LABORATORY STUDIES OF OIL ENCAPSULATION UNDER GROWING SEA ICE

摘要

Oil reaching the underside of sea ice after a blow-out is able to spread laterally, governed by buoyancy and surface tension, under-ice topography, and currents. However, the possibility of lateral spread and the direct contact with the ocean are inhibited once oil begins to get encapsulated by the advancing ice front. Encapsulation removes oil largely from the environment, influencing risk management strategies. We performed laboratory tank experiments to quantify the encapsulation process. A 130 L tank was built from Perspex with removable insulation to allow for in-situ observation of the ice underside. Heat flux into the water was controlled to ensure the development of a realistic crystal fabric. Oil was injected under ice of 0.1 m thickness. Observations on crystal structure and encapsulation process are consistent with previous studies. Following the initial development of a lip around the oil lens, initial overgrowth was due to crystals with vertical c-axes. Temperature probes recorded vertical heat flux and ice growth rate under the lens. Encapsulation appeared to be governed by common thermodynamic and fluid dynamic principles. No indications were found that crystal alignment would need to be considered explicitly to describe encapsulation numerically.