A New Approach to Study on Thixotropic Properties of Waxy Crude Oils from Dragon and White Tiger Fields Offshore Vietnam

摘要

In production and transportation of waxy crude oil as well asrnin practical Rheological studies of non-Newtonian liquids, it isrnvery important to find and characterize its thixotropicrnproperties. There are some ways to study this phenomenon,rnbut nowadays the existing equations still can not quantifiablyrndescribe the time-dependent behavior of thixotropic liquidsrnwith acceptable accuracy using in this case an exponential orrnhyperbolic functions.rnThe authors have conducted the screening studies onrnrotational viscometer Rotovisco RV-20 with different kinds ofrnwaxy crude oils from JV “Vietsovpetro” fields offshorernVietnam. Based on the received experimental data and itsrnanalysis the authors have proposed a new equation showing arnvery good agreement between experimental and calculatedrndata (the average deviation is less than 2%). The general timedependencernof shear stress at constant shear rate can be muchrnmore precisely expressed.rnA new idea “the measure of thixotropicity” of liquids atrngiven shear rate and temperature is also proposed torncharacterize the properties of thixotropic liquids.