A molecular dynamics study of thermal diffusion in a porous medium

Colombani, Jean; Galliéro, Guillaume; Duguay, B.; Caltagirone, Jean‐Paul; Montel, François; Bopp, P.

doi:10.1039/b106800h

Cited by 31 publications

(17 citation statements)

References 23 publications

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“…In this study, we perform non-equilibrium molecular dynamics simulations of fluid flow by the capillary walls under steady-state conditions. The steady-state is established using periodic boundary conditions and applying an external force field, which introduces a constant rate of acceleration to the fluid molecules [28]. This acceleration in our simulations is typically 0.01 nanometers per nanosecond 2 which can be roughly converted to a pressure gradient of 0.65 psi per nanometer for the current system.…”

Section: Simulation Model Of Fluids In Organic Capillarymentioning

confidence: 99%

Insights into Mobilization of Shale Oil using Microemulsion

Bui¹,

Akkutlu²,

Zelenev³

et al. 2015

Unconventional Resources Technology Conference

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Molecular dynamics simulation is employed to investigate the nature of two-phase (oil-water) flow in organic capillaries. The capillary wall is modeled using graphite to represent kerogen pores in liquid-rich resource shale. We consider that the water carries a nonionic surfactant and a solubilized terpene solvent in the form of a microemulsion, and that it has previously been introduced to the capillary during hydraulic fracturing operation. The water has already displaced a portion of the oil in-place mechanically and now occupies the central part of the capillary. The residual oil, on the other hand, stays by the capillary walls as a stagnant film.Equilibrium simulations show that, under the influence of organic walls, the solvent inside the microemulsion droplets enables not only the surfactant but also the complete droplet to adsorb to the interfaces. Hence, delivering the surfactant molecules to the oil-water interface is achieved faster and more effectively in the organic capillaries. Once the droplet arrives at the interface, the droplet breaks down, the solvent dissolves into the oil film and diffuses. This process is similar to drug delivery at nano-scale.Using non-equilibrium simulations based on the external force field approach we numerically performed steady-state flow measurements to establish that the solvent and the surfactant molecules play separate roles that are both essential in mobilizing the oil film. The surfactant deposited at the oil-water interface reduces the surface tension and acts as a linker that diminishes the slip at the interface. Hence, it effectively enables momentum transfer from the mobile water phase to the stagnant oil film. The solvent penetrating the oil film, on the other hand, modifies flow properties of the oil. In addition, due to selective adsorption, the solvent displaces the adsorbed oil molecules and transforms that portion of the oil into the free oil phase. Consequently, the fractional flow of oil is additionally increased in the presence of solvent. The results of this work are important for understanding the effect of the microemulsion on flow in organic capillaries and its effect on shale oil recovery.

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Section: Simulation Model Of Fluids In Organic Capillarymentioning

confidence: 99%

Insights into Mobilization of Shale Oil using Microemulsion

Bui¹,

Akkutlu²,

Zelenev³

et al. 2015

Unconventional Resources Technology Conference

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“…Such an approach has already proves its efficiency, at least concerning the microscopic mechanism responsible of thermodiffusion on rather academic systems, Lennard-Jones binary mixtures [11][12][13][14] and ternary ones 15 , molecular fluids [16][17][18][19] , associative mixtures 20 , reactive mixtures 21 , ionic systems 22 , polymer 23 , and fluids in porous media [24][25][26] . Concerning the modeling of thermodiffusion using MD results, we can mention in particular the work of thermodiffusion using MD becomes too large to be reasonably accessible despite the continuous increase in computational power.…”

Section: Introductionmentioning

confidence: 99%

Thermodiffusion in model nanofluids by molecular dynamics simulations

Galliéro

Volz

2008

The Journal of Chemical Physics

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In this work, a new algorithm is proposed to compute single particle (infinite dilution) thermodiffusion using Non-Equilibrium Molecular Dynamics simulations through the estimation of the thermophoretic force that applies on a solute particle. This scheme is shown to provide consistent results for simple Lennard-Jones fluids and for model nanofluids (spherical non-metallic nanoparticles + Lennard-Jones fluid) where it appears that thermodiffusion amplitude, as well as thermal conductivity, decrease with nanoparticles concentration. Then, in nanofluids in the liquid state, by changing the nature of the nanoparticle (size, mass and internal stiffness) and of the solvent (quality and viscosity) various trends are exhibited. In all cases the single particle thermodiffusion is positive, i.e. the nanoparticle tends to migrate toward the cold area. The single particle thermal diffusion 2 coefficient is shown to be independent of the size of the nanoparticle (diameter of 0.8 to 4 nm), whereas it increases with the quality of the solvent and is inversely proportional to the viscosity of the fluid. In addition, this coefficient is shown to be independent of the mass of the nanoparticle and to increase with the stiffness of the nanoparticle internal bonds. Besides, for these configurations, the mass diffusion coefficient behavior appears to be consistent with a Stokes-Einstein like law.3

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“…Such statistical analysis involved normalization of data that accounted for proppant amount, time on production, reservoir quality, and flowing pressure, thus allowing one to isolate the impact of chemicals on oil and gas production from other essential factors. The results of such studies were presented in a number of publications (Crafton et al 2009;Noe and Crafton 2013;Crafton and Noe 2013) and are based on the use of the reciprocal-productivity-index method (Denney 1997;Crafton 1998). The method allows one to assess the general performance of a well in terms of the apparent fracture length, which is a metric with the units of length describing the degree of connectivity between the reservoir and the wellbore, not an actual distance measurement.…”

Section: Introductionmentioning

confidence: 99%

Insights Into Mobilization of Shale Oil by Use of Microemulsion

et al. 2016

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Molecular-dynamics simulation is used to investigate the nature of two-phase (oil/water) flow in organic capillaries. The capillary wall is modeled with graphite to represent kerogen pores in liquid-rich resource shale. We consider that the water carries a nonionic surfactant and a solubilized terpene solvent in the form of a microemulsion, and that it was previously introduced to the capillary during hydraulic-fracturing operation. The water has already displaced a portion of the oil in place mechanically and now occupies the central part of the capillary. The residual oil, on the other hand, stays by the capillary walls as a stagnant film.Equilibrium simulations show that, under the influence of organic walls, the solvent inside the microemulsion droplets enables not only the surfactant but also the complete droplet to adsorb to the interfaces. Hence, delivering the surfactant molecules to the oil/water interface is achieved faster and more effectively in the organic capillaries. After the droplet arrives at the interface, the droplet breaks down and the solvent dissolves into the oil film and diffuses. This process is similar to drug delivery at nanoscale.Using nonequilibrium simulations based on the external forcefield approach, we numerically performed steady-state flow measurements to establish that the solvent and the surfactant molecules play separate roles that are both essential in mobilizing the oil film. The surfactant deposited at the oil/water interface reduces the surface tension and acts as a linker that diminishes the slip at the interface. Hence, it effectively enables momentum transfer from the mobile water phase to the stagnant oil film. The solvent penetrating the oil film, on the other hand, modifies flow properties of the oil. In addition, as a result of selective adsorption, the solvent displaces the adsorbed oil molecules and transforms that portion of the oil into the free oil phase. Consequently, the fractional flow of oil is additionally increased in the presence of solvent. The results of this work are important for understanding the effect of microemulsion on flow in organic capillaries and its effect on shale-oil recovery.

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A molecular dynamics study of thermal diffusion in a porous medium

Cited by 31 publications

References 23 publications

Insights into Mobilization of Shale Oil using Microemulsion

Insights into Mobilization of Shale Oil using Microemulsion

Thermodiffusion in model nanofluids by molecular dynamics simulations

Insights Into Mobilization of Shale Oil by Use of Microemulsion

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