Foam flow through an oil-wet porous medium. A laboratory study

A laboratory study of the steady generation and flow of gas and surfactant solution through an oil-wet porous medium indicates that foam is formed and is effective in reducing gas permeability. A comparison of the flow characteristics of foam in oil-wet and water-wet media has shown that gas permeability reduction in both systems, at similar surfactant concentrations, is approximately equal in magnitude. The ability to form stable foam in-situ in an oil-wet porous medium appears to result from the alteration of the initially hydrophobic surface to hydrophilic by two mechanisms: (1) surface tension lowering and, (2) surfactant adsorption. No alteration in either the liquid or gas relative permeability was found to occur with added surfactant when a residual mineral oil was present in the oil-wet system.