Two sensor impedance estimation for uplink telemetry signals

• US 20060132328A1
• Filed: 12/19/2005
• Published: 06/22/2006
• Est. Priority Date: 12/21/2004
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Reckmann, Hanno, Neubert, Michael, Wassermann, Ingolf
• Granted Patent: US 7,423,550 B2
• Time in Patent Office: Days
• US Class Current: 340/855.400
• CPC Class Codes: E21B 47/18 through the well fluid , e.g. mud pressure pulse telemetry

Abstract

Measurements made with dual sensors (flow rate or pressure) are used to attenuate pump noise in a mud pulse telemetry system.

Claims

1. A method of communicating a signal through a fluid in a borehole between a first location and a second location, the method comprising:

(a) measuring first and second signals in the fluid at spaced apart first and second positions at or near the second location in response to operation of at least one of (A) a noise source, and (B) a message source at the first location;

(b) estimating from the first and second signals a characteristic of a fluid channel between the first and second positions;

(c) generating a message signal at the first location simultaneously with operation of the noise source;

(d) measuring third and fourth signals at the first and second positions responsive to the message signal and the simultaneous operation of the noise source; and

(e) estimating the message signal from the third and fourth signals and the estimated fluid channel characteristic

2. The method of claim 1 wherein the first and second signals comprise at least one of (i) a pressure signal, and (ii) a flow rate signal.

3. The method of claim 1 wherein the noise source is on a side of the first and second positions opposite to the first location.

4. The method of claim 1 wherein the characteristic of the fluid comprises a transfer function between at least one of (i) the first and second positions, and (ii) the second and first positions.

5. The method of claim 1 wherein estimating the characteristic of the fluid channel further comprises performing a unitary transform of the first and second signals.

6. The method of claim 1 wherein the unitary transform comprises a Fourier transform.

7. The method of claim 1 wherein estimating the message signal further comprises performing a differential filtering based on one of (i) a zero forcing, and (ii) a least squares minimization.

8. The method of claim 1 wherein generating the message signal further comprises at least one of (i) Amplitude Shift Keying (ASK), (ii) Frequency Shift Keying (FSK), and, (iii) Phase Shift Keying (PSK).

9. The method of claim 1 wherein the message signal further comprises a swept frequency signal.

10. A system for communicating a signal through a fluid in a borehole between a bottomhole assembly (BHA) and a surface location, the system comprising:

(a) a message source on the bottomhole assembly (BHA) capable of generating a message signal;

(b) first and second sensors at spaced apart first and second positions that measure first and second signals in response to operation of at least one of (A) a noise source, and, (B) the message source; and

(c) a processor which estimates from the first and second signals a characteristic of a fluid channel between the first and second positions;

wherein the first and second sensors further receive third and fourth signals responsive to a message signal at the downhole location generated simultaneously with operation of the noise source; and

wherein the processor further estimates the message signal from the third and fourth signals and the estimated fluid characteristic

11. The system of claim 10 wherein the first and second signals are selected from the group consisting of (i) pressure signals, and, (ii) flow rate signals.

12. The system of claim 10 wherein the noise source is on a side of the first and second positions opposite to the message source.

13. The system of claim 10 wherein the characteristic of the fluid channel comprises a transfer function between at least one of (i) the first and second positions, and, (ii) the second and first positions.

14. The system of claim 10 wherein in estimating the characteristic of the fluid channel the processor further performs a unitary transform of the first and second signals.

15. The system of claim 14 wherein the unitary transform comprises a Fourier transform.

16. The system of claim 10 wherein in estimating the message signal the processor further performs a differential filtering based on one of (i) a zero forcing, and (ii) a least squares minimization.

17. The system of claim 10 wherein generating the message signal further comprises at least one of (i) Amplitude Shift Keying (ASK), (ii) Frequency Shift Keying (FSK), and, (iii) Phase Shift Keying (PSK).

18. The system of claim 10 wherein the message signal further comprises a swept frequency signal.

19. The system of claim 10 wherein the BHA is conveyed on a drilling tubular.

20. The system of claim 10 wherein the message source comprises an oscillating valve.

21. A machine readable medium for use in conjunction with a bottomhole assembly (BHA), conveyed in a borehole in an earth formation, the medium comprising instructions for:

(a) estimating from first and second signals in a fluid at spaced apart first and second positions at or near a surface location in response to operation of at least one of (A) a noise source, and, (B) a message source at the downhole location, a characteristic of a fluid channel between the first and second positions;

(c) estimating a value of a message signal generated at the BHA simultaneously with operation of the noise source from;

(A) third and fourth signals measured at the first and second positions responsive to the message signal and the simultaneous operation of the noise source, and

(B) the estimated fluid channel characteristic.

22. The machine readable medium of claim 21 further comprises at least one of (i) a ROM, (ii) an EPROM, (iii) an EAROM, (iv) a Flash Memory, and, (v) an Optical disks.

23. The machine readable medium of claim 21 further comprising instructions for performing a unitary transform of the first and second signals.

24. The machine readable medium of claim 21 further comprising instructions for performing a differential filtering.

25. The machine readable medium of claim 21 wherein generating the message signal further comprises at least one of (i) Amplitude Shift Keying (ASK), (ii) Frequency Shift Keying (FSK), and, (iii) Phase Shift Keying (PSK).

26. The machine readable medium of claim 21 further comprising instructions for generating the message signal in response to at least one of (i) a measurement of a parameter of the BHA, and, (ii) a measurement of a property of the earth formation.