Revised Quartz Solubility Temperature Dependence Equation Along the Water-Vapor Saturation Curve

Abstract

From the application of chemical thermodynamics a quartz solubility regression expression along the water-vapor saturation curve for whole range of temperature from 0 to 374?C was developed. The equation is the following ( ) ( ) 08. 0 88. 4 ) ( 7. 31 7 1175 ) ( log 2 ± + ± ? - = K T ppm SiO The correction of total discharge silica composition from a well for the vapor fraction in the geothermal reservoir is a fundamental limitation to use this equation as a geothermometer. For knowing the vapor fraction there is indirectly need of knowing the reservoir temperature. It is possible to calculate the deep reservoir temperature with iteration process, but a basic assumption is that the reservoir fluid is in equilibrium with quartz. The concept is elucidated in case of the Cerro Prieto geothermal system.