When an oil spill occurs under pack ice fields in the ocean, oil would spread beneath the ice cover and then would be trapped into recesses under the pack ice. In this paper, the method for separating oil that is trapped into recesses of pack ice is investigated as an elemental technique for oil recovery. In this method, it is proposed to remove oil from recesses by introducing air bubbles and flush out through relative velocity between ice floes and seawater. A series of laboratory experiments were carried out to investigate the behavior of oil and air bubbles.
Off the northeastern coast of Sakhalin Is. in the sea of Okhotsk, production of oil and natural gas has started since the summer of 1999. The produced oil is transported by tankers via adjacent waters of the Hokkaido Island. In the first stage of this project, the oil production is carried out during the summer season, according to the ice floes. However, the construction of pipelines is currently under way for the second stage of the project, and oil production is to take place throughout the year (Sakhalin Energy, 2004). If an oil spill accident occurs in the pack ice fields during the winter season, spilled oil would spread beneath the ice cover, because the density of oil is less than the seawater in low temperature. Also, spilled oil would be trapped into recesses under pack ice (Izumiyama et al., 2002, Yapa and Weerasuriya, 1997, Otsuka et al, 2002). In order to recover the oil, it is necessary to separate oil from ice floes. In order to separate the spilled oil from ice floes, the authors are proposing the method by using ice booms as shown in Fig.1 (Oshima et al., 1998, Otsuka et al, 2000).
