Droplet size distributions in chemical dispersion of oil spills: Towards a mathematical model

The results of a series of chemical dispersion tests are presented, in which three crude oils (Gullfaks, Statfjord and Arabian heavy), each at 4 states of weathering, have been dispersed at 13°C with two dispersants (Finasol OSR-5 and OSR-12) using three laboratory tests (Warren Spring Rotating Flask — WSL test, Institute Français du Pétrole flow test — IFP test and MackayNadeau—Steelman — MNS test). Effectiveness and dispersed oil droplet size distributions in the different test methods have been studied and an attempt has been made to develop correlation or mathematical models of the chemical dispersion phenomena. This mathematical treatment helps to explain the reasons that the tests give different results, but it is concluded that, at present, our understanding of the basic dispersion phenomena is not sufficient to form a basis for a reliable model. Several modelling approaches are discussed in the hope that as further data and insights become available, reliable models may be developed to describe this complex process.