Abstract: Dissolution of CO₂ in crude oil can change its rheological properties notably, which makes it widely used in the fields of oil displacement, viscosity reduction, transportation and so on. In this study, a pressurized stirring-viscometric equipment was designed based on the stirring viscometry theory, and the corresponding viscometric method was also proposed, so that the viscosity of CO₂ heavy oil mixture could be determined under the simulation conditions of pipeline transportation. On the basis of this equipment and method, the effects of pressure, shear rate and temperature on the viscosity of CO₂ heavy oil mixture were probed. It was found that the viscosity of CO₂ heavy oil mixture decreased exponentially with the increase of pressure. The viscosity of heavy oil system can be greatly reduced by dissolving gas pressure of 2 MPa. Meanwhile, the shear thinning feature became more obvious with increasing pressure of CO₂. Moreover, the viscosity reducing rate became greater with decreasing temperature at the same pressure. The results of this study provide technical support for the feasibility of transporting viscosity-reduced heavy crude oil by CO₂.

Key words: Carbon dioxide, Heavy oil, Stirring viscometry, Viscosity reduction, Pressure

摘要： CO₂在原油中的溶解度能够显著改变原油的流变性质，从而使其在驱油、降黏输送等领域具有广泛应用前景。基于搅拌测黏原理设计了一套带压溶气原油搅拌测黏装置并制定了相应的搅拌测黏方法，从而可在模拟管输条件下对溶CO₂稠油体系的黏度进行测量。在此基础上，探讨了溶CO₂压力、剪切率以及温度对CO₂稠油混合体系黏度的影响。通过研究发现，CO₂稠油混合体系的黏度随着压力的上升呈指数方式降低，只需2 MPa的溶气压力就可使稠油体系的黏度大幅降低。同时，随着溶解CO₂压力的增加，CO₂稠油混合体系的剪切稀释性增强。此外，在同样的溶解压力时，CO₂的降黏幅度随着温度的降低而增大。该研究结果为CO2降黏输送稠油的可行性提供了技术支撑。

关键词: 二氧化碳, 稠油, 搅拌测黏, 降黏, 压力