Identification of the channel frequency response using chirps and stepped frequencies
AssigneeBaker Hughes Incorporated
InventorsNabil Hentati, Hanno Reckmann, Ingolf Wassermann
Life of this patent
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Abstract
The transfer function of the communication channel in a mud pulse telemetry system is determined by sending a known signal through the channel and spectral analysis of the received signal. The known signal may be a chirp signal or a stepped frequency signal. Based on the determined transfer function, operating parameters of the pulser are adjusted.
Claims38
A method of communicating signals in a wellbore between a surface location and a downhole location, the method comprising:
- (a) generating a mechanical signal at one of the surface location and downhole location, the mechanical signal being selected from the group consisting of:
- (A) a stepped frequency signal, (B) a linear chirp signal, (C) a nonlinear chirp signal, (D) a pseudo-random sequence, and (E) a pseudo-random binary sequence;
- (b) receiving a signal indicative of the generated mechanical signal at the other of the surface and downhole locations;
- and
- (c) estimating from the received signal and the generated mechanical signal a characteristic of a communication channel between the surface and downhole locations.
A system for communicating signals in a wellbore between a surface location and a downhole location, the system comprising:
- (a) a mechanical source configured to generate a mechanical signal at one of the surface location and downhole location, the mechanical signal being selected from the group consisting of:
- (A) a stepped frequency signal, (B) a linear chirp signal, (C) a nonlinear chirp signal, (D) a pseudo-random sequence, and (E) a pseudo-random binary sequence;
- (b) a receiver configured to produce a signal indicative of the generated mechanical signal at the other of the surface and downhole locations;
- and
- (c) a processor configured to determine from the received signal and the generated mechanical signal a characteristic of a communication channel between the surface and downhole locations.
A computer readable medium for use with a system for communicating signals in a wellbore between a surface location and a downhole location, the system comprising:
- (a) a mechanical source which generates a mechanical signal at one of the surface location and downhole location, the mechanical signal being selected from the group consisting of:
- (A) a stepped frequency signal, (B) a linear chirp signal, (C) a nonlinear chirp signal, (D) a pseudo-random sequence, and (E) a pseudo-random binary sequence;
- (b) a receiver configured to produce a signal indicative of the generated mechanical signal at the other of the surface and downhole locations;
- the medium further comprising instructions which enable a processor to estimate from the received signal and the generated mechanical signal a characteristic of the communication channel between the surface and downhole locations.
A method of determining a characteristic of a communication channel associated with an earth formation, the method comprising:
- (a) using a mechanical device for generating a swept frequency signal which propagates in the channel, the propagating signal including a harmonic distortion;
- (b) receiving the propagating signal at least one receiver to produce a received signal responsive to the characteristic of the channel;
- (c) processing the received signal to estimate the characteristic of the channel, the processing including the use of a chirp transform.
A system for determining a characteristic of a communication channel associated with an earth formation, the system comprising:
- (a) a mechanical device configured to generate a swept frequency signal which propagates in the channel, the propagating signal including a harmonic;
- (b) a receiver configured to produce a signal responsive to the propagating signal;
- (c) a processor configured to estimate the characteristic of the channel from the produced signal using a processing which includes the use of a chirp transform.
Dependencies are inferred from the claim text.