Experimental Study on the Criticality of a Methane/Ethane Mixture Confined in Nanoporous Media

Qiu, Xingdong; Tan, Sugata P.; Dejam, Morteza; Adidharma, Hertanto

doi:10.1021/acs.langmuir.9b01399

Cited by 40 publications

(44 citation statements)

References 49 publications

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“…30,31 The detailed information of the experimental apparatus used can be found elsewhere. 50 The nanopores are kept in a drying oven at 393 K for at least 24 h before the DSC measurement. Prior to each measurement, a certain amount of nanopores is introduced into the test vessel using a small spatula.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Before DSC measurements, the nanopores are characterized using standard N 2 adsorption measurement at 77 K. 30 Both SBA-15 and KIT-6 are purchased from Advanced Chemicals Supplier and used without further treatment. The SBA-15 samples used in this work are referred to as S2 and S3 in our previous work, 50 while the KIT-6 sample is used for the first time. For convenience, the main physical properties of the nanopores are summarized in Table 1.…”

Section: Introductionmentioning

confidence: 99%

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Experiments on the Capillary Condensation/Evaporation Hysteresis of Pure Fluids and Binary Mixtures in Cylindrical Nanopores

et al. 2021

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A new experimental method, i.e., isochoric cooling/heating cycle measurement using differential scanning calorimetry (DSC), is applied to investigate the hysteretic phenomenon of pure components and mixtures confined in two different types of cylindrical nanopores (SBA-15 and KIT-6). The capillary condensation/evaporation hysteresis end point T he for a specific system is determined by performing a series of measurements with different densities by increasing initial temperature and pressure. We confirm that for a pure component, T he is lower when confined in smaller nanopores, whereas the T he values for CH4/CO2 and CH4/C2H6 mixtures at the specific composition investigated are higher than those of pure CO2 and C2H6, respectively, when confined in the same nanopores. To the best of our knowledge, this is the first time that T he of fluid mixture is experimentally studied, which further demonstrates that binary mixtures behave similarly to pure fluids when confined in nanoporous media. At low temperatures, where hysteresis is observed, the shape as well as the duration of the exothermic peak (due to capillary condensation) and endothermic peak (due to capillary evaporation) indicate that capillary condensation, rather than capillary evaporation, takes place at/near thermodynamic equilibrium. Within the accuracy of the measurements, we find that the total heat of capillary condensation is identical to that of capillary evaporation for all systems examined, regardless of the presence of hysteresis. By comparing the heat per unit volume among different systems, we also find that the heat per unit volume of the phase transition of confined pure fluid is lower than that of bulk, which further demonstrates that at the same temperature the molar density of confined pure liquid is less than that of bulk pure liquid at saturation.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experiments on the Capillary Condensation/Evaporation Hysteresis of Pure Fluids and Binary Mixtures in Cylindrical Nanopores

et al. 2021

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“…The fatal deficiency of the experimental method is the limitation of atmosphere pressure, the shale gas reservoirs have fairly high pressure; however, current experimental devices are hard to achieve and remain it. Additionally, the data accuracy measured from experimental investigation heavily depends on apparatus up to date (Qiu et al 2019;Ji et al 2021a, b;Zhao et al 2019;Zhao and Huang 2021) and is still unfavorable, especially for the nanoscale experiments. In contrast, on the basis of relative mature theory and reasonable assumptions, a lot of analytical models have been proposed to capture multiple gas flow mechanisms or fluid storage modes inside both shale organic/inorganic matrix, encompassing gas adsorption, surface diffusion, water distribution features, wall roughness (Sheikholeslami et al, 2020(Sheikholeslami et al, , 2021a(Sheikholeslami et al, , 2021b.…”

Section: Introductionmentioning

confidence: 99%

Nanoconfined methane flow behavior through realistic organic shale matrix under displacement pressure: a molecular simulation investigation

Sun

Huang

et al. 2021

J Petrol Explor Prod Technol

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Academic investigations digging into the methane flow mechanisms at the nanoscale, closely related to development of shale gas reservoirs, had attracted tremendous interest in the past decade. At the same time, a good understanding of the complex essence remains challenging, while the broad theoretical scope, as well as application value, possesses great attraction. In this work, with the help of molecular dynamics methods nested in LAMMPS software, a fundamental framework is established to mimic the nanoconfined fluid flow through realistic organic shale matrix. Denoting evident discrepancy with existed contributions, shale matrix in this work is composed of specific number of kerogen molecules, rather than simple carbon-based nanotube. Recently, promotion efforts have been implemented in the academic community with the use of kerogen molecules, however, gas flow simulations are still lacking, and the pore shape in the current papers is always hypothesized as slit pores. The pore-geometry assumption seriously conflicts with the general observation phenomenon according to the advanced laboratory experiments, such as SEM image, AFM technology, that the organic pores tend to have circular pore geometry. In order to fill the knowledge gap, the circular nanopore with desirable pore size surrounded by kerogen molecules is constructed at first. The organic nanopore with various thermal maturity can be obtained by altering the kerogen molecular type, expecting to achieve more physically and theoretically similar to the realistic shale matrix. After that, methane flow simulation is performed by utilization of non-equilibrium molecular dynamics, the methane density as well as velocity distribution under different displacement pressures are depicted. Furthermore, detailed discussion with respect to the simulation results is provided. Results show that (a) displacement pressure acts as a dominant role affecting methane flow velocity and, however, fails to affect methane density distribution, a behavior mainly controlled by molecular–wall interactions; (b) the velocity distribution feature appears to be in line with the parabolic law under high atmosphere pressure, which can be attributed to small Knudsen number; (c) the simulation time will be prolonged with larger displacement pressure imposed on nanoconfined methane. Accordingly, this work can provide profound basis for accurate evaluation of nanoconfined gas flow behavior through shale matrix.

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“…In addition to capillary pressure, the strong wallmolecul interactions present in nanopores also alter the critical point of the constituting components in reservoir fluids [41]. An analytical solution to express the critical point shift due to the confinement effect was originally proposed by Zarragoicoechea and Kuz [34].…”

Section: Methodsmentioning

confidence: 99%

A modified cell-to-cell simulation model to determine the minimum miscibility pressure in tight/shale formations

Sun

2021

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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A new oil–gas Minimum Miscibility Pressure (MMP) calculation algorithm is developed in this work based on the classic cell-to-cell simulation model. The proposed algorithm couples the effects of capillary pressure and confinement in the original cell-to-cell simulation model to predict the oil–gas MMPs in a confined space. Given that the original cell-to-cell algorithm relies on the volume predictions of the reservoir fluids in each cell, a volume-translated Peng-Robinson Equation of State (PR-EOS) is applied in this work for improved accuracy on volume calculations of the reservoir fluids. The robustness of the proposed algorithm is examined by performing the confined MMP calculations for four oil–gas systems. The tie-line length extrapolation method is used to determine the oil–gas MMP in confined space. The oil recovery factor calculated by the proposed MMP calculation algorithm is then used to validate the results. First, to achieve stable modeling results for all four examples, a total cell number of 500 is determined by examining the variations in the oil recovery as a function of cell number. Then, by calculating the oil recovery factor near the MMP region, it is found that the MMP determined by tie-line length method is slightly lower than the inflection point of the oil recovery curve. Through the case studies, the effects of temperature, pore radius, and injection gas impurity on the confined oil–gas MMP calculations are studied in detail. It is found that the oil–gas MMP is reduced in confined space and the degree of this reduction depends on the pore radius. For all the tested pore radii, the confined MMP first increases and then decreases with an increasing temperature. Furthermore, compared to pure carbon dioxide (CO2) injection, the addition of methane (CH4) in the injection gas increases the oil–gas MMP in confined nanopores. Therefore, it is recommended to control the content of CH4 in the injection gas in order to achieve a more efficient gas injection design.

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Experimental Study on the Criticality of a Methane/Ethane Mixture Confined in Nanoporous Media

Cited by 40 publications

References 49 publications

Experiments on the Capillary Condensation/Evaporation Hysteresis of Pure Fluids and Binary Mixtures in Cylindrical Nanopores

Experiments on the Capillary Condensation/Evaporation Hysteresis of Pure Fluids and Binary Mixtures in Cylindrical Nanopores

Nanoconfined methane flow behavior through realistic organic shale matrix under displacement pressure: a molecular simulation investigation

A modified cell-to-cell simulation model to determine the minimum miscibility pressure in tight/shale formations

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