Marshall Bishop, Mike Stephens and Willie Reneau, Drilling Specialties Company
Cement spacer fluids have traditionally been supplied by the cementing service companies. Specific performance properties and design criteria of most spacer systems have not been well defined. A cement spacer's basic function is to prevent non-compatible fluids from intermixing. It must perform with a wide range of additives under varying conditions while remaining compatible with both the drilling fluid and cement slurry. Spacer systems have traditionally been shrouded in secrecy and considered user unfriendly. This system has been successfully used in multiple wells drilled with both aqueous and non-aqueous based fluids at temperatures up to 350_ F (177_ C). Information is provided to help demystify spacers and provide operators with simple tools to adapt the spacer system to various drilling fluids and cement slurry formulations. Information is provided on performance properties as well as how to design a spacer system for specific applications.