Составители:
The Sixteenth European Conferen e c
on Thermophysical Properties
London, UK 2002
Thermophysical properties and phase-behaviour
of asphaltene-containing petroleum fluids
Igor N. Evdokimov , Nikolaj Yu. Eliseev, Dmitrij Yu. Eliseev
Dept. of Physics, Gubkin Russian State University of Oil and Gas,
Leninsky Prospekt, 65, Moscow B-296, GSP-1, 119991, Russia.
E-mail: [email protected] (I.N.Evdokimov).
Abstract
We have measured the effects of a thermal pre-treatment of a
crude oil on its pour point T
pour
and on the activation energy U of a
viscous flow at 8–30°C. A dramatic increase of both T
pour
and U
was observed in oil samples pre-heated to temperatures in the spe-
cific range from 28–30°C to 39–40°C. This effect may be triggered
by a structural phase transitions in the oil asphaltene/resin sub-
system, resulting in formation of asphaltene molecular aggregates.
Below the wax appearance temperature these aggregates evidently
act as cementing species in extended networks of wax crystals. The
optical absorption measurements revealed an increase of a vertical
concentration gradient in the samples, heated to the above specific
temperatures, which may be indicative of some phase separation in
the studied crude oil.
Keywords: Crude oil; Thermal treatment; Pour point; Activation
energy; Asphaltenes; Aggregation; Phase transition
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