Investigating terminal film thickness in oil spreading dynamics under opposing net surface tension force on calm water.

Heavy oils, particularly in cold water, spread slowly and eventually stop at a certain film thickness, known as the terminal film thickness. A few studies have specifically addressed the conditions and physical mechanisms that terminate the spreading process. However, traditional models for oil spreading on calm water do not predict this behavior, which may be due to a net negative surface tension effect.

Extending Voronoi-diagram based modeling of oil slick spreading to surface tension-viscous spreading regime.

An earlier paper demonstrated a methodology for modeling the spreading process with a Gaussian random walk procedure, but was limited to the gravity-viscous spreading regime. Here we extend the methodology of representing spread and transport of oil slicks on calm sea surface by updated Voronoi diagrams to account for the surface tension-viscous spreading regime as well. We have utilized the analogy between diffusion and spreading processes by defining a step length for the particle-based random walk scheme.

Random walk particle-tracking method for modeling changes of sediment characteristics in marine sediments after drilling discharges.

Adverse impacts of drilling discharges on marine benthic environments have been observed since the advent of offshore drilling operations for exploration and production of oil and gas. This study utilizes a marine sediment model based on a system of equations that has been developed earlier to assess environmental impacts of drilling waste discharges. Bioturbation, bio-degradation and natural burial processes are included in the model.

Modeling spreading of oil slicks based on random walk methods and Voronoi diagrams.

We introduce a methodology for representation of a surface oil slick using a Voronoi diagram updated at each time step. The Voronoi cells scale the Gaussian random walk procedure representing the spreading process by individual particle stepping. The step length of stochastically moving particles is based on a theoretical model of the spreading process, establishing a relationship between the step length of diffusive spreading and the thickness of the slick at the particle locations.

Dynamic modeling of environmental risk associated with drilling discharges to marine sediments.

Drilling discharges are complex mixtures of base-fluids, chemicals and particulates, and may, after discharge to the marine environment, result in adverse effects on benthic communities. A numerical model was developed to estimate the fate of drilling discharges in the marine environment, and associated environmental risks. Environmental risk from deposited drilling waste in marine sediments is generally caused by four types of stressors: oxygen depletion, toxicity, burial and change of grain size.

Development of a numerical model for calculating exposure to toxic and nontoxic stressors in the water column and sediment from drilling discharges.

Drilling discharges are complex mixtures of chemical components and particles which might lead to toxic and nontoxic stress in the environment. In order to be able to evaluate the potential environmental consequences of such discharges in the water column and in sediments, a numerical model was developed. The model includes water column stratification, ocean currents and turbulence, natural burial, bioturbation, and biodegradation of organic matter in the sediment.