Abstract
Properties and stability of water-in-oil emulsions influence oil behavior and response decisions. Closed-system
lab protocols that assess emulsion stability cannot fully represent oil behavior in the open sea. We developed
a novel test system that allows emulsions to spread over a laboratory flat pan. Nine highly weathered oils were
studied and seven formed very stable emulsions in a closed-system. Results from our tests show that these oils
underwent significant spreading unless the testing temperature were well below the oils’ pour point. These
findings indicate that emulsions may be less stable than laboratory tests indicate under some at-sea conditions (e.
g. offshore in either high-energy or low-energy seas). Oil thinning due to spreading causes emulsions to break and
the resulting thin oil film would be more susceptible to natural dispersion. Additional carefully designed laboratory
and controlled field tests are needed to determine the operational relevance of our findings.
lab protocols that assess emulsion stability cannot fully represent oil behavior in the open sea. We developed
a novel test system that allows emulsions to spread over a laboratory flat pan. Nine highly weathered oils were
studied and seven formed very stable emulsions in a closed-system. Results from our tests show that these oils
underwent significant spreading unless the testing temperature were well below the oils’ pour point. These
findings indicate that emulsions may be less stable than laboratory tests indicate under some at-sea conditions (e.
g. offshore in either high-energy or low-energy seas). Oil thinning due to spreading causes emulsions to break and
the resulting thin oil film would be more susceptible to natural dispersion. Additional carefully designed laboratory
and controlled field tests are needed to determine the operational relevance of our findings.