On the use of Chemical Geothermometry: A Reactive Transport Modeling Study of the Dixie Valley Geothermal Area

Abstract

A 2D reactive transport model of the Dixie Valley geothermal field in Nevada, USA was developed to assess the conditions under which chemical geothermometers operate as powerful exploration tools. Model concentrations read out at the surface were processed by multicomponent geothermometry to compare inferred reservoir temperatures with true reservoir temperatures of the model. Varying reactive fracture surface areas revealed that re-equilibration does not occur if the effective fracture surface area is 1-3 orders of magnitude lower than the corresponding geometric surface area. Moreover, it could be shown that a full re-equilibration is hindered if the fluid velocity within a fracture is on the order of 1 m/day. It was concluded that such upflow rates and relatively low reactive fracture surface areas are likely occurring at a wide series of geothermal fields, confirming that geothermometers can be used as powerful geochemical exploration tools.