High Temperature Synthetic Cement Retarder

Abstract

Abstract A synthetic cement retarder which provides excellent retardation and compressive strength development has been synthesized. The response properties and temperature ranges of the synthetic retarder far exceed those of commonly used retarders such as lignosulfonates. The chemical nature of the new retarder is discussed and compared to another synthetic retarder. Introduction One of the most important design parameters of a cement job is the thickening time. This is essentially the amount of time at which a cement slurry will remain in a fluid, pumpable state and is therefore the amount of time available to perform the cement job. When mixed at the proper cement to water ratio, an unretarded slurry with API class H or G cement can safely be placed at a depth of 8,000 ft. when the bottomhole circulating temperature is less than about 125°F As the temperature increases, the rate of hydration of the cement also increases; therefore, at higher temperatures, retarders are used to slow the hydration and keep the slurry in a pumpable state. The performance of these additives becomes critical as the bottom-hole circulating temperatures increase.