Removing and cleaning drilling fluid from the wellbore before the cementing operation is crucial  for a good hydraulic isolation between the well and formations, to reduce migration risks and increase the well integrity. For that washers and spacers with different densities are injected into the well. The use of direct microemulsions systems arises as an alternative to solvent/surfactantcombinations, once that these systems are capable to solubilize large volumes of oil, can cause wettability reversal andreduce the amount of surfactant. Thus, the present work aimed to study the formulation of a microemulsion base spacer for the removal of oil-based drilling fluids. For this, a ternary diagram of the system composed by UNT L90, Kerosene, ADT and n-Butanol was formulated, and after choosing the optimun point the spacers with xantana-gum, defoamer, barytes and microemulsion at different densities were formulated. The drilling fluid and cement slurry used followed the premises from field operations, being it characterized and maintaining fluid hierarchy. Analysis of removal efficiency, wettability and compatibility were carried out for different formulations at room temperature and pressure. At the end of the tests it was possible to obtain up removal efficiencies of to 100 %, wettability reversal with, approximately, 10% of the drilling fluid volume and comaptibility at certian concentrations. Therefore, the results obtained in this work corraborate with the literature, showing a possible application of these systems. However, tests under different conditions of BHCT should be carried out to assess the performance of these spacers.