Programme

P.66 -- Posters, VCTP-50

Date: Thursday, 7 August 2025

Time: 08:30 - 10:00

Molecular Simulation of Noble Gas Fractionation in CO₂-Water Systems under Geological Conditions

Tu Khai Nam Nguyen (1), Huy Tien Truong (1), Magali Pujol (3), Galliero Guillaume (3), Hai Hoang (1)

(1) Institute of Fundamental and Applied Sciences, Duy Tan University, Tran Nhat Duat Street, District 1, Ho Chi Minh City, Vietnam (2) TotalEnergies, CSTJF, Avenue Larribau, Pau, 64018, France (3) Laboratoire des Fluides Complexes et leurs Réservoirs, Université de Pau et des Pays de l’Adour, E2S UPPA, CNRS, 64000, Pau, France

Abstract: Understanding the fractionation of noble gases in CO₂-H₂O equilibrium systems is crucial for their application as geochemical tracers in geological carbon storage and subsurface fluid processes [1]. However, both accurate data and a comprehensive molecular-level understanding of noble gas partitioning under relevant geological conditions remain limited [2]. In this study, we investigate the equilibrium fractionation of noble gases between CO₂ and water phases using Gibbs ensemble Monte Carlo (GEMC) simulations, combined with the continuous fractional component approach [3]. Carbon-dioxide, water, and noble gases (He, Ne, Ar, Kr, Xe) molecules are described using the TraPPE, TIP4P/2005, and spherical Lennard-Jones force fields, respectively [4-6]. Unlike interaction parameters are systematically adjusted to reproduce available experimental solubility data [2, 3]. Extensive GEMC simulations are performed over a wide range of thermodynamic conditions relevant to deep subsurface reservoirs. We systematically analyze effects of temperature and pressure on noble gas fractionation induced by solubility, providing molecular-level insight into partitioning processes in CO₂-H₂O equilibrium systems. Acknowledgements We gratefully acknowledge TotalEnergies S.E. for their scientific support. We also thank the University of Pau and Pays de l’Adour and the MCIA for providing computational facilities. References [1] P. Burnard, The Noble Gases as Geochemical Tracers (Springer, New York, 2013). [2] O. Warr, C. A. Rochelle, A. Masters, and C. J. Ballentine, Geochim. Cosmochim. Acta 159, 112 (2015). [3] H. Kerkache, H. Hoang, P. Cézac, G. Galliéro, and S. Chabab, J. Mol. Liq. 400, 124497 (2024). [4] J. J. Potoff and J. I. Siepmann, AIChE J. 47, 1676 (2001). [5] J. L. Abascal and C. Vega, J. Chem. Phys. 123, 234505 (2005). [6] G. Rutkai, M. Thol, R. Span, and J. Vrabec, Mol. Phys. 115, 1104 (2017).

Presenter: Nguyen Tu Khai Nam