Measurement, Theoretical Modeling and Molecular Simulation of Interfacial Properties of Gas + N-Alkane Binary Mixtures.
Abstract
Thermophysical characterization of phase equilibrium, bulk densities and interfacial properties of gases (e.g., CO2, CH4) in contact to n-alkanes and aromatics plays a central role in big scale processes such as enhanced oil recovery (EOR), geological carbon capture and sequestration (CCS), among others. Their relevance is based on the fact that the overall performance of these processes depends on the accurate quantification of these thermophysical properties as a function of temperature, pressure, and composition. However, the appropriate characterization of them is a no easy task, especially at high temperatures and pressures. Indeed, it needs a crafty combination of experimental determinations, theoretical predictions, and molecular simulations.
In this work, we illustrate the application this three-party approach to describe selected interfacial properties (e.g., interfacial concentration, surface activity, interfacial tension) of gases + n-alkanes and aromatics relates to EOR and CSS. Specifically, the selected mixtures are CO2 + n-alkane, CO2 + n-alkane + aromatic, and CH4 + n-alkane, with n = 10 to 20 at 344 K and over 0.1 MPa to slightly below to the critical pressure. In this interrelate methodology, the experimental determinations are carried out on a combined device that includes a high-pressure vibrating tube densimeter and a high-pressure pendant drop tensiometer. The theoretical modeling of the interfacial properties is carried out by employing the Square Gradient Theory (SGT) using the Statistical Associated Fluid Theory (SAFT VR Mie) equation of state (EoS). In this version of SAFT EoS, the molecules are represented by "super"-united-atoms or coarse-grained (CG) model generating a full predicting model due to the involved parameters in both SGT and SAFT are obtained by using corresponding state principia. Molecular Dynamics (MD) simulations are performed in the canonical ensemble using the same intermolecular potential (CG model) used for SAFT EoS. This combination provides to carry out a viz-viz approach. Additionally, the CG representation allowing the efficient exploration of longer computational times, larger length scales, bigger molecular systems in comparison to the more commonly-used all-atom or united-atom schemes.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMMR13D0101M
- Keywords:
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- 3611 Thermodynamics;
- MINERALOGY AND PETROLOGY;
- 3612 Reactions and phase equilibria;
- MINERALOGY AND PETROLOGY;
- 5134 Thermal properties;
- PHYSICAL PROPERTIES OF ROCKS;
- 5139 Transport properties;
- PHYSICAL PROPERTIES OF ROCKS