Oil properties and behaviour at sea

Behaviour is driven by density, viscosity, pour point and flash point. Light products evaporate fast and pose a vapour and fire risk. Heavy fuel oil (HFO) spreads slowly, can emulsify if asphaltene content is high, and is recovered with oleophilic skimmers and robust pumps.

Weathering covers spreading, evaporation, dispersion, emulsification, oxidation, dissolution and sedimentation, and it changes the oil hour by hour: what was pumpable in the morning may be tar-like by evening. Sampling and documentation must start early so the weathered product can still be identified.