Oil spill forecast assessment using Fractions Skill Score.

In the event of an oil spill, emergency responders must quickly deploy cleanup and protection equipment using guidance provided by a forecast trajectory. Forecasting the location of the surface oil over time is standard practice; however, current performance metrics used for assessing the quality of the spill forecast lack both an appropriate numerical model accuracy score and specification of the expected spatial resolution limit for useful forecast information. This paper adapts the Fractions Skill Score method, commonly used in weather forecasting, to oil forecasting. A subset of satellite images and trajectory forecasts from the Deepwater Horizon oil spill are used as an example of the method.

Oil spill modeling in deep waters: Estimation of pseudo-component properties for cubic equations of state from distillation data.

Deep-water oil spills represent a major, localized threat to marine ecosystems. Multi-purpose computer models have been developed to predict the fate of spilled oil. These models include databases of pseudo-components from distillation cut analysis for hundreds of oils, and have been used for guiding response action, damage assessment, and contingency planning for marine oil spills. However, these models are unable to simulate the details of deep-water, high-pressure chemistry. We present a new procedure to calculate the chemical properties necessary for such simulations that we validate with 614 oils from the ADIOS oil library. The calculated properties agree within 20.4% with average values obtained from data for measured compounds, for 90% of the chemical properties. This enables equation-of-state calculations of dead oil density, viscosity, and interfacial tension. This procedure enables development of comprehensive oil spill models to predict the behavior of petroleum fluids in the deep sea.

Extended oil spill spreading with Langmuir circulation.

When spilled in the ocean, most crude oils quickly spread into a thin film that ruptures into smaller slicks distributed over a larger area. Observers have also reported the film tearing apart into streaks that eventually merge forming fewer but longer bands of floating oil. Understanding this process is important to model oil spill transport. First, slick area is calculated using a spreading model. Next, Langmuir circulation models are used to approximate the merging of oiled bands. Calculations are performed on Troll blended and Alaska North Slope crude oils and results compared with measurements from the 1990s North Sea field experiments. Langmuir circulation increases the oil area but decreases the surface coverage of oil. This work modifies existing oil spreading formulas by providing a surface area correction due to the effects of Langmuir circulation. The model's simplicity is advantageous in situations with limited data, such as emergency oil spill response.

Comparison of hypothetical LNG and fuel oil fires on water.

Large spills of refined petroleum products have been an occasional occurrence over the past few decades. This has not been true for large spills of liquefied natural gas (LNG). This paper compares the likely similarities and differences between accidental releases from a ship of sizable quantities of these different hydrocarbon fuels, their subsequent spreading, and possible pool-fire behavior. Quantitative estimates are made of the spread rate and maximum slick size, burn rate, and duration; effective thermal radiation; and subsequent soot generation.