Technique for signal detection using adaptive filtering in mud pulse telemetry

• US 6,308,562 B1
• Filed: 12/22/1999
• Issued: 10/30/2001
• Est. Priority Date: 12/22/1999
• Status: Expired due to Term

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: W-H Energy Systems, Inc.
• Inventors: Beattie, Mark S., Abdallah, Ali H.
• Primary Examiner(s): Larkin, Daniel S.
• Assistant Examiner(s): WIGGINS, JOHN DAVID
• Application Number:
  US09/469,989
• Time in Patent Office: 678 Days
• Field of Search: 731/521.8, 731/521.9, 731/522.2, 731/523.2, 731/525.8, 731/520.4, 731/521.6, 736/02, 736/24, 736/28, 340/855.6, 340/854.3, 340/856.4, 340/853.2, 340/606, 340/310.03
• US Class Current: 73/152.18
• CPC Class Codes: E21B 47/18 through the well fluid , e.g. mud pressure pulse telemetry

Abstract

A mud pulse telemetry adaptive noise canceler (ANC) employs a primary transducer and a reference transducer downstream from a position of the primary transducer. The primary transducer receives a primary signal based on a combination of a transmitted pulse and a reflected pulse, and the reference transducer receives a reference signal based on the transmitted pulse. The ANC linearly relates the secondary signal to the primary signal by means of a fast recursive least squares algorithm and calculates a set of weighting coefficients. The finite impulse response (FIR) filter of the ANC uses the set of weighting coefficients to adaptively noise cancel correlated portions between the primary signal and the secondary signal to produce an ANC output signal based on uncorrelated portions between the primary signal and the secondary signal.

Claims

1. A method of detecting telemetry in drilling fluid during drilling operations, comprising the steps of:

generating a drilling fluid pressure pulse in a bore hole downstream of a position of a primary transducer creating an upstream traveling, transmitted pulse;

detecting a combination of the transmitted pulse and a reflected pulse corresponding to the transmitted pulse at the primary transducer and producing a primary signal based upon the detected combination of the transmitted pulse and the detected reflected pulse;

detecting the transmitted pulse at a reference transducer upstream from the position of the primary transducer and producing a secondary signal based upon the detected transmitted pulse; and

generating an adaptive noise canceler (ANC) output signal based upon a difference between the primary signal and the secondary signal.

2. The method of claim 1, the generating step comprising the step of:

adaptive noise canceling correlated portions between the primary signal and the secondary signal by calculating a fit between the primary signal and the secondary signal to produce the ANC output signal based on uncorrelated portions between the primary signal and the secondary signal.

3. The method of claim 1, wherein the ANC output signal comprises an ANC output pulse with a sharply defined peak at a leading edge of the ANC output pulse and a sharply defined dip at a trailing edge of the ANC output pulse.

4. The method of claim 1, wherein the reference transducer is located at a point where the transmitted pulse is reflected.

5. The method of claim 1, wherein the ANC output signal is also generated based upon a difference between a previous primary signal at the primary transducer and a previous secondary signal at the reference transducer.

6. The method of claim 1, the generating step comprising the steps of:

calculating a set of weighting coefficients based upon the fit; and

generating the ANC output signal based upon the set of weighting coefficients.

7. The method of claim 2, wherein the weighting coefficients are calculated by means of a least squares algorithm.

8. The method of claim 2, wherein the weighting coefficients are calculated by means of a fast recursive least squares (RLS) type algorithm.

9. An adaptive noise canceler (ANC) for use in a Measurement-While-Drilling/Logging-While-Drilling (MWD/LWD) system for telemetry detection, comprising:

a recursive least squares (RLS) module to calculate a fit based upon a difference between a primary signal corresponding to a combination of a transmitted pulse and a reflected pulse detected at a primary transducer and a secondary signal corresponding to the transmitted pulse detected at a reference transducer upstream from a position of the primary transducer; and

an adaptive finite impulse response (FIR) filter to generate an ANC output signal based upon the difference between the primary signal and the secondary signal.

10. The ANC of claim 9, wherein the adaptive FIR filter adaptive noise cancels correlated portions between the primary signal and the secondary signal by calculating a fit between the primary signal and the secondary signal with a set of weighting coefficients to produce the ANC output signal based on uncorrelated portions between the primary signal and the secondary signal.

11. The ANC of claim 10, wherein the fit is also based upon a fit between a difference between a previous primary signal corresponding to a previously transmitted pulse and a previous secondary signal corresponding to the previously transmitted pulse.

12. The ANC of claim 9, wherein the ANC output signal comprises:

an ANC output pulse with a sharply defined peak at a leading edge of the ANC output pulse; and

a sharply defined dip at a trailing edge of the ANC output pulse.

13. The ANC of claim 9, further comprising:

weighting coefficient generation logic for computing a set of weighting coefficients based upon the fit between the primary signal and the secondary signal calculated by the RLS module; and

weighting coefficient application logic for applying the set of weighting coefficients for generation of the ANC output signal by the adaptive FIR filter.

14. The ANC of claim 13, wherein the set of weighting coefficients is based upon phase and amplitude of the primary signal and the secondary signal.

15. The ANC of claim 9, wherein the fit between the primary signal and the secondary signal is based upon a least squares fit.

16. The ANC of claim 15, wherein the least squares fit is calculated by means of a fast recursive least squares (RLS) type algorithm.

17. A computer-readable medium used for storing adaptive noise cancellation (ANC) software for telemetry detection, the ANC software comprising:

code for detecting at a primary transducer a combination of a transmitted pulse and a reflected pulse and producing a primary signal;

code for detecting the transmitted pulse at a reference transducer upstream from a position of the primary transducer and producing a secondary signal;

code for calculating a fit between the primary signal and the secondary signal to create a linear relationship between a first plurality of points of the primary signal and a second plurality of points of the secondary signal; and

code for creating an adaptive noise cancellation (ANC) output signal based upon the difference between the primary signal and the secondary signal.

18. The computer-readable medium of claim 17, wherein the code for creating comprises:

code for adaptive noise canceling correlated portions between the primary signal and the secondary signal by calculating a fit between the primary signal and the secondary signal to produce the ANC output signal based on uncorrelated portions between the primary signal and the secondary signal.

19. The computer-readable medium of claim 18, further comprising:

code for calculating a set of weighting coefficients based upon the fit between the primary signal and the secondary signal; and

code for adjusting the ANC output signal based upon the set of weighting coefficients.

20. The computer-readable medium of claim 18, wherein the fit is also based upon a fit between a previous primary signal and a corresponding previous secondary signal.

21. The computer-readable medium of claim 18, wherein the fit is based upon phase and amplitude of the primary signal and the secondary signal.

22. The computer-readable medium of claim 19, wherein the calculation of the set of weighting coefficients is performed by means of a least squares algorithm.

23. The computer-readable medium of claim 22, wherein the least squares algorithm is a fast recursive least squares (RLS) type algorithm.