Study and application of ultra-retarding cement slurry system

The properties of the conventional cement slurry such as thickening time, rheology and stability cannot meet the requirement of complex technology of expansion pipe cementing and long construction time. A new type of ultra-retarding cement slurry system has been developed to solve this problem, which contains a new type retarder CH88, matched optimal filtrate reducer WJ60S and drag reducer CUSZ. And then its comprehensive properties were studied. The results show that the ultra-retarding cement slurry system can maintain perfect settlement stability in a long time under static condition, with more than 10 hours thickening time, and performs obviously thickening characteristics of right-angle. Field application results represent that the ultra-retarding slurry system was featured by stable performance, safety and convenience used in field, which can satisfy the expansion pipe cementing operation requirements.