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The experimental research on the non-Newtonian flow characteristic of a waxy crude oil was conducted through a rotational parallel-plates rheometer system. The test temperature is about 6.5 ℃ higher than its gel point. The shear stress and viscosity of the waxy crude oil show sophisticate non-Newtonian characteristics in the shear rate of 10 −4 −10 2 s −1 , in which the shear stress can be divided into three parts qualitatively, i.e. stress-up region, leveling-off region, and stress-up region. This indicates that there is a yielding process in shearing for the waxy crude oil at the experimental temperature, which is similar to the yield phenomenon in thixotropy-loop test discussed by CHANG and BOGER. Furthermore, the steady shear experiment after the preshear process shows that the stress leveling-off region at low shear rate disappears for the waxy crude oil and the stress curve becomes a monotonic climbing one, which demonstrates that the internal structure property presenting through yielding stress at low shear rate can be changed by shearing. The experimental results also show that the internal structure of waxy crude oil presenting at low shear rate has no influence on the shear viscosity obtained at the shear rate higher than 0.1 s −1 . The generalized Newtonian model is adopted to describe the shear-thinning viscosity property of the waxy crude oil at high shear rate.

In the present paper, a structure-based viscoelastic model is employed to characterize and predict the viscoelastic properties of a wormlike micellar solution at 20 °C. Considering the effect of shear rate on linear viscoelastic property, a structural parameter f is obtained. Meanwhile, another structural parameter ζ is determined when the effects of time and shear rate are considered simultaneously. Both structural parameters are calculated by using linear interpolation method. The startup experiment can be described well by the model. The prediction on the shear stress in the ramping-up region of the hysteresis loop experiment shows an apparent relation between the rheological behaviors in the startup experiment and those in the hysteresis loop experiment. For the hysteresis loop experiment with 30 s time interval, the defect of the calculation in 0.001-0.01 s −1 is due to the lack of the ramping-down history effect. In addition, the model can improve completeness of perimental data used for characterizing rheological property.