The effectiveness of relevant dispersants for use under “Arctic conditions” has been tested with the IFP dilution test. “Arctic conditions” in this context are defined as low temperature (0°C) and water salinities varying between 0.5% and 3.5%. The study was performed in three steps with a screening activity first, where 14 dispersants were tested on water-in-oil (w/o) emulsions from two weathered oil types. In the next step five dispersants were tested on both weathered water free oils and w/o emulsions from four different oil types. As a third step, dispersant effectiveness as a function of salinity (0.5 to 3.5%) was tested with the most effective dispersants at high and low salinity.
The results from this study shows that many of the most used dispersants which previously have shown an excellent effectiveness at high sea water salinity (3.5%) may give a very low effectiveness at low salinity (0.5%). Recently developed products especially designed for low salinity use (e.g. Inipol IPF) are very effective at low salinities, but suffer from a rather poor effectiveness at higher salinities. This is of significant operational importance in Arctic oil spill combat operations since the salinity of the surface water may vary due to ice melting.
This study of dispersants' effectiveness under Arctic conditions shows the need for development of dispersants with high effectiveness both at low temperature (0°C) and over a wide range of salinities (3.5% to 0.5%). Dispersant development has been an limited but important activity at IKU for the last five years and one of the objectives for an ongoing Arctic program at IKU is to develop such new dispersants for use under Arctic conditions.