The use of infrared data (presumably gathered by a FLIR camera) can be used to detect petroleum releases, but the FLIR approach has several issues... Mainly, background noise. Two approaches are commonly used:
- A temperature differential between the surrounding soil and hydrocarbon being released can be see on the FLIR camera
- A illuminating source (laser, sun, etc.)... With a spectrum that includes the absorption band of the hydrocarbon being released. Using a FLIR a contrast difference can be seen caused by the hydrocarbon absorbing the wavelengths in its absorption band.
Some of issues with the FLIR approach are: The viewing angle between the illuminating source and the FLIR need to be just 'right' to see any contrast. If the camera is mounted on an airborne platform, it is very easy to miss a hydrocarbon release. With a large release, viewed on the ground, with time to walk around the leak site... a hydrocarbon release can be observed. Using the temperature differential method, one must verify good contrast between where a leak occurs and the surrounding earth. For crude oil (normally warm), observations in the early morning (before the surrounding ground heats up) are best. For natural gas, early afternoon might be better (after the surrounding ground heats up).
Using DIAL LIDAR has many advantages to the FLIR approach (accuracy, sensitivity, and speed). The LIDAR does not require specific ground temperatures, and because the system uses a laser, the viewing angle problem goes away. Also if the LIDAR fire rate is sufficient, it can be put onto an airborne platform, and flown very quickly.
A possible combined approach could be to use a LIDAR for initial leak detection and then follow up with a FLIR (on the ground) to identify where to expose the pipeline for repair.