Author(s): D. Wang; E. E. Adams; A. Chow
Linked Author(s): Eric Adams
Keywords: Oil well blowout; Multiphase plume; Intrusion dynamics; Chemical dispersants; Droplet size
Abstract: This paper explores the trapping elevation of oil droplets released from the Deepwater Horizon spill in 2010, and the dependence of this height on ambient current speed. Previous model predictions show good agreement with field data for the mean trap behaviour (Socolofsky et al., 2011), but do not capture the variability observed in the data. This variability can be attributed, at least in part, to temporal variability in plume buoyancy, bubble/droplet size, ambient stratification, and ambient current speed. Here we focus on the effect of ambient current by presenting preliminary results from ongoing experiments. In these experiments we adopt an inverted frame of reference, releasing a continuous mixture of dense beads and brine containing fluorescent dye from a surface carriage towed in a stratified tank. Geometric characteristics of the intrusion are documented by observing dye concentrations. We find that a weak crossflow creates enhanced ambient entrainment, which in turn leads to a smaller particle trapping depth (droplet trapping elevation) compared to the quiescent case. Data are being used to develop a semi-empirical model that extends previous models to account for weak crossflow effects, allowing more accurate prediction of mean trapping elevation of the intrusion layer hT as a function of crossflow velocity Ua, droplet rising velocity Us, buoyancy flux B and ambient stratification frequency N.
Year: 2016