Abstract: In porous media, oil-containing foam is in a dynamic balance between rupture and regeneration. Waring Blender method was used to simulate the regeneration of oil-containing foam by repeatedly shearing zwitterionic surfactant solution (RC) with crude oil. We focused on the solution properties and the change of foaming ability and foam stability after RC solution interaction with different contents of crude oil (0~60%). The results showed that the distribution of RC molecules in the oil phase and at the oil-water interface significantly decreased RC concentration in the foaming system (up to 72%), and the solubilization of crude oil in RC micelles markedly weakened the stability of foam films. Therefore, the performance of regenerated foam from RC solutions was severely damaged. Within an oil content below 40%, as the oil content increased, the foam drainage half-life for the first-sheared oil-containing foam continuously extended to 2.4 times that of the oil-free foam, while for the twice-sheared foam it decreased to 27% of the oil-free foam. During the secondary shearing, the oil phase was emulsified into a large number of small oil droplets due to the reduced oil-aqueous interfacial tension, which could not hinder the drainage and drained easily with water phase. As a result, the oil content in the foam film reduced, and there was little difference between half-lives for first-sheared and twice-sheared oil-containing foams. The research results are expected to provide new insight into the regeneration behavior of oil-contenting foam and contribute to the formulation of oil-tolerant foam system. This study provides new insight into the regeneration behavior of oil-contenting foam, and will contribute to the formulation of oil-tolerant foam system.

Key words: oil-containing foam, repeated-shear, solubilized oil, interfacial tension, foam stability