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.

由于Helgeson-Kirkham-Flowers（HKF）静电模型不适用于低密度地区的水物种，因此对超临界地热储层中的矿物-流体平衡了解得很少。我们通过实验研究了钠长石–长石–石英在400、420°C和20–35 MPa水热溶液中的溶解平衡，并将实验结果与热力学计算进行了比较。通过SUPCRT92获得的基于HKF模型的热力学数据被外推到具有水密度的低密度区域。我们的结果表明，外推数据可用作评估超临界和低密度热液条件下长石-流体平衡的第一近似值。