Model results from the Deepwater Horizon oil spill simulation using the Connectivity Modeling System adapted for oil modeling (oil-CMS), featuring log-normal size distribution of multi-fraction oil droplets at the initial release time

The latest version of the oil application of the Connectivity Modeling System (CMS), or oil-CMS, is used to simulate the far-field oil modeling of the Deepwater Horizon (DWH) blowout in the Gulf of Mexico (2010-04-20). The presented simulations feature multi-phase droplets that have a log-normal droplet size distribution (DSD) at the initial release time. The simulation is 100 days long, in which the oil spill stops after 87 days. Oil particles were released at 28.736°N, 88.365°W at a depth of 1222 m (300 m above the oil well), which is taken as a trap height. The model time step is 1200 seconds; 3,000 particles are released every two hours, equivalent to a total of 3,132,000 oil particles released over 87 days of the oil spill. Each liquid oil droplet contains three (3) pseudo-components corresponding to differential oil densities: 10% light oil with a density of 800 kg/m^3, 75% oil with 840 kg/m^3, and 15% heavy oil with 950 kg/m^3 density. The half-life decay rates of oil fractions were 30 days, 40 days, and 180 days, respectively, accounting for the biodegradation. The surface evaporation half-life was set to 250 hours; horizontal diffusivity is set to 10 m^2/s. At the initial release time, the droplets have a log-normal DSD with standard parameters µ=117 mm and σ = 0.62, based on best-known estimates from the observational and experimental data. These parameters assume the oil is not treated with chemical dispersants. CMS has a horizontal resolution of 0.02º. The vertical grid is 0-2500m with 20-m increments, except the top two layers bounded as 0-1m and 1-20m and the last layer is 2500-4500m. The transport and evolution of the oil particles are tracked by the oil-CMS model during the 100 days of the simulation, recording each droplet’s horizontal position, depth, diameter, and density every two hours. This dataset contains mass, diameter, and depth statistics of the evolving particles at five times over their history; their initial mass and diameter distributions; horizontally-cumulative oil concentration as a function of time; daily-averaged oil concentrations at the surface and near the release depth; and the three-dimensional oil concentration fields.