Heat and Mass Transfer in Hypersaline Geothermal Systems

Abstract

Fluid density in hypersaline geothermal systems is controlled by temperature and salinity. For example, brines in the Salton Sea Geothermal System (SSGS) are stably stratified with maximum densities near m in the hot. hypersaline regions at depth. In geothermal systems, the porous medium affects double-diffusive convection (free convection with two sources of buoyancy). For example, the permeability of the medium exerts the fundamental control on the flow field. A more subtle effect of the porous medium is to increase the effective diffusivity of the brine through hydrodynamic dispersion. In addition, heat transport is affected by porosity due to heat exchange between the fluid and the solid rock matrix. In forced convection, the increased pore velocity in porosity regions enhances brine transport relative to heat transport. In double-diffusive convection, the heat and brine transport are strongly coupled and enhanced transport of brine over heat is limited by density effects. These effects have been investigated using the reservoir simulator TOUGH2 with a newly developed dispersion