Improved solubility model for pure gas and binary mixture of CO2-H2S in water: A geothermal case study with total reinjection

Pouriya H. Niknam*, Lorenzo Talluri, Daniele Fiaschi, Giampaolo Manfrida

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)
246 Downloads (Pure)


Geothermal energy is acknowledged globally as a renewable resource, which, unlike solar, wind or wave energy, can be continuously exploited. The geothermal fluids usually have some acid gas content, which needs to be precisely taken into account when predicting the actual potential of a power plant in dealing with an effective reinjection. One of the key parameters to assess is the solubility of the acid gas, as it influences the thermodynamic conditions (saturation pressure and temperature) of the fluid. Therefore, an enhanced solubility model for the CO2-H2S-water system is developed in this study, based on the mutual solubility of gases. The model covers a wide range of pressures and temperatures. The genetic algorithm is employed to calculate the correlation constants and corresponding solubility values of both CO2 and H2S as functions of pressure, temperature and the balance of the gas. The results are validated against previously published models and experimental data available in the literature. The proposed model estimates the pure gas solubility, which is also a feature of other models. The more innovative feature of the model is the solubility estimation of each CO2 or H2S in simultaneous presence, such as when the binary gas is injected into the pure water of the geothermal reinjection well. The proposed solubility model fits well with the available experimental data, with a mean deviation lower than 0.2%.

Original languageEnglish
Article number2883
Issue number11
Publication statusPublished - 5 Jun 2020

Bibliographical note

Publisher Copyright:
© 2020 by the authors.


  • Acid gas
  • Geothermal fluids
  • NCG reinjection
  • Solubility

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Energy (miscellaneous)
  • Control and Optimization
  • Electrical and Electronic Engineering


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