(389m) Microscopic Behavior of Chemical Demulsifiers At the Water-in-Brazilian Asphaltene Model Oil Emulsions: Langmuir Monolayers and Their Corresponding Langmuir-Blodgett Films

Heavy oil fields represent a challenge for the oil industry because of its undesirable tendency to form stable water-in-oil emulsions during the crude oil exploration, causing high transportation costs and damage to processing equipment.  Despite the recent new findings of light medium crude oil reserves in Brazil, the heavier crude oil fields still account for most of the overall oil production.  The presence of asphaltenes in heavy oil is known to enhance emulsion stability owing to the formation of a viscoelastic film at the water-crude oil interface.  To break-up these stable emulsions to accelerate the process of dehydration of the crude oil, chemical agents are generally employed.  It is known that the demulsifiers act by reducing the interfacial tension between oil and water and also by impacting the viscoelastic properties of the interfacial film.  Nevertheless, the disruption mechanism of the continuous interfacial film is still not well understood, and highly dependent on the chemistry of the asphaltene film, which in turn is highly depended upon the type of crude.

In our previous studies, a class of chemical additives was found to be effective in demulsifying water-in- Brazilian crude oil emulsions.  In this work, we investigate the impact of chemical additives on the asphalene films from a Brazilian crude oil formed at the water-heptol (heptane/toluene) interface in situ, by determining the surface pressure vs. area isotherms in absence and presence of a range of chemical demulsifiers.  We also probe the microstructure of the corresponding films as they are transferred onto solid substrates using atomic force microscopy (AFM).  These results combined help us gain a deeper / more microscopic understanding of the effect of the chemistry of the demulsifiers on their ability to break up water-in-Brazilian crude oil emulsions.