Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media

CO<sub>2</sub> flooding plays a crucial role in enhancing oil recovery and achieving carbon reduction targets, particularly in unconventional reservoirs with complex pore structures. The phase behavior of CO<sub>2</sub> and hydrocarbons at different scales significantly affec...

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Main Authors: Feiyu Chen, Linghui Sun, Bowen Li, Xiuxiu Pan, Boyu Jiang, Xu Huo, Zhirong Zhang, Chun Feng
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/2/277
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author Feiyu Chen
Linghui Sun
Bowen Li
Xiuxiu Pan
Boyu Jiang
Xu Huo
Zhirong Zhang
Chun Feng
author_facet Feiyu Chen
Linghui Sun
Bowen Li
Xiuxiu Pan
Boyu Jiang
Xu Huo
Zhirong Zhang
Chun Feng
author_sort Feiyu Chen
collection DOAJ
description CO<sub>2</sub> flooding plays a crucial role in enhancing oil recovery and achieving carbon reduction targets, particularly in unconventional reservoirs with complex pore structures. The phase behavior of CO<sub>2</sub> and hydrocarbons at different scales significantly affects oil recovery efficiency, yet its underlying mechanisms remain insufficiently understood. This study improves existing thermodynamic models by introducing Helmholtz free energy as a convergence criterion and incorporating adsorption effects in micro- and nano-scale pores. This study refines existing thermodynamic models by incorporating Helmholtz free energy as a convergence criterion, offering a more accurate representation of confined phase behavior. Unlike conventional Gibbs free energy-based models, this approach effectively accounts for confinement-induced deviations in phase equilibrium, ensuring improved predictive accuracy for nanoscale reservoirs. Additionally, adsorption effects in micro- and nano-scale pores are explicitly integrated to enhance model reliability. A multi-scale thermodynamic model for CO<sub>2</sub>-hydrocarbon systems is developed and validated through physical simulations. Key findings indicate that as the scale decreases from bulk to 10 nm, the bubble point pressure shows a deviation of 5% to 23%, while the density of confined fluids increases by approximately 2%. The results also reveal that smaller pores restrict gas expansion, leading to an enhanced CO<sub>2</sub> solubility effect and stronger phase mixing behavior. Through phase diagram analysis, density expansion, multi-stage contact, and differential separation simulations, we further clarify how confinement influences CO<sub>2</sub> injection efficiency. These findings provide new insights into phase behavior changes in confined porous media, improving the accuracy of CO<sub>2</sub> flooding predictions. The proposed model offers a more precise framework for evaluating phase transitions in unconventional reservoirs, aiding in the optimization of CO<sub>2</sub>-based enhanced oil recovery strategies.
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spelling doaj-art-00927763c29444d9b32d8c5cc2b76a522025-01-24T13:43:23ZengMDPI AGMolecules1420-30492025-01-0130227710.3390/molecules30020277Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous MediaFeiyu Chen0Linghui Sun1Bowen Li2Xiuxiu Pan3Boyu Jiang4Xu Huo5Zhirong Zhang6Chun Feng7University of Chinese Academy of Sciences, Beijing 100049, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaUniversity of Chinese Academy of Sciences, Beijing 100049, ChinaResearch Institute of Petroleum Exploration & Development, Beijing 100083, ChinaCO<sub>2</sub> flooding plays a crucial role in enhancing oil recovery and achieving carbon reduction targets, particularly in unconventional reservoirs with complex pore structures. The phase behavior of CO<sub>2</sub> and hydrocarbons at different scales significantly affects oil recovery efficiency, yet its underlying mechanisms remain insufficiently understood. This study improves existing thermodynamic models by introducing Helmholtz free energy as a convergence criterion and incorporating adsorption effects in micro- and nano-scale pores. This study refines existing thermodynamic models by incorporating Helmholtz free energy as a convergence criterion, offering a more accurate representation of confined phase behavior. Unlike conventional Gibbs free energy-based models, this approach effectively accounts for confinement-induced deviations in phase equilibrium, ensuring improved predictive accuracy for nanoscale reservoirs. Additionally, adsorption effects in micro- and nano-scale pores are explicitly integrated to enhance model reliability. A multi-scale thermodynamic model for CO<sub>2</sub>-hydrocarbon systems is developed and validated through physical simulations. Key findings indicate that as the scale decreases from bulk to 10 nm, the bubble point pressure shows a deviation of 5% to 23%, while the density of confined fluids increases by approximately 2%. The results also reveal that smaller pores restrict gas expansion, leading to an enhanced CO<sub>2</sub> solubility effect and stronger phase mixing behavior. Through phase diagram analysis, density expansion, multi-stage contact, and differential separation simulations, we further clarify how confinement influences CO<sub>2</sub> injection efficiency. These findings provide new insights into phase behavior changes in confined porous media, improving the accuracy of CO<sub>2</sub> flooding predictions. The proposed model offers a more precise framework for evaluating phase transitions in unconventional reservoirs, aiding in the optimization of CO<sub>2</sub>-based enhanced oil recovery strategies.https://www.mdpi.com/1420-3049/30/2/277CO<sub>2</sub> floodingmulti-scalephase behaviorenhanced oil recoveryconfined fluids
spellingShingle Feiyu Chen
Linghui Sun
Bowen Li
Xiuxiu Pan
Boyu Jiang
Xu Huo
Zhirong Zhang
Chun Feng
Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media
Molecules
CO<sub>2</sub> flooding
multi-scale
phase behavior
enhanced oil recovery
confined fluids
title Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media
title_full Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media
title_fullStr Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media
title_full_unstemmed Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media
title_short Computational Modeling and Experimental Investigation of CO<sub>2</sub>-Hydrocarbon System Within Cross-Scale Porous Media
title_sort computational modeling and experimental investigation of co sub 2 sub hydrocarbon system within cross scale porous media
topic CO<sub>2</sub> flooding
multi-scale
phase behavior
enhanced oil recovery
confined fluids
url https://www.mdpi.com/1420-3049/30/2/277
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