Drilling Industry Glossary

Density Hierarchy

During multi-fluid displacement operations such as cementing jobs, the density of displacing fluid is generally greater than that of the fluid being displaced to achieve better displacement efficiency. For example, the comparative densities of mud, spacer and cement should follow:
Pmud < Pspacer < Pcement
A rule of thumb is that the displacing fluid is at least 10% heavier than the displaced one.