Нефтегазовые нанотехнологии для разработки и эксплуатации месторождений. Часть 2. Евдокимов И.Н - 39 стр.

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Figure 2 presents a comparison of the “equilibrium” concen-

tration dependence of RI (filled symbols) with linear dependencies

(solid lines) based on the Lorentz–Lorenz ideal mixing rule (Eq. 1).

Solid line “1” represents the RI behavior in an ideal binary mixture

of toluene (RI=1.4969) with the “steady state” crude characterized

by a constant RI

oil

= 1.4785, the value estimated in concentrated

solutions, with asphaltenes remaining in an aggregated state.

Fig. 2. RI behavior in dilute solutions. Solid lines – ideal mixing rule

with different RIs of the crude.

Deviations of experimental data from “ideal” values (pre-

sumably due to a change of the crude’s properties caused by de-

aggregation of asphaltenes) become noticeable at asphaltene con-

centrations of ∼540–600 mg/l, i.e. in the range observed in our pre-

vious studies (cf. Introduction). “Non-ideality” of experimental re-

sults increases with dilution and an extrapolation of the experi-

mental concentration dependence does not terminate at the F(RI)

of pure toluene, as expected from Eq. (1). However, below asphal-

tene concentrations of ∼63–79 mg/l experimental data again form

an almost linear succession with the origin at the F(RI) of toluene.

Hence, these solutions, at least formally, may be regarded as “bi-

nary”, where the oil component in a modified “steady state” (con-

taining de-aggregated asphaltenes). Solid line “2” in Figure 2 is the

best linear fit (R

=0.980) to the data for asphaltene concentrations