An oil or water based fluid used to separate incompatible drilling fluid from cement. Spacers are compatible with both the drilling fluid and the cement. The purpose of spacers is to minimize cement contamination by drillllig fluid and to displace drilling fluid from the wellbore 60 that the cement can form an effective hydraulic seal.
Source: API BULLETIN E3, Environmental Guidance Document: Well Abandonment and Inactive Well Practices for U.S. Exploration and Production Operations, First Edition, January 1993 (Reaffirmed June 2000). Global Standards