Conclusion

The use of Unmanned Aircraft, with an on-board thermal imaging camera, to map the ground temperature would be a particularly energy and cost effective way in which this task could be routinely performed, with minimal atmospheric pollution:

  • the TAM 5 would have used only 1.33 Kg of fuel to fly the BTC pipeline
  • no pilots are needed and the takeoff and landing can be automated
  • 16 planes would be needed to have a spare at each pumping station
  • automated data analysis could take place anywhere in the world

Limitations and extensions to this suggestion

Time varying thermal properties of the soil around the pipeline would make it far more difficult to make any meaningful interpretation. Such variations are:

  • Rainfall increasing the thermal conductivity and heat capacity of the soil.
  • Growth / death of vegetation, changing the emissivity of the land surface.
  • Leaking oil might preferentially leak along and under a stretch of pipe, before diffusing laterally away from the pipeline, making early detection of a leak difficult, although the leak could be detected once lateral spreading occurred.

The effect of rain might be interesting. Should a leak occur, some leaking oil might seep to the surface if rain has dampened the ground to the point at which the moisture contacts the leaking oil. The small amount of oil that might reach the surface could change the emissivity of the surface and potentially could be detected.

If we were regularly to scan the entire length of the pipeline from a low flying UAV, we could use additional sensing schemes to detect leakage from a buried pipeline:

  • UWB (Ultra Wide Bandwidth: from 3.1 GHz to 10.6 GHz, -41.3 dBm/MHz) surface penetrating impulsive probing of the soil along the length of the pipeline, to detect changes in reflected waveform caused by leaking oil
  • Reflection complex impedance measurements of the ground along the pipeline, looking for a change in complex impedance of the soil, caused by leaking oil
  • High resolution (low ppb to hundreds of ppm) photo-ionization (Krypton 10.6 eV lamp) based gas chromatography, to detect benzene, toluene, ethylbenzene, m-xylene and other volatile organic compounds, leaking from the pipeline

Detecting oil leakage into the sea through the use of Synthetic Aperture RADAR (SAR)

SAR is used for a wide variety of environmental applications, such as monitoring crop characteristics, deforestation, ice flows, and oil spills. Oil spills can be detected in SAR imagery because the oil changes the backscatter characteristics of the ocean. Radar backscatter from the ocean results primarily from capillary waves through Bragg scattering (constructive interference from the capillary waves being close to the same wavelength as the SAR). The presence of oil dampens the capillary waves, decreasing the radar backscatter. Thus, oil slicks appear dark in SAR images, relative to oil-free areas.

from www.SANDIA.gov/RADAR

Discussion and conclusion

Thesuggestion is that a leak from a pipeline could be detected as a consequence of the increase in heat capacity of the soil + oil relative to that of the soil alone, suggesting that regular thermal imaging of the land in the vicinity of the pipeline, just after sunset, should reveal the different thermal properties attributable to the leakage.

Computer software would need to be used to automate the interpretation of the data and the availability of regular imaging data will increase the sensitivity of the data through the use of averaging techniques, to enable small differences in heat capacity of the soil to be detected, on a day-by-day basis.

The use of autonomously guided UAVs, with an on-board thermal imaging camera to map the ground temperature, would be a particularly energy and cost effective way in which this task could be routinely performed, with minimal atmospheric pollution:

  • the TAM 5 would have used only 1.33 Kg of fuel to fly the BTC pipeline
  • no pilots are needed and the takeoff and landing can be automated
  • 16 planes would be needed, to have a spare at each pumping station
  • automated data analysis could take place anywhere in the world