Pore-Scale Simulations of CO2/Oil Flow Behavior in Heterogeneous Porous Media under Various Conditions

Miscible and near-miscible flooding are used to improve the performance of carbon-dioxide-enhanced oil recovery in heterogeneous porous media. However, knowledge of the effects of heterogeneous pore structure on CO2/oil flow behavior under these two flooding conditions is insufficient. In this study...

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Bibliographic Details
Published in:Energies (Basel) 2021-02, Vol.14 (3), p.533
Main Authors: Ma, Qingsong, Zheng, Zhanpeng, Fan, Jiarui, Jia, Jingdong, Bi, Jingjing, Hu, Pei, Wang, Qilin, Li, Mengxin, Wei, Wei, Wang, Dayong
Format: Article
Language:English
Subjects:
Carbon dioxide
CO2-EOR
Contact angle
Efficiency
Enhanced oil recovery
Environmental policy
Flooding
Fluids
heterogeneous porous media
immiscible flooding
Injection
Interfaces
Miscibility
miscible flooding
Oil
Oil fields
Oil recovery
Permeability
pore-scale simulation
Porosity
Porous media
Velocity
Viscosity
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Summary:Miscible and near-miscible flooding are used to improve the performance of carbon-dioxide-enhanced oil recovery in heterogeneous porous media. However, knowledge of the effects of heterogeneous pore structure on CO2/oil flow behavior under these two flooding conditions is insufficient. In this study, we construct pore-scale CO2/oil flooding models for various flooding methods and comparatively analyze CO2/oil flow behavior and oil recovery efficiency in heterogeneous porous media. The simulation results indicate that compared to immiscible flooding, near-miscible flooding can increase the CO2 sweep area to some extent, but it is still inefficient to displace oil in small pore throats. For miscible flooding, although CO2 still preferentially displaces oil through big throats, it may subsequently invade small pore throats. In order to substantially increase oil recovery efficiency, miscible flooding is the priority choice; however, the increase of CO2 diffusivity has little effect on oil recovery enhancement. For immiscible and near-miscible flooding, CO2 injection velocity needs to be optimized. High CO2 injection velocity can speed up the oil recovery process while maintaining equivalent oil recovery efficiency for immiscible flooding, and low CO2 injection velocity may be beneficial to further enhancing oil recovery efficiency under near-miscible conditions.
ISSN:1996-1073
1996-1073
DOI:10.3390/en14030533