ORIMULSION(R) SPILL MODELING IN MARINE ENVIRONMENTS

Orimulsion, a fuel product developed in Venezuela and transported to m arkets by ocean going tankers, is an emulsion composed of about 70% bi tumen (a heavy hydrocarbon) and 30% water to which a surfactant has be en added. It has the potential to serve as an inexpensive alternative to Fuel Oil No. 6, an energy source presently used to heat large indus trial and electric utility boilers throughout the world. Although Orim ulsion is a heavy hydrocarbon fuel, its behavior in marine environment s is quite different than that observed for oil. When spilled, Orimuls ion rapidly separates in the affected water body into a dissolved frac tion that contains an emulsifier and a suspended fraction that contain s bitumen (a viscous asphalt like material). The bitumen does not have the cohesive properties exhibited by oil spilled into water, rather i t forms a ''cloud'' of individual bitumen particles. Under prolonged q uiescent conditions the bitumen particles can rise to the surface in s ea water or sink to the bottom in fresh water. However, in either case , an increase in the energy state of the water can rapidly remix the b itumen into the water column. In this paper, the status of modeling Or imulsion spills in marine environments is discussed. The physical and chemical processes that would take place in an Orimulsion spill are ex amined and incorporated into the design of the model ORL-SLIK, a fate and transport model for marine environments.