This paper presents an experimental study of the displacement process in a 60° deviated laboratory well with a 55 % eccentric annulus. The inner pipe was lying near the bottom of the simulated wellbore. In this geometry the displacing fluid have a tendency to flow in the upper, wide part of the annulus, and to bypass mud in the narrow part of the annulus. The results from the tests were applied to practical field operations.
The data presented show how fluid viscosities, degree of turbulence and buoyancy forces particularly affects the displacement process in the lower, narrow part of the annulus. When a displacing fluid with higher density than the displaced fluid was used, the simulated mud in the narrow part of the annulus floated up into the wide part and was transported away. This reduced the tendency of the simulated cement to bypass the fluid in the narrow part of the annulus. Significant improvements in the displacement efficiency were observed.