Abstract: In order to improve the calculation accuracy of slurry displacement efficiency in cementing operation,four-parameter rheological model was proposed for exact description of slurry rheological performance.The parameters of Bingham,Power-law,Carson,H-B and four-parameter rheological models were obtained by mathematical regression analysis.The fitting result between the calculated values of each model and the measured values is described by the mean of the residual sum of squares (Sr).Considering the balance of all the forces,a mathematical model of slurry displacing drilling fluid in inclined eccentric annulus with four-parameter model was developed.The rheological models were verified by measured rheological data of six types of cementing slurries.The means of the residual sum of squares between measured values and calculated values,six slurries with four-parameter rheological model,are all less than 1.1,generally at about 0.2,and minimum value is 0.04.Moreover,the residual sum of squares is 2.81,much less than that of Bingham,Power-law,Carson,H-B models.The results showed that the mean of the residual sum of squares with four-parameter rheological model for six kinds of slurries is the smallest,it can precisely describe cementing slurry rheological characteristics at the full range of shear rate,and the displacement models are suitable for all kinds of slurries in all well types.