Abstract
Spills resulting in sunken oil are expected to increase due to the rise in production and transport of heavier oils, such as diluted bitumen (dilbit). While successful detection technologies for sunken oil exist, there are only a few sunken oil spill models that are capable of tracking sunken oil, and these models require hydrodynamic data on the bottom as input. Therefore, the objectives of this work include (1) reviewing the literature for successful sunken oil response technologies and current sunken oil models, (2) expanding the multi-modal Bayesian inferential sunken oil model, SOSim (Subsurface Oil Simulator), to incorporate field concentration data and bathymetric data for use during operational response, and (3) further expanding SOSim v2 to locate and track sunken oil in rivers, as sunken oil transport processes differ in rivers from those in oceans. Rather than requiring hydrodynamic and fate data as input, SOSim v2 accepts available field concentration data along with default or custom bathymetric data, for inference of the location and trajectory of sunken oil, as fate and transport processes are inferred from these data. Novel aspects include inference based on bathymetry and the Coriolis Effect as appropriate given the scale of the assessment, by constructing a prior likelihood function from sampled bathymetric data, scaled proportionally with field concentration data. SOSim v2 is then demonstrated versus field data on the ITB DBL-152 oil spill in the Gulf of Mexico with sensitivity analysis and versus field observations taken following the M/T Athos I oil spill. The model was also modified to operate in 1-D, to assess the longitudinal distribution of sunken oil in a non-navigable river using available poling data collected following the Enbridge Kalamazoo River oil spill in 2010. Results of the case studies were consistent with observed data and local bathymetry in 2-D and 1-D. Overall, results suggest that the inferential approach presented can be effective for modeling sunken oil, when field concentration data are available.