The process of foaming oil well cements entails the injection of a known quantity of nitrogen gas into a given volume of cement slurry and foaming agent. The amount of nitrogen injected at surface, to produce a foamed cement of a desired density in situ, is a function of the temperature and pressure conditions in the annulus where the slurry will reside when pumping ceases.

Pressure and temperature variations between the point of injection of nitrogen into the slurry and its final annular location create a system that will fluctuate in density, viscosity, volume, and rate depending on the downhole conditions at the moment of observation. This inherent variability in the gas fraction (quality) of a nitrified cement is an important engineering consideration since formations will be exposed to fluids whose dynamic properties are different than those anticipated when in place. These variances can profoundly impact the success of the cementing operation.

Mathematical solutions originally developed for foam fracturing treatments have been applied to nitrified cements. This paper provides a method of quantifying the dynamic and static properties of a nitrified cement at any point in its pumping history.

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