Pore-scale gas flow simulations by the DSBGK and DVM methods

Li, Jun; Ho, Minh Tuan; Borg, Matthew K.; Cai, Chunpei; Li, Zhihui; Zhang, Yonghao

doi:10.1016/j.compfluid.2021.105017

Cited by 13 publications

(6 citation statements)

References 38 publications

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“…This work now provides a route to implement new flux boundary conditions that model the time-varying sorption processes in higher scale flow models, where the TL model and the calibration of MD data presented can be used. Advanced flow models − currently being developed to model the three-dimensional low-speed, rarefied-to-dense gas flows inside shale rock are currently missing these types of boundary models. Therefore, simulations showing the effect of time-varying adsorption/desorption processes near kerogen boundaries on the transport inside the larger meso/macropores can now be studied.…”

Section: Discussionmentioning

confidence: 99%

Interfacial Adsorption Kinetics of Methane in Microporous Kerogen

Wang

Datta

et al. 2023

Langmuir

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Rapid declines in unconventional shale production arise from the poorly understood interplay between gas transport and adsorption processes in microporous organic rock. Here, we use highfidelity molecular dynamics (MD) simulations to resolve the timevarying adsorption of methane gas in realistic organic rock samples, known as kerogen. The kerogen samples derive from various geological shale fields with porosities ranging between 20% and 50%. We propose a kinetics sorption model based on a generalized solution of diffusive transport inside a nanopore to describe the adsorption kinetics in kerogen, which gives excellent fits with all our MD results, and we demonstrate it scales with the square of the length of kerogen. The MD adsorption time constants for all samples are compared with a simplified theoretical model, which we derive from the Langmuir isotherm for adsorption capacitance and the freevolume theory for steady, highly confined bulk transport. While the agreement with the MD results is qualitatively very good, it reveals that, in the limit of low porosity, the diffusive transport term dominates the characteristic time scale of adsorption, while the adsorption capacitance becomes important for higher pressures. This work provides the first data set for adsorption kinetics of methane in kerogen, a validated model to accurately describe this process, and a qualitative model that links adsorption capacitance and transport with the adsorption kinetics. Furthermore, this work paves the way to upscale interfacial adsorption processes to the next scale of gas transport simulations in mesopores and macropores of shale reservoirs.

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Section: Discussionmentioning

confidence: 99%

Interfacial Adsorption Kinetics of Methane in Microporous Kerogen

Wang

Datta

et al. 2023

Langmuir

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“…Nanoporous materials often have random bicontinuous structures with complex pore morphologies in which heat and fluid flow are inherently three-dimensional. Computational costs associated with running three-dimensional models to simulate gas flow in nanoporous materials using particle-based methods, such as molecular dynamics (MD) and direct simulation Monte-Carlo (DSMC), are often considerably high and thus current studies are limited, to a great extent, to two-dimensional problems (see for instance [ 9 , 19 , 40 , 41 , 42 ]). Figure 1 shows a representative geometry of the computational domain, the grid used in the simulations, and the boundary conditions applied to the outer boundaries of the computational domain.…”

Section: Methodsmentioning

confidence: 99%

Numerical Study of Gas Flow in Super Nanoporous Materials Using the Direct Simulation Monte-Carlo Method

2023

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The direct simulation Monte Carlo (DSMC) method, which is a probabilistic particle-based gas kinetic simulation approach, is employed in the present work to describe the physics of rarefied gas flow in super nanoporous materials (also known as mesoporous). The simulations are performed for different material porosities (0.5≤ϕ≤0.9), Knudsen numbers (0.05≤Kn≤1.0), and thermal boundary conditions (constant wall temperature and constant wall heat flux) at an inlet-to-outlet pressure ratio of 2. The present computational model captures the structure of heat and fluid flow in porous materials with various pore morphologies under rarefied gas flow regime and is applied to evaluate hydraulic tortuosity, permeability, and skin friction factor of gas (argon) flow in super nanoporous materials. The skin friction factors and permeabilities obtained from the present DSMC simulations are compared with the theoretical and numerical models available in the literature. The results show that the ratio of apparent to intrinsic permeability, hydraulic tortuosity, and skin friction factor increase with decreasing the material porosity. The hydraulic tortuosity and skin friction factor decrease with increasing the Knudsen number, leading to an increase in the apparent permeability. The results also show that the skin friction factor and apparent permeability increase with increasing the wall heat flux at a specific Knudsen number.

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“…Based on the DSMC method, Li et al computed the gas permeabilities of representative pore geometries by the direct simulation Bhatnager–Gross–Krook (DSBGK) simulations over a wide range of Kn . The comparisons of DSBGK with the conventional DVM or DSMC method also have been investigated, particularly in the case of low speed flow . The lattice Boltzmann method (LBM), which has an easy boundary implementation, has become a very useful method for wide range of complex transport processes. , Lu et al simulated shale gas flow under low-pressure conditions in kerogen pore networks.…”

Section: Multiscale Flow Simulationmentioning

confidence: 99%

“…126 The comparisons of DSBGK with the conventional DVM or DSMC method also have been investigated, particularly in the case of low speed flow. 127 The lattice Boltzmann method (LBM), which has an easy boundary implementation, has become a very useful method for wide range of complex transport processes. 6,7 Lu et al simulated shale gas flow under low-pressure conditions in kerogen pore networks.…”

Section: Diffusion and Flowmentioning

confidence: 99%

Recent Advances in Multiscale Digital Rock Reconstruction, Flow Simulation, and Experiments during Shale Gas Production

Yang

Zhang

et al. 2023

Energy Fuels

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The complex and multiscale nature of shale gas transport imposes new challenges to the already well-developed techniques for conventional reservoirs, especially digital core analysis. Multiscale complicated pore systems and distinctive properties limit most reconstruction methods not applicable. High-precision imaging experiments play a key role in the characterization of pore structures and mineral components. While the exhilarating breakthroughs in physical experimental methods and hybrid superposition methods have made significant achievements in shale digital rock reconstruction, rapidly evolving deep learning methods also present a promising option. Benefiting from the digital rock techniques, the pore-scale flow of shale gas can be directly simulated based on digital rock or indirectly modeled using the pore network model. It is precise and realistic to investigate the shale gas flow at the pore scale considering the desorption, surface diffusion, and slippage in nanopores. In this paper, we reviewed the recent advances in off-mentioned methods and processes and presented a hand for the research in this field.

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Pore-scale gas flow simulations by the DSBGK and DVM methods

Cited by 13 publications

References 38 publications

Interfacial Adsorption Kinetics of Methane in Microporous Kerogen

Interfacial Adsorption Kinetics of Methane in Microporous Kerogen

Numerical Study of Gas Flow in Super Nanoporous Materials Using the Direct Simulation Monte-Carlo Method

Recent Advances in Multiscale Digital Rock Reconstruction, Flow Simulation, and Experiments during Shale Gas Production

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