Rheological characterization and flow or non-Newtonian, shear-degradable crudes

An experimental study is reported on the timedependent rheological behavior exhibited by non-Newtonian crudes. The objectives were to quantitatively characterize the general rheological behavior of these materials and to use this characterization in the analysis of certain practical flow situations, such as pipeline startup. A number of experimental tests were employed to measure the yield, equilibrium, and dynamic properties of these materials associated with different shear and thermal histories. In addition to providing various insights into the general behavior of these materials, such data provide a basis for testing various time-dependent rheological models. Also the tests at different thermal histories illustrate the importance of different thermal treatments on the ultimate flow behavior. Finally, the analysis of pipeline flow and start-up is outlined and described. The accurate description of flow under such conditions is critically dependent upon the accuracy of the rheological characterization.