Thin-film forces in hydrocarbon foam films and their application to gas-blocking foams in enhanced oil recovery

Utilizing novel fluorocarbon-based surfactants we show that it is possible to form strong long-lived non-aqueous foams at relatively low surfactant concentrations. Contrary to previous work using conventional surfactant systems, liquid crystalline phases are not required to stabilize these oil-based foams. Instead, within the films, overlapping surfactant layers adsorbed to the air/oil interface create repulsive disjoining pressures which lead to a strong robust foam. We also document new film-thinning dynamics and find that our high-molecular-weight surfactant (M-W approximate to 20000) produces the same gel-like structures recently seen in aqueous foam films stabilized by polymer-surfactant complexes. Finally, as with aqueous foam-flow in porous media, we conclude that high repulsive disjoining pressures in single dodecane foam films, lead to a strong gas-blocking foam in porous media. (C) 1997 Elsevier Science B.V.