Good oil spill contingency planning and response calls for an ability to predict the behavior and fate of spills over time. At SL Ross we have developed a sophisticated model that can deal with all kinds of oil spill situations. The model works best if the properties of the spilled oil are fully understood beforehand, so we have developed a laboratory testing program, involving spill-related experiments with oils of interest, to provide oil property data for input to the model. The oil testing program and the SL Ross model are described below.
Spills of petroleum oils, including crude oils and refined products, behave differently because the oils themselves have different composition and physical properties. Some oils spread quickly and disperse naturally; some rapidly evaporate; others may separate in to small mats or patches; and still others may emulsify and persist for many weeks. To complicate things further, the properties of an oil, and thus its behavior, change dramatically when it evaporates while exposed to the environment.
Understanding the key spill-related properties of an oil is important because the suitability and effectiveness of most spill-response techniques (e.g., dispersants, in situ burning and skimming) are dependent on the physical characteristics of the oil. Prior knowledge of the key spill-related properties of an oil is necessary in order to plan an appropriate response to an oil spill.
To provide this information SL Ross has developed an inexpensive yet reliable method that uses simulated spill experiments and standard test procedures. The laboratory tests involve weathering samples of the oil, then determining the physical properties (including density, viscosity, interfacial tension, pour point and emulsion behavior) of the fresh and weathered samples. Other tests can be conducted at the same time to determine the effectiveness of dispersants and in situ burning on the fresh and weathered oil samples. Go to Countermeasures for further information on these two popular responses to oil spills.
The data from these tests is suitable for use with various computer models, including NOAA's ADIOS model and the SL Ross Oil Spill Model.
The oil spill behavior model developed at SL Ross is one of the most comprehensive available and has been "ground-truthed" on a number of experimental and real offshore spills. The model describes the trajectory and behavior of marine oil spills as a function of type, size, oil properties and prevailing environmental conditions. The model calculates the results of the weathering spill processes of spreading, evaporation, natural dispersion and emulsification at regular intervals and provides data on the spill's viscosity, density, water content, volume-on-surface, areas, dispersed and evaporated volumes, pour point and thickness.
The model has the unique capability of describing the fate and behavior of oil in unusual situations such as spills involving waxy, high-pour-point oils, spills of heavy oils that submerge or sink beneath the water surface, and spills in broken ice conditions. Another unique aspect of the SL Ross model is the ability to accurately model the effect of different spill sources, such as surface spills, blowouts and subsea pipelines. The model can also simulate countermeasures operations like in situ burning, dispersant application and skimming.
A nine-page description of the history and technical aspects of the model is available as a PDF.
Lists of studies done by SL Ross in each of the areas mentioned above are available through the links to the left of this page.