DOWNHOLE OPTICAL FIBER WITH ARRAY OF FIBER BRAGG GRATINGS AND CARBON-COATING

• US 20180230049A1
• Filed: 02/13/2017
• Published: 08/16/2018
• Est. Priority Date: 02/13/2017
• Status: Abandoned Application

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Wysocki, Paul Francis, Balagopal, Ajit, Lambert, Christopher Howard, Homa, Daniel Scott
• Application Number:
  US15/431,032
• Publication Number:
  US 20180230049A1
• Time in Patent Office: Days
• CPC Class Codes: C03B 37/032 for glass optical fibres
• CPC Class Codes: C03C 25/1062 Carbon
• CPC Class Codes: C03C 25/109 with at least one organic coating and at least one inorganic coating
• CPC Class Codes: C03C 25/26 Macromolecular compounds or prepolymers
• CPC Class Codes: C03C 25/285 Acrylic resins
• CPC Class Codes: C03C 25/40 Organo-silicon compounds
• CPC Class Codes: C03C 25/44 Carbon, e.g. graphite
• CPC Class Codes: C03C 25/6208 Laser
• CPC Class Codes: E21B 47/00 Survey of boreholes or wells monitoring pressure or flow of drilling fluid E21B21/08
• CPC Class Codes: E21B 47/113 using electrical indications; using light radiations
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G02B 2006/02157 Grating written during drawing of the fibre
• CPC Class Codes: G02B 6/02142 based on illuminating or irradiating an amplitude mask, i.e. a mask having a repetitive intensity modulating pattern
• CPC Class Codes: G02B 6/02152 involving moving the fibre or a manufacturing element, stretching of the fibre G02B6/02147 takes precedence
• CPC Class Codes: G02B 6/02395 Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104

Abstract

A method for producing a protected optical fiber with distributed sensors includes heating an optical fiber preform and drawing the heated optical fiber preform to form a drawn optical fiber. The method also includes coating the drawn optical fiber with a carbon coating after the optical fiber is drawn to provide a carbon coated optical fiber and then writing a series of fiber Bragg gratings (FBGs) into the carbon coated optical fiber to provide a carbon coated optical fiber with FBGs. The method further includes coating the carbon coated optical fiber with FBGs with one or more layers of a polymer to provide the protected optical fiber with distributed sensors, wherein the heating, drawing, carbon coating the drawn optical fiber, writing, coating the carbon coated optical fiber are performed in that sequence while the protected optical fiber is being produced.

Claims

1. A method for producing a protected optical fiber with distributed sensors, the method comprising:

heating an optical fiber preform;

drawing the heated optical fiber preform to form a drawn optical fiber;

coating the drawn optical fiber with a carbon coating after the optical fiber is drawn to provide a carbon coated optical fiber;

writing a series of fiber Bragg gratings (FBGs) into the carbon coated optical fiber to provide a carbon coated optical fiber with FBGs; and

coating the carbon coated optical fiber with FBGs with one or more layers of a polymer to provide the protected optical fiber with distributed sensors;

wherein the heating, drawing, carbon coating the drawn optical fiber, writing, coating the carbon coated optical fiber are performed in that sequence while the protected optical fiber is being produced.

2. The method according to claim 1, wherein the optical preform is heated in a range of 1900-2100°

C.

3. The method according to claim 1, wherein a temperature of the optical fiber when the carbon coating is applied is less than the temperature of the optical fiber preform when drawn.

4. The method according to claim 3, wherein the optical fiber is in a temperature range of 900-1000°

C. when the carbon coating is applied.

5. The method according to claim 1, wherein writing the series of FBGs is performed when a temperature of the carbon coated optical fiber is less than the temperature of the optical fiber when the carbon coating was applied.

6. The method according to claim 5, wherein the temperature of the carbon coated optical fiber is less than or equal to 300°

C. when the series of FBGs is written into the optical fiber.

7. The method according to claim 1, wherein coating the carbon coated fiber with FBGs with one or more layers of a polymer is performed when a temperature of the carbon coated optical fiber with FBGs is less than or equal to 100°

C.

8. The method according to claim 1, wherein the polymer comprises polyimide and the method further comprises thermal curing of the polyimide.

9. The method according to claim 1, wherein the polymer comprises acrylate and the method further comprises curing the acrylate with ultra-violet light.

10. The method according to claim 1, wherein the polymer comprises silicone and the method further comprises curing the silicone with ultra-violet light.

11. The method according to claim 1, wherein the polymer comprises a layer of acrylate over the layer of silicone and the method further comprises curing the acrylate with ultra-violet light.

12. The method according to claim 1, wherein the optical fiber is drawn using a powered-capstan and the heating, drawing, coating the optical fiber, writing, coating the carbon coated optical fiber are performed before the protected optical fiber with distributed sensors is wound on the powered-capstan.

13. The method according to claim 12, further comprising selecting a distance between:

the drawing and the coating the drawn optical fiber with a carbon coating;

the coating the drawn optical fiber with a carbon coating and the writing a series of fiber FBGs into the carbon coated optical fiber; and

/or the writing a series of fiber FBGs into the carbon coated optical fiber and the coating the carbon coated optical fiber with FBGs with one or more layers of a polymer to provide proper cooling.

14. The method according to claim 1, wherein writing a series of FBGs into the carbon coated optical fiber comprises writing each FBG in the series of FBGs using a single pulse of light traveling through an FBG mask.

15. A system to produce a protected optical fiber with distributed sensors, the system comprising:

a draw furnace configured to heat an optical fiber preform so that an optical fiber can be drawn;

a drawing device configured to draw an optical fiber from the optical fiber preform and wind the protected optical fiber with distributed sensors on a capstan;

a carbon coating applicator configured to coat the drawn optical fiber with carbon to provide a carbon coated optical fiber;

a fiber Bragg grating writing apparatus configured to write a series of fiber Bragg gratings (FBGs) in the carbon coated optical fiber to provide a carbon coated optical fiber with FBGs;

a polymer coating applicator configured to coat the carbon coated fiber with FBGs with one or more layers of a polymer to provide the protected optical fiber with distributed sensors;

wherein the carbon coating applicator, fiber Bragg grating writing apparatus, and polymer coating applicator are configured to process the drawn optical fiber in that sequence before the protected optical fiber with distributed sensors is wound on the capstan of the drawing device.

16. The system according to claim 15, wherein the polymer coating applicator comprises a curing device configured to cure the polymer after the polymer is applied to the carbon coated optical fiber with FBGs.

17. The system according to claim 16, wherein the curing device comprises at least one of a curing furnace and source of ultra-violet light.

18. The system according to claim 15, wherein a distance between:

the drawing and the coating the drawn optical fiber with a carbon coating;

the coating the drawn optical fiber with a carbon coating and the writing a series of fiber FBGs into the carbon coated optical fiber; and

/or the writing a series of fiber FBGs into the carbon coated optical fiber and the coating the carbon coated optical fiber with FBGs with one or more layers of a polymer provides proper cooling.

19. The system according to claim 15, wherein the fiber Bragg grating writing apparatus is configured to write each FBG in the series of FBGs using a single pulse of light traveling through an FBG mask.