A Quadripolymer Cementing Slurry Retarder for High Temperature Operation

A quadripolymer cementing slurry retarder has been synthesized for use in high temperature operations to improve the performance of cementing slurries experiencing temperature changes from intermediate temperatures to high temperatures. The retarder is synthesized with raw materials such as AMPS, acrylic acid, acrylamide, and N, N-dimethyl acrylamide through aqueous solution polymerization. No monomers exist in the final product, as indicated by IR spectrum characterization. Laboratory evaluation of the synthesized retarder has proven that the retarder shows good retarding performance in 80-120℃ and is insensitive to the changes in temperature. At the same temperature, an increase in the concentration of the retarder in cement slurry results in an increase in thickening time, and there is a good linear relationship between the concentration and the thickening time. At 100℃, cement slurry treated with 0.8%, 1.0% and 1.5% of the retarder has thickening time of 161 min, 197 min and 227 min, respectively. At the same concentration, an increase in temperature leads to a decrease in thickening time. At a concentration of 1.5%, it takes 248 min, 227 min and 208 min for the cement slurry to thick at 80℃, 100℃and 120℃, respectively. In 80-120℃, the retarder only slightly affects the compressive strength of set cement. It is resistant to the salt contamination of 18%, and compatible with other cement slurry additives. The working mechanism of the retarder is also analyzed.