Asphaltene was fractionated into four subfractions with different
polarities, and used to conduct the hydrate formation and dissociation
experiments. It was observed that the more polar fraction could result
in a higher tendency of self-aggregation and fewer asphaltenes adsorbing
at the water-oil interface mainly due to the larger C/H ratio, higher
aromaticity, and shorter length of the alkyl side chain. The nucleation
rate decreased with the presence of asphaltenes, and the induction time
increased with a reduction in asphaltene polarity in water-in-oil
emulsions. The results showed that the formed amount of hydrates were
reduced by the addition of asphaltenes. For the asphaltene containing
emulsions, less hydrate was formed with the presence of a more polar
asphaltene fraction. The presence of asphaltenes was also found to
affect the growth rate of hydrate, which varies with the polarity.
Meanwhile, all four asphaltene fractions were found to promote the
dissociation of hydrate.