Raman spectroscopic measurements of H2S solubility in pure water over a wide range of pressure and temperature and a refined thermodynamic model

Abstract Dissolution of H2S in the H2S–H2O system can be used to characterize some geochemical and hydrocarbon processes, such as ore formation and natural-gas extraction from shale. However, experimental data on H2S solubility in H2O under high pressure (P) and temperature (T) conditions are insufficient. In this study, a method was developed to quantitatively analyze the equilibrium concentration of H2S in H2O under fixed P–T conditions using a high-pressure optical cell coupled with in situ Raman spectroscopy. The H2S solubility data were obtained at temperatures up to 573 K and pressures up to 100 MPa. Based on these new and previous solubility data, three existing solubility models were re-examined. Our results show that these models are in good agreement with our new experimental data under applicable range of them. However, extrapolations based on these models are not satisfactory because they deviate considerably from our newly obtained solubility data. In order to extend the predictable range of an existing model, the parameters of the model by Duan et al. (2007) were refined using the solubility data from both this study and previous literature. The average absolute deviation between this refined model and all experimental data is 3.42%. The new solubility model can be used over a wide range P–T conditions (i.e., 0–100 MPa, 273–573 K). The solubility model is available as a computer software, which is included in the Supplementary data.