiver module  26  and extends uphole to equipment disposed on the ground surface, as disclosed in the above-identified patent application. Each data communication cable  28  and  30  contains at least one electrical conductor for conducting electrical signals in a manner to be discussed. 
   It is understood that the data source  20  and the modules  24  and  26  are normally provided with power sources (not shown). Alternately, one of the modules  24  or  26  can deliver power to the other module, by inductive coupling at a frequency other than the transmission frequency, while simultaneously sending or receiving data. This eliminates the need for a power source for the other module. Also, a power source for the data source  20  can be eliminated and the data source  20  can receive power from the transmitter module  24  and/or the receiver module  26  in the above manner. 
   In operation, and assuming that the data source  20  is in the form of a sensor that senses data downhole, such as leakage across the packer  14 , such data are outputted to the transmitter module  24  via the data communication cable  28 . The transmitter module  24  creates corresponding high frequency oscillations in the manner discussed above that propagate, either singly or in combination, through the packer  14 . The receiver module  26  receives and measures the encoded signals and converts them back into electrical impulses which are transmitted, via the data communication cable  30 , to ancillary equipment (not shown) at the ground surface. This auxiliary equipment processes the signal outputted from the receiver module  26  and performs additional functions such as, for example, adjusting the packer  14  to eliminate the above leakage. 
   The communication path between the modules  24  and  26  can be tuned to find a preferred frequency range for transmission. In general, the tool  10 , including the packer  14  and the slip  16 , will have different attenuation at different frequencies and it is preferred to send the signals from the transmitter module  24  to the receiver module  26  at the frequencies that have lower attenuation. These frequencies can be chosen, a priori based upon numerical modeling, based upon previous experience, or they can be adjusted in the well based upon measured parameters. Also, the frequencies can be remotely adjusted by using a neural network algorithm or by using an adaptive feedforward algorithm. 
   The attenuation at different frequencies can be measured by having the transmitter module  24  send a signal and then listen for the reflected frequencies. Alternatively, the transmitter module  24  could send signals and it, or a receiver placed adjacent to it, could be set to listen for the rebroadcast of the signals by the receiver module  26 , or a transmitter placed adjacent to the latter module. In the latter case the frequencies that are returned to the transmitter module  24  would be the preferred frequencies for transmission between the modules  24  and  26 . 
   The embodiment of  FIG. 2  is similar to that of  FIG. 1  and identical components are given the same reference numerals. According to the embodiment of  FIG. 2 , the data source  20  is mounted on the upper portion of the packer  14 . The data communication cable  28  extends between, and is electrically connected to, the data source  20  and the transmitter module  24 ; and one end of the data communication cable  30  is electrically connected to the receiver module  26  and extends downhole to equipment (not shown) for processing the signal outputted from the receiver module  26 , as disclosed in the above-identified patent application. Otherwise the embodiment of  FIG. 2  is identical to that of  FIG. 1 . 
   The embodiment of  FIG. 3  is similar to that of  FIG. 1  and identical components are given the same reference numerals. According to the embodiment of  FIG. 3 , the modules  24  and  26  of the embodiment of  FIG. 1  are replaced by two inductive coils  34  and  36 , respectively. The coil  34  is wrapped around the lower portion of the packer  14  and is connected to one end of the data communication cable  28 ; while the coil  36  is wrapped around the upper portion of the packer  14  and is connected to one end of the data communication cable  30 . The other end of the data communication cable  28  is connected to the data source  20 , and the data communication cable  30  extends to equipment at the ground surface for the reasons described in connection with the embodiment of  FIG. 1 . 
   Thus, in the embodiment of  FIG. 3 , the coil  34  receives the signal from the data source  20  corresponding to the sensed data, which, in the above example, is the leakage across the packer  14 , and transmits corresponding data to the coil  36  which functions as a receiver and, as such, receives the data from the coil  34  and passes it to the data communication cable  30  for transmission to the ground surface. 
   The elements of the packer  14  can include a ferromagnetic material in order to facilitate inductive coupling of the coils  34  and  36 . For example, a standard packer rubber could incorporate a metallic element (such as nickel, steel, iron, cobalt, dysprosium, or gadolinium powder) or a ceramic element in order to increase the coupling between the coils  34  and  36 . The ferromagnetic materials could be incorporated into the formation of the packer  14  as a powder, rod, or mesh. The steel mandrel of the packer  14  could also serve to improve the connection between the coils  34  and  36 . 
   It is understood that the embodiment of  FIG. 3  can be adapted to function in the same manner as the embodiment of  FIG. 2 , i.e., the data source  20  can be mounted on the upper surface of the packer  14  and connected, via the data communication cable  28 , to the coil  36  which receives the output of the source  20  and transmits corresponding signals to the coil  34 . The data communication cable  30  would then transmit corresponding signals from the coil  34  downhole to equipment for further processing. 
   Thus, each of the above embodiments permits a wireless, non-evasive transmission of data across a downhole component, in an efficient, low-cost manner. 
   VARIATIONS AND EQUIVALENTS 
   It is understood that several variations may be made in the foregoing without departing from the scope of the invention. 
   1. A primary or rechargeable battery could be incorporated with the modules  24  and/or  26 . 
   2. A power generator could be provided in the wellbore or the casing  12  to convert hydraulic power from the fluid flow in the wellbore to electrical power to drive the data source  20  and/or the modules  24  and  26 . This downhole power generator could have a rechargeable battery to provide power at times when there is no flow. 
   3. The data source  20  can be replaced with another data source such as a hard-wired umbilical or a downhole electronics module, a source disclosed in the above-identified application, or any other source. 
   4. The signals can be transmitted between the modules  24  and  26  by electromagnetic waves rather than acoustically as described above. 
   5. The signals can be transmitted across, or through, any other conventional component, other than a packer, located downhole. 
   6. The data source  20  could be mounted on any surface of the component or packer  14 , or embedded in or adjacent to, the component or packer. 
   7. If the component is a packer, the modules  24  and  26  could be mounted on the outer edge of the packer, within its shoe, setting sleeve, and/or retainer, and/or on the slip  16 . 
   8. The number of data sources  20  and modules  24  and  26  can be varied. For example an array of transmitter modules  24  could be used to direct the transmission towards an array of receiver modules  26  which could be designed to preferentially sense the transmissions coming from the transmitter modules  24 . 
   9. The location of the modules  24  and  26  can be varied. For example, both modules  24  and  26  can be located above the component, or packer, in which case the data source  20  would be located below the component. In this case the data source  20  would function to change the impedance of the casing  12  in one of several ways so that different amounts of energy are reflected which would reduce the power requirement at the downhole location. Also, the electrical impedance could be changed by connecting/disconnecting the casing  12  with the tool  10 . Further, the magnetic impedance could be changed in the magnetic flux return path, such as through the casing  12 . Still further, the acoustic impedance could be changed by grabbing the casing  12  by energizing a magnetorheological fluid or an electrorheological fluid. 
   It is understood that spatial references, such as “upper”, “lower”, “inner”, “outer”, etc., as used above are for the purpose of illustration only and do not limit the specific spatial orientation or location of the components described above. 
   Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many other modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims.

Summary:
A system and method for transferring data across a component in a well, according to which a first module receives the data and transmits the data, via electromagnetic waves, through the component, and a second module receives the transmitted data from the first module.