AQUEOUS SPACER COMPOSITION COMPATIBLE WITH DRILLING MUDS AND CEMENT SLURRIES INCLUDING SALINE SLURRIES, AND APPLICATION THEREOF TO DRILLING OIL AND GAS WELLS

摘要

An aqueous spacer composition, compatible with drilling muds and cement slurries including saline slurries, and application there of drilling oil and gas wells. Preferred spacer bases in accordance with the invention comprise a biopolymer of the type produced by Azotobacter indicus, a high molecular weight sulfanated styrene or toluene-styrene polymer, and a dispersing agent. This base fluid has no solid particles. The final spacer composition additionally contains a weighting agent (barite) and water. Total compatibility is provided with muds and/or cement slurries whether or not they are saline, together with excellent fluid loss controlling, rheological, and anti-settling properties. A wetting agent may be added to provide compatibility with oil-based muds.