Abstract: With regard to slow development or super retarding happening at the top of cement slurry in deep and ultra-deep wells with long cementing intervals,a new type of cementing retarder ZOC-H50S was developed and its properties were evaluated. Thickening property tests different temperatures for slurry with cementing retarder ZOC-H50S and IR, DSC and TG analysis show that: cementing retarder ZOC-H50S has good temperature-resistance performance and stable molecular structure, It can be used at the bottom hole circulating temperature of 70 to 200℃. The thickening time of the slurry can be regulated effectively by adjusting the additive amount of cementing retarder ZOC-H50S.Thickening property tests for slurry with different salt contents show that cementing retarder ZOC-H50S has good sat-resistance performance and can be used in salty cement slurry.Strength development,thickening time,fluidity and API filtration of slurry with cementing retarder ZOC-H50S were studied at different top-bottom temperature differences.The results show that: The slurry with cementing retarder ZOC-H50S develops well in strength at large temperature difference and can overcome super retarding of the top of the slurry in long cementing interval. Cementing retarder ZOC-H50S is applicable for large temperature range and can be used for slurry with both high and low densities. The slurry with cementing retarder ZOC-H50S has good overall performance,easy to regulate and control,and can satisfy cementing requirements for long cementing interval.

Key words:cementing retarder,cementing:long cementing interval;slurry,thickening time