Fiber optic cable with increased directional sensitivity

• US 9,091,589 B2
• Filed: 06/18/2012
• Issued: 07/28/2015
• Est. Priority Date: 06/20/2011
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Den Boer, Johannis Josephus, Koelman, Johannes Maria Vianney Antonius, Pearce, Jeremiah Glen, Franzen, Andre, Lumens, Paul Gerard Edmond, Joinson, Daniel
• Primary Examiner(s): LEPISTO, RYAN A
• Application Number:
  US14/126,868
• Publication Number:
  US 20140199017A1
• Time in Patent Office: 1,135 Days
• Field of Search: 385/13
• US Class Current: 1/1
• CPC Class Codes: G01H 9/004 using fibre optic sensors light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125
• CPC Class Codes: G01V 1/16 Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
• CPC Class Codes: G02B 2006/12138 Sensor
• CPC Class Codes: G02B 6/4405 with longitudinally spaced waveguide clamping G02B6/4429, G02B6/4439, G02B6/4479 take precedence
• CPC Class Codes: G02B 6/4415 Cables for special applications G02B6/4429, G02B6/4439, G02B6/4479 take precedence

Abstract

A distributed acoustic sensor, comprises a housing having a longitudinal bore therethrough, an optical fiber supported in the bore; and an inertial member supported within the bore, wherein the fiber is mechanically coupled to the inertial member. The inertial member may include a weight and may provides isotropic stiffness such that it deforms more readily in a first direction normal to the bore than it does in a second direction that is normal to both the bore and the first direction. The sensor may include a plurality of axially-spaced centralizers in the bore, and at least one of the inertial member and the centralizers may comprise swellable material.

Claims

1. A distributed acoustic sensor, comprising:

a housing having a longitudinal bore therethrough;

an optical fiber supported in the bore; and

an inertial member supported within the bore;

wherein said fiber is mechanically coupled to the inertial member; and

wherein the inertial member provides anisotropic stiffness such that it deforms more readily in a first direction normal to the bore than it does in a second direction that is normal to both the bore and the first direction.

2. The sensor according to claim 1 wherein the inertial member comprises a weight.

3. The sensor according to claim 1, wherein the inertial member is wider in said second direction than it is in said first direction.

4. The sensor according to claim 3 wherein the inertial member comprises a membrane extending along at least a part of the bore and being more flexible in a first direction normal to the bore than it is in a second direction that is normal to both the bore and the first direction.

5. The sensor according to claim 1, wherein the sensor includes a plurality of axially-spaced centralizers in the bore, each centralizer supporting the inertial member away from the inside wall of the bore in said first direction.

6. The sensor according to claim 5 wherein at least one of the inertial member and the centralizers comprises a swellable material.

7. The sensor according to claim 1, wherein the inertial member contacts the inside wall of the bore in the second direction.

8. The sensor according to claim 1, wherein the inertial member does not contact the inside wall of the bore in the second direction.

9. The sensor according to claim 1, wherein the inertial member extends across the inside diameter of the bore.

10. A distributed acoustic sensor, comprising:

a housing having a longitudinal bore therethrough;

an optical fiber supported in the bore; and

an inertial member supported within the bore;

wherein said fiber is mechanically coupled to the inertial member; and

wherein the inertial member comprises a membrane extending along at least a part of the bore and being more flexible in a first direction normal to the bore than it is in a second direction that is normal to both the bore and the first direction.

11. The sensor according to claim 10, wherein the inertial member is wider in said second direction than it is in said first direction.

12. The sensor according to claim 10 wherein the inertial member comprises a weight.

13. The sensor according to claim 10, wherein the inertial member contacts the inside wall of the bore in the second direction.

14. The sensor according to claim 10, wherein the inertial member extends across the inside diameter of the bore.

15. A distributed acoustic sensor, comprising:

a housing having a longitudinal bore therethrough;

an optical fiber supported in the bore; and

an inertial member supported within the bore;

wherein said fiber is mechanically coupled to the inertial member;

wherein the sensor includes a plurality of axially-spaced centralizers in the bore, each centralizer supporting the inertial member away from the inside wall of the bore in a first direction; and

wherein the centralizers comprise a swellable material.

16. The sensor according to claim 15, wherein the inertial member comprises a swellable material.

17. The sensor according to claim 15, wherein the inertial member comprises a weight.

18. A distributed acoustic sensor, comprising:

a housing having a longitudinal bore therethrough;

an optical fiber supported in the bore; and

an inertial member supported within the bore;

wherein said fiber is mechanically coupled to the inertial member;

wherein the inertial member comprises a swellable material and, wherein the sensor includes a plurality of axially-spaced centralizers in the bore, each centralizer supporting the inertial member away from the inside wall of the bore in a first direction.

19. The sensor according to claim 18, wherein the inertial member comprises a weight.