Passive acoustic resonator for fiber optic cable tubing

• US 9,279,317 B2
• Filed: 03/14/2013
• Issued: 03/08/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Lee, Erik N.
• Primary Examiner(s): Harcourt, Brad
• Application Number:
  US13/803,049
• Publication Number:
  US 20140262594A1
• Time in Patent Office: 1,090 Days
• US Class Current: 1/1
• CPC Class Codes: E21B 47/107 using acoustic means
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01V 2210/1429 Subsurface, e.g. in borehole or below weathering layer or mud line

Abstract

A passive acoustic system and a method of utilizing the passive acoustic system in a subsurface borehole are discussed. The method includes disposing the passive acoustic system in the borehole, the passive acoustic system including at least one passive acoustic resonator, and monitoring a frequency of an acoustic signal at the at least one passive acoustic resonator. The passive acoustic system includes a protective tubing, a fiber optic cable disposed within the protective tubing, a fluid layer between the fiber optic cable and the protective tubing, and at least one passive acoustic resonator, the at least one passive acoustic resonator representing an area within the protective tubing having a known geometry, wherein the fluid layer affects a frequency of an acoustic signal obtained from the at least one passive acoustic resonator.

Claims

1. A method of utilizing a passive acoustic system in a subsurface borehole, the method comprising:

disposing the passive acoustic system in the borehole, the passive acoustic system including at least one passive acoustic resonator;

monitoring a frequency of an acoustic signal at the at least one passive acoustic resonator and

determining properties of wellbore fluid, the determining including identifying an ingress of the wellbore fluid into the passive acoustic system, based on the frequency of the acoustic signal and a known geometry of the at least one passive acoustic resonator.

2. The method according to claim 1, wherein the monitoring the frequency is based on a fiber optic distributed acoustic sensing system.

3. The method according to claim 1, further comprising measuring temperature based on the frequency.

4. The method according to claim 1, further comprising measuring pressure based on the frequency.

5. The method according to claim 1, further comprising calibrating a depth of the at least one passive acoustic resonator based on a completion system component disposed at a known depth in the borehole.

6. The method according to claim 1, further comprising correlating the frequency of the acoustic signal with a vibration level.

7. The method according to claim 6, wherein the correlating includes calibrating the passive acoustic resonator to determine a set of vibration levels corresponding with a set of frequencies prior to disposing the passive acoustic resonator in the borehole.

8. The method according to claim 1, further comprising disposing another passive acoustic resonator and monitoring another frequency of another acoustic signal at the another passive acoustic resonator, wherein the at least one passive acoustic resonator is at a first depth and the another passive acoustic resonator is at a second depth.

9. The method according to claim 8, further comprising estimating a depth of a breach causing the ingress based on the monitoring the frequency at the first depth and the another frequency at the second depth.

10. The method according to claim 1, further comprising determining a type of the wellbore fluid based on the properties and on temperature and pressure in the borehole determined by one or more sensors.

11. The method according to claim 1, wherein the disposing the passive acoustic system includes disposing a protective tubing surrounding a fiber optic cable with a deployment fluid therebetween, the at least one passive acoustic resonator representing an area within the protective tubing having a known geometry.

12. The method according to claim 11, further comprising monitoring a temperature of the deployment fluid based on the frequency of the acoustic signal.

13. A passive acoustic system disposed in a downhole environment, the passive acoustic system comprising:

a protective tubing;

a fiber optic cable disposed within the protective tubing;

a fluid layer between the fiber optic cable and the protective tubing; and

at least one passive acoustic resonator, the at least one passive acoustic resonator representing an area within the protective tubing having a known geometry, wherein the fluid layer affects a frequency of an acoustic signal obtained from the at least one passive acoustic resonator and at least one of the at least one passive acoustic resonator is separated from the fiber optic cable by the fluid layer.

14. The system according to claim 13, wherein the passive acoustic resonator is within a splice enclosure.

15. The system according to claim 13, wherein the geometry is shaped within the protective tubing.