Effect of casing rotation on displacement efficiency of cement slurry in highly deviated wells

Rotating casing is helpful to improve cementing quality. In the case of casing rotation and non-rotation, the influence of density difference and casing eccentricity on displacement efficiency and displacing interface in highly deviated wells have been numerically simulated based on Herschel-Bulkley model. The simulation results indicate that the displacement efficiency increases first and then decreases as the density difference or casing eccentricity increases. Under the same displacement conditions, rotating casing can improve displacement efficiency. In order to visually observe the casing rotation change the fluid flow state, the displacement process and displacing interface are experimentally simulated by using substitute drilling fluid and cement slurry. To select reasonable casing rotation speed while cementing, the impact of casing rotation speed on displacement efficiency is analyzed by combining experiments and simulations. Considering cementing requirements and operating risks, the casing rotary speed is recommended at 20-30 r/min in highly deviated wells.