Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration
Abstract CO2 enhanced oil recovery plays an important role in carbon storage and utilization. However, the incomplete understanding of the underlying microscopic convection–diffusion mechanisms in complex pore structures has constrained the broader industrial application of CO2 geo-sequestration. Th...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-06-01
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| Series: | International Journal of Coal Science & Technology |
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| Online Access: | https://doi.org/10.1007/s40789-025-00793-2 |
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| author | Xiangjie Qin Han Wang Jinsui Wu Gang Wang David A. Wood Jianchao Cai |
| author_facet | Xiangjie Qin Han Wang Jinsui Wu Gang Wang David A. Wood Jianchao Cai |
| author_sort | Xiangjie Qin |
| collection | DOAJ |
| description | Abstract CO2 enhanced oil recovery plays an important role in carbon storage and utilization. However, the incomplete understanding of the underlying microscopic convection–diffusion mechanisms in complex pore structures has constrained the broader industrial application of CO2 geo-sequestration. This work develops a pore-scale numerical model considering molecular convection–diffusion to investigate CO2-oil miscible displacement in two- and three-dimensional porous structures of conglomerate rocks. The effects of CO2 injection rates and pore structure properties on convection–diffusion are analyzed. By reconstructing the distribution of unexploited pores, the CO2 sweep efficiency is quantitatively evaluated. Furthermore, a sequestration factor is proposed to evaluate the CO2 storage capacity during miscible displacement. Convection significantly enhances the CO2 mass fraction in fractures with high flow rates. Subsequently, CO2 gradually diffuses into matrix pores without velocity distribution. Both convection and diffusion contribute to improving CO2 displacement efficiency. Diffusion facilitates the dissolution of CO2 into oil within small-diameter pores, and convection effectively mobilizes oil in large pore bodies. Developed and homogeneous pore structures enhance CO2 displacement efficiency, whereas CO2 flows along the main flow channels in heterogeneous pore structures, resulting in lower displacement efficiency. Diffusion plays a crucial role in CO2 storage within porous media. At low injection rates, dissolved CO2 is trapped in poorly connected and blind-end pores. The injection rate is negatively correlated with the sequestration factor. |
| format | Article |
| id | doaj-art-6370e42cec894e0d8cfc818f3dae30d9 |
| institution | OA Journals |
| issn | 2095-8293 2198-7823 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | International Journal of Coal Science & Technology |
| spelling | doaj-art-6370e42cec894e0d8cfc818f3dae30d92025-08-20T02:06:23ZengSpringerOpenInternational Journal of Coal Science & Technology2095-82932198-78232025-06-0112111910.1007/s40789-025-00793-2Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestrationXiangjie Qin0Han Wang1Jinsui Wu2Gang Wang3David A. Wood4Jianchao Cai5State Key Laboratory of Petroleum Resources and Engineering, China University of PetroleumState Key Laboratory of Petroleum Resources and Engineering, China University of PetroleumDepartment of Management Science and Engineering, Khalifa UniversityCollege of Safety and Environmental Engineering, Shandong University of Science and TechnologyDWA Energy LimitedState Key Laboratory of Petroleum Resources and Engineering, China University of PetroleumAbstract CO2 enhanced oil recovery plays an important role in carbon storage and utilization. However, the incomplete understanding of the underlying microscopic convection–diffusion mechanisms in complex pore structures has constrained the broader industrial application of CO2 geo-sequestration. This work develops a pore-scale numerical model considering molecular convection–diffusion to investigate CO2-oil miscible displacement in two- and three-dimensional porous structures of conglomerate rocks. The effects of CO2 injection rates and pore structure properties on convection–diffusion are analyzed. By reconstructing the distribution of unexploited pores, the CO2 sweep efficiency is quantitatively evaluated. Furthermore, a sequestration factor is proposed to evaluate the CO2 storage capacity during miscible displacement. Convection significantly enhances the CO2 mass fraction in fractures with high flow rates. Subsequently, CO2 gradually diffuses into matrix pores without velocity distribution. Both convection and diffusion contribute to improving CO2 displacement efficiency. Diffusion facilitates the dissolution of CO2 into oil within small-diameter pores, and convection effectively mobilizes oil in large pore bodies. Developed and homogeneous pore structures enhance CO2 displacement efficiency, whereas CO2 flows along the main flow channels in heterogeneous pore structures, resulting in lower displacement efficiency. Diffusion plays a crucial role in CO2 storage within porous media. At low injection rates, dissolved CO2 is trapped in poorly connected and blind-end pores. The injection rate is negatively correlated with the sequestration factor.https://doi.org/10.1007/s40789-025-00793-2Pore-scale simulationCO2 miscible displacementPorous mediaConvection and diffusion |
| spellingShingle | Xiangjie Qin Han Wang Jinsui Wu Gang Wang David A. Wood Jianchao Cai Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration International Journal of Coal Science & Technology Pore-scale simulation CO2 miscible displacement Porous media Convection and diffusion |
| title | Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration |
| title_full | Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration |
| title_fullStr | Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration |
| title_full_unstemmed | Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration |
| title_short | Pore-scale evaluation of CO2 miscible displacement in porous rocks induced by convection and diffusion: implications for CO2 geo-sequestration |
| title_sort | pore scale evaluation of co2 miscible displacement in porous rocks induced by convection and diffusion implications for co2 geo sequestration |
| topic | Pore-scale simulation CO2 miscible displacement Porous media Convection and diffusion |
| url | https://doi.org/10.1007/s40789-025-00793-2 |
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