Weathering of Oil Spills Under Arctic Conditions: Field Experiments with Different Ice Conditions Followed by In-Situ Burning

摘要

The knowledge regarding weathering processes in Arctic oil spills and especially with the presence of ice is limited. Experimental studies have been performed in laboratories, but only to a limited degree in the field. This presentation summarized and compared results from field experiments performed in Norway in 1989, 1993 and 2003–2006. Two full-scale field measurements from experimental oil releases in Norway are initially used to compare the behavior of oil spilled in open water and in an Arctic broken ice scenario. Similar oil types and amounts (25–30 m3) were used in an experimental oil release in open water at Haltenbanken (65° N) in 1989 and in dynamic broken ice at Svalbard (75° N) in 1993. Results from small-scale field experiments performed later (2003–2006) on Svalbard are also discussed and compared to the earlier field data. Several weathering properties for the oil spill in broken ice are strongly influenced by the low temperature, reduced oil spreading and reduced wave action caused by the high ice coverage. Reduced water uptake, viscosity, evaporation and pour point extend the operational time window for several contingency methods compared to oil spills in open waters. This could open up for dispersant treatment and in-situ burning even after an extended period of weathering for an oil spill in broken ice. In the period of 2003–2006, SINTEF and the University Centre in Svalbard (UNIS), and later also co-workers from US (DF Dickins and Boise State University) have performed field weathering studies with oil entrapped in and under ice followed with in-situ burning. This presentation will present recent results from these field experiments regarding oil weathering under different ice conditions (slush ice, 30% and 90% ice coverage) and the consequences for the ignitability and in-situ burning of the weathered oil. This research has been funded by Norwegian and US authorities (the Norwegian Research council and US Mineral Management Services) and several oil and industry companies (Statoil, Norsk Hydro, Shell, Alaska Clean Seas, ExxonMobile, ConnocoPhillips and Store Norske Spitsbergen kullkompani).