A thermodynamic consistency test for experimental isobaric data of wax solubility in gaseous systems

• A thermodynamic consistency test is utilized for isobaric conditions.
• A thermodynamic model is utilized for prediction of wax solubility in gaseous systems.
• Available experimental data for wax solubility in gaseous systems are tested.
• The Gibbs–Duhem approach is applied for analysis of experimental data.
• From the analysis, the experimental data are classified as TC, NFC, and TI.

The ever-increasing demand for natural gas as an energy source has led to a great deal of interest and numerous studies being undertaken by researchers in the field. The efficient production of natural gas from deep well reservoirs has always been an area of intense research in the gas production industry, with immense efforts to understand and mitigate issues which can affect this efficiency. The solubility of the waxy compounds in some natural gases can be regarded as one of these issues that may affect production efficiency. In order to fully understand the phenomenon of wax solubility in natural gas, reliable experimental data are required. This study aims to investigate the reliability of such data using a thermodynamic model. For this purpose, the wax solubility in supercritical constituents of natural gas, such as carbon dioxide and ethane, has been estimated using the Peng–Robinson equation of state and two-fluid van der Waals (vdW2) mixing rules. The residual enthalpies were evaluated using the results obtained. The Gibbs–Duhem equation at constant pressure was applied for evaluation of the consistency of the experimental data. From the analysis, the data were classified as thermodynamically consistent (TC), not fully consistent (NFC), and thermodynamically inconsistent (TI).