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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional application of U.S. patent application Ser. No. 11/431,736, filed on May 10, 2006, which takes priority from U.S. patent application Ser. No. 60/679,406 filed on May 10, 2005, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to data telemetry apparatus and methods for oilfield wellbore operations. 
         [0004]    2. Description of the Related Art 
         [0005]    A variety of communication and transmission techniques have been used to provide real time data from the vicinity of a drill bit to the surface during drilling. The utilization of measurement-while-drilling (MWD) sensors with real time data transmission provides substantial benefits during a drilling operation. For example, continuous monitoring of downhole conditions allows for a prompt response to potential well control problems and results in improved drilling efficiency and hole cleaning. 
         [0006]    MWD systems provide drilling operators greater control over the construction of a well by providing information about conditions at the bottom of a wellbore substantially in real time as the wellbore is being drilled. Certain information is of interest to drilling operators, and is preferably obtained from the bottom of the wellbore substantially in real time. This information commonly includes directional drilling variables such as inclination and direction (azimuth) of the drill bit, and geological formation data, such as natural gamma ray radiation levels and electrical resistivity of the rock formation. The term MWD system should be understood to encompass equipment and techniques for data transmission from within the well to the earth&#39;s surface. 
         [0007]    Measurement of drilling parameters such as bit weight, torque, wear and bearing condition in real time provides for more efficient drilling operations. In fact, faster penetration rates, better trip planning, reduced equipment failures, fewer delays for directional surveys, and the elimination of a need to interrupt drilling for abnormal pressure detection is achievable using MWD techniques. 
         [0008]    Common telemetry systems that have been used in an attempt to provide real-time data from the vicinity of the drill bit to the surface include mud pressure pulse systems, insulated conductor system, acoustic systems, and electromagnetic systems. 
         [0009]    In a mud pressure pulse system, the resistance of mud flow through a drill string is modulated by means of a valve and control mechanism mounted in a drill collar near the bit and generates a pressure pulse that travels in the mud column to the surface. This type of system typically transmits data at low rates, typically less than 10 bits per second due to attenuation and distortion of the generated pulses. 
         [0010]    An insulated conductor, or hard wire connection from MWD sensors to the surface, is an alternative method for establishing downhole communications. As used herein, the term insulated conductor means both electrical and optical conductors. This type of system is capable of a high data rate and high-speed two way communication is possible. This type of system may employ a special drill pipe and special tool joint connectors having the insulated conductors disposed therein. An alternative installation may use a cable within the pipe bore as the insulated conductor. 
         [0011]    Acoustic systems have provided a third alternative. Typically, an acoustic signal is generated near the bit and is transmitted as stress waves through the wall of the drill pipe, or as pressure pulses or waves in the mud column. For acoustic signals transmitted as stress waves through the walls of the pipe, reflective and refractive interference resulting from changing diameters and thread makeup at the tool joints results in a reduced signal bandwidth. In addition, contact between the drill pipe and the borehole wall, such as may occur, for example, in a directional well, results in a very high level of signal attenuation that makes signal detection difficult at the surface. 
         [0012]    The fourth technique used to telemeter downhole data to the surface uses the transmission of electromagnetic waves through the earth. A current carrying downhole data signal is input to a toroid or collar positioned adjacent to the drill bit or input directly to the drill string across an electrical isolator. When a toroid is utilized, a primary winding carrying the data for transmission, is wrapped around the toroid and a secondary winding is formed by the drill pipe. A receiver is connected to the ground at the surface where the electromagnetic data is picked up and recorded. It has been found, however, that in deep or noisy well applications, conventional electromagnetic systems experience difficulty in extracting the data signal from the ambient noise at the surface. The surface noise includes telluric noise as well as manmade noise from electric machinery and generators associated with the drilling process. In addition, electromagnetic noise may be generated by the movement of the conductive drill string in the wellbore. In addition, the attenuation of electromagnetic waves above about 20 Hz is extreme, resulting in very small signal at the surface. It is common that the noise source signals are significantly greater than the desired transmitted signals. While much of the noise can be removed from the surface measurements, the high attenuation and low transmission bandwidth limit the use of common electromagnetic techniques to relatively shallow depths and/or low bit rates. 
         [0013]    All of the systems mentioned above employ some type of signal acquisition at the surface. In many cases, the presence of a rotating drill string makes optimal placement of the detection sensors a problem. For example, pressure pulse signals are commonly detected by a pressure transducer mounted upstream (closer to the pump) of a Kelly hose on a non-rotating portion of the fluid supply line. However, this location makes detection more difficult due to pressure pulse signal attenuation due to the compliant Kelly hose and due to reflections from pipe connections. Mounting of the pressure transducer on the rotating drill string, for example above the Kelly joint and before the Kelly hose, or within the rotating portion of a top drive, can provide superior detection. However, the transfer of the signal from the rotating framework to the stationary rig environment requires slip-rings or inductive couplers. Likewise, the use of hard-wired drill string connections, as described above, commonly requires slip rings or inductive couplers mounted on the Kelly to transfer the signal from the rotating to non-rotating environment, and vice versa. In addition, when a slip-ring or inductive coupler is used to transfer the signal from the rotating member to the stationary rig environment, a cable is commonly run through the top drive and along the Kelly hose to connect the slip-ring or inductive coupler with a surface controller for both signal and power transfer. These cables can pose repair and maintenance problems. Thus, there is a need for an improved surface telemetry system for use during wellbore operations. 
       SUMMARY OF THE DISCLOSURE 
       [0014]    In one aspect of the present invention, a system for communicating data between a downhole tool and a surface controller comprises a rotating drill string extending in a borehole and having a downhole telemetry module disposed proximate a bottom end thereof and transmitting a first signal across a telemetry channel. A surface telemetry module is disposed proximate a top end of the rotating drill string and is adapted to receive the first signal transmitted by the downhole telemetry module across the transmission channel. The surface telemetry module include a radio frequency transmitter disposed therein for transmitting a second signal related to the first signal. A stationary communication module has a radio frequency receiver adapted to receive the second signal. 
         [0015]    In another aspect, a method of communicating between a downhole tool and a surface controller comprises extending a rotating drill string, having a downhole telemetry module disposed proximate a bottom end thereof, in a borehole and transmitting a first signal across a telemetry channel. The first signal is received at a surface telemetry module mounted proximate a top end of the rotating drill string and transmits a second signal related to the first signal. The second signal is received at a stationary communication module. 
         [0016]    Examples of the more important features of the invention thus have been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contributions to the art may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    For detailed understanding of the present invention, references should be made to the following detailed description of the embodiments, taken in conjunction with the accompanying drawings, in which like elements have been given like numerals, wherein: 
           [0018]      FIG. 1  is a schematic diagram of one embodiment of a drilling system having a radio frequency communication system according to one embodiment of the present invention; 
           [0019]      FIG. 1A  is a schematic diagram showing placement of a trans/receiver according to one embodiment of the present invention; 
           [0020]      FIG. 1B  is a schematic diagram showing placement of a trans/receiver according to another embodiment of the present invention; 
           [0021]      FIG. 2  is a plan view showing placement of an exemplary transmitter and a plurality of receivers at a surface of a drilling system according to one embodiment of the present invention; and 
           [0022]      FIG. 3  is a block functional diagram of a telemetry system according to one embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0023]      FIG. 1  shows a schematic diagram of an exemplary drilling system  10 . As shown, the system  10  includes a conventional derrick  11  erected on a derrick floor  12 . A drill string  20  that includes a drill pipe section  22  that extends downward into a borehole  26 . A drill bit  50  attached to the drill string at the downhole end disintegrates the geological formations when it is rotated. The drill string  20  is coupled to a drawworks  30  via a kelly joint  21 , top drive  28  and line  29  through a system of pulleys  17 . Top drive  28  provides power to rotate drill string  20 . During drilling operations, the drawworks  30  is operated to control the weight on the drill bit  50  and the rate of penetration of the drill string  20  into the borehole  26 . The operation of the drawworks  30  is well known in the art and is thus not described in detail herein. 
         [0024]    During drilling operations, a suitable drilling fluid  31  (commonly referred to in the art as “mud”) from a mud pit  32  is circulated under pressure through the drill string  20  by a mud pump  34 . The drilling fluid  31  passes from the mud pump  34  into the drill string  20  via a desurger  36 , fluid line  38 , through a swivel (not shown) in top drive  28  and the kelly joint  21 . The drilling fluid is discharged at the borehole bottom  51  through an opening in the drill bit  50 . The drilling fluid circulates uphole through the annular space  27  between the drill string  20  and the borehole  26  and is discharged into the mud pit  32  via a return line  35 . Alternatively, the kelly joint  21  may be driven by a drive table  14  disposed in derrick floor  12  that rotationally engages kelly joint  21  and also allows axial motion of the kelly joint through the drive table. Such a drive system is known in the art, and is not described here further. 
         [0025]    In one embodiment, a drilling motor or mud motor  55  coupled to the drill bit  50  via a drive shaft (not shown) disposed in a bearing assembly  57  also rotates the drill bit  50  when the drilling fluid  31  is passed through the mud motor  55  under pressure. The bearing assembly  57  supports the radial and axial forces of the drill bit  50 , the downthrust of the drill motor  55  and the reactive upward loading from the applied weight on bit. A stabilizer  58  coupled to the bearing assembly  57  acts as a centralizer for the lowermost portion of the mud motor assembly. 
         [0026]    The downhole subassembly  59  (also referred to as the bottomhole assembly or “BHA”), which contains the various sensors and MWD devices that provide information about the formation and downhole drilling parameters relating to the drill string, including the mud motor, is coupled between the drill bit  50  and the drill pipe  22 . The downhole assembly  59  may be modular in construction, in that the various devices are interconnected sections so that the individual sections may be replaced when desired. 
         [0027]    Still referring to  FIG. 1 , the BHA also contains sensors and devices in addition to the above-described sensors. Such devices include a device  64  for measuring the formation resistivity near and/or in front of the drillbit  50 , a gamma ray device  76  for measuring the formation gamma ray intensity and devices for determining the inclination and azimuth of the drill string  20 . The formation resistivity measuring device  64  is preferably coupled above the lower kick-off subassembly  62  that provides signals, from which resistivity of the formation near or in front of the drill bit  50  is determined. A dual propagation resistivity device (“DPR”) having one or more pairs of transmitting antennae  66   a  and  66   b  spaced from one or more pairs of receiving antennae  68   a  and  68   b  may be used. Magnetic dipoles are employed which operate in the medium frequency and lower high frequency spectrum. In operation, the transmitted electromagnetic waves are perturbed as they propagate through the formation surrounding the resistivity device  64 . The receiving antennae  68   a  and  68   b  detect the perturbed waves. Formation resistivity is derived from the phase and amplitude of the detected signals. The detected signals are processed by a downhole circuit that is typically placed in a housing above the mud motor  55  and transmitted to a surface using a suitable downhole telemetry system  72 . 
         [0028]    The inclinometer  74  and gamma ray device  76  are suitably placed along the resistivity measuring device  64  for respectively determining the inclination of the portion of the drill string near the drill bit  50  and the formation gamma ray intensity. Any suitable inclinometer and gamma ray device may be utilized for the purposes of this invention. In addition, an azimuth device (not shown), such as a magnetometer or a gyroscopic device, may be used to determine the drill string azimuth. Such devices are known in the art and are, thus, not described in detail herein. In the above-described configuration, the mud motor  55  transfers power to the drill bit  50  via one or more hollow shafts that run through the resistivity measuring device  64 . The hollow shaft enables the drilling fluid to pass from the mud motor  55  to the drill bit  50 . In an alternative embodiment of the drill string  20 , the mud motor  55  may be coupled below the resistivity measuring device  64  or at any other suitable place. 
         [0029]    The downhole assembly  59  may include an MWD section that contains a nuclear formation porosity measuring device, a nuclear density device and an acoustic sensor system placed above the mud motor  55  for providing information useful for evaluating and testing subsurface formations along borehole  26 . The present invention may utilize any suitable formation density device. Any density device using a gamma ray source may be used. In use, gamma rays emitted from a source enter the formation where they interact with the formation and attenuate. The attenuation of the gamma rays is measured by a suitable detector from which density of the formation is determined. 
         [0030]    An exemplary porosity measurement device may employ a neutron emission source and a detector for measuring the resulting gamma rays. In use, high energy neutrons are emitted into the surrounding formation. A suitable detector measures the neutron energy delay due to interaction with hydrogen and atoms present in the formation. 
         [0031]    The above-noted devices transmit data to the downhole telemetry system  72 , which in turn transmits the received data uphole to the surface control unit  112  via a suitable communications link or channel. The downhole telemetry system  72  also receives signals and data from the uphole control unit  112  and transmits such received signals and data to the appropriate downhole devices. 
         [0032]    In one embodiment, the present invention utilizes a wired-pipe telemetry technique to communicate data between downhole sensors and devices and a surface telemetry system during drilling operations. As shown in  FIG. 1 , in such a configuration, an electrical conductor  150  is mounted along the length of each individual section of pipe with electrical and/or inductive connections at each threaded joint between pipe sections. The electrical wire may be run in conduit (not shown) within the bore of each pipe section. Such a system is disclosed in U.S. Pat. No. 6,670,880 to Hall et al. and is incorporated herein by reference. Alternatively, any other suitable technique for running an electrical conductor from downhole to the surface may be used. 
         [0033]    Still referring to  FIG. 1 , the present invention provides a surface telemetry system that provides bi-directional data communication with the downhole telemetry system  72 . The surface telemetry system includes a wireless transmitter or a transmitter and receiver (trans/receiver) module  100 , a plurality of wireless receivers, such as receivers  101   a  and  101   b , or  101   a ′ and  101   b ′ (collectively designated by numeral  101 ) that are located spaced apart at suitable locations around the mast  11  and/or proximate the derrick floor  12  and a surface control unit or a controller  112 . 
         [0034]    In one aspect, the trans/receiver module  100  may be placed so that it rotates with the drill string and in another aspect, the module  100  may be non-rotating.  FIG. 1  shows that the module  100  is coupled to the communications link  150  and placed in the drill pipe below a top drive  28  that rotates the drill pipe  21 . 
         [0035]    In one embodiment, the trans/receiver  100  is placed in a module or sub that is attached to a rotating section of the drill string, as shown and described in reference to  FIG. 1A  below. In another aspect, the module  100  may be placed in a top drive, such as top drive  28 . The module  100  may also be an integral part of the top drive  28 . In another aspect, the module  100  may be non-rotating as described in reference to  FIG. 1B  below. In the configuration of  FIG. 1 , the module  100  that includes a trans/receiver  103  is coupled to the link  150  for receiving signals from and transmitting signals to the downhole telemetry system  72 . If drilling fluid or mud is used as a communication link between the surface and downhole telemetry systems, a pressure sensor and associated circuitry is included in the module  100  to generate signals that correspond to the signals transmitted from a downhole pressure pulser. 
         [0036]    In the configuration of  FIG. 1A , the module  100  is attached to drill pipe  21  and coupled to the wire link  150 . In this embodiment, the module  100  that contains the trans/receiver  103  and associated circuitry and devices rotate with the drill string. The module  100  may be placed below the links  155 , which are shown to be below the top drive  28  of  FIG. 1 . In the embodiment of  FIG. 1B , the module  100  that contains the trans/receiver  103  and associated circuitry and devices is non-rotating and is shown attached to a flexible cable  86  that moves down with the drill pipe  22  as the well is drilled and moves up when a new drill pipe section is added to the drill string. The wire link  150  terminates at a coupling device  82  that transfers the signals received from the downhole system  72  between a rotating member  82   a  to a non-rotating member  82   b.  The module  100  is coupled to the non-rotating member  82   b  by a link  84 , which may be any suitable link, including a wire connection or a fiber optic link. In one aspect, the coupling device  82  may be a slip ring type device that transfers data and power between the rotating and non-rotating members  82   a  and  82   b.  In another aspect, the coupling device  82  may be an inductive coupling device or another suitable device. 
         [0037]    In the surface telemetry system, the multiple receivers may be located at any suitable location. A drilling rig, such as shown in  FIG. 1  or an offshore platform (not shown) includes a large number of metallic and electrical equipment introduces noise that can interfere or corrupt wireless signals transmitted from the module  100  and thus the number of receivers and location thereof may be selected depending upon the size and shape of the rig structure. 
         [0038]      FIG. 2  shows a plan view of the placement and interconnection of certain components of the surface telemetry system including multiple receivers according to one embodiment of the invention. As shown in  FIG. 2 , receivers  101   a - 101   d  are placed around the mast  11 , while the module  100  containing the trans/receiver is connected to the drill pipe  21 . One or more receivers, such as receivers  101   e  and  101   f , may be placed a certain distance away from the mast  11 . Thus, the system may include multiple spaced apart receivers, each receiver being connected to the controller  112 . The controller further may include a router  115  that performs an error-detection and error-correction scheme on the signals received from the receivers  101   a - 101   f  and passes the signals that meet a selected criterion to the processor of the controller  112  for further processing, as described in more detail later. The controller  112  may be coupled (directly or via a wireless connection to a remote cite  113 , such as a client office). Controller  112  includes the peripherals connected to the controller. 
         [0039]    The surface control unit  112  receives signals from and transmits commands and information to the downhole sensors and devices via the surface telemetry module  100  as described in more detail below. In one embodiment, the surface telemetry system is a bidirectional telemetry system that includes the surface control unit  112  that processes signals received from the downhole devices and transmits commands signals and other information to the downhole devices. The surface control unit  112  processes signals (also referred to herein as data signals) according to programmed instructions provided to the surface control unit. The surface control unit  112  contains a computer or processor, memory for storing data, computer programs, models and algorithms, a data recorder and other peripherals, collectively designated by numeral  140 . The surface control unit  112  uses the models and algorithms to process data according to programmed instructions and responds to user commands entered through a suitable device, such as a keyboard. The surface control unit  112  displays desired drilling parameters and other information on a display/monitor  140 , and the displayed information is used by an operator to control the drilling operations. 
         [0040]      FIG. 3  shows a functional block diagram of the telemetry system according to one aspect of the invention. In one aspect, the module  100  includes an interface circuitry  123 , a processor having a memory  122 , a radio frequency (RF) transmitter  110   a  and a receiver  110   b,  which in one embodiment also may be an RF receiver. Transmitter  110   a  and receiver  110   b  may be integrated into a single unit or alternatively may be separate devices in the module  100 . Module  100  may be powered by batteries (not shown) or another suitable means. 
         [0041]    The operation of the telemetry system is described below while referring to  FIGS. 1-3 . During operation of the drilling system  10 , data from downhole sensors is transmitted to the surface by the downhole telemetry module  72  via the communications channel or link  150 . The surface telemetry module  100  receives signals from and transmits signals to the downhole telemetry module  72  via the communication link  150 . The interface circuits  123  associated with the module  100  receive and process the downhole signals and provide the processed signals to the processor  122 . The transmitter  110   a,  while rotating, transmits wirelessly the received signals in the form of data blocks or packets toward the receivers  101   a - 101   f.  The data bits to be transmitted are encoded with error detection and correction bits using a suitable coding scheme. The coding scheme typically adds the parity bits to the data bits. Thus, each transmitted data packet includes a certain number of data bits and a certain number of error detection and correction bits. The processor  122 , using programs and the coding schemes, encodes the data bits. Such programs and coding schemes are stored in memory associated with the processor. The transmitter section  110   a  transmits the data signals provided to it by the processor. The transmitter  110   a  also may include an antenna that directs the data signals to the receivers. The transmitter and receiver configurations described herein provide an omni-directional or a substantially omni-directional transmission system. 
         [0042]    The processor  122  controls the operation of the transmitter  110   a . In one aspect, the transmitter transmits the signals at a preselected frequency. In another aspect, the processor can change the frequency of operation of the transmitter by selecting a frequency from among a group or range of frequencies. Any suitable frequency may be used for the system of this invention. A transmission frequency of 2.4 G Hz and 5.4 G Hz have been found to operate satisfactorily with the receivers, such as receivers  101   a - 101   f , placed around the mast  11 . 
         [0043]    Due to the nature of the metallic structure and due to the movement of metal objects around the rig and other factors, signals received by the receivers can have errors, such as missing bits, incorrect bits, etc. However, the error is often not the same for each receiver and the error can be at different times for any receiver. In one aspect, the processor  122  causes the transmitter  110   a  to transmit each signal, which is received by one or more receivers in the plurality of receivers and than a selection is made as to which receiver has monitored the correct data signals. This can enable each receiver to receive the same signal, i.e., the same data packet corresponding to a particular signal. Such a method can in affect provide omni-directional transmission of data signals. The present disclosure provides an apparatus and method that can select or use error-free signals from the receivers and discard the ones that have errors. The system, due to the presence of multiple receivers, also provides redundancy. In one aspect, the signals from each receiver are first sent to a router  115 , which includes circuitry and a processor that applies an error detection and correction code, scheme or algorithm to the data packets received by each receiver to determine if the received signal corresponds to the transmitted signal, i.e., that the received signal is error free. In some instances, the error detection and correction scheme or algorithm can correct the error and in such instances the corrected signal will be error free. If the received signal from a receiver meets this criterion, then the router sends the signal to the processor  112  for further processing. If a data packet from a particular receiver has an error that can not be corrected, the router looks to the signals from the next receiver and so on. In one method, the router continues to send signals from a receiver (e.g. the first receiver) as long as that receiver is providing error-free signals. When an error from such a receiver is detected that cannot be corrected, the router sends the signals from the next receiver that meets the error criterion and continues to send signals from such next receiver until an error signal is detected. The router in this manner continues to switch to other receivers in the system. Any suitable error detection and correction or encoding and decoding scheme algorithm or code may be used for the purpose of this invention. Reed-Solomon codes have been found to be applicable for the system and methods of this invention. Reed-Solomon codes are known in the art and are thus not described in detail herein. When a non-rotating RF transmitter, such as shown in  FIG. 1B , is used, the RF signals may be directed to one or more particular receivers. 
         [0044]    To transmit surface signals downhole, a transmitter associated with the surface controller  112  wirelessly transmits such signals to the receiver  110   b  in the rotating module  100 , which signals are processed and sent by the transmitter  110   a  to the downhole telemetry module  72  via link  150 . 
         [0045]    The transmitter  110   a  may also be used to send signals from multiple sensors in the drill string. In another aspect, the surface telemetry module  100  may include any number of sensors  111  for measuring various parameters, including surface drilling parameters. The sensor  111  measures parameters that include, but are not limited to, hook load, drillstring torque, drilling fluid pressure, rotary speed, and temperature. These parameters may be transmitted as raw and/or processed data to surface controller  112  via communication modules  101   a - f . In operation, a hard wired system as described herein may have telemetry of any suitable data rate. As an example, the data rates may be 100 kilobits per second (kbps) to about 2 megabits per second (mbps), 4 megabits per second, etc. Such telemetry rates are highly useful in closed loop drilling and/or geosteering operations known in the art. In one embodiment, such high data rates enable vertical seismic profiling using multiple seismic receivers in the downhole assembly. 
         [0046]    Thus, in one aspect the present invention provides a telemetry system for use in a drilling system that includes a rotating transmitter associated with the drilling system that transmits data signals wirelessly; a plurality of spaced apart receivers, each such receiver receiving the transmitted data signals; and a processor that receives the data signals from each of the receivers in the plurality of receivers and processes the data signals from the receivers that meet a selected criterion. The transmitter may be placed in a drill string such as attached to a drill pipe or drill stem or placed in a top drive that rotates the drill string. The transmitter module maybe an integral part of the top drive. In one aspect, the processor applies an error detection and correction scheme to the data signals received by each of the receivers and processes signals that meet the selected criterion. The selected criterion may be that the data signal received by a receiver is error free; or that the data signal has been made error free by using an error correction scheme. In one aspect, the receivers in the plurality of receivers are placed around a mast and/or at other locations so that multiple receivers can receive the same data signal as a packet when the transmitter sends the data signal. In another aspect, the transmitter transmits each data signal a plurality of times so as to provide an effect of substantially omni-directional transmission of the data signals to the receivers. The transmitter receives the data signals from a downhole location via a data communication link associated with a drill string, which may be a wire link that carries data signals from a downhole device, a mud column associated with a drill string that carries data signals from a downhole device, or a fiber optic link associated with a drill string. In another aspect, a processor associated with the transmitter encodes the data signals with parity bits and the processor that receives the data signals from the receiver decodes the received data signals and corrects the data signals upon detection of an error in the received data signals. In yet another aspect, a router coupled to each receiver determines which data signals from each receiver in the plurality of signals are used. The transmitted signals may include parity bits based on a Reed-Solomon code, and the processor uses Reed-Solomon code to detect errors in the data signals received by the receivers. The transmitter can transmit the data signals at any selected frequency including 2.4 GHz and 5.4 GHz. In one aspect an 80 MHz of 2.4 to 2.4835 GHz band may be used. A suitable data bit rate, such as 500k bits/sec., 1 m bits/sec or 2 m bits/sec, etc. may be used. The data rates can be selected with a trade off in error rate. 
         [0047]    The present disclosure also provides a method for use in wellbore operations, that includes: transmitting data signals wirelessly from a rotating transmitter associated with a drilling system; receiving the transmitted data signals at a plurality of spaced apart receivers; and processing data signals from each receiver in the plurality of receivers that meet a selected criterion. The transmitter may be placed in a drill string or in a top drive that rotates a drill string. The telemetry method may apply an error detection and correction scheme to the data signals received by each of the receivers and process the data signals from each of the receivers that meet the selected criterion. The multiple receivers are placed around the drilling system and the transmitter transmits each data signal as a packet of bits that include parity bits. The data signals are transmitted to the receivers in a manner that provides an effect of substantially omni-directional transmission of the data signals to the receivers. In one aspect, the transmitter transmits each data signal a plurality of times to ensure that each receiver receives the same data signal. 
         [0048]    The method further provides for transmitting encoded data signals with parity bits before transmitting the data signals and decoding the data signals from the receivers before processing the data signals. The method further provides correcting the data signals upon detection of an error in the received data signals using a suitable error detection and correction scheme or code. In the method, signals from a receiver are processed as long as the received signals are error free and have been corrected. The method switches between receivers to obtain error free signals. In another aspect, the disclosure provides a telemetry system for use in a wellbore operation that includes a data communication link in a drill string that rotates with the drill string and carries data signals between a downhole device and a surface location; a coupling device coupled to the data communication link that transfers data signals from the rotating data communications link to a non-rotating member; a transmitter coupled to the non-rotating member that receives the data signals and wirelessly transmits the received data signals at a selected frequency; at least one receiver that receives the data signals from the transmitter; and a processor at the surface that processes the received data signals. 
         [0049]    The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible. It is intended that the following claims be interpreted to embrace all such modifications and changes.

Summary:
A system and method for communicating data between a downhole tool and a surface controller is provided that comprises a rotating drill string extending in a borehole and having a downhole telemetry module disposed proximate a bottom end thereof and transmitting a first signal across a telemetry channel. A surface telemetry module is disposed proximate a top end of the rotating drill string and is adapted to receive the first signal transmitted by the downhole telemetry module across the transmission channel. The surface telemetry module has a radio frequency transmitter disposed therein for transmitting a second signal related to the first signal. A stationary communication module has a radio frequency receiver adapted to receive the second signal.