Negative viscosity anomaly in liquid petroleum products after heat treatmentle

Heat treatment is a common method of improving the properties of heavy crude oils and petroleum products. Measurements showed for the first time that after heat treatment at 28-40degreesC, the rheological parameters of petroleum systems become much worse. The results obtained are important for improving shipping and storage technologies in conditions of periodic temperature drops. A theoretical explanation of these effects is given with consideration of the phase diagrams of petroleum systems and thermally induced changes in their colloidal structure.