Oilfield conduit leakage detection system

Patent metadata

Field	Value
Publication number	US-9846103-B2
Application number	US-201113695613-A
Country	US
Kind code	B2
Filing date	May 12, 2011
Priority date	May 12, 2010
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

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.

First claim

What is claimed is:

1. A system for identifying a leak in an oilfield conduit made up of a plurality of conduit sections, the system comprising:
a measurement device deployed along a length of the conduit traversing each of the sections and configured to measure a distributed temperature along the length of the conduit; and
a processor configured to:
calculate a change in volume of a fluid in the conduit for each of the plurality of sections based on the distributed temperature obtained from the device;
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 any of the sections of 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:
Δ V=∫0L [Kp−Kv]·Δ T (z)· z; and
the change in volume stored (ΔV) by the conduit is given by a change in temperature (ΔT) provided by the distributed temperature at each of the plurality of sections (dz) of the conduit, multiplied by the difference between a volume expansion of the conduit (Kp) and that of the fluid (Kv), integrated over a predetermined length (0-L) of the conduit.

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 an oilfield conduit consisting of a plurality of conduit sections, the method comprising the steps of:
obtaining a distributed temperature using a measurement device deployed along a length of the conduit traversing each of the sections;
calculating a change in volume of a fluid over the length of the conduit based on the distributed temperature from each of the plurality of conduit sections;
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 any of the conduit sections of the oilfield 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:
Δ V=∫0L [Kp−Kv]·Δ T (z)· z; and
the change in volume stored (ΔV) by the conduit is given by a change in temperature (ΔT) provided by the distributed temperature at each of the plurality of sections (dz) of the conduit, multiplied by the difference between a volume expansion of the conduit (Kp) and that of the fluid (Kv), integrated over a predetermined length (0-L) of the conduit.

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 non-transitory computer readable medium containing computer instructions stored therein for causing a computer processor to perform, the computer program product includes at least one component operable to:
obtain a distributed temperature using a measurement device along a length of an oilfield conduit made up of a plurality of conduit sections;
calculate a change in volume of a fluid in the conduit for each of the plurality of sections 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 any of the sections of 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:
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Assignees

• Strong Andrew
• Schlumberger Technology Corp

Inventors

• Strong Andrew

Classifications

• G01M3/2892

  for underground fuel dispensing systems (G01M3/30 takes precedence) · CPC title

• G06F15/00

  Digital computers in general (details G06F1/00 – G06F13/00); Data processing equipment in general · CPC title

• G01M3/002 Primary

  by using thermal means · CPC title

• G01M3/007 Primary

  Leak detector calibration, standard leaks (G01M3/207 takes precedence) · CPC title

• G01M3/28

  for pipes, cables or tubes; for pipe joints or seals; for valves {; for welds} · CPC title