Progress in operational modeling in support of oil spill response

Following the 2010 Deepwater Horizon accident of a massive blow-out in the Gulf of Mexico, scientists from government, industry, and academia collaborated to advance oil spill modeling and share best practices in model algorithms, parameterizations, and application protocols. This synergy was greatly enhanced by research funded under the Gulf of Mexico Research Initiative (GoMRI), a 10-year enterprise that allowed unprecedented collection of observations and data products, novel experiments, and international collaborations that focused on the Gulf of Mexico, but resulted in the generation of scientific findings and tools of broader value. Operational oil spill modeling greatly benefited from research during the GoMRI decade. This paper provides a comprehensive synthesis of the related scientific advances, remaining challenges, and future outlook. Two main modeling components are discussed: Ocean circulation and oil spill models, to provide details on all attributes that contribute to the success and limitations of the integrated oil spill forecasts. These forecasts are discussed in tandem with uncertainty factors and methods to mitigate them. The paper focuses on operational aspects of oil spill modeling and forecasting, including examples of international operational center practices, observational needs, communication protocols, and promising new methodologies

On the transport and landfall of marine oil spills, laboratory and field observations

The dynamics of crude oil and different surface ocean drifters were compared to study the physical processes that govern the transport and landfall of marine oil spills. In a wave-tank experiment, drifters with drogue did not follow oil slicks. However, patches of undrogued drifters and thin bamboo plates did spread at the same rate and in the same direction as the crude oil slicks. Then, the trajectories of the Deepwater Horizon oil spill and 1300 drifters released near the spill source were investigated. Undrogued drifters were transported twice as fast as drogued drifters across the isobaths. 25% of the undrogued drifters landed, versus about 5% of the drogued ones, for the most part, on the same coastline locations where oil was found after Deepwater Horizon. Results highlight the importance of near surface gradients in controlling the cross-shelf transport and landing of surface material on the Gulf of Mexico's northern shores. •Undrogued drifters and crude oil slicks advect and disperse similarly in waves.•Undrogued drifters make landfall 5 times more than near-surface drogued drifters.•Near-surface vertical shear sets the cross-shelf transport of surface material

Direct coupling of near-field and far-field models hones predictions of oil spill transport and fate from deep-sea blowout

Deep-water spills pose a unique challenge for reliable predictions of oil transport and fate, since live oil spewing out under very high hydrostatic pressure has characteristics remarkably distinct from oil spilling in shallow water. It is thus important to describe the complex thermodynamic processes occurring in the near-field, meters above the wellhead, and the hydrodynamic processes in the far field, up to kilometers away. However, these processes are typically modeled separately since they occur at different scales. Here we directly couple two oil prediction applications developed during the Deepwater Horizon blowout operating at different scales: the near-field Texas A&M Oilspill Calculator (TAMOC) and the far field oil application of the Connectivity Modeling System (oil-CMS). To achieve this coupling, new oil-CMS modules were developed to read TAMOC output, which consists of the description of distinct oil droplet “types”, each of specific size and pseudo-component mixture that enters at a given mass flow rate, time and position into the far field. These variables are transformed for use in the individual-based framework of oil-CMS, where each droplet type fits into a droplet size distribution (DSD). Here we used 19 pseudo-components representing a large range of hydrocarbon compounds and their respective thermodynamic properties. Simulation results show that the dispersion pathway for different droplet types varies significantly. Indeed, some droplet types are predicted to remain suspended in the subsea over months, while others accumulate in the surface layers. In addition, the biodegradation and dissolution rates of oil pseudo-components significantly alter the dispersion, denoting the importance of more biodegradation and dissolution studies of dispersed live oil at high pressure, with and without subsea dispersant injection (SSDI). This new modeling tool shows the potential for improved accuracy in predictions of oil partition in the water column, and of advancing impact assessment and response during a deep water spills

Technological Advances for Ocean Surface Measurements by the Consortium for Advanced Research on Transport of Hydrocarbons in the Environment (CARTHE)

AbstractFormed in the aftermath of the Deepwater Horizon event, the largest accidental marine oil spill, the Consortium for Advanced Research on Transport of Hydrocarbons in the Environment (CARTHE) focused on understanding the physical processes controlling the transport of material from a deep blowout all the way to the coast. Even though CARTHE was initially a modeling-oriented team, it progressively became more focused on observations in order to collect the data needed for model evaluation. A number of new technological advances needed to be made to collect the necessary data. This article reviews most of these, with special focus on surface sampling, where much of the oil is located during oil spills, as well as the measurement of near-field droplet size distribution