A Matlab implementation of the Driesner and Heinrich (2007) H2O-NaCl EOS for hydrothermal flow modeling in the systems PTX and PHX
Abstract
Numerical modeling has become an indispensable tool for investigating magmatic hydrothermal systems. Yet, multi-phase simulations of thermohaline flow continue to be numerically challenging and are still not routinely done. There are two main challenges: 1) a transport scheme is required that can handle the strong coupling between the governing conservation equations as well as the non-linearity of the coefficients; 2) an equation-of-state is required that fully describes the fluid state and associated thermodynamic properties over sufficiently wide pressure (P), temperature (T), salinity (X) ranges. Here we focus on the latter problem. Driesner and Heinrich (2007) and Driesner (2007) provide complete and realistic correlation formulae for phase stability relations and fluid properties at temperatures from 0 to 1000°C, pressures from 0 to 5000 bar and compositions from 0 to 1 weight fraction NaCl. This EOS is formulated in the system PTX. However, for some coupled numerical transport schemes that require a unique fluid state for a given set of primary variables, a translation into the system, P, specific enthalpy (H), and X is preferable as it allows to uniquely resolve pure water boiling and the three-phase liquid+vapor+halite region.
We have implemented the Driesner and Heinrich (2007) and Driesner (2007) EOS completely in Matlab to make it more accessible. We here present how easy querying of the EOS can help to understand phase separation phenomena in hydrothermal systems. First, we review the original PTX formulation and then present the new mapping to the PHX scheme and how the fluid state can be described in terms of specific enthalpy. References: Driesner, T., and C. A. Heinrich, 2007, The system H2O-NaCl. Part I: Correlation formulae for phase relations in temperature-pressure-composition space from 0 to 1000 degrees C, 0 to 5000 bar, and 0 to 1 X-NaCl: Geochimica Et Cosmochimica Acta, v. 71, p. 4880-4901. Driesner, T., 2007, The system H2O-NaCl. Part II: Correlations for molar volume, enthalpy, and isobaric heat capacity from 0 to 1000 degrees C, 1 to 5000 bar, and 0 to 1 X-NaCl: Geochimica Et Cosmochimica Acta, v. 71, p. 4902-4919.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.V33E0230R
- Keywords:
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- 0450 Hydrothermal systems;
- BIOGEOSCIENCES;
- 3616 Hydrothermal systems;
- MINERALOGY AND PETROLOGY;
- 8135 Hydrothermal systems;
- TECTONOPHYSICS;
- 8424 Hydrothermal systems;
- VOLCANOLOGY