Amphoteric ionic polymer large temperature difference retarder for long sealing section cementing low‐density cement slurry: Preparation, application, and working mechanism

Abstract In this study, a novel amphoteric ionic large temperature difference retarder (marked with CLL‐1) was prepared by using functional monomer through aqueous solution polymerization method. First, the chemical structure and molecular weight of retarder CLL‐1 were obtained, and then the thermal stability of retarder CLL‐1 was investigated at the temperature range of 40–400°C, and the result shows that the retarder CLL‐1 has well thermal stability, which could be used to control the thickening time of cement slurry at higher temperatures. Second, the influences of retarder CLL‐1 on the settlement stability of cement slurry were studied by the density difference at the temperature of 150, 120, 90, and 30°C, respectively. Third, the thickening time of cement slurry samples with different retarder CLL‐1 adding amount was studied at the temperature range of 80–180°C, and the results showed that the retarder CLL‐1 can adapt well to the working conditions of large temperature difference cementing operations. Simultaneously, the compressive strength of cement slurry with different retarder CLL‐1 adding amount was obtained. Finally, the working mechanism of retarder CLL‐1 at large temperature difference was revealed depends on the methods of x‐ray diffraction, scanning electron microscope, and TG.