Novel Insight into the Viscosity-Temperature Characteristic by the Comparison of Tahe Ordinary- And Ultra- Heavy Oils

Extensive attention is being paid to the exploitation of unconventional oils, mainly heavy and ultra-heavy oils. Thereinto, the high viscosity nature of heavy and ultra-heavy oils is a major obstruction and challenge to the recovery of the heavy oil reservoir and the selection of the enhanced oil recovery methods. In order to investigate the characteristic of the viscosity variation in sequence temperature regions and the internal mechanism of the shear thinning property, the ordinary heavy and ultra-heavy oils were employed and studied. On the basis of the fundamental physic-chemical analyses, the viscosity-temperature and viscosity-shear rate characteristics in sequence temperature regions were evaluated comparatively for both heavy oils. In addition, the free volume theory was involved to clarify the mechanism of the shear thinning property and viscosity variation. Then the viscous activation energy variation in sequence temperature regions was validated and analyzed with the negative linear relationship between the viscous activation energy and the frequency factor (compensation effect). Satisfying viscosity prediction curves were obtained for both heavy oils with high regression precision ( R 2 > 0.99). A further understanding of the compensation effect existence and thermal oxidation characteristic comparison for the ultra-heavy oil and its components were obtained. From this study, a novel insight into the characteristic and prediction of viscosity-temperature relationship can be brought based on the viscous activation energy variation in sequence temperature regions.