Prediction model of elemental sulfur solubility in sour gas mixtures

• Roberts's model describes sulfur solubility in pure H2S but not in sour gas mixtures.
• Sulfur solubility in sour gas mixtures may change with gas density variation.
• Subsection function as density to inflection point is established to predict sulfur solubility.
• Calculation values using the new solubility model are closer to experimental data.

Predicting the solubility of elemental sulfur in sour gas mixtures is one of the most important issues in sour gas reservoirs development. Many experiments have shown the relationship between sulfur solubility and sour gas properties at different temperatures and pressures. However, the solubility model that can be used to predict sulfur solubility at different reservoir temperatures and pressures is rare. Nowadays, Roberts's solubility formula, according to fitting two groups of experiment data, is often used in sour gas reservoirs. Thus, building a solubility formula that contains more experimental data and experimental conditions is very critical. In this paper, based on the correlation formulas for the solubility of various solutes in super critical solvents, a new sulfur solubility formula is built by using a large number of experimental data. Through the comparison and analysis for the new solubility formula and Roberts's solubility formula, the calculation results utilizing the new solubility formula are closer to the experimental data. Therefore, the new formula can be used to predict sulfur solubility in sour gas reservoirs at different temperatures and pressures accurately. The new solubility model can calculate the change of sulfur solubility in sour gas well production and help reservoir engineers to develop the plan of sour gas reservoir development.