Nanoconfinement-induced alterations of CO2-oil IFT and MMP in shale reservoirs, incorporating sorption, capillarity, and critical property shifts

Authors

  • Lijun He College of Energy, Chengdu University of Technology
  • Professor Heng Wang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology
  • Haolin Zhuo College of Energy, Chengdu University of Technology
  • Guoyou Ren College of Energy, Chengdu University of Technology
  • Chengyang Li College of Energy, Chengdu University of Technology
  • Mancero Hidalgo Sebastian Andres College of Energy, Chengdu University of Technology

DOI:

https://doi.org/10.62813/see.2026.01.02

Keywords:

CO2 EOR, Nanoconfinement effect, Adsorption thickness, Critical properties, Interfacial tension, Minimum miscibility pressure

Abstract

Phase behavior and miscibility during CO2 flooding for shale oil reservoirs would deviate from bulk conditions due to nanoconfinement. Besides, competitive adsorption between CO2 and alkanes on pore surfaces affects the adsorption layer thickness, often overlooked in previous studies. In this research, a thermodynamic model considering the nanoconfinement and CO2 adsorption is developed to predict the interfacial tension (IFT) and minimum miscibility pressure (MMP) using the vanishing interfacial tension (VIT) method. First, the critical properties of the bulk fluid that are essential for determining the adsorption layer thickness were predicted using the modified Kreglewski and Li (KL) method. Then, the effect of CO2 on the adsorption thickness of CO2-alkane mixtures in nanopores was analyzed under different alkane types and compositions. Results indicate that CO2 adsorption induces pronounced thinning of the adsorption layer in nanopores for longer-chain alkanes and higher CO2 fraction cases. Thereafter, the corrected adsorption thickness is incorporated into the Peng-Robinson equation of state (PR-EOS) to predict the IFT and MMP of CO2-alkane mixtures and shale oil systems. It’s found that nanoconfinement, especially critical property shifts, significantly reduces IFT and MMP compared with bulk conditions. The predicted MMP increases with alkane chain length and pore size, shows a nonmonotonic dependence on temperature, and approaches bulk values for pore radius that exceeds 10 nm. This study sheds light on CO2 miscible flooding in shale oil reservoirs.

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Additional Files

Published

2026-09-09

How to Cite

He, L., Wang, H., Zhuo, H., Ren, G., Li, C., & Sebastian Andres, M. H. (2026). Nanoconfinement-induced alterations of CO2-oil IFT and MMP in shale reservoirs, incorporating sorption, capillarity, and critical property shifts. Subsurface Exploration and Exploitation, 3, 1–12. https://doi.org/10.62813/see.2026.01.02

Issue

Vol. 3 (2026): SEE

Section

Articles

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Copyright (c) 2026 Lijun He, Professor Heng Wang, Haolin Zhuo, Guoyou Ren, Chengyang Li; Mancero Hidalgo Sebastian Andres

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