Apparatus and method of multiplexed or distributed sensing

Patent metadata

Field	Value
Publication number	US-2016003648-A1
Application number	US-201314769977-A
Country	US
Kind code	A1
Filing date	Aug 7, 2013
Priority date	Aug 7, 2013
Publication date	Jan 7, 2016
Grant date	—

Abstract

Various embodiments include apparatus and methods to measure a parameter of interest using a fiber optic cable. The parameters can be provided by a process that provides for multiplexed or distributed measurements. A multiplexed or a distributed architecture can include acoustic sensor units placed selectively along an optical fiber such that the acoustic sensor units effectively modulate the optical fiber with information regarding a parameter to provide the information to an interrogator coupled to the optical fiber that is separate from the acoustic sensor units.

First claim

What is claimed is:

1 . A method comprising:
making a measurement using a sensor disposed at a location, the measurement corresponding to a parameter related to the location; generating a signal correlated to the parameter in response to the measurement; applying the signal to an actuator such that that the actuator perturbs an optical fiber disposed in vicinity of the location, based on the signal, the optical fiber and the actuator arranged in proximity to each other; and extracting a value of the parameter, at an interrogator coupled to the optical fiber, in response to receiving an optical signal from perturbing the optical fiber.

2 . The method of claim 1 , wherein extracting the value of the parameter includes extracting a value of the parameter in response to receiving an optical signal backscattered from perturbing the optical fiber.

3 . The method of claim 1 , wherein perturbing the optical fiber includes perturbing a fiber Bragg grating disposed in the optical fiber in vicinity of the location.

4 . The method of claim 1 , wherein perturbing the optical fiber includes perturbing a non-wavelength selective in-line mirror disposed in the optical fiber in vicinity of the location.

5 . The method of claim 4 , wherein perturbing the non-wavelength selective in-line mirror includes perturbing an in-line connector of the optical fiber in vicinity of the location or an in-line reflective material coated fiber splice of the optical fiber in vicinity of the location.

6 . The method of claim 1 , wherein perturbing the optical fiber and extracting the value of the parameter at the interrogator includes using intrinsic Fabry-Perot interferometers as a mode of interrogation from fiber Bragg gratings placed apart in the optical fiber.

7 . The method of claim 1 , wherein perturbing the optical fiber and extracting the value of the parameter at the interrogator includes using Fizeau sensor strings in the optical fiber.

8 . The method of claim 1 , wherein extracting the value of the parameter at the interrogator includes using a second optical fiber to transmit an optical signal from perturbing the optical fiber to a detection unit of the interrogator.

9 . The method of claim 1 , wherein the parameter includes one of a chemical concentration, a pH, a temperature, or a pressure.

10 . The method of claim 1 , wherein the actuator is in contact with the optical fiber.

11 . The method of claim 1 , wherein the actuator is at a distance from the optical fiber.

12 . The method of claim 1 , wherein extracting the value of the parameter includes using an interferometric interrogator.

13 . The method of claim 1 , wherein the method includes using a number of additional sensors disposed along the length of the optical fiber, each sensor spaced apart from the other sensors of the number of sensors, for selected ones of the number of sensors:
making a measurement using the respective sensor, the measurement corresponding to the parameter; generating a signal correlated to the parameter in response to the measurement; applying the signal to an actuator coupled to the respective sensor such that the actuator perturbs the optical fiber, based on the signal, the optical fiber and the actuator arranged in proximity to each other; and extracting a value of the parameter, at the interrogator in response to receiving an optical signal from the perturbing of the optical fiber.

14 . The method of claim 1 , wherein generating the signal correlated to the parameter in response to the measurement includes generating a difference signal as the difference of the measurement using the sensor and a reference.

15 . The method of claim 1 , wherein extracting the value of the parameter at an interrogator includes measuring frequency based on coherent Rayleigh scattering using interferometry, measuring dynamic changes in attenuation, or measuring a dynamic shift of Brillioun frequency.

16 . The method of claim 1 , wherein applying the signal to the actuator such that that the actuator perturbs the optical fiber includes encoding digital data onto the optical fiber through vibration or strain of the optical fiber.

17 . The method of claim 16 , wherein encoding digital data onto the optical fiber includes using a phase-shift keying communication scheme.

18 . A method comprising:
making a measurement using a first circuit of a sensor disposed at a location, the measurement generating, from the first circuit, a first signal having a frequency based on a parameter related to the location; using a second circuit of the sensor disposed at the location, the second circuit generating a reference signal having a reference frequency unaffected by the parameter; mixing the first signal and the reference signal, generating a measurement signal having a measurement frequency; applying the measurement signal to an actuator such that that the actuator perturbs an optical fiber disposed in vicinity of the location, based on the measurement signal, the optical fiber and the actuator arranged in proximity to each other; and extracting a value of the parameter, at an interrogator coupled to the optical fiber, in response to receiving an optical signal from perturbing the optical fiber.

19 . The method of claim 18 , wherein extracting the value of the parameter includes extracting a value of the parameter in response to receiving an optical signal backscattered from perturbing the optical fiber.

20 . The method of claim 18 , wherein extracting the value of the parameter at the interrogator includes extracting, from the optical signal, a characteristic of the measurement frequency with the measurement frequency equal to a difference between the first frequency and the reference frequency.

21 . The method of claim 18 , wherein parameter includes one of a chemical concentration, a pH, a temperature, or a pressure.

22 . The method of claim 18 , wherein making the measurement using the first circuit includes using a circuit having a resonating element that has a complex impedance that changes based on pressure.

23 . The method of claim 22 , wherein using the second circuit includes using a circuit having a resonating element that has a complex impedance, the resonating element of the second circuit arranged to be unaffected by the pressure that changes the complex impedance of the resonating element of the first circuit.

24 . The method of claim 23 , wherein the resonating element of the first circuit includes a first quartz crystal coupled to pressure external to the sensor such that the first quartz crystal changes frequency based on the external pressure, and the resonating element of the second circuit includes a second quartz crystal not coupled to the external pressure such that the second quartz crystal does not change frequency based on the external pressure.

25 . The method of claim 18 , wherein the method includes using the optical fiber to determine temperature at the location through a distributed temperature sensing measurement.

26 . The method of claim 18 , wherein extracting the value of the parameter at an interrogator includes measuring frequency based on coherent Rayleigh scattering using interferometry.

27 . The method of claim 18 , wherein extracting the value of the parameter at an interrogator includes using one or more of a fiber Bragg grating disposed in the optic

Assignees

• Halliburton Energy Services Inc
• Haliburton Energy Services Inc

Inventors

• Barfoot David Andrew
• Mccolpin Glenn
• Jaaskelainen Mikko
• Maida John

Classifications

• E21B47/135 Primary

  using light waves, e.g. infrared or ultraviolet waves · CPC title

• G01D5/35306

  using an interferometer arrangement · CPC title

• G01D5/35312 Primary

  using a Fabry Perot · CPC title

• G01D5/35338 Primary

  using other arrangements than interferometer arrangements · CPC title

• G01V8/16

  using optical fibres · CPC title