Molecular simulation of the constant composition expansion experiment in shale multi-scale systems

Bi, Ran; Nasrabadi, Hadi

doi:10.1016/j.fluid.2019.04.026

Cited by 34 publications

(18 citation statements)

References 53 publications

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“…Currently, lots of approaches have been employed to address the problem, which can be classified as two types, i.e., molecular simulation and analytical model. When the rarefied effect becomes evident, an alternative method to continuum flow is the molecular simulation, which recognizes the fluid as a swarm of discrete particles (Bi and Nasrabadi 2019;Chen and Doolen 1998;Loyalka and Hamoodi 1990;Adzumi 1937a). In the molecular simulation, the position, inertia and the state of all individual particles are calculated either deterministically or probabilistically at all times.…”

Section: Introductionmentioning

confidence: 99%

A non-empirical model for gas transfer through circular nanopores in unconventional gas reservoirs

Wei

Ji³

et al. 2021

J Petrol Explor Prod Technol

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It is difficult to predict the flow performance in the nanopore networks since traditional assumptions of Navier–Stokes equation break down. At present, lots of attempts have been employed to address the proposition. In this work, the advantages and disadvantages of previous analytical models are seriously analyzed. The first type is modifying a mature equation which is proposed for a specified flow regime and adapted to wider application scope. Thus, the first-type models inevitably require empirical coefficients. The second type is weight superposition based on two different flow mechanisms, which is considered as the reasonable establishment method for universal non-empirical gas-transport model. Subsequently, in terms of slip flow and Knudsen diffusion, the novel gas-transport model is established in this work. Notably, the weight factors of slip flow and Knudsen diffusion are determined through Wu’s model and Knudsen’s model respectively, with the capacity to capture key transport mechanism through nanopores. Capturing gas flow physics at nanoscale allows the proposed model free of any empirical coefficients, which is also the main distinction between our work and previous research. Reliability of proposed model is verified by published molecular simulation results as well. Furthermore, a novel permeability model for coal/shale matrix is developed based on the non-empirical gas-transport model. Results show that (a) nanoconfined gas-transport capacity will be strengthened with the decline of pressure and the decrease in the pressure is supportive for the increasing amplitude; (b) the greater pore size the nanopores is, the stronger the transport capacity the nanotube is; (c) after field application with an actual well in Fuling shale gas field, China, it is demonstrated that numerical simulation coupled with the proposed permeability model can achieve better historical match with the actual production performance. The investigation will contribute to the understanding of nanoconfined gas flow behavior and lay the theoretical foundation for next-generation numerical simulation of unconventional gas reservoirs.

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Section: Introductionmentioning

confidence: 99%

A non-empirical model for gas transfer through circular nanopores in unconventional gas reservoirs

Wei

Ji³

et al. 2021

J Petrol Explor Prod Technol

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“…Monte Carlo (MC) molecular simulations have been widely used to support experiments and validate theoretical models for the investigation of fluid phase behavior under confinement [18,[20][21][22][23][24][25]. The inhomogeneous molecular distribution and the fluid-pore interactions of different absorbents and hydrocarbons are more accurately described at the molecular level by MC methods in contrast to theoretical models.…”

Section: Introductionmentioning

confidence: 99%

Confinement-mediated phase behavior of hydrocarbon fluids: Insights from Monte Carlo simulations

Li¹,

Rao²,

Xia³

et al. 2020

Preprint

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The phase behavior of hydrocarbon fluids confined in porous media has been reported to deviate significantly from that in the bulk environment due to the existence of sub-10nm pores. Though experiments and simulations have measured the bubble/dew points and sorption isotherms of hydrocarbons confined in both natural and synthetic nanopores, the confinement effects in terms of the strength of fluid-pore interactions tuned by surface wettability and chemistry have received comparably less discussion. More importantly, the underlying physics of confinement-induced phenomena remain obfuscated. In this work, we studied the phase behavior and capillary condensation of n-hexane to understand the effects of confinement at the molecular level. To systematically investigate the pore effects, we constructed two types of wall confinements; one is a structureless virtual wall described by the Steele potential and the other one is an all-atom amorphous silica structure with surface modified by hydroxyl groups. Our numerical results demonstrated the importance of fluid-pore interaction, pore size, and pore morphology effects in mediating the pressure-volume-temperature (PVT) properties of hydrocarbons. The most remarkable finding of this work was that the saturation pressure predicted from the van der Waals-type adsorption isothermal loop could be elevated or suppressed relative to the bulk phase, as illustrated in the graphical abstract. As the * Approved for public release

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“…In confinement, forces of solid-fluid and fluid-fluid interactions significantly affect surface phenomena such as capillary condensation, layering transitions, adsorption [10][11][12]. Besides, even a small concentration of energetically more potent particles can significantly change fluid behavior in confinement [13,14]. To study fluid mixture in pores, it is crucial to consider the following phenomena: selectivity --the relation of component concentration in the pore and the bulk and segregation --composition difference between fluid near the pore wall and in the pore center [15][16][17][18].…”

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confidence: 99%

“…Presently, the behavior of fluid mixtures at the molecular scale is mainly studied using Molecular Dynamics (MD) [5,6,42,43], Statistical Associating Fluid Theory (SAFT) [23,[44][45][46][47], Grand Canonical Monte Carlo simulations (GCMC) [7,[48][49][50], and Gibbs Ensemble Monte Carlo simulations (GEMC) [13,51]. However, only a few studies use DFT [16,37,52] caused by the number of limitations of the DFT approach.…”

mentioning

confidence: 99%

“…It has also been shown for the GCMC simulation in [53]. Despite this, the LB mixing rule is widely used in mixture molecular modeling [5,13,23,[48][49][50][51]. There are also other mixing rules to select the parameters of intermolecular interactions: Halgren HHG (H -HHG), Waldman -Hagler (WH), and others [54][55][56][57], which allow predicting fluid mixture behavior accurately.…”

mentioning

confidence: 99%

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Adaptive intermolecular interaction parameters for accurate Mixture Density Functional Theory calculations

Нестерова¹,

Kanygin²,

Lomovitskiy³

et al. 2021

Preprint

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The description of fluid mixtures molecular behavior is significant for various industry fields due to the complex composition of fluid found in nature. Statistical mechanics approaches use intermolecular interaction potential to predict fluids behavior on the molecular scale. The paper provides a comparative analysis of mixing rules applications for obtaining intermolecular interaction parameters of mixture components. These parameters are involved in the density functional theory equation of state for mixtures (Mixture DFT EoS) and characterize thermodynamic mixture properties in the bulk. The paper demonstrates that Mixture DFT EoS with proper intermolecular parameters agree well with experimental mixtures isotherms in bulk: Ar + N e, CO2 + CH4, CO2 + C2H6 and CH4 + C2H6. However, predictions of vapor-liquid equilibrium (VLE) experimental data for CO2 + C4H10 are not successful. Halgren HHG, Waldman -Hagler, and adaptive mixing rules that adjust on the experimental data from the literature are used for the first time to obtain intermolecular interaction parameters for the mixture DFT model. The results obtained provide a base for understanding how to validate the DFT fluid mixture model for calculating thermodynamic properties of fluid mixtures on a micro and macro scale.

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Molecular simulation of the constant composition expansion experiment in shale multi-scale systems

Cited by 34 publications

References 53 publications

A non-empirical model for gas transfer through circular nanopores in unconventional gas reservoirs

A non-empirical model for gas transfer through circular nanopores in unconventional gas reservoirs

Confinement-mediated phase behavior of hydrocarbon fluids: Insights from Monte Carlo simulations

Adaptive intermolecular interaction parameters for accurate Mixture Density Functional Theory calculations

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