Molecular Modeling of CO 2 and n -Octane in Solubility Process and ? -Quartz Nanoslit

Jun Pu, Xuejie Qin, Feifei Gou, Wenchao Fang, Fengjie Peng, Runxi Wang and Zhaoli Guo
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Jun Pu: State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
Xuejie Qin: State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
Feifei Gou: State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
Wenchao Fang: State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
Fengjie Peng: School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
Runxi Wang: School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
Zhaoli Guo: School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China

Energies, 2018, vol. 11, issue 11, 1-11

Abstract: After primary and secondary oil recovery, CO 2 -enhanced oil recovery (EOR) has become one of the most mentioned technologies in tertiary oil recovery. Since the oil is confined in an unconventional reservoir, the interfacial properties of CO 2 and oil are different from in conventional reservoirs, and play a key role in CO 2 EOR. In this study, molecular dynamics simulations are performed to investigate the interfacial properties, such as interfacial tension, minimum miscibility pressure (MMP), and CO 2 solubility. The vanishing interfacial tension method is used to get the MMP (~10.8 MPa at 343.15 K) which is in agreement with the reported experimental data, quantitatively. Meanwhile, the diffusion coefficients of CO 2 and n -octane under different pressures are calculated to show that the diffusion is mainly improved at the interface. Furthermore, the displacement efficiency and molecular orientation in α -quartz nanoslit under different CO 2 injection ratios have been evaluated. After CO 2 injection, the adsorbed n -octane molecules are found to be displaced from surface by the injected CO 2 and, then, the orientation of n -octane becomes more random, which indicates that and CO 2 can enhance the oil recovery and weaken the interaction between n -octane and α -quartz surface. The injection ratio of CO 2 to n -octane is around 3:1, which could achieve the optimal displacement efficiency.

Keywords: CO 2 -enhanced oil recovery; n -octane; ? -quartz pore; minimum miscibility pressure; molecular dynamics simulation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
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