Modelling Study Quantifies Gas Bubbles Effects on Oil Plume Dynamics
(GoMRI) September 30, 2015
Scientists assessed subsurface hydrocarbon plume simulations to understand the role of released gases on plume behavior.
The simulations showed that the presence of gas, even at relatively small volumes, significantly increased the mixing of hydrocarbons in the plume. Gas bubbles moving past the slower-moving oil amplified vertical and horizontal plume growth. The team published their study in Ocean Modelling: Numerical simulations of turbulent thermal, bubble and hybrid plumes.
Deep oil spills, such as the Deepwater Horizon, generate buoyant plumes that can transport hydrocarbons thousands of meters across the water column. The dispersion of the pollutants depends on the many physical and chemical processes related to turbulent mixing as the plume grows.
To improve oil transport prediction model accuracy, there needs to be careful examination of assumptions and parameter values for these complex processes. Lead author Alexandre Fabregat explained, “A variety of tools have been used to predict the evolution of buoyant plumes. However, in these models, it is necessary to specify several parameters that control how fast the plume width increases as it travels vertically or how much the bubbles enhance the mixing.”
To understand and quantify the basic physical properties of deepwater plumes, the study team compared thermal plumes (single-phase), bubble plumes, and hybrid plumes (multiphase). They analyzed plume behavior, varying the inlet gas contributions to the models. Simplification of the system to a single momentum equation – the gas slip velocity relative to that of the liquid phase – allowed computation of nearfield turbulence over scale ranges similar to previous and potential deepwater releases.