Leakage Detection System

• US 20130090867A1
• Filed: 05/12/2011
• Published: 04/11/2013
• Est. Priority Date: 05/12/2010
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Strong, Andrew
• Granted Patent: US 9,846,103 B2
• Time in Patent Office: Days
• US Class Current: 702/51
• CPC Class Codes: G01M 3/002 by using thermal means
• CPC Class Codes: G01M 3/007 Leak detector calibration, standard leaks G01M3/207 takes precedence
• CPC Class Codes: G01M 3/2892 for underground fuel dispensing systems G01M3/30 takes precedence
• CPC Class Codes: G06F 15/00 Digital computers in general details G06F1/00 – G06F13/00; Data processing equipment in general

Abstract

A system and method for identifying and measuring the quantity of leakage from a conduit used in the conveyance of a fluid, such as a hydrocarbon fluid, for example oil, or a gas, such as natural gas. The system includes a measurement device configured to measure a distributed temperature along a length of the conduit. The system further includes a processor configured to calculate a change in volume of the fluid in the conduit for each of a plurality of sections of the length of the conduit based on the distributed temperature. The processor is further configured to calculate a correction factor based on the change in volume of the fluid. The processor is also configured to calculate a corrected mass-balance differential using the correction factor, and compare the corrected mass-balance differential to a predetermined leakage threshold to identify whether a leak exists in the conduit.

Claims

1. A system for identifying a leak in a conduit comprising:

a measurement device configured to measure a distributed temperature along a length of the conduit; and

a processor configured to;

calculate a change in volume of a fluid in the conduit for each of a plurality of sections of the length of the conduit based on the distributed temperature;

calculate a correction factor based on the change in volume of the fluid;

calculate a corrected mass-balance differential using the correction factor; and

compare the corrected mass-balance differential to a predetermined leakage threshold to identify whether a leak exists in the conduit.

2. The system of claim 1, further comprising another measurement device configured to measure a distributed acoustic signal along the length of the conduit, wherein the processor is further configured to compare the distributed acoustic signal to the result of the comparison of the corrected mass-balance differential and the predetermined leakage threshold to identify whether the leak exists in the conduit.

3. The system of claim 1, wherein the calculation of the correction factor comprises:

acquiring an input and output mass flow from an entry point and exit point of the conduit, respectively;

using known properties of the fluid and the conduit to calculate the change in volume for each of the plurality of sections of the conduit relative to a predetermined baseline; and

integrating the changes in volume for each of the plurality of sections to calculate a total change in volume of the conduit,

wherein the total change in volume of the conduit is the correction factor.

4. The system of claim 3, wherein the known properties of the fluid comprise a volume expansion coefficient and the known properties of the conduit comprise a diameter of the conduit and a linear coefficient of expansion.

5. The system of claim 4, wherein the predetermined baseline value is a baseline of the conduit taken when the conduit is empty of any fluid.

6. The system of claim 5, wherein:

the total change in volume of the conduit is calculated using the formula;

7. The system of claim 6, wherein the measurement device is an optical fibre.

8. The system of claim 7, further comprising another measurement device configured to measure a distributed acoustic signal along the length of the conduit, wherein the processor is further configured to compare the distributed acoustic signal to the result of the comparison of the corrected mass-balance differential and the predetermined leakage threshold to identify whether the leak exists in the conduit.

9. The system of claim 8, wherein the another measurement device is an optical fibre.

10. A method for identifying a leak in a conduit, the method comprising the steps of:

obtaining a distributed temperature using a measurement device along a length of the conduit;

calculating a change in volume of a fluid in the conduit for each of a plurality of sections of the length of the conduit based on the distributed temperature;

calculating a correction factor using a processor based on the change in volume;

calculating a corrected mass-balance differential using the correction factor; and

comparing the corrected mass-balance differential to a predetermined leakage threshold to identify whether a leak exists in the conduit.

11. The method of claim 10, further comprising:

obtaining a distributed acoustic signal along the length of the conduit; and

compare the distributed acoustic signal to the result of the comparison of the corrected mass-balance differential and the predetermined leakage threshold to identify whether the leak exists in the conduit.

12. The method of claim 10, wherein the calculating of the correction factor comprises:

acquiring an input and output mass flow from an entry point and exit point of the conduit, respectively;

using known properties of the fluid and the conduit to calculate the change in volume for each of the plurality of sections of the conduit relative to a predetermined baseline; and

integrating the changes in volume for each of the plurality of sections to calculate a total change in volume of the conduit,

wherein the total change in volume of the conduit is the correction factor.

13. The method of claim 12, wherein the known properties of the fluid comprise a volume expansion coefficient and the known properties of the conduit comprise a diameter of the conduit and a linear coefficient of expansion.

14. The method of claim 13, wherein the predetermined baseline value is a baseline of the conduit taken when the conduit is empty of any fluid.

15. The method of claim 14, wherein:

the total change in volume of the conduit is calculated using the formula;

16. The method of claim 15, wherein the measurement device is an optical fibre.

17. The method of claim 16, further comprising:

obtaining a distributed acoustic signal along the length of the conduit; and

compare the distributed acoustic signal to the result of the comparison of the corrected mass-balance differential and the predetermined leakage threshold to identify whether the leak exists in the conduit.

18. A computer program product comprising a computer-usable storage medium having readable program code embodied in the storage medium, the computer program product includes at least one component operable to:

obtain a distributed temperature using a measurement device along a length of a conduit;

calculate a change in volume of a fluid in the conduit for each of a plurality of sections of the length of the conduit based on the distributed temperature;

calculate a correction factor based on the change in volume of the fluid;

calculate a corrected mass-balance differential using the correction factor; and

compare the corrected mass-balance differential to a predetermined leakage threshold to identify whether a leak exists in the conduit.

19. The computer program product of claim 18, further operable to:

obtain a distributed acoustic signal along the length of the conduit; and

compare the distributed acoustic signal to the result of the comparison of the corrected mass-balance differential and the predetermined leakage threshold to identify whether the leak exists in the conduit.

20. The computer program product of claim 18, wherein the calculating of the correction factor comprises:

acquiring an input and output mass flow from an entry point and exit point of the conduit, respectively;

using known properties of the fluid and the conduit to calculate the change in volume for each of the plurality of sections of the conduit relative to a predetermined baseline; and

integrating the changes in volume for each of the plurality of sections to calculate a total change in volume of the conduit,

wherein the total change in volume of the conduit is the correction factor.