A Robust, Field Friendly, Cement Spacer System

Cement spacer fluids have traditionally been supplied by the cementing service companies. The specific performance properties of most spacer systems are not well defined. How a spacer is designed for a specific application has also not been well defined. Cement spacers are required to be compatible with both the drilling fluid and the cement slurry. A cement spacer’s basic function is to prevent non-compatible fluids from intermixing. The spacer must perform with a wide range of additives under varying conditions and still remain compatible with both the drilling fluid and cement slurry. The drilling fluid can range from simple aqueous to complex non-aqueous synthetic based systems. The cement slurry itself can also range from a very simple system with minimal additives to highly modified slurries designed for high densities, temperatures, and pressures. 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 drilling fluids at temperatures up to 350°F (177°C). Information is provided to help demystify spacers and provide the operator with simple tools to adapt the spacer system to various drilling fluids and cement slurry formulations. This paper provides an overview of a new spacer system developed to be user and field friendly. Information is provided on performance properties as well as how to design a spacer system for specific applications.