Spectroscopy is the study of the absorption and emission of light and other radiation by matter, concerning the dependence of these processes on the wavelength of the radiation.

This technique can be used in oil detection as different particles absorb and/or emit light of different wavelengths and so it is possible to differentiate between oil types using a spectrograph.

Not all oils are the same

Advanced Sensors uses fluorescence as its principle technique for measuring oil in water.  With a single oil type the measurement at a fixed wavelength can be used to represent the amount of oil in the water.  The measurement device is typically a PMT (Photo Multiplier Tube) or similar piece of equipment that can measure a fixed wavelength.

As oils of different types emit light at different wavelengths and intensities, it is possible to differentiate these oils using a spectrograph.  Given that different oil types do not fluoresce with the same intensity under the same excitation light levels, it is important to know which oil type is being monitored.  Advanced Sensors uses spectral information to allow its analyzer to automatically switch between oil types, and therefore ensure that the appropriate oil curve is always used.

Chemical Interference

The oil industry uses a significant volume of chemicals.  Many of these chemicals will fluoresce in similar wavelengths as oils.  By using a spectrograph, Advanced Sensors can compare the spectra of pure oil samples versus produced water containing chemicals and optimize the wavelength at which the oils are detected – ensuring the most accurate possible result.

The Advanced Sensors EX-1000 units have also been used simply for the detection of chemicals in the water.  Using the spectroscopy feature of the EX-1000, it has been possible to detect trace elements of various chemicals in an open-loop heat exchanger used with the chemical injection system on an offshore platform.  The EX-1000 was tested with various Hydrate Inhibitors (LDHIs) and Asphaltene Inhibitors (AIs)

Diagnostic Detection

There are many times when analyzers show unexpectedly high or low results.  It is important to be able to quickly determine the cause of the change.  The change could be due to a malfunctioning separator, a spike in concentration or the introduction of a different oil or chemical.  Checking the spectra of the water will show any change in the composition of the water, which can be further compared to chemicals or oil types results.