WELLBORE LEAK DETECTION SYSTEMS AND METHODS OF USING THE SAME

• US 20140110124A1
• Filed: 08/17/2012
• Published: 04/24/2014
• Est. Priority Date: 08/19/2011
• Status: Abandoned Application

• Current Assignee: Seismic Solutions Incorporated
• Original Assignee: Seismic Solutions Incorporated
• Inventors: Goldner, Eric Lee, Andersen, James Kengo
• Application Number:
  US14/127,228
• Publication Number:
  US 20140110124A1
• Time in Patent Office: Days
• US Class Current: 166/337
• CPC Class Codes: E21B 47/117 Detecting leaks, e.g. from tubing, by pressure testing

Abstract

A leak detection system for a wellbore. The leak detection system includes: (1) at least one sensor configured to be positioned outside of a casing of the wellbore; (2) an interrogation system for sending signals to, and receiving signals from, the at least one sensor; and (3) an optical lead cable disposed between the interrogation system and the at least one sensor. A method of detecting a fluid leak in a wellbore is also disclosed.

Claims

1. A leak detection system for a wellbore having a casing with an exterior surface, the leak detection system comprising:

at least one sensor configured to be positioned outside of the casing of the wellbore;

an interrogation system for sending signals to, and receiving signals from, the at least one sensor; and

an optical lead cable disposed between the interrogation system and the at least one sensor.

2. The leak detection system of claim 1 wherein the at least one sensor includes a fiber optic cable configured as part of an interferometer.

3. The leak detection system of claim 2 wherein the interferometer is a Michelson interferometer.

4. The leak detection system of claim 2 wherein the interferometer is a Sagnac interferometer.

5. The leak detection system of claim 2 wherein the interferometer is a Fabry-Perot interferometer.

6. The leak detection system of claim 1 wherein the interrogator includes an optical source, an optical receiver, and a digitizer.

7. The leak detection system of claim 1 wherein the at least one sensor includes a fiber optic cable optically divided into a series of sensing zones.

8. The leak detection system of claim 7 wherein the fiber optic cable is optically divided into a series of sensing zones using fiber Bragg gratings written into the fiber optic cable, thereby forming a series of Fabry-Perot interferometers.

9. The leak detection system of claim 1 wherein the at least one sensor includes at least one of an acoustic or a seismic sensor.

10. The leak detection system of claim 1 wherein the at least one sensor includes an optical fiber and an accelerometer, the accelerometer including a fixed mandrel and a moveable mandrel, wherein the optical fiber is wrapped around the fixed mandrel and the moveable mandrel.

11. The leak detection system of claim 1 wherein the at least one sensor is secured to the exterior surface of the casing of the wellbore.

12. The leak detection system of claim 1 wherein the at least one sensor is embedded in a fill material outside of the casing of the wellbore.

13. The leak detection system of claim 1 wherein the interrogator is a Rayleigh backscatter interrogator configured to process scattered intensity return signals from the at least one sensor.

14. The leak detection system of claim 1 wherein the interrogator is a Rayleigh backscatter interrogator configured to process scattered phase return signals from the at least one sensor.

15. A method of detecting a fluid leak in a wellbore, the method comprising the steps of:

(a) transmitting light from an interrogator to at least one sensor positioned outside of a casing of a wellbore;

(b) receiving return signals from the at least one sensor at the interrogator; and

(c) processing the return signals to determine if there is an indication of a fluid leak from the wellbore casing.

16. The method of claim 15 further comprising the step of installing a plurality of optical fiber sensors outside the casing of the wellbore prior to step (a).

17. The method of claim 15 wherein step (c) includes converting return optical signals into electrical signals for processing by a signal processor.

18. The method of claim 17 wherein step (c) further includes generating an instantaneous spectrum of the electrical signals and comparing the instantaneous spectrum against a predetermined spectra related to a leak condition.

19. The method of claim 15 further comprising the step of (d) determining a location of the fluid leak if a determination is made at step (c) that there is a fluid leak.

20. The method of claim 19 wherein step (d) includes determining the location of the fluid leak using a Rayleigh backscatter interrogator.

21. The method of claim 15 wherein the signals received in step (c) have been converted into phase change and light intensity change signals.

22. The method of claim 21 wherein step (c) includes demodulating and demultiplexing the phase change and light intensity change signals.

23. The method of claim 15 further comprising the step of installing the at least one sensor against an exterior surface of the casing of the wellbore before step (a).

24. The method of claim 15 wherein the at least one sensor includes a plurality of sensors.

25. The method of claim 24 wherein the at least one sensor includes a fiber optic cable configured as part of an interferometer.

26. The method of claim 25 wherein the interferometer is a Michelson interferometer.

27. The method of claim 25 wherein the interferometer is a Sagnac interferometer.

28. The method of claim 25 wherein the interferometer is a Fabry-Perot interferometer.