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Recently [1–3], we have shown that the rheological parameters of
some petroleum fluids are sensitive to such subtle structural trans-
formations, which often can not to be detected by other experimen-
tal techniques. Hence, in this study we regarded a viscometer as a
probe not only of the macroscopic flow parameters but also of the
microscopic features of the molecular-structure in petroleum emul-
sions
Samples and Experimental Methods
The crude oil/water samples (25 vol.% of the emulsified reservoir
water) were obtained directly from the oil-production well (Ro-
mashkinskoje reservoir, Tatarstan). The water-free oil phase con-
tained 3.5 wt.% asphaltenes, 1.6 wt.% waxes, 22 wt.% resins. Dur-
ing prolonged laboratory storage at room temperature, oil and wa-
ter phases separated from the samples by gravity, so that the stud-
ied W/O emulsions were formed again by intensive mixing of the
separated phases.
The bitumen emulsions were formed from the “HIMEKO” con-
centrate (HIMEKO Co., Moscow) which contains 50 vol.% of bitu-
men, 40 vol.% of water and 10 vol. % of stabiliser (CaCl
2
), acid
(HCl), various surfactants, dispersants and modificators. According
to the technological recommendations of by the producer, the final
bitumen emulsions were formed by 1/1 dilution of the concentrate
with the separately provided “KORE” solvent (hydrocarbon rectifi-
cation residues).
The effect of formation temperature on rheology of all samples
have been investigated at flow temperatures of 8–30°C , for shear
rates up to 150 s
–1
, in a Brookfield Programmable DV-II+ Vis-
cometer (Brookfield Eng. Labs., Inc., USA), equipped with a
YULA–15 Adapter with a concentric cylinder geometry. The inner
cylinder diameter was 25.15 mm with the gaps of 1.23 mm. Each
rheological experiment has been performed with a new, freshly-
prepared sample.
In studies of water/oil emulsions (25 vol.% of reservoir water),
two gravitationally separated phases were mixed again directly in
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