Ultrasonic Speed and Isentropic Compressibility of Asymmetric Liquid Ternary Mixtures under High Pressure: a Test for Equations of State and Associated Mixing Rules

With a view to carrying out compositional modelling of reservoir fluids and to forecast a number of their thermodynamic properties, experimental speed of sound measurements were made at different pressures and temperatures for a ternary system: C1 - CO2 - nC16 (for a wide range of concentration). These ultrasonic speed data were then used to compare the results obtained by means of equation of state and associated mixing rules and hence determine the combinations of these tools which appear most appropriate. From knowledge of both ultrasonic speed and density we also calculate the adiabatic compressibility of the investigated mixtures.