Subsurface oil releases – Experimental study of droplet distributions and different dispersant injection techniques Version 2

The main objectives with this project have been to answer the following questions regarding dispersant injection during a subsea blowout. How do dispersant injection method, dispersant to oil ratio (DOR) and dispersant type affect oil droplet size (Volume Median Diameter – VMD)? How does the dispersant-oil mixing vary as a function of distance from the orifice for different injection methods and how does this affect oil droplet size? The experimental work has been performed in SINTEFs Tower basin in Trondheim, Norway. This unique facility consist of a 6 meter high, 3 meter wide tank that holds 42 m3 of natural sea water and is equipped with the latest technology for such experiments. - A clear correlation between DOR and the shift in droplet size distribution towards smaller droplets was observed. Very limited effect was observed for the lowest concentrations (DOR 1:1000-1:500), steadily increasing up to a shift corresponding to a third of the initial VMD at the highest concentration (1:25).   - The three different injection methods tested in this project gave similar results (reduction or shift in VMD), independent of whether the dispersant was injected immediately before the outlet (simulated injection tool) or immediately after the outlet.