LOW-TEMPERATURE RHEOLOGICAL BEHAVIOR OF UMBARKA WAXY CRUDE AND INFLUENCE OF FLOW IMPROVER

The low temperature flow properties; pour point and rheological parame ters; have been determined for untreated and additive treated Umbarka waxy crude. The rheological characteristics of the crude showed non-Ne wtonian yield pseudoplastic flow behavior and pronounced thixotropic e ffect. Viscometric data are fitted to Bingham, Casson and Herschel-Bul kley plastic flow models using linear and non-linear computer regressi on analysis. Herschel parameters showed inconsistent results whereas C asson equation fitted the data reasonably well. Treatment of the crude with flow improver ameliorated both rheological properties and pour p oint but in a different manner. The influence of the additive on the r heology of the crude is greatly affected by shear rate. The thixotropi c phenomenon of the crude is likely to be temperature-dependent in add ition to the other controlling factors.