EXPERIMENTAL AND THEORETICAL CHARACTERIZATION OF THERMOPHYSICAL PROPERTIES AND ELECTRICAL PERMITTIVITY OF CO2 AND DODECANE MIXTURES

Multiphase Flow Meters (MPFMs) play a key role in reservoir management and in maximizing oil and gas production. Recent discoveries of pre-salt reservoirs, which often exhibit high carbon dioxide (CO₂) content, have increased the need to evaluate the performance of flow-metering technologies under CO₂-rich conditions. Consequently, understanding the influence of dissolved CO₂ on the thermophysical properties of multiphase mixtures and its impact on MPFM measurements has become increasingly important.

This study presents an experimental and theoretical investigation of the influence of dissolved CO₂ in the liquid phase of a CO₂–dodecane mixture. The main objective is to evaluate how variations in CO₂ solubility affect the thermophysical and electrical properties of the liquid phase.

Experiments were carried out over a wide range of pressures (1–170 bar) and temperatures (5–80 °C), resulting in CO₂ solubilities ranging from 0 to 100%. A laboratory-scale experimental setup was developed to measure density, viscosity, solubility, and dielectric permittivity. The results show that density increases with increasing CO₂ content and, for a fixed CO₂ concentration, with decreasing temperature. In contrast, viscosity decreases with increasing CO₂ content and increasing temperature. A similar trend was observed for dielectric permittivity.

A thermodynamic model based on the Cubic Plus Association (CPA) equation of state was implemented to predict the mixture properties and to compare theoretical results with experimental data. The comparison yielded average relative errors of approximately 4.36% for density, 4.21% for viscosity, and 0.91% for dielectric permittivity, indicating good agreement between experiments and modeling.