Abstract
Summary Polymeric surfactants display brilliant capabilities in expanding sweep volume and improving oil displacement efficiency as compared with that of traditional displacing agents attributing to the co-existence of hydrophilic and hydrophobic groups in molecular chains. The displacement effect of emulsification and the difficulty of demulsification are the key factors affecting the application of polymeric surfactants. In order to study the formation, stability, and oil displacement ability of the polymeric surfactants emulsion in porous media, we took the newly synthesized anti high temperature and high salt polymeric surfactants as the research object to study the influence of different concentrations, different oil-polymer ratios, and different migration distances on the stability of polymeric surfactants emulsion. The generative mechanism of emulsified oil droplets with the polymeric surfactants and its relationship with EOR were then elucidated by comparing core flooding experiments with different injection rates, different saturated oil types, and different polymeric surfactants concentrations. The results showed that the main reasons for the formation of polymeric surfactant emulsions are a certain shearing action, the snapping action of hydrophobic microdomains on residual oil droplets and assisted effect of colloidal asphaltene. The longer the migration distance of polymeric surfactants in porous media, the larger the size of the emulsion and the weaker the stability. Contrary to the migration distance, the higher the ratio of oil to water and the concentration, the easier it is to produce the emulsion, and the smaller the particle size of the emulsion, the better the stability. The combination of dimensionless pressure gradient and capillary number as the characterization parameters of polymeric surfactants emulsion can effectively determine whether emulsification can occur during the polymeric surfactants displacement process. The results of this paper can provide some theoretical guidance for formulating the production plan of polymeric surfactants in offshore oil fields.
Published Version
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