Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations
The hybrid CO2 thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process. Using microscopic visualization experiments and molecular dynamics (MD) simulations, this study investigates the microscopic enh...
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KeAi Communications Co., Ltd.
2025-06-01
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| Series: | Energy Geoscience |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2666759225000150 |
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| author | Ning Lu Xiaohu Dong Haitao Wang Huiqing Liu Zhangxin Chen Yu Li Deshang Zeng |
| author_facet | Ning Lu Xiaohu Dong Haitao Wang Huiqing Liu Zhangxin Chen Yu Li Deshang Zeng |
| author_sort | Ning Lu |
| collection | DOAJ |
| description | The hybrid CO2 thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process. Using microscopic visualization experiments and molecular dynamics (MD) simulations, this study investigates the microscopic enhanced oil recovery (EOR) mechanisms underlying residual oil removal using hybrid CO2 thermal systems. Based on the experimental models for the occurrence of heavy oil, this study evaluates the performance of hybrid CO2 thermal systems under various conditions using MD simulations. The results demonstrate that introducing CO2 molecules into heavy oil can effectively penetrate and decompose dense aggregates that are originally formed on hydrophobic surfaces. A stable miscible hybrid CO2 thermal system, with a high effective distribution ratio of CO2, proficiently reduces the interaction energies between heavy oil and rock surfaces, as well as within heavy oil. A visualization analysis of the interactions reveals that strong van der Waals (vdW) attractions occur between CO2 and heavy oil molecules, effectively promoting the decomposition and swelling of heavy oil. This unlocks the residual oil on the hydrophobic surfaces. Considering the impacts of temperature and CO2 concentration, an optimal gas-to-steam injection ratio (here, the CO2: steam ratio) ranging between 1:6 and 1:9 is recommended. This study examines the microscopic mechanisms underlying the hybrid CO2 thermal technique at a molecular scale, providing a significant theoretical guide for its expanded application in EOR. |
| format | Article |
| id | doaj-art-92fb1b3f62de418187516b74c91cdf24 |
| institution | OA Journals |
| issn | 2666-7592 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Energy Geoscience |
| spelling | doaj-art-92fb1b3f62de418187516b74c91cdf242025-08-20T02:33:12ZengKeAi Communications Co., Ltd.Energy Geoscience2666-75922025-06-016210039410.1016/j.engeos.2025.100394Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulationsNing Lu0Xiaohu Dong1Haitao Wang2Huiqing Liu3Zhangxin Chen4Yu Li5Deshang Zeng6National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, T2N 1N4, CanadaNational Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; Corresponding author.Petroleum Exploration and Production Research Institute, SINOPEC, Beijing, 100083, ChinaNational Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, ChinaNational Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, T2N 1N4, Canada; Eastern Institute for Advanced Study, Ningbo, 315200, ChinaNational Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, ChinaNational Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, ChinaThe hybrid CO2 thermal technique has achieved considerable success globally in extracting residual heavy oil from reserves following a long-term steam stimulation process. Using microscopic visualization experiments and molecular dynamics (MD) simulations, this study investigates the microscopic enhanced oil recovery (EOR) mechanisms underlying residual oil removal using hybrid CO2 thermal systems. Based on the experimental models for the occurrence of heavy oil, this study evaluates the performance of hybrid CO2 thermal systems under various conditions using MD simulations. The results demonstrate that introducing CO2 molecules into heavy oil can effectively penetrate and decompose dense aggregates that are originally formed on hydrophobic surfaces. A stable miscible hybrid CO2 thermal system, with a high effective distribution ratio of CO2, proficiently reduces the interaction energies between heavy oil and rock surfaces, as well as within heavy oil. A visualization analysis of the interactions reveals that strong van der Waals (vdW) attractions occur between CO2 and heavy oil molecules, effectively promoting the decomposition and swelling of heavy oil. This unlocks the residual oil on the hydrophobic surfaces. Considering the impacts of temperature and CO2 concentration, an optimal gas-to-steam injection ratio (here, the CO2: steam ratio) ranging between 1:6 and 1:9 is recommended. This study examines the microscopic mechanisms underlying the hybrid CO2 thermal technique at a molecular scale, providing a significant theoretical guide for its expanded application in EOR.http://www.sciencedirect.com/science/article/pii/S2666759225000150Heavy oilHybrid CO2 thermal systemMicroscopic visualization experimentMolecular dynamics simulationMicroscopic mechanism |
| spellingShingle | Ning Lu Xiaohu Dong Haitao Wang Huiqing Liu Zhangxin Chen Yu Li Deshang Zeng Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations Energy Geoscience Heavy oil Hybrid CO2 thermal system Microscopic visualization experiment Molecular dynamics simulation Microscopic mechanism |
| title | Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations |
| title_full | Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations |
| title_fullStr | Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations |
| title_full_unstemmed | Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations |
| title_short | Hybrid CO2 thermal system for post-steam heavy oil recovery: Insights from microscopic visualization experiments and molecular dynamics simulations |
| title_sort | hybrid co2 thermal system for post steam heavy oil recovery insights from microscopic visualization experiments and molecular dynamics simulations |
| topic | Heavy oil Hybrid CO2 thermal system Microscopic visualization experiment Molecular dynamics simulation Microscopic mechanism |
| url | http://www.sciencedirect.com/science/article/pii/S2666759225000150 |
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