No abstract

No abstract

No abstract

Density measurements of the n-heptane + n-dodecane binary mixture were performed with a vibrating tube densitometer in the temperature range of (293.15 to 363.15) K and pressure up to 70 MPa at six different n-heptane mole fractions: x 1 = 0, 0.1999, 0.3991, 0.5999, 0.7998, and 1. Densities of the CO2 + n-heptane + n-dodecane ternary mixtures were also measured at the same temperature and pressure ranges for two different isopleths: CO2 (0.4904) + n-heptane (0.2548) + n-dodecane (0.2548), and CO2 (0.7425) + n-heptane (0.1288) + n-dodecane (0.1288). The obtained experimental data were correlated by a polynomial model and by a Tait-based equation. Density values for pure n-heptane and n-dodecane were found to be in agreement with literature data within approximately 0.3%. The isothermal compressibility and thermal expansion values of these mixtures were obtained by differentiation from the models as a function of pressure and temperature. Analysis of these properties pointed out that the polynomial model provided more accurate results related to derived properties. The excess volume of the mixtures was also determined. In general, they are negative, but they become positive for binary mixtures in the heptane-rich region as well as at higher pressures for ternary mixtures.

In this study, highly accurate measurements of density and dynamic viscosities of a recombined live oil and its mixture with additional CO2 were performed. The experiments were carried out under pressure and temperature gradients found in Brazilian Pre-salt reservoirs, that is, in the pressure range from (27.6 to 68.9) MPa and at (333.15 and 353.15) K. The assumption of volume change on mixing is evaluated from the experimental results, and the influence of pressure and temperature on the volume change upon mixing is assessed. The densities of mixtures are calculated considering (i) the excess volume approach, and (ii) no volume change. The densities are better correlated using the excess volume approach with Average Absolute Deviations (AAD) of 0.03%. Thirteen mixing rules of viscosity are examined by comparing the predicted values with the experimental viscosity of the recombined live oil + CO2 mixture. The performance of some rules using compositional fractions (molar, volume and weight) is also evaluated. Thus, a total of 28 different ways to calculate the mixture viscosities were tested in this study. The worst result was obtained with Bingham’s method, leading to 148.6% AAD. The best result was obtained from Lederer’s method with 2% AAD and a maximum deviation of 5.8% using volume fractions and the fitting parameter α. In addition, deviations presented by the predictive methods of Chevron, Double log, and Kendall did not exceed 9% AAD, using weight fractions (Chevron and Double log) and molar fractions (Kendall and Monroe).