Analytical analysis of gas diffusion into non-circular pores of shale organic matter

Mehrabi, Mehran; Javadpour, Farzam; Sepehrnoori, Kamy

doi:10.1017/jfm.2017.180

Cited by 24 publications

(6 citation statements)

References 38 publications

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“…Jin and Firoozabadi (2016) adopted the solid-solution model for wax and asphaltene precipitation (Pan and Firoozabadi 1997;Won 1986) to model the gas dissolution in kerogen. The kerogen is believed to be similar to bitumen or solid heavy oil (Mehrabi et al 2017;Jin and Firoozabadi 2016;Yang et al 2016). According to Yang et al (2016), gas dissolves into the organic matter just as natural gas dissolves into heavy oil and gas dissolution in the organic material (kerogen) delays the adsorption process.…”

Section: Introductionmentioning

confidence: 99%

“…Divided by the total organic content (TOC) values, the normalized dissolved gas volume was obtained and the slopes of the normalized dissolved gas volume with respect to pressure for different samples are the same. Mehrabi et al (2017) fully reviewed the studies related to dissolved gas and established a model for simulating gas flow in noncircular pores. Their results supported the significance of dissolved gas in shale reservoir production.…”

Section: Introductionmentioning

confidence: 99%

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Gas sorption and non-Darcy flow in shale reservoirs

Wang

Sheng

2017

Pet. Sci.

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Gas sorption and non-Darcy flow are two important issues for shale gas reservoirs. The sorption consists of dissolution and adsorption. Dissolved gas and adsorbed gas are different. The former is dissolved in the shale matrix, while the latter is concentrated near the solid walls of pores. In this paper, the Langmuir equation is used to describe adsorption and Henry's law is used to describe dissolution. The K coefficient in Henry's law of 0.052 mmol/(MPa g TOC) is obtained by matching experimental data. The amount of dissolved gas increases linearly when pressure increases. Using only the Langmuir equation without considering dissolution can lead to a significant underestimation of the amount of sorbed gas in shales. For non-Darcy gas flow, the apparent permeability model for free gas is established by combining slip flow and Knudsen flow. For adsorbed gas, the surface diffusion effect is also considered in this model. The surface diffusion coefficient is suggested to be of the same scale as the gas self-diffusion coefficient, and the corresponding effective permeability is derived. Whenincreases, but the relationship is not linear as the Klinkenberg effect suggests. The effect of adsorption on the gas flow is significant in nanopores (r 2 nm). Adsorption increases apparent permeability in shales at low pressures and decreases it at high pressures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gas sorption and non-Darcy flow in shale reservoirs

Wang

Sheng

2017

Pet. Sci.

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“…As the reservoir pressure drops, the adsorbed gas desorbs from the surface of organic matter pores and enters the center of organic matter pores and matrix. Then, the desorbed gas and remaining adsorbed gas diffuses in the organic matter and rock matrix . When the pressure continues to decrease, a small amount of dissolved gas in the kerogen block precipitates and diffuses to the pore surface to replace the desorbed gas.…”

Section: Introductionmentioning

confidence: 99%

Review of Shale Gas Transport Prediction: Basic Theory, Numerical Simulation, Application of AI Methods, and Perspectives

et al. 2023

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The gas transport mechanism in shale reservoirs is extremely complex and is a typical multiscale and multiphysics coupled transport process, considering the complex shale rock structure, wide distribution of micropores and nanopores in shale gas reservoirs, diverse gas occurrence forms, and large pore size spans. An accurate understanding of the shale gas transport process and mechanism is important for effective exploration of shale gas reservoirs. In this work, a review of the recent progress in the prediction of shale gas transport in porous media is presented. The basic theory of gas transport in nanopores is discussed. The gas transport in organic and inorganic matter and the gas adsorption effect are covered. Then, gas transport simulations with conventional multiscale numerical methods, including molecular dynamics and lattice Boltzmann simulations, are reviewed, and the multiscale modeling methods are discussed. Furthermore, the application of artificial intelligence (AI) methods in shale gas transport research is discussed. The focus is on the characterization of the shale porous geometry, including porosity, tortuosity, pore size distribution, and reconstruction of the shale porous medium. The application of AI-based methods such as neural networks and machine learning for the prediction of porous flow properties is discussed. This study intends to provide a comprehensive review of shale gas transport characteristics and to enable the accessibility of AI tools in the research of shale gas.

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“…Transport of the van der Waals fluids through microscale/nanoscale confined geometries appears in many engineering applications, such as shale gas production (Wu et al. 2016; Mehrabi, Javadpour & Sepehrnoori 2017), carbon dioxide geological sequestration (Wang, Wang & Chen 2018), energy-efficient cooling (Rana, Lockerby & Sprittles 2018; Van Erp et al. 2020) and ultrafast filtration using membranes (Joseph & Aluru 2008; Torres-Herrera & Poiré 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Transport of the van der Waals fluids through microscale/nanoscale confined geometries appears in many engineering applications, such as shale gas production (Wu et al 2016;Mehrabi, Javadpour & Sepehrnoori 2017), carbon dioxide geological sequestration (Wang, Wang & Chen 2018), energy-efficient cooling (Rana, Lockerby & Sprittles 2018;Van Erp et al 2020) and ultrafast filtration using membranes (Joseph & Aluru 2008;Torres-Herrera & Poiré 2021). The definition of the van der Waals fluids originates from the celebrated van der Waals equation of state (EoS) (van der Waals 1873; Maxwell 1874), which extends the ideal gas law by coupling the effects of both the finite size of gas molecules and the long-range attraction between gas molecules.…”

Section: Introductionmentioning

confidence: 99%

Molecular kinetic modelling of non-equilibrium transport of confined van der Waals fluids

Shan,

Su,

Gibelli

et al. 2023

J. Fluid Mech.

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A thermodynamically consistent kinetic model is proposed for the non-equilibrium transport of confined van der Waals fluids, where the long-range molecular attraction is considered by a mean-field term in the transport equation, and the transport coefficients are tuned to match the experimental data. The equation of state of the van der Waals fluids can be obtained from an appropriate choice of the pair correlation function. By contrast, the modified Enskog theory predicts non-physical negative transport coefficients near the critical temperature and may not be able to recover the Boltzmann equation in the dilute limit. In addition, the shear viscosity and thermal conductivity are predicted more accurately by taking gas molecular attraction into account, while the softened Enskog formula for hard-sphere molecules performs better in predicting the bulk viscosity. The present kinetic model agrees with the Boltzmann model in the dilute limit and with the Navier–Stokes equations in the continuum limit, indicating its capability in modelling dilute-to-dense and continuum-to-non-equilibrium flows. The new model is examined thoroughly and validated by comparing it with the molecular dynamics simulation results. In contrast to the previous studies, our simulation results reveal the importance of molecular attraction even for high temperatures, which holds the molecules to the bulk while the hard-sphere model significantly overestimates the density near the wall. Because the long-range molecular attraction is considered appropriately in the present model, the velocity slip and temperature jump at the surface for the more realistic van der Waals fluids can be predicted accurately.

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Analytical analysis of gas diffusion into non-circular pores of shale organic matter

Cited by 24 publications

References 38 publications

Gas sorption and non-Darcy flow in shale reservoirs

Gas sorption and non-Darcy flow in shale reservoirs

Review of Shale Gas Transport Prediction: Basic Theory, Numerical Simulation, Application of AI Methods, and Perspectives

Molecular kinetic modelling of non-equilibrium transport of confined van der Waals fluids

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