(83f) Effect of Cooling Rate on the Yield Stress Properties of the Model – Oil System

Wax deposition is a common and costly problem in oil industry, especially in pipelines, storage tanks, barges, and containers. Wax precipitation occurs when the temperature in the tanks fall below the cloud point or wax appearance temperature (WAT). WAT is dependent on the composition of the oil, cooling rate and also the thermal history of the oil. Lighter hydrocarbons are generally stripped from shale oil to meet the minimum vapor pressure standards. As light ends of the oil are stripped off, the solventâ??s quality decreases. Also, this leads to changes in the WAT and the rheological properties of the oil. In this work we have studied the effect on the temperature and shear history effects on the model oil system with lighter hydrocarbons such as heptane, hexane, pentane and cyclopentane. Particularly, the yield stress behavior of the model oil system was probed with change in cooling rates and thermal and shear histories. A vane, cone and plate and serrated plate geometries were used to make the rheological measurements.