In the recent Gulf of Mexico oil spill, nearly two million gallons of dispersants were sprayed both at the surface and 1.5 kilometers below the surface in order to disperse leaking oil.  Many decisions on application were made without detailed knowledge of the efficacy of these dispersants in different environments. At the well head, the temperature of the oil is significantly higher than temperatures for typical dispersant application and the process involves flow conditions previously unexplored for dispersant application.  In this work, we quantify the interfacial tension dynamics and rheology of a model oil-water-surfactant (squalane-brine-Tween80) system, to characterize how the influence of interface curvature, flow conditions, and temperature impact fundamental surfactant transport.  Our goal is to use this characterization to inform decisions in the dispersion process.  Using a recently-developed microtensiometer, interfacial tension dynamics and interfacial rheology measurements are performed on curved interfaces approaching 30 microns in radius, over a wide temperature range.  The advantage of the use of microscale interfaces is rapid measurement and the ability to control the local environment. We are able to exchange one of the fluids near an oil-water interface to use convection to shift transport regimes and also to investigate situations such as step changes in bulk concentration on interfacial properties.  Results on the interfacial properties (equilibrium and dynamic) of these interfaces will be presented and discussed in the context of dispersant design.

Quantification of the interfacial dynamics of a model oil-brine-dispersant system for improved surfactant design

243rd National Meeting (2012)

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