WELLBORE TELEMETRY AND NOISE CANCELLATION SYSTEMS AND METHOD FOR THE SAME
First Claim
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1. A method of signal processing, comprising:
- providing at least a first pressure sensor and a second pressure sensor spaced in a drilling system; and
using an algorithm to separate the downwardly propagating waves from the upwardly propagating waves.
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Abstract
A method of signal processing includes providing at least a first pressure sensor and a second pressure sensor spaced in a drilling system and using an algorithm to separate the downwardly propagating waves from the upwardly propagating waves. In one or more examples, an algorithm may include determining a velocity of pressure signals in a wellbore, time-shifting and stacking pressure signals from at least the first pressure sensor and the second pressure sensor to determine a downwardly propagating noise signal, and subtracting the downwardly propagating noise signal from at least the signal from the first pressure sensor.
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Citations
37 Claims
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1. A method of signal processing, comprising:
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providing at least a first pressure sensor and a second pressure sensor spaced in a drilling system; and using an algorithm to separate the downwardly propagating waves from the upwardly propagating waves. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A wellbore communication system, comprising:
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a plurality of pressure sensors spaced within a drilling system along a drilling fluid flow path and communicatively coupled to a surface system; and a mud pulse telemetry system positioned within a downhole tool. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A method for wellbore communications, comprising:
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obtaining a first corrected pressure signal and a downwardly propagating noise signal from at least a first pressure sensor; computing a cross-correlation function between the first corrected pressure signal and the downwardly propagating noise signal for at least the first pressure sensor; computing the standard deviation of the downwardly propagating noise signal; computing a reflection coefficient for the downwardly propagating noise signal; computing the reflected, upwardly propagating noise signal, and subtracting the upwardly propagating noise signal from the first corrected pressure signal. - View Dependent Claims (34, 35, 36)
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37. A method for wellbore communications, comprising:
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obtaining signals representing pressure measurements over time at a first pressure sensor, a second pressure sensor, and a third pressure sensor positioned within a drilling system; determining a cross-correlation function between the signals from the first pressure sensor and the second pressure sensor for a downwardly propagating noise signal; determining a cross-correlation function between the signals from the second pressure sensor and the third pressure sensor for the downwardly propagating noise signal; determining a maximum value for the each cross-correlation function; determining the velocity of the signals in the wellbore fluid based on the maximum values for the cross-correlation functions. time-shifting and stacking the signals from the first, second, and third pressure sensors to determine a downwardly propagating noise signal; subtracting the downwardly propagating noise signal from the signal from the first, second, and third pressure sensors to obtain a first corrected pressure signal, a second corrected pressure signal, and a third corrected pressure signal; computing a cross-correlation function between the corrected pressure signal and the downwardly propagating noise signal for first, second, and third corrected pressure signals; computing the standard deviation of the downwardly propagating noise signal; computing a reflection coefficient for downwardly propagating noise signal; computing the reflected, upwardly propagating noise signal, subtracting the upwardly propagating noise signal from the corrected pressure signal for the first, second, and third sensors to obtain a twice corrected first pressure signal, a twice corrected second pressure signal, and a twice corrected third pressure signal; and time-shifting and stacking the twice corrected first pressure signal, the twice corrected second pressure signal, and the twice corrected third pressure signal to obtain an upwardly propagating data signal.
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Specification