Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process
Abstract Due to the confinement effect of nanopores, the fluid-phase behavior of shale oil reservoirs is much different from that of conventional reservoirs. The accurate description of the phase change characteristics of fluid in nanopores is the basis to design development plan, production system,...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2023-12-01
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| Series: | Journal of Petroleum Exploration and Production Technology |
| Subjects: | |
| Online Access: | https://doi.org/10.1007/s13202-023-01730-2 |
| _version_ | 1797259514380025856 |
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| author | Xiangji Dou Yisong Zhang Jing Guo Kun Qian |
| author_facet | Xiangji Dou Yisong Zhang Jing Guo Kun Qian |
| author_sort | Xiangji Dou |
| collection | DOAJ |
| description | Abstract Due to the confinement effect of nanopores, the fluid-phase behavior of shale oil reservoirs is much different from that of conventional reservoirs. The accurate description of the phase change characteristics of fluid in nanopores is the basis to design development plan, production system, and EOR methods of shale oil reservoirs. In this study, molecular dynamics simulation was employed to analyze the phase behavior of single-component system and hydrocarbon–CO2 mixture system in organic nanopores. The results show that the confinement effect on the phase change pressure of the single-component system is influenced by the distribution of the electron cloud. The phase change pressure of hydrocarbons with even distribution of the electron cloud would be increased, while that of CO2 would be decreased due to the instantaneous dipole moment. In addition, as the length of carbon chains increases, the confinement effect on hydrocarbons becomes stronger. When the temperature increases, the confinement effect becomes weaker. In the hydrocarbon–CO2 mixture system, when the occurrence condition changes from bulk to the nanopore of 5 nm, the bubble point pressure decreases by 39.21–68.85%, and the critical temperature and pressure decrease by 75.98% and 7.13%, respectively. On the whole, the P–T phase envelope is shrunken under the confinement effect. CO2 is much easier to be miscible with shale oil in nanopores. Moreover, full mixing and keeping in single liquid phase of CO2–hydrocarbons mixture system can reduce the adsorption of hydrocarbons on organic pore walls. Therefore, CO2 injection could be a feasible method to enhance oil recovery in the matrix of shale oil reservoirs. |
| first_indexed | 2024-04-24T23:10:38Z |
| format | Article |
| id | doaj.art-983b04dcb4a84ad2bf99902e2439b2f4 |
| institution | Directory Open Access Journal |
| issn | 2190-0558 2190-0566 |
| language | English |
| last_indexed | 2024-04-24T23:10:38Z |
| publishDate | 2023-12-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of Petroleum Exploration and Production Technology |
| spelling | doaj.art-983b04dcb4a84ad2bf99902e2439b2f42024-03-17T12:16:13ZengSpringerOpenJournal of Petroleum Exploration and Production Technology2190-05582190-05662023-12-0114374575910.1007/s13202-023-01730-2Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection processXiangji Dou0Yisong Zhang1Jing Guo2Kun Qian3School of Petroleum and Natural Gas Engineering, Changzhou UniversitySchool of Petroleum and Natural Gas Engineering, Changzhou UniversitySchool of Petroleum and Natural Gas Engineering, Changzhou UniversitySchool of Petroleum and Natural Gas Engineering, Changzhou UniversityAbstract Due to the confinement effect of nanopores, the fluid-phase behavior of shale oil reservoirs is much different from that of conventional reservoirs. The accurate description of the phase change characteristics of fluid in nanopores is the basis to design development plan, production system, and EOR methods of shale oil reservoirs. In this study, molecular dynamics simulation was employed to analyze the phase behavior of single-component system and hydrocarbon–CO2 mixture system in organic nanopores. The results show that the confinement effect on the phase change pressure of the single-component system is influenced by the distribution of the electron cloud. The phase change pressure of hydrocarbons with even distribution of the electron cloud would be increased, while that of CO2 would be decreased due to the instantaneous dipole moment. In addition, as the length of carbon chains increases, the confinement effect on hydrocarbons becomes stronger. When the temperature increases, the confinement effect becomes weaker. In the hydrocarbon–CO2 mixture system, when the occurrence condition changes from bulk to the nanopore of 5 nm, the bubble point pressure decreases by 39.21–68.85%, and the critical temperature and pressure decrease by 75.98% and 7.13%, respectively. On the whole, the P–T phase envelope is shrunken under the confinement effect. CO2 is much easier to be miscible with shale oil in nanopores. Moreover, full mixing and keeping in single liquid phase of CO2–hydrocarbons mixture system can reduce the adsorption of hydrocarbons on organic pore walls. Therefore, CO2 injection could be a feasible method to enhance oil recovery in the matrix of shale oil reservoirs.https://doi.org/10.1007/s13202-023-01730-2Shale oilConfinement effectPhase behaviorMolecular simulationCO2 injection |
| spellingShingle | Xiangji Dou Yisong Zhang Jing Guo Kun Qian Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process Journal of Petroleum Exploration and Production Technology Shale oil Confinement effect Phase behavior Molecular simulation CO2 injection |
| title | Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process |
| title_full | Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process |
| title_fullStr | Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process |
| title_full_unstemmed | Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process |
| title_short | Investigation of the confinement effect on fluid-phase behavior in shale oil reservoirs during CO2 injection process |
| title_sort | investigation of the confinement effect on fluid phase behavior in shale oil reservoirs during co2 injection process |
| topic | Shale oil Confinement effect Phase behavior Molecular simulation CO2 injection |
| url | https://doi.org/10.1007/s13202-023-01730-2 |
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