Wetting behavior of oil droplets on CO2 bubbles influenced by interfacial shear elasticity

Considering the interfacial/surface tensions of the three phases, the equilibrium wetted state would be that of an oil droplet fully encapsulating a CO₂ bubble. This is true for the low asphaltene concentration and short aging time system. When aged for longer, or for the high asphaltene concentration, partial encapsulation is observed. The change in wetting behavior is a result of the shear elasticity of the asphaltene film at the oil-brine interface. As the asphaltene film fractures/yields, the oil droplet begins to wet the CO₂ bubble, causing the interfacial film to be stretched. With the asphaltene film resistive force acting opposite to the wetting force, complete encapsulation is prevented, and for the highest film elasticity, partial dewetting of the oil droplet on the CO₂ bubble is seen, indicating a stronger resistive force than the wetting force (Gibbs energy).