油の水中挙動に及ぼす油性状の影響

抄録

  During the 2010 Deepwater Horizon oil well accident in the Gulf of Mexico, an oil treatment agent, normally used for oil slicks spread on the sea surface, was sprayed into water for the first time in the world. However, the details of how it was sprayed were unclear. Subsequently, experimental and theoretical studies on the use of oil treatment agents in water were conducted in Norway and the United States．At the same time, the authors conducted a series of experimental studies on this issue. The purpose of spraying oil treatment agents to combat oil spilled from the seabed is to reduce the buoyancy of oil by refining it and dispersing it at sea in an attempt to reduce secondary damage. Furthermore, the finer oil becomes, the more likely it is to promote biodegradation.

  However, despite these ongoing efforts, it is still difficult to elucidate possible changes in the properties of oil and the level of oil refinement, depending on whether oil treatment agents are sprayed into water. Therefore, we decided to investigate the behavior of spilled oil, including its shape, particle size, floating speed, etc., and the effect of oil treatment agents. Oils with different properties were spilled from the bottom of a transparent cylindrical tank (φ0.3×1.0 m), and images of these oils were taken with a camera for analysis. As a result, we obtained data on possible changes in the shape of oil particles depending on the presence of an oil treatment agent. Then we correlated such data with the shape of oil particles using the Re number, Eo number and Mo number in line with Clift's classification diagram．Finally, the effect of spraying oil treatment agents into water was confirmed based on the obtained findings.