Albite–K-feldspar–quartz equilibria in hydrothermal fluids at 400, 420°C and 20–35 MPa: Experimental measurements and thermodynamic calculations. (July 2021)

• Record Type: Journal Article
• Authors: Okamoto, Atsushi; Ishii, Hajime; Oyanagi, Ryosuke; Tsuchiya, Noriyoshi
• Is Part Of: Geothermics. Volume 94(2021)
• Publication Date: 2021-07
• Subjects: Feldspar dissolution -- Supercritical fluids -- Thermodynamic data -- Density model -- Hydrothermal experiments; Hydrogeology -- Periodicals; Geothermal resources -- Periodicals; Énergie géothermique -- Périodiques; GEOTHERMAL ENGINEERING; GEOTHERMAL ENERGY; GEOTHERMAL EXPLORATION; Geothermal resources; Hydrogeology; Periodicals; Electronic journals; 621.44
• DOI: 10.1016/j.geothermics.2021.102109
• Languages: English
• ISSNs: 0375-6505

Abstract

Highlights: Hydrothermal experiments on feldspars-quartz equilibria were conducted. The log keq 's data from SUPCRT92 was extended to low-density region by water density. Extended log k eq 's are useful for predicting supercritical water-rock interaction. Abstract: Mineral–fluid equilibria in supercritical geothermal reservoirs is poorly understood, due to the non-applicability of the Helgeson–Kirkham–Flowers (HKF) electrostatic model for aqueous species in low-density regions. We experimentally investigated the dissolution equilibria of albite–K-feldspar–quartz in hydrothermal solutions at 400, 420 °C and 20–35 MPa, and compared the experimental results with thermodynamic calculations. The thermodynamics data based on the HKF model available through SUPCRT92 were extrapolated into the low-density regions with water density. Our results suggest that the extrapolated data are useful as a first approximation for evaluating feldspars–fluid equilibria under supercritical and low-density hydrothermal conditions.