Abstract:
Temperature dependencies of electron paramagnetic resonance spectra of intrinsic paramagnetic vanadyl complexes
and dynamical viscosity for two heavy crude oils and asphalt samples are measured. Transitions between
the different motional conditions (from the rigid to the fast motion regimes) are observed. The rotational correlation
times (in the model of the isotropic diffusion) are extracted. It is shown that the characteristic temperatures
for the motional regime transitions are mainly defined by the asphaltenes' content. From our analysis it
follows that the thermal treatment leads to the destruction of the asphaltene complexes onto the 4-5 small pieces.
The results indicate that paramagnetic vanadyl complexes are the sensitive intrinsic probes to study qualitatively
and quantitatively structural transformations of aspahltenes of heavy crude oils in-situ.
