pH prediction in concentrated aqueous solutions under high pressure of acid gases and high temperature

• Published in: Corrosion science 2013-08, Vol.73, p.143-149
• Main Authors: Plennevaux, C., Ferrando, N., Kittel, J., Frégonèse, M., Normand, B., Cassagne, T., Ropital, F., Bonis, M.
• Format: Article
• Language: English
• Subjects: A. Acid solutions; Accounting; Applied sciences; B. Modeling studies; C. Thermodynamic diagrams; Carbon dioxide; Chemical Sciences; Corrosion; Corrosion environments; Exact sciences and technology; Gas phases; Liquids; Mathematical models; Metals. Metallurgy; Natural gas; Strength
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2013.04.002

•An extended model for pH prediction in oil and gas environments under high pressure and high temperature is proposed.•The model takes into account gas fugacities calculated using Soreide and Whitson model.•The activity of components in the liquid phase is calculated with Pitzer’s model.•The model shows a good agreement with experimental data. An extended model for pH prediction in oil and gas environments has been developed. Accurate pH calculations for high pressure and high temperature applications depends mainly on CO2 and H2S partial pressures, the ionic strength, the chemical composition of the solution, and the temperature. Accounting for the non-ideal behaviors of liquid and gas phases allows pH calculations up to 200°C, 2000bar total pressure, and ionic strengths up to 5molL−1. The results are consistent with experimental measurements and with other models reported in the literature.