SYSTEMS AND METHODS FOR DISTRIBUTED INTERFEROMETRIC ACOUSTIC MONITORING

• US 20090114386A1
• Filed: 11/02/2007
• Published: 05/07/2009
• Est. Priority Date: 11/02/2007
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Brown, J. Ernest, Elphick, Jonathan, Hartog, Arthur H., Johnson, Ashley Bernard, Hammond, Paul S., Cook, John Mervyn
• Granted Patent: US 7,946,341 B2
• Time in Patent Office: Days
• US Class Current: 166/250.80
• CPC Class Codes: E21B 41/0064 Carbon dioxide sequestration storing fluids in porous layers B65G5/005
• CPC Class Codes: E21B 43/26 by forming crevices or fractures
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G01V 1/226 Optoseismic systems
• CPC Class Codes: G01V 8/02 Prospecting
• CPC Class Codes: G01V 8/16 using optical fibres
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

This disclosure relates in general to a method and system for monitoring a conduit, a wellbore or a reservoir associated with hydrocarbon production or transportation and/or carbon dioxide sequestration. More specifically, but not by way of limitation, embodiments of the present invention provide for using an optical fiber as a distributed interferometer that may be used to monitor the conduit, wellbore or reservoir. In certain aspects, the distributed interferometric monitoring provides

Claims

1. A method for acoustically monitoring a wellbore, a reservoir or a pipeline, comprising:

transmitting a monitoring signal through a fiber optic cable, wherein the monitoring signal comprises a coherent beam of electromagnetic radiation and the fiber optic cable is disposed along or is disposed appurtenant to at least a section of the wellbore, the reservoir or the pipeline;

detecting coherent Raleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic; and

processing the detected coherent Raleigh noise to identify an acoustic occurrence in the section of the wellbore, the reservoir or the pipeline.

2. The method of claim 1, wherein the transmitted signal comprises a pulse of the coherent beam of electromagnetic radiation.

3. The method of claim 2, wherein a coherence time of the monitoring signal is equal to or longer than a duration of the pulse.

4. The method of claim 2, further comprising:

using a time-of-flight of the pulse to identify a location of the acoustic occurrence in the section of the wellbore, the reservoir or the pipeline.

5. The method of claim 1, wherein the step of processing the detected coherent Raleigh noise to identify an acoustic occurrence comprises comparing the detected coherent Raleigh noise to an acoustic signature of the acoustic occurrence.

6. The method of claim 5, wherein the acoustic signature is determined by at least one of theoretical analysis, modeling, experimentation and previous acoustic monitoring analysis.

7. The method of claim 1, wherein:

the step of transmitting a monitoring signal through the fiber optic cable comprises repeatedly transmitting pulses of the coherent beam of electromagnetic radiation through the fiber optic cable;

the step of detecting coherent Raleigh noise comprises detecting the coherent Raleigh noise generated by each of the transmitted pulses; and

the step of processing the detected coherent Raleigh noise to identify the acoustic occurrence comprises comparing the coherent Raleigh noise generated by one of the repeated pulses with a previous pulse or a reference.

8. The method of claim 5, wherein the reference comprises the coherent Raleigh noise generated by transmission of one of the pulses of the coherent beam of electromagnetic radiation under baseline conditions.

9. The method of claim 1, further comprising:

disposing one or more acoustic transducers along the fiber optic cable.

10. The method of claim 1, further comprising:

monitoring temperatures at one or more locations in the wellbore, the reservoir or the pipeline.

11. The method of claim 10, further comprising:

identifying a leak in the wellbore or the pipeline by determining an occurrence of an acoustic anomaly and a temperature anomaly at a same location in the pipeline or the wellbore.

12. The method of claim 1, further comprising:

disposing one or more vortex-shedding devices in the pipeline or wellbore; and

measuring a frequency of an acoustic output from the vortex-shedding device, wherein the acoustic output is generated by contact between the vortex-shedding device and a fluid flowing in the wellbore or the pipe.

13. The method of claim 12, further comprising:

using the measured frequency to determine a velocity of the fluid flow.

14. The method of claim 13, further comprising:

using a time of flight measurement to determine a fluid flow rate of the fluid flow in the pipe or wellbore.

16. The system of claim 12, wherein the source of coherent electromagnetic radiation is a laser.

17. The system of claim 12, wherein the source of coherent electromagnetic radiation has a coherence time that is equal to or greater than a duration of the pulse.

18. The system of claim 12, wherein the fiber optic has a non-reflecting end.

19. The system of claim 12, wherein said detector comprises a photo-detector.

20. The system of claim 12, wherein the detector comprises a signal analyzer.

21. The system of claim 12, further comprising:

one or more acoustic transducers coupled with the fiber optic.

22. The system of claim 12, further comprising:

a distributed temperature system disposed along the wellbore or the pipeline.

15. A system for acoustically monitoring a wellbore or a pipeline, comprising:

a fiber optic coupled with or disposed adjacent to a section of the wellbore or the pipeline;

a source of coherent electromagnetic radiation coupled with the fiber optic and configured to inject a pulse of the coherent electromagnetic radiation into the fiber optic;

a detector coupled with the fiber optic and configured to detect coherent Rayleigh noise generated in the fiber optic by the pulse of coherent electromagnetic radiation; and

a processor coupled with the detector and configured to process an output from the detector to identify acoustic events in the wellbore or pipeline.

23. A method for acoustically monitoring a wellbore, a reservoir or a pipeline, comprising:

transmitting a monitoring signal through a fiber optic cable, wherein the monitoring signal comprises a pair of mutually coherent beams of electromagnetic radiation and the fiber optic cable is disposed along or is disposed appurtenant to at least a section of the wellbore, the reservoir or the pipeline, and wherein a first frequency of a first beam of the pair of mutually coherent beams is not equal to a second frequency of a second beam of the pair of mutually coherent beams;

detecting coherent Raleigh noise generated by the transmission of the pair of mutually coherent beams through the fiber optic; and

processing the detected coherent Raleigh noise to identify an acoustic occurrence in the section of the wellbore, the reservoir or the pipeline.