Experiments were run to investigate the effect of surfactant concentration, injection rate, foam quality, oil saturation, and rock absolute permeability on the formation and propagation of foams in Berea sandstones and Ottawa sandpacks.

First, constant pressure unsteady-state gas-liquid relative permeability experiments were conducted in Berea sandstone for varying residual saturations of synthetic oil. It was found that high oil saturations can hinder the formation of foam (no substantial decrease in the gas phase relative permeability). In such cases, some of the oil must first be displaced from the core before a foam can form.

Other experiments were performed by flowing preformed foams into cores at various conditions. The foams were preformed at high rates representative of tubing or sandface rates. They were injected into the porous medium at lower rates representative of near wellbore conditions (1.5-5 m from the wellbore) but not of in-depth reservoir conditions. Results showed that the foam propagation rate was significantly affected by rock permeability and injected foam texture. In high permeability sandpacks (40-50 darcies), the foam propagated at the same rate as the liquid phase. Foam propagation rates decreased substantially in lower permeability media.

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