TOPIC 4: Asphaltenes
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ERIOT
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NIVERSITY B41OA December 2018 v3
Because detailed description of heavy oil fraction
samples is generally not
available, the most practical approach is to describe the components that form
asphaltenes by a continuous function. The information on fractions of paraffin-
naphthane-aromatic (PNA) in the heavy end is generally required to develop
such a distribution function.
In the absence of measured data correlations based on some property of the
heavy end, such as that using the refractive index, density and molecular
weight (v
an Ness K. and van Westen,1951),
may be used to estimate the
fraction of each class of compounds.
Several distribution functions have been proposed to describe asphaltenes.
They are mostly a continuous function of molecular weight
M
. It should be
noted that the continuous distribution is valid at all the values of
M
, within the
identified range of the heavy components. The mole fraction of single carbon
number (SCN) group
n
can be determined simply by integrating the
distribution function between
)
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