Dispersive thermohaline convection near salt domes: a case at Napoleonville Dome, southeast Louisiana, USA

Density-driven flow around salt domes is strongly influenced by salt concentration and temperature gradients. In this study, a thermohaline convection numerical modeling is developed to investigate flow, salinity, and heat transport around salt domes under the impact of fluid dispersivity and variable density and viscosity. 'Dispersive fluid flux of total fluid mass' is introduced to the density-driven flow equation to improve thermohaline modeling in porous media. The dispersive fluid flux term is derived to account for an additional fluid flux driven by the density gradient and mechanical dispersion. The model is first tested by a hypothetical salt-dome problem, where a circulation of flow is induced by an overpressure and density effect. The result shows a distinct salt-transport change due to the inclusion of the dispersive fluid flux and temperature effect. Then, the model is applied to investigate changes of groundwater flow, salinity, and heat transport near the west of Napoleonville salt dome, southeastern Louisiana, USA, due to a salt cavern failure. The result shows that an instant overpressure assumed to be created by the salt-cavern wall breach has little impact on salinity near the ground surface within a period of 3 months. However, salinity is significantly elevated near the breach area of the salt cavern, caused by strong flow velocities.