Purging of Fiber Optic Conduits in Subterranean Wells

• US 10,221,677 B2
• Filed: 01/03/2012
• Issued: 03/05/2019
• Est. Priority Date: 12/28/2007
• Status: Expired due to Fees

• Current Assignee: Welldynamics, Inc. (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Skinner, Neal G.
• Primary Examiner(s): Lepisto, Ryan A
• Assistant Examiner(s): Chiem, Erin D
• Application Number:
  US13/342,652
• Publication Number:
  US 20120118578A1
• Time in Patent Office: 2,618 Days
• Field of Search: 385 12, 385100, 385125, 385113, 385109, 367 25, 367 64, 367 69, 367 81, 367 82, 367 83, 367 86, 367103, 367119, 367911, 1663051, 1661773
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G02B 6/3827 Wrap-back connectors, i.e. containing a fibre having an U shape
• CPC Class Codes: G02B 6/4427 Pressure resistant cables, e.g. undersea cables
• CPC Class Codes: G02B 6/4436 Heat resistant
• CPC Class Codes: G02B 6/52 using fluid, e.g. air

Abstract

Purging of fiber optic conduits in subterranean wells. A downhole optical sensing system includes an optical line, at least two tubular conduits, one conduit being positioned within the other conduit, and the optical line being positioned within at least one of the conduits, and a purging medium flowed in one direction through one conduit, and flowed in an opposite direction between the conduits. A method of purging a downhole optical sensing system includes the steps of: installing at least two conduits and an optical line in a well as part of the sensing system, one conduit being positioned within the other conduit, and the optical line being positioned within at least one of the conduits; and flowing a purging medium through the conduits in the well, so that the purging medium flows in one direction through one conduit and in an opposite direction between the conduits.

Claims

1. A downhole optical sensing system for use in a well, comprising:

optical lines;

a first conduit being positioned within a second conduit, and the optical lines positioned within either or both the first or the second conduit such that one of the optical lines comprises a turnaround to form a continuous optical waveguide configured to perform double-ended measurements, an interior of the first conduit being in fluid communication with an annulus between the first and second conduits;

a downhole chamber in fluid communication with the interior of the first conduit and the annulus between the first and second conduits;

a downhole sensor in fluid communication with the downhole chamber outside the first and second tubular conduits; and

wherein the first conduit and the annulus are configured such that a purging medium comprising a hydrogen scavenging substance in gas or gel form is able to flow in a first direction through the first conduit and is able to flow through the annulus in a second direction opposite to the first direction and chemically react with and purge hydrogen from about the optical lines as the substance flows into contact with the hydrogen while the first and second conduits are downhole in the well.

2. The system of claim 1, wherein one of the optical lines is operatively connected to the downhole sensor.

3. The system of claim 1, wherein one of the optical lines comprises the downhole sensor.

4. The system of claim 1, wherein the downhole sensor comprises a pressure gauge.

5. The system of claim 1, wherein the first conduit and the annulus are configured such that the hydrogen scavenging medium is able to flow downhole in the first direction and is able to return in the second direction.

6. The system of claim 1, wherein the first conduit and the annulus are configured such that the purging medium is able to flow downhole in the second direction and is able to return in the first direction.

7. The system of claim 1, further comprising:

a turnaround disposed in the downhole chamber;

two splices to connect two optical lines to the turnaround in the downhole chamber; and

a splice disposed in the downhole chamber to operatively connect one of the optical lines to the downhole sensor.

8. A method of purging a downhole optical sensing system, the method comprising:

installing first and second conduits and optical lines in a well, the first conduit being positioned within the second conduit, and the optical lines being positioned within either or both of the first and second conduits such that one of the optical lines comprises a turnaround to form a continuous optical waveguide configured to perform double-ended measurements, an interior of the first conduit being in fluid communication with an annulus between the first and second conduits, and the interior of the first conduit and the annulus between the first and second conduits in fluid communication with a downhole chamber, the downhole chamber in fluid communication with a downhole sensor outside the first and second tubular conduits; and

flowing a purging medium comprising a hydrogen scavenging substance in gas or gel form through the first and second conduits in the well, so that the purging medium flows in a first direction through the first conduit and in a second direction opposite to the first direction between the first and second conduits and chemically reacts with and purges hydrogen from about the optical lines as the substance flows into contact with the hydrogen.

9. The method of claim 8, wherein installing further comprises operatively connecting the at least one optical line to the downhole sensor.

10. The method of claim 8, further comprising utilizing the at least one optical line as a downhole sensor.

11. The method of claim 8, wherein the downhole sensor comprises a pressure gauge.

12. The method of claim 8, wherein flowing the purging medium further comprises flowing the purging medium downhole in the first direction and returning the purging medium from downhole in the second direction.

13. The method of claim 8, wherein flowing the urging medium further comprises flowing the purging medium downhole in the second direction and returning the purging medium from downhole in the first direction.

14. The method of claim 8, wherein installing further comprises:

providing a turnaround disposed in the downhole chamber;

forming a splice connecting two optical lines to the turnaround in the downhole chamber; and

forming a splice disposed in the downhole chamber operatively connecting one of the optical lines to the downhole sensor.