A recent research project was conducted to determine whether a stable, fine-textured, 95% gas content foam could be made. The viscosities of 95-quality N2 foams were measured in a recirculating flow loop viscometer.

Only foam prepared from 2% of an anionic surfactant with plain water had uniform, fine-bubble structure (texture) at 95 quality. All other combinations of additives or other foamers (nonionic, amphoteric or anionic, and/or 0.24% guar) produced unstable foams at 95 quality and stable foams at lower quality.

Foams that were unstable at 95 quality typically contained large slugs of N2 gas within the foam structure. Unstable, high-quality foams did not invert phases to form a mist. Instead, such foams were mixtures of very small and very large bubbles. The net viscosity and stability of those fluid systems were lower than that of a uniform, fine-textured foam.

Yield points were measured for fine-textured foams at 70 to 95 quality. These new yield points were higher than yield points in earlier data.

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