OPTICAL LEAK DETECTOR FOR SUBSEA EQUIPMENT

• US 20120091364A1
• Filed: 03/06/2009
• Published: 04/19/2012
• Est. Priority Date: 03/06/2009
• Status: Active Grant

• Current Assignee: FMC Technologies Incorporated (TechnipFMC, plc)
• Original Assignee: FMC Technologies Incorporated (TechnipFMC, plc)
• Inventors: McStay, Daniel, Costello, Laurle, Kane, David
• Granted Patent: US 8,927,924 B2
• Time in Patent Office: Days
• US Class Current: 250/458.1
• CPC Class Codes: G01M 3/20 using special tracer materials, e.g. dye, fluorescent material, radioactive material
• CPC Class Codes: G01M 3/38 by using light G01M3/02 takes precedence
• CPC Class Codes: G01N 21/8507 Probe photometers, i.e. with optical measuring part dipped into fluid sample

Abstract

A leak detector (190) includes a sensor head (260), a light source (200) optically coupled to the sensor head and operable to generate excitation light. A detector (205) is optically coupled to the sensor head and operable to detect fluorescence light. A signal processing unit (210) is coupled to the detector and operable to signal a leak condition responsive to an intensity of the fluorescence light exceeding a threshold. A fluid-tight enclosure (235) encloses at least the light source, the detector, and the signal processing unit.

Claims

1. An underwater leak detector, comprising:

a sensor head;

a light source optically coupled to the sensor head and operable to generate excitation light;

a detector optically coupled to receive detection light from the sensor head and operable to detect fluorescence light in the detection light;

a signal processing unit coupled to the detector and operable to signal a leak condition responsive to an intensity of the fluorescence light exceeding a threshold; and

a fluid-tight enclosure enclosing at least the light source, the detector, and the signal processing unit.

2. The detector of claim 1, further comprising an optical cable coupled between the sensor head and the fluid-tight enclosure.

3. The detector of claim 2, further comprising an interference filter mounted between the light source and the optical cable.

4. The detector of claim 2, further comprising an interference filter mounted between the detector and the optical cable.

5. The detector of claim 4, wherein the detector comprises at least one of a photo diode or an avalanche diode.

6. The detector of claim 2, further comprising an optical connector mounted on the fluid-tight enclosure for interfacing with the optical cable through a pressure boundary defined by the fluid-tight enclosure.

7. The detector of claim 1, wherein the detector comprises a spectrometer.

8. The detector of claim 1, wherein the light source is operable to amplitude modulate the excitation light, and the detector comprises a phase sensitive photo detector.

9. The detector of claim 2, wherein the optical cable comprises a single optical fiber operable to communicate the excitation light and the detection light, and the detector further comprises a beam splitter mounted between the light source and the optical cable and operable to pass the excitation light to the single optical fiber and direct the detection light from the single optical fiber to the detector.

10. The detector of claim 1, further comprising:

a plurality of sensor heads;

a plurality of optical cables coupled to the sensor heads each optical cable being configured to filter the detection light using a bandpass range unique from the other optical cables; and

an optical coupler coupled to the light source and the detector and being operable to distribute the excitation light to the plurality of optical cables and direct the detection light from each of the plurality of sensor heads to the detector.

11. The detector of claim 1, further comprising:

a plurality of sensor heads; and

an optical switch optically coupled to the light source and the plurality of sensor heads and operable to direct the excitation light to a selected one of the sensor heads.

12. The detector of claim 11, further comprising an optical coupler coupled to each of the sensor heads and operable to direct the detection light from the sensor heads to the detector.

13. The detector of claim 1, further comprising a leak channeling device mounted to the sensor head.

14. The detector of claim 13, wherein the leak channeling device comprises a canopy having an underside surface, and the sensor head is mounted proximate a high point of the underside surface.

15. The detector of claim 13, wherein the leak channeling device comprises a collar.

16. The detector of claim 1, wherein the signal processing unit is operable to evaluate a leakage rate based on a magnitude of the intensity of the fluorescence light.

17. A subsea leak detection system, comprising:

a subsea structure operable to contain a hydrocarbon material; and

a leak detection module, comprising;

a sensor head mounted proximate a source of potential leakage on the subsea structure;

a light source optically coupled to the sensor head and operable to generate excitation light;

a detector optically coupled to receive detection light from the sensor head and operable to detect fluorescence light in the detection light;

a signal processing unit coupled to the detector and operable to signal a leak condition responsive to an intensity of the fluorescence light exceeding a threshold; and

a fluid-tight enclosure enclosing at least the light source, the detector, and the signal processing unit.

18. The system of claim 17, further comprising:

a topside control module;

a subsea control module operable to control the subsea structure and to communicate with the topside control module, wherein the leak detection module is operable to communicate the leak detection to the control module.

19. The system of claim 17, further comprising a leak channeling device operable to collect leakage from the subsea structure, wherein the sensor head is mounted to the leak channeling device.

20. The system of claim 19, wherein the leak channeling device comprises a canopy having an underside surface, and the sensor head is mounted proximate a high point of the underside surface.

21. The system of claim 19, wherein the leak channeling device comprises a collar.

22. The system of claim 17, further comprising a plurality of sensor heads mounted proximate sources of potential leakage on the subsea structure, wherein each of the sensor heads is optically coupled to the light source and the detector.

23. The system of claim 22, wherein the leak detection module employs wavelength multiplexing to communicate with the plurality of sensor heads.

24. The system of claim 22, wherein the leak detection module employs optical switching to communicate with a selected one of the plurality of sensor heads.

25. The system of claim 17, wherein the subsea structure comprises at least one of a Christmas tree, a well head, a valve, a joint, a flange, a pipe connector, a seal, or a jumper.