Publications on correlations among various properties of crude oils
reveal that the amount of asphaltene is a significant variable in all
cases. In particular, it has been repeatedly stated that there are
positive correlations between density and viscosity of crude oils and
asphaltene concentration. Moreover, it is widely held that each of
these correlations may be represented by a single analytical function (a
single curve), which may be employed in various “universal” models of
petroleum.
We have performed a detailed analysis of databases
for more than 390 world’s recovered (dead) crude oils. For densities
and viscosities of oils the analysis revealed a definite absence of
frequently quoted single-function correlations with asphaltene content
and the existence of two distinct
types of world’s crude oils as classified with respect to their
asphaltene-based correlations.
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