Density fluctuations and transport properties of supercritical carbon dioxide calculated by molecular dynamics simulation near the Widom line

Du, Yuntao; Liu, Lijun; Liao, Gaoliang; Zhang, Feng; Jiaqiang, E

doi:10.1016/j.supflu.2023.106003

Cited by 6 publications

(3 citation statements)

References 53 publications

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“…The rate of interface formation between the fluids is equal to the local pressure gradient, i.e. (Du et al, 2023;Iwasaki et al, 2023):…”

Section: Control Of Non-equilibrium State At the Interface During Gas...mentioning

confidence: 99%

Modelling of Internal Transformations of Gas Phase in Porous Media

Panahov

2024

AMMA

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The paper presents the research of temperature change in the investigated medium during dynamic expansion of gas (CO2) generated in reservoir conditions, diffusion of carbon dioxide into the displacing fluid and their influence on the displacement process. In-situ gas generation can provide a way to control the nonequilibrium fractal state at the interface under displacement in a porous medium. The change from fractal growth to non-fractal growth can be characterised as a function of density and viscosity ratios. This effect is shown in the increase of hydrocarbon displacement coefficient due to the equalisation of densities of displacing and displaced agents as a consequence of the increase in gas saturation of the fluid.

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“…The rate of interface formation between the fluids is equal to the local pressure gradient, i.e. (Du et al, 2023;Iwasaki et al, 2023):…”

Section: Control Of Non-equilibrium State At the Interface During Gas...mentioning

confidence: 99%

Modelling of Internal Transformations of Gas Phase in Porous Media

Panahov

2024

AMMA

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“…As an oil displacement agent to enhance oil recovery, CO 2 has attracted extensive attention in scientific research and engineering applications [ 13 , 14 , 15 ]. Existing studies have shown that CO 2 in the supercritical state exhibits the characteristics of gas-like viscosity and liquid-like solubility [ 16 ]. In most reservoir conditions, CO 2 exists in a supercritical state, which can reduce the viscosity of crude oil, improve the oil–water mobility ratio, and cause crude oil to expand.…”

Section: Introductionmentioning

confidence: 99%

Research Progress on Displacement Mechanism of Supercritical CO2 in Low-Permeability Heavy Oil Reservoir and Improvement Mechanism of Displacement Agents

Sun,

Zhang,

Tian

et al. 2023

Molecules

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With the continuous growth of global energy demand and the late stage of conventional oilfield exploitation, the demand for developing and utilizing low-permeability heavy oil reservoirs is becoming increasingly urgent. However, the exploitation of low-permeability heavy oil reservoirs faces many challenges due to their high viscosity, low permeability, and complex geological conditions. To overcome these challenges, researchers have gradually introduced SC-CO2 as an oil displacement agent in the exploitation of heavy oil reservoirs. However, the oil displacement mechanism of SC-CO2 in low-permeability heavy oil reservoirs and its improvement mechanism are still not completely understood. The article provides a detailed study and understanding of the oil displacement mechanism of SC-CO2, which involves the expansion of heavy oil volume through SC-CO2 dissolution. This mechanism reduces the capillary resistance and flow resistance during the oil flow process. The permeation of CO2 disrupts the internal structure and arrangement of heavy oil, reducing its viscosity. CO2 extracts both light and heavy components from the heavy oil, reducing the residual oil saturation. In addition, the mechanism of improving the effect of oil displacement agents such as nanoparticles, polymers, and surfactants on SC-CO2 displacement was also explored. By further exploring the mechanisms and improvement mechanisms of SC-CO2 displacement for heavy oil, it can guide the selection and optimization of oil displacement agents. Furthermore, understanding the mechanism can also provide a theoretical basis for engineering practice and technical innovation. While the research on CO2 flooding is analyzed and evaluated, the obstacles and challenges that still exist at this stage are indicated, and future research work on CO2 in low-permeability heavy oil reservoirs is proposed.

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“…Experimental techniques such as X-ray , and neutron scattering, vibration spectroscopy, − and NMR − often provide accurate and comprehensive data about the behavior of substances around their critical points, assisting in identifying the Widom line. Additionally, molecular dynamics (MD) simulations significantly contributed to the analysis of the Widom line in supercritical fluids, in particular, in water. − These simulations enable the observation of molecular behavior at the atomistic level, providing insights into the structural and dynamic properties of water under various conditions. MD simulations allow us to precisely track how the arrangement and movement of water molecules change as the temperature and pressure approach and cross the critical point.…”

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confidence: 99%

Widom Line in Supercritical Water in Terms of Changes in Local Structure: Theoretical Perspective

Shagurin,

Miannay,

Kiselev

et al. 2024

J. Phys. Chem. Lett.

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Performing molecular dynamics simulations with the TIP4P/2005 water model along 9 isobars (from 175 to 375 bar) in the temperature range between 300 and 1100 K, we have found that the loci of the extrema in the rate of change of specific structural properties can be used to define purely structure-based Widom lines. We have examined several parameters that describe the local structure of water, such as the tetrahedral arrangement, nearest neighbor distance, local density around the molecules, and the size of the largest dense domain. The last two parameters were determined using the Voronoi polyhedral and density-based spatial clustering of applications with noise methods, respectively. By analyzing the moments of the associated distributions, we show that along a given isobar, the temperature at which we observe a maximum in the fluctuation, the rate of change of the average values, or in the skewness values unambiguously determines the Widom line that is in agreement with the experimentally detected, thermodynamic response function-based ones.

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Density fluctuations and transport properties of supercritical carbon dioxide calculated by molecular dynamics simulation near the Widom line

Cited by 6 publications

References 53 publications

Modelling of Internal Transformations of Gas Phase in Porous Media

Modelling of Internal Transformations of Gas Phase in Porous Media

Research Progress on Displacement Mechanism of Supercritical CO2 in Low-Permeability Heavy Oil Reservoir and Improvement Mechanism of Displacement Agents

Widom Line in Supercritical Water in Terms of Changes in Local Structure: Theoretical Perspective

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