Adsorption induced critical shifts of confined fluids in shale nanopores

Song, Zhaojie; Song, Yilei; Guo, Jia; Zhang, Zhuoya; Hou, Jirui

doi:10.1016/j.cej.2019.123837

Cited by 50 publications

(36 citation statements)

References 40 publications

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“…Equations ( 11) and ( 12) exhibit that fluidwall interaction and adsorption effect influence the critical pressure and critical temperature in nanopores. It has been reported that the pore size r p and collision diameter σ LJ (Lennard-Jones molecular size parameter) are the important factors on shifts of critical pressure and critical temperature [27,31]…”

Section: ∂P ∂Vmentioning

confidence: 99%

“…Sandoval et al [30] explored the adsorption effect on the fluid phase behavior in nanopores and incorporated the adsorption film thickness into the calculation of the effective capillary radius. Song et al [31] introduced a novel method for describing fluid adsorption in nanopores by modifying the molar volume term in PR-EOS and showed that adsorption induced critical shifts of confined fluids in nanopores.…”

Section: Introductionmentioning

confidence: 99%

“…As mentioned above, nanopore confinement effects including capillary pressure, fluid-wall interaction, and molecule adsorption cannot be ignored in porous media with pore diameters less than 50 nm and greater than 2 nm [32][33][34]. Although numerous models have been proposed to explore the phase behavior in nanopores, they focused on one or both aspects of nanoscale confinement [23][24][25][26][27][28][29][30][31], and there still lack an accurate model that takes into account capillary pressure, fluid-wall interaction, and adsorption effect simultaneously. Additionally, despite methods being there to investigate nanopore confinement effect, only a few of them have studies the influence of nanopore confinement effect on CO 2 injection recovery mechanisms in tight oil reservoirs.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

Zheng

2021

Geofluids

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The pore sizes in tight reservoirs are nanopores, where the phase behavior deviates significantly from that of bulk fluids in conventional reservoirs. The phase behavior for fluids in tight reservoirs is essential for a better understanding of the mechanics of fluid flow. A novel methodology is proposed to investigate the phase behavior of carbon dioxide (CO2)/hydrocarbons systems considering nanopore confinement. The phase equilibrium calculation is modified by coupling the Peng-Robinson equation of state (PR-EOS) with capillary pressure, fluid-wall interaction, and molecule adsorption. The proposed model has been validated with CMG-Winprop and experimental results with bulk and confined fluids. Subsequently, one case study for the Bakken tight oil reservoir was performed, and the results show that the reduction in the nanopore size causes noticeable difference in the phase envelope and the bubble point pressure is depressed due to nanopore confinement, which is conductive to enhance oil recovery with a higher possibility of achieving miscibility in miscible gas injection. As the pore size decreases, the interfacial tension (IFT) decreases whereas the capillary pressure increases obviously. Finally, the recovery mechanisms for CO2 injection are investigated in terms of minimum miscibility pressure (MMP), solution gas-oil ratio, oil volume expansion, viscosity reduction, extraction of lighter hydrocarbons, and molecular diffusion. Results indicate that nanopore confinement effect contributes to decrease MMP, which suppresses to 650 psi (65.9% smaller) as the pore size decreases to 2 nm, resulting in the suppression of the resistance of fluid transport. With the nanopore confinement effect, the CO2 solution gas-oil ratio and the oil formation volume factor of the oil increase with the decrease of pore size. In turn, the oil viscosity reduces as the pore size decreases. It indicates that considering the nanopore confinement effect, the amount of gas dissolved into crude oil increases, which will lead to the increase of the oil volume expansion and the decrease of the viscosity of crude oil. Besides, considering nanopore confinement effect seems to have a slightly reduced effect on extraction of lighter hydrocarbons. On the contrary, it causes an increase in the CO2 diffusion coefficient for liquid phase. Generally, the nanopore confinement appears to have a positive effect on the recovery mechanisms for CO2 injection in tight oil reservoirs. The developed novel model could provide a better understanding of confinement effect on the phase behavior of nanoscale porous media in tight reservoirs. The findings of this study can also help for better understanding of a flow mechanism of tight oil reservoirs especially in the case of CO2 injection for enhancing oil recovery.

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Section: ∂P ∂Vmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

Zheng

2021

Geofluids

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“…Previous studies have demonstrated that the pore size and LJ size diameter are the key parameters to determine the shift of critical temperature. 6,7,29 Furthermore, the linear relationship in a log−log scale is found to be useful to describe the relationship between the dimensionless shift of critical temperature, ΔT, and the normalized pore dimension, m, which is the ratio of the pore radius to the LJ size parameter. 7,29 Meanwhile, MD simulations have shown the difference between ΔT in cylindrical nanopores and that in slit nanopores with the same pore dimension.…”

Section: ■ Introductionmentioning

confidence: 99%

“…6,7,29 Furthermore, the linear relationship in a log−log scale is found to be useful to describe the relationship between the dimensionless shift of critical temperature, ΔT, and the normalized pore dimension, m, which is the ratio of the pore radius to the LJ size parameter. 7,29 Meanwhile, MD simulations have shown the difference between ΔT in cylindrical nanopores and that in slit nanopores with the same pore dimension. 44 Therefore, the ΔT as a function of normalized pore dimension, m, in cylindrical nanopores and slit nanopores can be separately expressed as…”

Section: ■ Introductionmentioning

confidence: 99%

Nanoconfinement Effect on Surface Tension: Perspectives from Molecular Potential Theory

Feng

Bakhshian

et al. 2020

Langmuir

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Liquid–vapor surface tension (ST) in nanopores attracts great attention in many industries because of the prosperity of nanoscience and nanotechnology. Here, considering the important emerging new physical phenomena induced by nanoconfinement effects, including curvature-dependent and shift-critical temperature (T c)-dependent effects, the anomalous variation of ST in nanopores is captured from the molecular potential perspective. Furthermore, a simple analytical model is proposed to determine the ST in nanopores by correlating these two effects with an easily accessible parameter, that is, normalized pore dimension, which is the ratio of the pore radius to Lennard-Jones size parameter. The model is validated to be reliable for determining the STs of different substances both in the bulk phase as well as nanopores through comparison with the experimental results and molecular simulations. Our results show that the reduction of ST induced by the nanoconfinement effects is visible when the pore diameter is within tens of nanometers, and the reduction is more sensitive as the pore size decreases. In detail, the curvature-dependent effect is remarkable in the pores with diameters ranging from a few nanometers to tens of nanometers. Moreover, a simply generalized formula is obtained to determine the curvature-dependent effect and the Tolman length for different substances. The shift-T c-dependent effect is not only related to the pore dimension but also depends on the temperature. As the pore size decreases, the critical temperature of confined fluids diverges significantly from the bulk values. While at high temperatures, the range of pore size impacted by the shift-Tc-dependent effect is enlarged. Additionally, the nanoconfined STs of different substances are calculated and compared. Overall, the new model captures the underlying physics behind the variation of STs in nanopores and can determine the nanoconfined STs reasonably. Moreover, the simple formulation of the model is beneficial to the practical applications in many chemical engineering processes, such as chemical separation, nucleation phenomenon, and capillary condensation.

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Semiempirical equations of state of H2O/CO2 binary mixtures in graphite nanoslits

Zhao

Sun

et al. 2023

Sci. China Phys. Mech. Astron.

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Adsorption induced critical shifts of confined fluids in shale nanopores

Cited by 50 publications

References 40 publications

Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

Nanoconfinement Effect on Surface Tension: Perspectives from Molecular Potential Theory

Semiempirical equations of state of H2O/CO2 binary mixtures in graphite nanoslits

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