Physics supporting oil leak detection approach
Change in thermal conductivity, as water is added to soil
Change in volumetric heat capacity as water is added to soil. From “Soil Temperature Changes with Time and Depth: Theory” by D. L. Nofziger. One might expect a similar effect as oil (from a leaking pipe) is added to soil.
Depth dependence of the annual range of ground temperatures Ottawa.
The BTC pipeline seems to be buried no more than 3m down.
“The amplitude of a temperature variation at the surface is normally about equal to that of the corresponding one for air. It decreases exponentially with distance from the surface, at a rate dictated by the time necessary for one complete cycle. This behaviour is shown above for the annual temperature variation. For depths below 5 to 6 m, ground temperatures are essentially constant throughout the year.” – Canadian Building Digest, “CBD-180. Ground Temperatures” by G.P. Williams and L.W. Gold.
Annual temperature range in Baku and Tbilisi
Hourly variations in surface temperature for a location at 45° North latitude over a 24 hour period.
From the above information, it seems that one would need to:
- have a thermal imaging resolution, of less than 1 K (see NEdT data below)
- make use of differential thermal imaging
- use a computer, to compare images taken of the same region, on different days
- use advanced data fusion techniques, such as Kalman filtering.
NEdT = Noise Equivalent differential Temperature. ADC enob = effective number of bits in the Analog-to-Digital converter (ADC)