(216an) A Microscopic View of the Effect of Chemical Demulsifiers At the Water-Brazilian Model Oil Interface From Langmuir and Langmuir-Blodgett Films

Heavy oil fields represent a challenge for the oil industry due to their undesirable tendency to form stable water-in-oil emulsions during crude oil exploration, which increases transportation costs and negatively affects processing.  Despite the recent findings of light medium crude oil reserves in Brazil, the heavier crude oil fields still account for most of the overall oil production.  The abundance of asphaltenes in heavy oils is known to enhance the emulsion stability owing to the formation of a viscoelastic film preventing the coalescence of water droplets.  In the presence of such highly rigid films, chemical agents are used to speed up the process of dehydration of the crude oil.  It is known that the demulsifiers reduce the interfacial tension between oil and water and also influence the viscoelastic properties of the interfacial film.  However, the disruption mechanism of the continuous interfacial film is still not well understood, and is expected to be a strong function of asphaltene chemistry and type of crude.

In the present work, we investigate the effect of chemical additives on the molecular properties of asphaltene films through Langmuir and Langmuir-Blodgett films.  The elasticity of Langmuir films in the presence of the additives and as a function of additive concentration was correlated to the microstructure of the transferred films obtained by Atomic Force Microscopy (AFM).  The interfacial properties and diffusivity of asphaltenes and demulsifiers were investigated by pedant drop tensiometry.  These results are of relevance as they can serve as a guide for the design of demulsifiers for the petroleum industry.