Acoustic data transmission through a drillstring
AssigneeTeleco Oilfield Services Inc.
InventorDouglas S. Drumheller
Life of this patent
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Abstract
A method and apparatus for acoustically transmitting data along a drillstring is presented. In accordance with one embodiment of the present invention, acoustic data signals are conditioned to counteract distortions caused by the drillstring. Preferably, this conditioning step comprises multiplying each frequency component of the data signal by exp (-ikL) where L is the transmission length of the drillstring, k is the wave number in the drillstring at the frequency of each component and i is (-1).sup.1/2. In another embodiment of this invention, data signals having a frequency content in at least one passband of the drillstring are generated preferably traveling in only one direction (e.g., up the drillstring) while echoes in the drillstring resulting from the data transmission are suppressed.
Claims45
A method for transmitting a data signal though a drill string comprising the steps of:
- preconditioning said data signal to counteract distortions caused by said drill string, said distortions corresponding to the effects of a comb filter having characteristics dependent upon the properties of said drill string;
- applying and transmitting said preconditioned data signal to a first end of said drill string;
- and
- detecting said data signal at a second end of said drill string.
A method for transmitting a continuous data signal through a drillstring having low attenuation passbands and high attenuations stopbands of acoustical signals, comprising the steps of:
- preconditioning said data signal to counteract distortions caused by said drillstring by multiplying each frequency component of a first electrical signal by exp(-ikL) where L is the transmission length of the drill pipe section of said drill string and k is the wave number in said drill string at the frequency of each component, wherein said preconditioned data signal is a first electrical signal;
- converting said first electrical signal to a first acoustical signal, the frequencies of said first acoustical signal being in the passbands of said drillstring;
- applying said preconditioned electrical signal to a first end of said drillstring;
- detecting said acoustical signal at a second end of said drillstring;
- and
- converting said detected acoustical signal to a detected electrical signal at said second end of said drillstring.
A method for transmitting a data signal through a drillstring comprising the steps of:
- preconditioning said data signal to counteract distortions caused by said drillstring;
- applying said reconditioned data signal to a first end of said drillstring;
- suppressing acoustical echoes from the first end of said drillstring;
- detecting said data signal at a second end of said drillstring;
- and
- suppressing acoustical echos at the second end of said string by matching the acoustical impedance of said drill string and providing a sufficient loss factor to keep echo strength about 20 dB below signal level to terminate the signal.
A method for transmitting a data signal through a drillstring comprising the steps of:
- preconditioning said data signal to counteract distortions caused by said drillstring;
- applying said preconditioned data signal to a transmitter connected near a first end of said drillstring;
- suppressing acoustical echoes from the first end of said drillstring by applying energy to said drillstring in a position adjacent to said transmitter by:
- providing an output indicative of acoustical energy traveling from said first end toward the location on said drill string where said data is applied, and providing no indication of acoustical energy traveling from said location towards said first end;
- delaying said output;
- and
- applying said delayed output to said drill string to cancel noise traveling from said location towards said second end;
- detecting said data signal at a second end of said drillstring;
- and
- suppressing acoustical echoes at a second end of said drillstring;
- and
- suppressing acoustical echoes at the second end of said drillstring.
Apparatus for the transmission of data on a continuous carrier wave through a drillstring comprising a plurality of drill pipe sections connected end-to-end by tool joints, the length and cross-sectional area of the pipe sections being different from the length and cross-sectional area of the tool joints, said apparatus comprising:
- transmitter means for coupling data to said drillstring near a first end of said drillstring for acoustical transmission to a second end of said drillstring;
- anti-noise means near said first end of said drillstring for preventing acoustical noise from said first end from being transmitted through said drillstring to said second end, wherein said anti-noise means comprises:
- first noise-receiving means for providing a first output indicative of acoustical noise traveling from said first end toward said transmitter means, and for providing no indication of acoustical noise traveling from said transmitter means towards said first end;
- and
- noise-cancelling means for applying a delay output from said noise-receiving means to said transmitting means to cancel noise traveling from said transmitting means towards said second end of said drill string;
- and
- receiving means near said second end for receiving said acoustically transmitted data.
Apparatus for the transmission of data on a continuous carrier wave through a drillstring comprising a plurality of drill pipe sections connected end-to-end by tool joints, the length and cross-sectional area of the pipe sections being different from the length and cross-sectional area of the tool joints, said apparatus comprising:
- transmitter means for coupling data to said drillstring near a first end of said drillstring for acoustical transmission to a second end of said drillstring, wherein said transmitting means comprises:
- a first and a second acoustical transmitter spaced along said drill string a distance equal to an odd multiple of a quarter wavelength of said carrier wave, said first transmitter being closer to said first end than said second transmitter;
- first signal applying means for applying a delayed, inverted, data signal to said first transmitter, the delay being equal to the transmission time of the transmitted signal from said first transmitter to said second transmitter, whereby said data signal is transmitted only toward said second end;
- and second signal applying means for applying said data signal to said second transmitter;
- anti-noise means near said first end of said drillstring for preventing acoustical noise from said first end from being transmitted through said drillstring to said second end;
- and
- receiving means near said second end for receiving said acoustically transmitted data.
A method for transmitting data through a drill string having a plurality or drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the method comprising the steps of:
- generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- applying said data signal to the drill string at said first location for transmission to said second location;
- actively suppressing echoes in the drill string resulting from transmission of the data signal;
- and
- detecting the data signal at said second location.
Apparatus for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the apparatus comprising:
- signal generator means for generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- transmitter means for applying said data signal to the drill string at said first location for transmission to said second location;
- suppression means for actively suppressing echoes in the drill string resulting from transmission of the data signal;
- and
- detecting means for detecting the data signal at said second location.
A method for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the method comprising the steps of:
- generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- applying said data signal to the drill string at said first location for transmission to said second location;
- suppressing echoes in the drill string resulting from transmission of the data signal;
- detecting the data signal at said second location;
- wherein the step of applying said data signal to the drill string includes:
- generating a signal which travels up the drill string while substantially suppressing the travel of the signal down the drill string;
- and
- wherein the step of substantially suppressing travel of the signal down the drill string includes:
- generating signals in the drill string at two downhole locations spaced apart axially along the drill string by a distance of approximately one quarter wavelength of the center frequency of said one passband.
A method for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the method comprising the steps of:
- generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- applying said data signal to the drill string at said first location for transmission to said second location;
- suppressing echoes in the drill string resulting from transmission of the data signal;
- detecting the data signal at said second location;
- wherein the step of suppressing echoes includes:
- sensing, at a location below said first location, and generating a noise signal corresponding only to acoustic energy moving up the drill string;
- and
- cancelling said noise signal;
- and
- wherein the step of sensing and generating a noise signal corresponding only to acoustic energy moving up the drill string includes;
- sensing the outputs from two sensors spaced apart axially along the drill string by a distance of approximately one quarter wavelength of the center frequency of said passband;
- and
- delaying and inverting one of said outputs relative to the other by a time equal to b/c, where b is one quarter wavelength of said center frequency and c is the speed of sound in the drill string.
A method for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the method comprising the steps of:
- generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- applying said data signal to the drill string at said first location for transmission to said second location;
- suppressing echoes in the drill string resulting from transmission of the data signal;
- detecting the data signal at said second location;
- conditioning the data signal to compensate for distortion caused by the passbands of the drill string;
- and
- wherein the step of conditioning the data includes:
- multiplying each frequency component of the data signal by exp (-ikL), where L is the transmission length of the drill string, k is the wave number in said drill string at the frequency of each component, and i is .sqroot.-1.
Apparatus for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the apparatus comprising:
- signal generator means for generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- transmitter means for applying said data signal to the drill string at said first location for transmission to said second location;
- suppression means for actively suppressing echoes in the drill string resulting from transmission of the data signal;
- detecting means for detecting the data signal at said second location;
- wherein said transmitter means includes;
- means for generating a signal which travels up the drill string while substantially suppressing the travel of the signal down the drill string;
- and
- wherein said means for substantially suppressing travel of the signal down the drill string includes;
- transducer means for generating signals in the drill string at two downhole locations spaced apart axially along the drill string by a distance of approximately one quarter wavelength of the center frequency of said one passband.
Apparatus for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the apparatus comprising:
- signal generator means for generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- transmitter means for applying said data signal to the drill string at said first location for transmission to said second location;
- suppression means for actively suppressing echoes in the drill string resulting from transmission of the data signal;
- detecting means for detecting the data signal at said second location;
- wherein said suppression means includes;
- transducer means for sensing, at a location below said first location, and generating a noise signal corresponding only to acoustic energy moving up the drill string;
- and
- cancelling said noise signal;
- and
- wherein said transducer means for sensing and generating a noise signal corresponding only to acoustic energy moving up the drill string includes;
- first and second transducers spaced apart axially along the drill string by a distance of approximately one quarter wavelength of the center frequency of said passband;
- and
- delaying and inverting one of said outputs relative to the other by a time equal to b/c, where b is one quarter wavelength of said center frequency and c is the speed of sound in the drill string.
Apparatus for transmitting data through a drill string having a plurality of drill pipe sections connected end-to-end by joints from a first location below the surface of the earth to a second location at or near the surface of the earth, the length and cross-sectional area of the drill pipe sections being different from the length and cross-sectional area of the joints, the apparatus comprising:
- signal generator means for generating a continuous wave data signal having a frequency content in at least one passband of the drill string;
- transmitter means for applying said data signal to the drill string at said first location for transmission to said second location;
- suppression means for actively suppressing echoes in the drill string resulting from transmission of the data signal;
- detecting means for detecting the data signal at said second location;
- means for conditioning the data signal to compensate for distortion caused by the passbands of the drill string;
- and
- wherein the means for conditioning the data includes;
- p1 means for multiplying each frequency component of the data signal by exp (-ikL), where L is the transmission length of the drill string, k is the wave number in said drill string at the frequency of each component, and i is .sqroot.-1.
Dependencies are inferred from the claim text.