Multiple spectrum channel, multiple sensor fiber optic monitoring system

• US 9,417,103 B2
• Filed: 09/20/2011
• Issued: 08/16/2016
• Est. Priority Date: 09/20/2011
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Chen, Yuehua, Wilson, Colin
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Gray, Sunghee Y
• Application Number:
  US13/237,082
• Publication Number:
  US 20130070235A1
• Time in Patent Office: 1,792 Days
• Field of Search: 385/12, 385/13, 356/364, 356/369, 356/72, 356/73, 356300-317
• US Class Current: 1/1
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/07 Temperature
• CPC Class Codes: G01D 5/35303 using a reference fibre, e.g. interferometric devices
• CPC Class Codes: G01D 5/35312 using a Fabry Perot
• CPC Class Codes: G01D 5/35387 using wavelength division multiplexing
• CPC Class Codes: G01K 11/3206 at discrete locations in the fibre, e.g. using Bragg scattering
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings
• CPC Class Codes: G01L 11/025 using a pressure-sensitive optical fibre
• CPC Class Codes: G01V 8/24 using optical fibres

Abstract

A multiple sensor fiber optic sensing system includes an optical fiber having at least first fiber optic sensors and second fiber optic sensors deployed along its length. In response to an interrogating pulse, the first fiber optic sensors generate responses in a first optical spectrum window, and the second fiber optic sensors generate responses in a second, different optical spectrum window. The responses in the first optical spectrum window are measured in a first optical spectrum channel, and the responses in the second optical spectrum window are measure in a second, different optical spectrum channel and provide simultaneous indications of one or more parameters, such as temperature and pressure, in the environment in which the sensors are deployed.

Claims

1. A system for monitoring at least one parameter in a region of interest, comprising:

an optical fiber having a plurality of first fiber optic sensors and a plurality of second fiber optic sensors disposed along its length to deploy in the region of interest; and

an interrogating system coupled to the optical fiber to launch an optical pulse to interrogate the first and second fiber optic sensors and to detect reflected signals generated by the first and second fiber optic sensors in response to the optical pulse, wherein each of the first fiber optic sensors generate a first reflected signal in a first optical spectrum window and each of the second fiber optic sensors generate a second reflected signal in a second optical spectrum window, the first optical spectrum window being different than the second optical spectrum window,

the interrogating system including a first optical spectrum channel having a narrow bandwidth to measure the first reflected signals and a second optical spectrum channel having a wide bandwidth to measure the second reflected signals, the measured first and second reflected signals providing simultaneous indications of at least one parameter in the region of interest.

2. The system as recited in claim 1, wherein the first fiber optic sensors are fiber grating sensors and the second fiber optic sensors are polarimetric sensors, wherein the first reflected signals generated by the fiber grating sensors provide an indication of temperature in the region of interest and the second reflected signals generated by the polarimetric sensors provide an indication of pressure in the region of interest.

3. The system as recited in claim 2, further comprising a plurality of sensing units coupled to the optical fiber at a plurality of unique locations along its length, wherein each sensing unit includes one of the fiber grating sensors and one of the polarimetric sensors, and the first reflected signal and the second reflected signal generated by each sensing unit provide simultaneous indications of temperature and pressure at the corresponding unique location.

4. The system as recited in claim 3, wherein each polarimetric sensor is built on a side hole fiber or a polarization maintaining crystal fiber.

5. The system as recited in claim 3, wherein each sensing unit further comprises an enclosure defining a chamber, the chamber containing the fiber grating sensor, the polarimetric sensor and a liquid metal.

6. The system as recited in claim 1, wherein the first fiber optic sensors are first fiber grating sensors that generate the first reflected signals at substantially a same first central wavelength, and wherein the second fiber optic sensors are second fiber grating sensors that generate the second reflected signals at substantially a same second central wavelength that is different than the first central wavelength.

7. The system as recited in claim 1, wherein the interrogating system includes a semiconductor optical amplifier (SOA) optically coupled to the optical fiber to select for amplification a reflected signal generated by a particular fiber optic sensor of the first and second fiber optic sensors, and a controller to selectively turn on the SOA to enable the SOA to select the reflected signal based on a travel time of the optical pulse in the optical fiber.

8. The system as recited in claim 7, wherein the SOA is coupled to the first optical spectrum channel to select for amplification particular first reflected signals generated by the first fiber optic sensors, and wherein the interrogating system includes another SOA coupled to the second optical spectrum channel to select for amplification particular second reflected signals generated by the second fiber optic sensors.

9. The system as recited in claim 7, wherein the interrogating system includes an optical spectrum analyzer (OSA) optically coupled to the SOA to detect the selectively amplified first and second reflected signals.

10. The system as recited in claim 9, further comprising a processing system coupled to the OSA to derive the at least one parameter from the detected reflected signals.