A Lattice Boltzmann Model for Simulating Gas Flow in Kerogen Pores

Ren, Junjie; Guo, Ping; Guo, Zhaoli; Wang, Zhouhua

doi:10.1007/s11242-014-0401-9

Cited by 98 publications

(86 citation statements)

References 32 publications

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“…This increment indicates that surface diffusion is an important factor influencing the flow in small pores and it should be considered when estimating or calculating the flux. 52,53 …”

Section: Velocity Profiles In Small Poresmentioning

confidence: 99%

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Chen

Fan

et al. 2017

AIP Advances

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Understanding the flow characteristics of shale gas especially in nanopores is extremely important for the exploitation. Here, we perform molecular dynamics (MD) simulations to investigate the hydrodynamics of methane in nanometre-sized slit pores. Using equilibrium molecular dynamics (EMD), the static properties including density distribution and self-diffusion coefficient of the confined methane are firstly analyzed. For a 6 nm slit pore, it is found that methane molecules in the adsorbed layer diffuse more slowly than those in the bulk. Using nonequilibrium molecular dynamics (NEMD), the pressure-driven flow behavior of methane in nanopores is investigated. The results show that velocity profiles manifest an obvious dependence on the pore width and they translate from parabolic flow to plug flow when the width is decreased. In relatively large pores (6 – 10 nm), the parabolic flow can be described by the Navier-Stokes (NS) equation with appropriate boundary conditions because of its slip flow characteristic. Based on this equation, corresponding parameters such as viscosity and slip length are determined. Whereas, in small pores (∼ 2 nm), the velocity profile in the center exhibits a uniform tendency (plug flow) and that near the wall displays a linear increase due to the enhanced mechanism of surface diffusion. Furthermore, the profile is analyzed and fitted by a piecewise function. Under this condition, surface diffusion is found to be the root of this anomalous flow characteristic, which can be negligible in large pores. The essential tendency of our simulation results may be significant for revealing flow mechanisms at nanoscale and estimating the production accurately.

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“…This increment indicates that surface diffusion is an important factor influencing the flow in small pores and it should be considered when estimating or calculating the flux. 52,53 …”

Section: Velocity Profiles In Small Poresmentioning

confidence: 99%

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Chen

Fan

et al. 2017

AIP Advances

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“…Various studies have confirmed that the adsorption can change K app;om of shale matrix and the surface diffusion is an important transport mechanism at reservoir conditions [4,43]. In some treatments, the surface diffusion is considered as an extra flux in capillary models [21,14,39]. However the sensitivity of permeability to adsorption and surface diffusion are seldom mentioned.…”

Section: Permeability Of Ommentioning

confidence: 99%

“…Because of its inherent kinetic nature, the LB method has attracted huge interest in its extension to simulating microgaseous flows, and tremendous efforts have been made to advance the LBM since 2002 [18][19][20]. With the implementation of appropriate slip boundary conditions and/or effective relaxation time, the LBM was successfully extended for simulation of gaseous flows in slip flow and transition flow regimes, and these LBM approaches have been applied to study gas transport in shale gas reservoir [21][22][23]. However, because of the complexity of boundary conditions, most of the applications of the slip-based LBM are limited to single channel or bundle of channels [23].…”

Section: Introductionmentioning

confidence: 99%

Apparent permeability prediction of organic shale with generalized lattice Boltzmann model considering surface diffusion effect

Wang

Chen

Kang

et al. 2016

Fuel

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a b s t r a c tGas flow in shale is associated with both organic matter (OM) and inorganic matter (IOM) which contain nano-pores ranging in size from a few to hundreds of nano-meters. In addition to the non-continuum effect which leads to an apparent permeability of gas higher than the intrinsic permeability, the surface diffusion of adsorbed gas in organic pores also can influence the apparent permeability through its own transport mechanism. In this study, a generalized lattice Boltzmann model (GLBM) is employed for gas flow through the reconstructed shale matrix consisting of OM and IOM. The ExpectationMaximization (EM) algorithm is used to assign the pore size distribution to each component, and the dusty gas model (DGM) and generalized Maxwell-Stefan model (GMS) are adopted to calculate the apparent permeability accounting for multiple transport mechanisms including viscous flow, Knudsen diffusion and surface diffusion. Effects of pore radius and pressure on permeability of both IOM and OM as well as effects of Langmuir parameters on OM are investigated. The effect of total organic content and distribution on the apparent permeability of the reconstructed shale matrix at different surface diffusivity is also studied. It is found that the influence of pore size and pressure on the apparent permeability of organic matter is affected by the surface diffusion of adsorbed gas. Moreover, surface diffusion plays a significant role in determining apparent permeability and the velocity distribution of shale matrix.

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“…Due to the existence of concentration gradients, adsorbed gas itself undergoes surface diffusion (Sheng et al 2014), especially in nano-scale porous media, where surface diffusion is an important transport mechanism. In ultra-tight nano-scale porous media, surface diffusion even dominates the gas transport mechanisms (Sheng et al 2014;Etminan et al 2014;Mi et al 2014;Ren et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Influence of gas transport mechanisms on the productivity of multi-stage fractured horizontal wells in shale gas reservoirs

Wang

Sun

et al. 2015

Pet. Sci.

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In order to investigate the influence on shale gas well productivity caused by gas transport in nanometersize pores, a mathematical model of multi-stage fractured horizontal wells in shale gas reservoirs is built, which considers the influence of viscous flow, Knudsen diffusion, surface diffusion, and adsorption layer thickness. A discrete-fracture model is used to simplify the fracture modeling, and a finite element method is applied to solve the model. The numerical simulation results indicate that with a decrease in the intrinsic matrix permeability, Knudsen diffusion and surface diffusion contributions to production become large and cannot be ignored. The existence of an adsorption layer on the nanopore surfaces reduces the effective pore radius and the effective porosity, resulting in low production from fractured horizontal wells. With a decrease in the pore radius, considering the adsorption layer, the production reduction rate increases. When the pore radius is less than 10 nm, because of the combined impacts of Knudsen diffusion, surface diffusion, and adsorption layers, the production of multi-stage fractured horizontal wells increases with a decrease in the pore pressure. When the pore pressure is lower than 30 MPa, the rate of production increase becomes larger with a decrease in pore pressure.

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A Lattice Boltzmann Model for Simulating Gas Flow in Kerogen Pores

Cited by 98 publications

References 32 publications

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Channel-width dependent pressure-driven flow characteristics of shale gas in nanopores

Apparent permeability prediction of organic shale with generalized lattice Boltzmann model considering surface diffusion effect

Influence of gas transport mechanisms on the productivity of multi-stage fractured horizontal wells in shale gas reservoirs

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