Several in-situ spectroscopic techniques have been employed to investigate the fouling processes in crude oils. The studies have shown that the stability of crude oils depends largely on oil fractions which presumably influence the local environment of the asphaltenes, leading to precipitation and deposition.The ATR-FTIR chemical imaging approach has been applied to observe the dynamics of asphaltene precipitation in-situusing n-heptane as flocculation agent. It was found that light crude oil with relatively low asphaltene content can be less stable than heavy crude oil with higher asphaltene content due to the influence of other fractions that possibly form local environment of the asphaltene molecules. ESR data corroborate that the introduction of coagulant leads to the competitive displacement of the fractions stabilizing asphaltenes from the local environment of the asphaltene molecules leading to the decrease of the rotational dynamics of the asphaltene and their aggregation.The NMR Imaging data confirm that considering relative asphaltene stability for various crude oils, one should take into account their overall composition and look for the local environment of the asphaltenes. Furthermore it was revealed that, asphaltenes aggregation under certain conditions can occur in the bulk of oil sample leading to the formation of the asphaltene enriched region corresponding areas with the highest heptane/heavy gradient changes.

In-situ studies of crude oil stability and direct visualization of asphaltenes aggregation processes via some spectroscopy techniques

248th National Meeting (2014)

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