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OSRR-663-Heavy Oil Dispersion Research

Office/Division Program
Project Number
Research Initiation Date (Award Date)
Research Performing Activity
S.L. Ross Environmental Research Ltd.
Research Principal Investigator
Mr. Randy Belore and Dr. Ken Trudel

The objective of the project was to study the mechanism by which oil viscosity limits the effectiveness of dispersants. Specifically, two viscosity issues were studied. One was the ability of the dispersant to penetrate into viscous oil upon initial application prior to being washed away by surface water. The other was the internal visco-elasticity of the oil-dispersant mix (in conjunction with the dispersant dosage that has successfully mixed into the oil) that may prevent the oil from being broken into droplets when wave energy is applied.

The first study goal was to investigate pre-mixed oil-dispersant viscosities and final dispersant dosages to determine limiting viscosities for successful mixing at different dispersant dosages. The success achieved at the high dose (Dispersant to Oil Ratio = 1:5) for the most viscous oil indicates that the viscosity limit for dispersion is a function of both the amount of dispersant mixed into the oil and the oil-dispersant mix viscosity. Based on the small- and large-scale test results of this study oil-dispersant mixes with final viscosities of about 10,000cP appear to need a Dispersant to Oil Ratio of 1:10 or better to achieve significant dispersion. Both the reduction in viscosity due to the addition of the more fluid dispersant and the presence of more surfactant improve the final dispersant effectiveness.

The second study goal was to investigate if there is an initial oil viscosity that prevents successful mixing or penetration of the dispersant into the oil during spray applications prior to it being washed away by water. The large-scale test results did not confirm that effectiveness is controlled by oil viscosity preventing the penetration of the dispersant into the oil where it could do its work.

Latest progress update

The final report has been completed and is posted below.