The first step to ensure an optimum completion is to remove leftover drilling fluid residue and casing debris. This requires that the drilling mud be changed out with solids-free completion fluids. Completion fluid displacement involves multiple fluids sequenced in circulation. Varying flow rates, flow paths, circulation subs, multiple stages and possible HTHP conditions make it increasingly difficult to determine pump pressures and bottomhole ECDs. Despite these significant challenges, however, detailed planning of the wellbore cleanup operations can help ensure both job success and well productivity.