Methods for gas leak detection and localization in populated areas using two or more tracer measurements

1. A method of gas leak detection and localization, the method comprising:

performing one or more primary gas concentration measurements of a target gas species from a moving platform that proceeds along at least one platform track disposed near one or more potential gas leak locations;

performing two or more secondary tracer measurements of the target gas species from the moving platform as it proceeds along the at least one platform track;

automatically determining whether or not a gas leak is present at the potential gas leak locations based on the primary gas concentration measurements and the two or more secondary tracer measurements, wherein the secondary tracer measurements provide source identification for detected leaks of the target gas species into three or more distinct categories; and

providing a leak indication at the potential gas leak locations to an end user.

2. The method of claim 1 , wherein the performing two or more secondary tracer measurements comprises using a gas handling system to acquire one or more samples and providing acquired samples to an off-line tracer measuring instrument.

3. The method of claim 1 , wherein the secondary tracer measurements are optical absorption measurements made in a resonant optical cavity disposed in an instrument in the moving platform.

4. The method of claim 1 , further comprising

performing one or more of the primary gas concentration measurements at two or more transversely separated locations on the moving platform as it proceeds along the at least one platform track;

performing an automatic transverse spatial scale analysis of the primary gas concentration measurements;

wherein the automatically determining whether or not a gas leak is present at the potential gas leak locations is also based on the automatic transverse spatial scale analysis.

5. The method of claim 1 , further comprising performing one or more stationary gas concentration measurements when the platform is stationary.

6. The method of claim 1 ,

wherein one of the two or more secondary tracer measurements is selected from the group consisting of: ethane concentration, ethane/methane concentration ratio, ethane/methane background-corrected concentration ratio, hydrogen stable isotope ratio and carbon stable isotope ratio; and

wherein another of the two or more secondary tracer measurements is selected from the group consisting of: ethylene concentration, acetylene concentration, carbon monoxide concentration, nitrous oxide concentration, nitrogen dioxide concentration, ethylene/methane concentration ratio, acetylene/methane concentration ratio, carbon monoxide/methane concentration ratio, nitrous oxide/methane concentration ratio, nitrogen dioxide/methane concentration ratio, ethylene/methane background-corrected concentration ratio, acetylene/methane background-corrected concentration ratio, carbon monoxide/methane background-corrected concentration ratio, nitrous oxide/methane background-corrected concentration ratio, and nitrogen dioxide/methane background-corrected concentration ratio.

7. The method of claim 6 , wherein T plume is a tracer species concentration in a gas plume, wherein T background is a background concentration of the tracer species, wherein C plume is a primary gas species concentration in the gas plume, wherein C background is a background concentration of the primary gas species, and wherein the background-corrected concentration ratio r is given by

r

=

T

plume

-

T

background

C

plume

-

C

background

.

8. The method of claim 1 , wherein the leak indication is a binary yes/no indication of whether or not a leak is present.

9. The method of claim 1 , further comprising providing a display showing a map with leak figures superposed on the map to show detected leaks, wherein the leak figures include pointers showing the locations of detected leaks.

10. The method of claim 9 , wherein sizes of the leak figures are scaled with the measured primary gas concentration.

11. The method of claim 9 , wherein sizes of the leak figures are scaled with a difference between the measured primary gas concentration and a local background level.

12. The method of claim 9 , wherein distinct colors of the leak figures correspond to the three or more distinct categories.

13. The method of claim 9 , further comprising superposing tracer measurements on the map corresponding to one or more of the detected leaks.

14. The method of claim 1 , wherein the secondary tracer measurements comprise one or more concentration measurements of tracer species.

15. The method of claim 1 , wherein the secondary tracer measurements comprise one or more concentration ratio measurements of tracer species concentration relative to the primary gas concentration measurements.

16. The method of claim 1 , wherein the secondary tracer measurements comprise one or more background-corrected concentration ratio measurements of tracer species concentration relative to the primary gas concentration measurements.

17. The method of claim 16 , wherein T plume is a tracer species concentration in a gas plume, wherein T background is a background concentration of the tracer species, wherein C plume is a primary gas species concentration in the gas plume, wherein C background is a background concentration of the primary gas species, and wherein the background-corrected concentration ratio r is given by

r

=

T

plume

-

T

background

C

plume

-

C

background

.

18. The method of claim 1 , wherein the secondary tracer measurements comprise one or more isotope ratio measurements of tracer species.