Optical frequency comb source for fiber sensor interferometer arrays

Patent metadata

Field	Value
Publication number	US-10871592-B2
Application number	US-201515755720-A
Country	US
Kind code	B2
Filing date	Nov 30, 2015
Priority date	Nov 30, 2015
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

An interrogation system may be coupled to a fiber-optic cable positioned in a wellbore to interrogate a plurality of optical sensors coupled to the fiber-optic cable. The interrogation system may include an optical frequency comb source having a plurality of narrowband optical carriers transmitting light to the plurality of optical sensors. Each of the plurality of optical sensors may include a pair of partial reflectors to reflect the light transmitted by the optical frequency comb to one or more optical receivers to receive the reflection signals In some aspects, the interrogation system may include a de-interleaver device for separating reflected light signals having adjacent wavelength into separate optical waveguides. In additional aspects, interrogation system may also include a data processing system having a processing device for performing interferometric measurements using the reflected light signals.

First claim

What is claimed is:

1. An interrogation system, comprising:
a plurality of optical sensors coupled to a fiber-optic cable positionable along an outer surface of a casing string in a wellbore to sense a condition of the wellbore, each optical sensor of the plurality of optical sensors including at least two partial reflectors;
an optical frequency comb operable to generate a plurality of optical carriers evenly spaced in a frequency;
a de-interleaver device couplable to the fiber-optic cable to separate optical reflection signals received from the at least two partial reflectors into at least two separate wavelength bands;
a first opto-electrical device couplable to the fiber-optic cable to receive a first band of the optical reflection signals of the at least two separate wavelength bands and convert the first band of the optical reflection signals into a first electrical signal;
a second opto-electrical device couplable to the fiber-optic cable to receive a second band of the optical reflection signals of the at least two separate wavelength bands and convert the second band of the optical reflection signals into a second electrical signal;
a data processing system couplable to the first opto-electrical device and the second opto-electrical device, the data processing system including a processing device couplable to a database having instructions for causing the processing device to perform optical phase measurements on the optical reflection signals using the first electrical signal and the second electrical signal; and
a plurality of coupling bands extendable around the casing string to secure at least a portion of the fiber-optic cable against the outer surface of the casing string.

2. The interrogation system of claim 1 , further comprising:
a pulser device positionable between the optical frequency comb and the plurality of optical sensors to generate a first pulse and a second pulse corresponding to the plurality of optical carriers;
an optical modulator device positionable between the pulser device and the plurality of optical sensors to modulate the first pulse; and
a delay fiber positionable between the pulser device and the plurality of optical sensors to delay the second pulse, the delay fiber having a length equal to twice a distance between the at least two partial reflectors in each of the plurality of optical sensors.

3. The interrogation system of claim 1 , further comprising an optical mixer positionable between the plurality of optical sensors and at least one of the first opto-electrical device or the second opto-electrical device to receive the optical reflection signals.

4. The interrogation system of claim 3 , further comprising a delay fiber positionable between the optical mixer and the plurality of optical sensors, the delay fiber having a length that is twice a width of each of the plurality of optical sensors.

5. The interrogation system of claim 3 , wherein the optical mixer is couplable to the optical frequency comb to combine a reference signal from the optical frequency comb with the optical reflection signals.

6. The interrogation system of claim 1 , wherein the plurality of optical sensors includes a first sensor having a first pair of partial reflectors and a second sensor having a second pair of partial reflectors,
wherein one of the second pair of partial reflectors is positioned between the first pair of partial reflectors.

7. The interrogation system of claim 1 , wherein the plurality of optical sensors includes fiber Bragg grating that are inscribed on the fiber-optic cable and operable to generate the optical reflection signals having differences in phase.

8. An interrogation system, comprising:
an optical frequency comb including a plurality of optical carriers evenly spaced to transmit the plurality of optical carriers to a plurality of optical sensors positioned on a fiber-optic cable along an outer surface of a casing string and a plurality of coupling bands extendable around the casing string to secure at least a portion of the fiber-optic cable against the outer surface of the casing string in a wellbore of a wellbore environment;
a de-interleaver device positionable between the fiber-optic cable and at least two electro-optical devices to separate optical reflection signals received from the plurality of optical sensors and route the optical reflection signals to the at least two electro-optical devices; and
a data processing system couplable to the at least two electro-optical devices, the data processing system including a processing device couplable to a data storage device having instructions for causing the processing device to perform optical phase measurements of a signal based on the optical reflection signals received from the plurality of optical sensors and received from the at least two electro-optical devices.

9. The interrogation system of claim 8 , wherein the at least two electro-optical devices includes a first electro-optical device and a second electro-optical device,
wherein the de-interleaver device is couplable to the first electro-optical device to route a first reflection signal having a first wavelength to the first electro-optical device,
wherein the de-interleaver device is couplable to the second electro-optical device to route a second reflection signal having a second wavelength to the second electro-optical device.

10. The interrogation system of claim 8 , further comprising a puller device positionable between the optical frequency comb and the plurality of optical sensors to generate one or more pulse signals corresponding to the plurality of optical carriers.

11. The interrogation system of claim 8 , further comprising the plurality of optical sensors, wherein the plurality of optical sensors includes fiber Bragg grating inscribed on the fiber-optic cable.

12. The interrogation system of claim 8 , further comprising a delay fiber having a length that is directly proportional to a width of each sensor of the plurality of optical sensors.

13. The interrogation system of claim 12 , further comprising an optical modulator positionable between a splitter device and a combiner device to modulate a first optical signal,
wherein the delay fiber is positionable between the splitter device and the combiner device to delay a second optical signal,
wherein the de-interleaver device is positionable to receive a first reflection signal corresponding to the first optical signal and a second reflection signal corresponding to the second optical signal at the same time.

14. The interrogation system of claim 8 , wherein the plurality of optical sensors includes a first sensor having a first pair of partial reflectors and a second sensor having a second pair of partial reflectors, wherein one optical sensor of the second pair of partial reflectors is positioned between the first pair of partial reflectors.

15. A method, comprising:
transmitting, via an optical frequency comb source, a plurality of optical frequencies to a plurality of sensors coupled to a fiber-optic cable along an outer surface of a casing string, at least a portion of the fiber-optic cable secured against the outer surface of the casing string by a plurality of coupling bands extending around the casing string;
separating, using a de-interleaver, optical reflection signals received from the plurality of sensors into a first set of reflection signals corresponding to a first set of wavelengths and a second set of reflection signals corresponding to a second set of wavelengths;
routing the first set of reflection signals to a first opto-electrical device;
routing the sec

Assignees

• Halliburton Energy Services Inc

Inventors

• Barfoot Andrew David
• Choi Han-Sun
• Lan Xinwei

Classifications

• G02B6/29386 Primary

  Interleaving or deinterleaving, i.e. separating or mixing subsets of optical signals, e.g. combining even and odd channels into a single optical signal · CPC title

• H04B10/071

  using a reflected signal, e.g. using optical time domain reflectometers [OTDR] · CPC title

• G01V8/16

  using optical fibres · CPC title

• G01V1/40

  specially adapted for well-logging · CPC title

• G01B9/02027

  Two or more interferometric channels or interferometers · CPC title