The density characteristics of CO₂ and alkane mixtures using PC‐SAFT EoS

Abstract

The density of CO 2 + crude oil mixtures is one of the most important parameters influencing CO 2 diffusion and migration in oil reservoirs. However, it would be quite time consuming to obtain comprehensive density data for CO 2 + alkane mixtures over a wide range of temperatures and pressures via experimental methods, therefore the development of a reliable model for predicting the densities of various CO 2 + alkane mixtures with high accuracy is crucial. In this paper, the parameters (m, σ , and ε/k) in the perturbed-chain statistical associating fluid theory (PC-SAFT) Equation of State (EoS) were optimized by correlating density data of pure n-alkanes from heptane to nonadecane (except undecane and hexadecane). For comparison, the G-S PC-SAFT and HTHP PC-SAFT EoS(s) were also employed to fit the densities of these n-alkanes, and the results demonstrated that the PC-SAFT EoS with the optimized parameters in this study exhibited superior accuracy. Subsequently, by correlating density data of CO 2 + alkane mixtures containing C7-C14 alkanes, the binary interaction parameter k ij was optimized. Furthermore, for the first time, correlations between the optimized parameters (m, σ , ε/k, and k ij) and alkane carbon number (n) were established. These correlations provided PC-SAFT EoS with a good universality and scalability for density prediction. Using the parameters calculated from these correlations, the densities of hexadecane and saturated CO 2 + alkane mixtures containing C10-C20 alkanes were successfully predicted with relatively high accuracy. This work provides a new way for modeling the thermodynamic properties of CO 2 + alkane mixtures.

Density Measurements and PC-SAFT Modeling for Beef Tallow Fatty Acid Methyl Esters (FAME Mixture) + Alkane up to 70 MPa

“…The parameters for each ester and alkane are listed in Table 13, which were taken elsewhere. 46,47 Specifically, eqs 14−16 in ref 46 were used for the case of esters; these equations are dependent on the molecular weight and were developed from the vapor pressure and density data of short carbon chain methyl esters. Regarding the alkanes, their parameters were optimized based on density data.…”

“…The first evaluation with PC-SAFT consisted in assuming the FAME mixture as a multicomponent (four components) sample with the mole fraction of each methyl ester reported in Table . The parameters for each ester and alkane are listed in Table , which were taken elsewhere. , Specifically, eqs 14–16 in ref were used for the case of esters; these equations are dependent on the molecular weight and were developed from the vapor pressure and density data of short carbon chain methyl esters. Regarding the alkanes, their parameters were optimized based on density data.…”

Liquid–Liquid Equilibrium Studies of Multicomponent Diluent/Bitumen System with Application to Solvent-Aided In Situ Bitumen Recovery

“…These studies include works by. − They used various pure solvents (methane, butane, pentane, heptane, carbon dioxide, toluene, water, nitrogen, hexane, propane, ethane, dimethyl ether, and ethyl acetate) at different conditions (temperatures of 22–260 °C and pressures up to a maximum of around 10 MPa). Additionally, the phase behavior of n -alkanes and bitumen mixtures, particularly the vapor–liquid equilibrium (VLE) of these systems, has been extensively investigated in the literature. ,,,− Chi et al also applied PC-SAFT EoS to predict the densities of various CO 2 + alkane mixtures and reported the optimized EoS parameters.…”

“…Additionally, the phase behavior of n-alkanes and bitumen mixtures, particularly the vapor−liquid equilibrium (VLE) of these systems, has been extensively investigated in the literature. 29,30,32,36−40 Chi et al 41 also applied PC-SAFT EoS to predict the densities of various CO 2 + alkane mixtures and reported the optimized EoS parameters.…”