Equation of State of a Fluid H2O-CO2 at Temperatures 50–350 °C and Pressures 0.2–3.5 kbar

Authors

  • Mikhail V. Ivanov

    Institute of Precambrian Geology and Geochronology Russian Academy of Sciences, nab. Makarova 2, St. Petersburg 199034, Russia

DOI:

https://doi.org/10.30564/jees.v7i1.7327
Received: 20 September 2024 | Revised: 15 October 2024 | Accepted: 25 October 2024 | Published Online: 14 January 2025

Abstract

An equation of state (EOS) was obtained that accurately describes the thermodynamics of the system H2O–CO2 at temperatures of 50-350°C and pressures of 0.2-3.5 kbar. The equation is based on experimental data on the compositions of the coexisting liquid and gas phases and the Van Laar model, within which the values of the Van Laar parameters A12 and A21 were found for each experimental P-T point. For the resulting sets A12(P,T), A21(P,T), approximation formulas describing the dependences of these quantities on temperature and pressure were found and the parameters contained in the formulas were fitted. This two-stage approach made it possible to obtain an adequate thermodynamic description of the system, which allows, in addition to determining the phase state of the system (homogeneous or heterogeneous), to calculate the excess free energy of mixing of H2O and CO2, the activities of H2O and CO2, and other thermodynamic characteristics of the system. The possibility of such calculations creates the basis for using the obtained EOS in thermodynamic models of more complicated fluid systems in P-T conditions of the middle and upper crust. These fluids play an important role in many geological processes including the transport of ore matter and forming hydrothermal ore deposits, in particular, the most of the world's gold deposits. The knowledge of thermodynamics of these fluids is important in the technology of drilling oil and gas wells. In particular, this concerns the prevention of precipitation of solid salts in the well.

Keywords:

High Pressure; Elevated Temperature; Water-Carbon Dioxide Fluid; Equation of State

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How to Cite

Mikhail V. Ivanov. (2025). Equation of State of a Fluid H2O-CO2 at Temperatures 50–350 °C and Pressures 0.2–3.5 kbar. Journal of Environmental & Earth Sciences, 7(1), 625–631. https://doi.org/10.30564/jees.v7i1.7327

Issue

Vol. 7 , Iss. 1 (January 2025)

Article Type

Short Communication

License

Copyright © 2025 Mikhail V. Ivanov

Creative Commons License

This is an open access article under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.

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