Comparison of biodegradation level and gas hydrate plugging potential of crude oils using FT-IR spectroscopy and multi-component analysis

Two methods aimed at classifying different crude oils with respect to biodegradation level and gas hydrate plugging potential are presented. Samples of ten crude oils from the Norwegian continental shelf were investigated using fourier transform infrared spectroscopy (FT-IR). All the oils with low plugging potential are biodegraded and the non-biodegraded oils have high plugging potential. The FT-IR spectra were examined using classical spectroscopic techniques (Method 1) and multi-component analysis (Method 2). A clear separation of the oil samples into two groups, biodegraded and non-biodegraded, was achieved independently with both methods of analysis. Method 1 fails, however, to separate the set of biodegraded oils into sub-sets of oils with high and with low plugging potential. This was achieved with Method 2. The oils with high plugging potential appear to contain predominantly longer and more linear compounds, while those with lower plugging tendency contain more branched, non-linear molecules, possibly with more than one functional group capable of attachment to the hydrate surface.