Study on the Sensitivity Mechanism of Setting Time Regulation and Preparation of Low‐Sensitivity Copolymer Retarder for High‐Temperature Cement Slurry

Accelerated hydration of cement slurry at high temperatures challenges setting‐time control. The practical applications of AMPS‐based copolymer retarders are limited by their high sensitivity to dosage and temperature. This study combines high‐temperature thickening performance and polymer structural characteristics to investigate how the copolymer synthesis process influences copolymer structure and cement slurry hydration control. The sensitivity mechanism of precisely controlling cement slurry setting time under high temperature was analyzed by combining hydration heat analysis, changes in cement slurry ion concentration, and polymer adsorption capacity. A low‐sensitivity copolymer retarder was prepared by optimizing synthesis conditions. Results show that the optimal IA dosage of PA5 is 19.3%, which exhibits 8.11% temperature sensitivity and 16.71% dose sensitivity at 180°C. Strong adsorption of polymer molecules onto cement particles significantly inhibits hydration, disrupting the dynamic equilibrium between adsorption driven by thermal motion and hydration acceleration, and leading to a temperature‐sensitive hydration process. Copolymer retarders with low molecular weight and a narrow distribution show better stability and lower sensitivity at high temperatures, making them better suited for stable control of cement slurry thickening time under high‐temperature conditions. These findings provide an understanding of sensitivity mechanisms and guide the design of retarders for high‐temperature cementing.