Phil Rae & Ernie Brown, Dowell Schlumberger
The cementing of wells penetrating massive salt formations has posed a number of problems over the years. The fact that some cements displayed poor characteristics in saline environments, and that conventional additives were of only limited use in these same systems contributed to these problems. Other additives, designed for use in salt water, were found to provide characteristics far from the optimum while, at the same time, causing detrimental effects on other slurry properties, notably rheology, thickening time and early compressive strength. This paper describes the characteristics of new materials which provide superior performance in high-salt cement systems and illustrates, by way of field case histories, how these materials have helped improve primary cementing results in several areas.