Flexible unbonded oil pipe system with an optical fiber sensor inside
The invention relates to an unbonded flexible pipe comprising an internal sheath, at least one armor layer surrounding said internal sheath and a bore defined by said internal sheath, the flexible pipe further comprising a fiber sensor arranged in said bore. By arranging the fiber in the bore of the unbounded flexible pipe, new opportunities for sensing desired properties of the unbounded flexible pipe is provided. The fiber sensor may preferably be a pressure fiber sensor. The unbonded flexible pipe may preferably be an offshore pipe, such as a riser for transportation of hydrocarbons.
1. An unbonded flexible pipe comprising an internal sheath, at least one armor layer surrounding said internal sheath and a bore defined by said internal sheath, the flexible pipe further comprising a fiber sensor arranged in said bore, the fiber sensor is an optical fiber sensor, wherein a protecting element is arranged around said fiber sensor, said protecting element allowing a liquid fluid and/or gas fluid flowing in said bore to act directly on said fiber sensor, wherein said flexible pipe is a riser.
2. The flexible pipe as claimed in claim 1 , wherein said fiber sensor is a pressure fiber sensor.
3. The flexible pipe as claimed in claim 1 , wherein said fiber sensor comprises at least one grating.
4. The flexible pipe as claimed in claim 1 , wherein said fiber sensor is a Bragg grating fiber sensor.
5. The flexible pipe as claimed in claim 1 , wherein said fiber sensor is a spectrally based fiber sensor.
6. The flexible pipe as claimed in claim 1 , wherein the fiber sensor further comprises a sensing fiber, for sensing the property to be determined, and a protective coating surrounding said sensing fiber.
7. The flexible pipe as claimed in claim 6 , wherein the protective coating and the sensing fiber together form a tape having an elongated outer cross section with a high aspect ratio between a shortest length direction and a longest length direction.
8. The flexible pipe as claimed in claims 7 , wherein the tape comprises two sides along the longest length direction, said two sides being substantially parallel over at least a part of the longest length direction.
9. The flexible pipe as claimed in claim 7 , wherein the tape has a thickness of from about 100% to about 2000% of an outer dimension of the sensing fiber.
10. The flexible pipe as claimed in claim 7 , wherein the tape has a width from about 10 to about 200 times the thickness of said tape.
11. The flexible pipe as claimed in claim 1 , wherein the fiber sensor comprises a pressure sensitive coating.
12. The flexible pipe as claimed in claim 1 , wherein the fiber sensor provides or is a part of a distributed pressure sensing system.
13. The flexible pipe as claimed in claim 1 , wherein said flexible pipe further comprises a distributed temperature sensor.
14. The flexible pipe as claimed in claim 1 , wherein said fiber sensor arranged in said bore comprises a temperature sensor and a pressure sensor.
15. The flexible pipe as claimed in claim 1 , wherein said fiber sensor arranged in said bore is configured to be in physical contact with a liquid flowing in said bore.
16. The flexible pipe as claimed in claim 1 , wherein said fiber sensor arranged in said bore is placed in an open carrier rod comprising a plurality of orifices for allowing a liquid in the bore acting directly on the fiber sensor.
17. The flexible pipe as claimed in claim 1 , wherein said fiber sensor is placed in contact with an inner side of said internal sheath.
18. The flexible pipe as claimed in claim 1 , wherein said flexible pipe comprises an internal armoring layer placed in said bore on the inner side of said internal sheath.
19. The flexible pipe as claimed in claim 18 , wherein said fiber sensor is placed between said internal sheath and said internal armoring layer.
20. The flexible pipe as claimed in claim 18 , wherein said fiber sensor is placed on the inner side of said internal armoring layer.
21. The flexible pipe as claimed in claim 18 , wherein said fiber sensor is at least partly integrated with or fixed to said internal armoring layer, while allowing a liquid in the bore to act directly on the fiber sensor.