The existence of wax in waxy crude oil makes its rheological property very complex. When the temperature of waxy crude oil is high enough, wax dissolves in the oil in molecular form and the whole system behaves as Newtonian fluid. When the temperature is reduced to a certain value which is called "wax appearance temperature", the dissolved wax begins to precipitate from the oil as a result of supersaturated and the whole system is still Newtonian fluid. If the temperature is further reduced, the amount of precipitated waxy will increases gradually, and the system turns from Newtonian to non-Newtonian. Once the mass percent of the precipitated waxy increases to 1wt%~6wt%, the wax crystals in crude oil will attract and interlock with each other to form a three-dimensional sponge-like network structure where liquid oil is wrapped in, and the whole system turns from sol to gel. The gelled waxy crude oil shows complex rheological behaviors, such as viscoelasticity, yield stress, and thixotropy.
展开▼
