THERMOHALINE CONVECTIVE MIXING AT A BRINE INTERFACE

Abstract

Thermohaline convection in hypersaline geothermal systems is driven by heat and salinity effects on liquid density. Thermal retardation in porous media causes thermal and brine plumes to separate, leading to segregation and mixing phenomena not observed in viscous liquid systems. We performed two-dimensonal numerical simulations of thermohaline convection to investigate mixing effects at a gravitationally stable brine interface such as that inferred to exist in the Salton Sea Geothermal System. Using plausible density and viscosity models that consider the influence of heat and salinity on liquid properties, simulations show that thermal retardation subtly enhances convective mixing by allowing the thermal and salinity effects on density to be expressed independently upon plume separation. Permeability anisotropy, where vertical permeability is smaller than horizontal permeability, and brine viscosity inhibit mixing.