Spill International reports that an oil-mass tracking model known as the Connectivity Modeling System has been utilised to examine the effect of dispersants at deep water spill sites.
The system simulates – in three dimensions – the oil discharge in deep waters at the Deepwater Horizon blowout. The system helped to examine the "possible effect of a deep water release of oil, with and without dispersants, on the oil droplet size and transport through the water column." This led to the conclusion that "the amount of oil reaching the surface may have been the same, independent of dispersant application."
Dispersants and oil surfacing
Scientists studying the use of subsea chemical dispersants during the Deepwater Horizon spill published their recent findings in the November 2012 issue of Environmental Science and Technology in an article entitled 'Evolution of the Macondo well blowout: Simulating the effects of the circulation and synthetic dispersants on the subsea oil transport'.
Based on fundamental oil droplet size models, the authors estimate that the turbulent discharge of oil resulted in naturally small droplets contributing to the observed deep intrusion.
While oil was flowing into the Gulf of Mexico, responders injected chemical dispersants at the Macondo wellhead to reduce the amount of oil from surfacing and impacting coastal and marsh areas. The numerical experiments suggested that the large fraction of gas may have caused the initial rapid surfacing of oil, due to an increase in overall buoyancy. This study revealed previously undocumented temporal aspects of the oil in the water column moved by local topographic and hydrodynamic processes.
The authors' numerical approach provides new insights on oil transport from deep blowouts and on future subsea use of dispersant in efforts to mitigate coastal damage.
Source: Spill International