Long-Term Redistribution of Residual Gas Due to Non-convective Transport in the Aqueous Phase

Li, Yaxin; Orr, Franklin M.; Benson, Sally M.

doi:10.1007/s11242-021-01722-y

Cited by 13 publications

(16 citation statements)

References 69 publications

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“…In long-term mineral entrapment, CO 2 reacts with the host rock and the local fluid, precipitating as carbonates. 5,6 In the long term, different nonconvective transport processes, such as Fickian diffusion, thermodiffusion, and gravitational segregation, could affect CO 2 distribution in subsurface aquifers. The driving forces for the above process are the gradients of concentration, temperature, and pressure, respectively.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In formations with an ideal liquid, gravitational segregation and thermodiffusion usually induce opposite effects in the species distribution: the lighter component tends to accumulate in the bottom (hotter region) due to thermodiffusion but in the top due to gravity segregation. 7 Recently, Li et al 5 have reported that the nonconvective transport redistribution time scale is around 10 5 years per meter for CO 2 in water, which indicates that the process is extremely slow compared with convective transport. 5 A simplified thermodynamic model for local equilibrium is employed to describe the fluid system, including an approximation for constant CO 2 activity coefficient.…”

Section: ■ Introductionmentioning

confidence: 99%

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Thermodiffusion of CO₂ in Water by Nonequilibrium Molecular Dynamics Simulations

2023

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The components of a fluid mixture may segregate due to the Soret effect, a coupling phenomenon in which mass flux can be induced by a thermal gradient. In this work, we evaluate systematically the thermodiffusion of the CO 2 −H 2 O mixture, and the influence of the geothermal gradient on CO 2 segregation in deep saline aquifers in CO 2 storage. The eHeX method, a nonequilibrium molecular dynamics simulation approach, is judiciously selected to simulate the phenomenon. At 350 K, 400 bar, and CO 2 mole fraction of 0.02 (aquifer conditions), CO 2 accumulates on the cold side, and the thermal diffusion factor is close to 1 in a number of force fields. The lower the temperature, the higher is the separation and the thermal diffusion factor. In colder regions, water self-association is stronger, whereas the CO 2 −H 2 O cross-association and the CO 2 −CO 2 interactions enhance at higher temperatures. Thermodiffusion and gravitational segregation have opposite effects on CO 2 segregation. At typical subsurface conditions, the Soret effect is more pronounced than gravity segregation, and CO 2 concentrates in the top (colder region). Our work sets the stage to model the effect of electrolytes on CO 2 segregation in subsurface aquifers and other areas of interest.

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Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Thermodiffusion of CO₂ in Water by Nonequilibrium Molecular Dynamics Simulations

2023

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“…Recent studies have explored implications of Ostwald ripening on the permanency of CO 2 ganglia in residual (or, capillary) trapping as a mechanism for CO 2 storage (de Chalendar et al 2017;Li et al 2020Li et al , 2022. Such disconnected ganglia can take many irregular shapes and span multiple pores.…”

Section: Introductionmentioning

confidence: 99%

A level set approach to Ostwald ripening of trapped gas bubbles in porous media

et al. 2022

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Ostwald ripening of gas bubbles is a thermodynamic process for mass transfer, which is important for both foam enhanced oil recovery and geological CO2 storage. We present a methodology for simulating Ostwald ripening of gas ganglia surrounded by liquid in arbitrary pore geometries. The method couples a conservative level set model for capillary-controlled displacement and a ghost-bubble technique that calculates mass transfer based on difference in chemical potentials. The methodology is implemented in a software framework for parallel computations. As a validation of the model, we show that simulations of bubble ripening in a pore throat connecting two pore bodies are consistent with previously reported trends in similar geometries. Then we investigate the impact of gas type, compressibility factor, and local capillary pressure on gas-bubble ripening in various water-wet pore geometries. The results confirm that gas solubility and compressibility factor are proportional to the rate of mass transfer. Our simulations suggest that Ostwald ripening has largest impact in heterogeneous or fractured porous structures where differences in gas-bubble potentials are high. However, if the liquid separating the gas bubbles is also a disconnected phase, which can happen in intermediate-wet porous media, the resulting local capillary pressure can limit the coarsening and stabilise smaller bubbles. Finally, we simulated Ostwald ripening on a 3-D pore-space image of sandstone containing a residual gas/water configuration after imbibition. Characterization of gas-bubble morphology during the coarsening shows that large ganglia get more ramified at the expense of small spherical ganglia that cease to exist.

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“…This claim is supported by the simulation results that R c evolution in a 200 × 200 lattice pore network overlaps with that in a 30 × 30 lattice pore network (Figure 3a). It is distinct from the anti‐coarsening stage in porous media that kinetics is strongly correlated to the scale of the system (Li et al., 2021). As a result, the time for the system to reach thermodynamic quasi‐equilibrium (transition from coarsening to anti‐coarsening), t e , is local and determined only by pore‐scale geometry and fluid properties.…”

Section: Equilibrium Time and Its Practical Implicationmentioning

confidence: 99%

Bubble Coarsening Kinetics in Porous Media

Wang

Liu

et al. 2022

Geophysical Research Letters

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Bubbles in subsurface porous media spontaneously coarsen to reduce free energy. Bubble coarsening dramatically changes surface area and pore occupancy, which affect the hydraulic conductivity, mass and heat transfer coefficients, and chemical reactions. Coarsening kinetics in porous media is thus critical in modeling geologic CO2 sequestration, hydrogen subsurface storage, hydrate reservoir recovery, and other relevant geophysical problems. We show that bubble coarsening kinetics in porous media fundamentally deviates from classical Lifshitz‐Slyozov‐Wagner theory, because porous structure quantizes the space and rescales the mass transfer coefficient. We develop a new coarsening theory that agrees well with numerical simulations. We identify a pseudo‐equilibrium time proportional to the cubic of pore size. In a typical CO2 sequestration scenario, local equilibrium can be achieved in 1s for media consisting of sub‐micron pores, while in decades for media consisting of 1 mm pores. This work provides new insights in modeling complex fluid behaviors in subsurface environment.

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Long-Term Redistribution of Residual Gas Due to Non-convective Transport in the Aqueous Phase

Cited by 13 publications

References 69 publications

Thermodiffusion of CO₂ in Water by Nonequilibrium Molecular Dynamics Simulations

Thermodiffusion of CO₂ in Water by Nonequilibrium Molecular Dynamics Simulations

A level set approach to Ostwald ripening of trapped gas bubbles in porous media

Bubble Coarsening Kinetics in Porous Media

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Long-Term Redistribution of Residual Gas Due to Non-convective Transport in the Aqueous Phase

Cited by 13 publications

References 69 publications

Thermodiffusion of CO2 in Water by Nonequilibrium Molecular Dynamics Simulations

Thermodiffusion of CO2 in Water by Nonequilibrium Molecular Dynamics Simulations

A level set approach to Ostwald ripening of trapped gas bubbles in porous media

Bubble Coarsening Kinetics in Porous Media

Contact Info

Product

Resources

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Thermodiffusion of CO₂ in Water by Nonequilibrium Molecular Dynamics Simulations

Thermodiffusion of CO₂ in Water by Nonequilibrium Molecular Dynamics Simulations