Features of composition of produced oils and residual heavy crude oils sampled of the Usinskoye oil field

It is shown that samples of crude oil produced from various objects of the Permian-Carboniferous deposit of the Usinskoye oil field and residual oils extracted from cores differ in their component and structural group composition. In the composition of the residual oil extracted from cores, the proportion of paraffin-naphthenic hydrocarbons is lower (by 14–25%) than that in the produced oil. It is found out the rate of asphaltene precipitation for extracted oils are significantly lower than that for residual oils.