Experimental investigation on the characteristics of gas diffusion in shale gas reservoir using porosity and permeability of nanopore scale

Kim, Changjae; Jang, Hochang; Lee, Jeonghwan

doi:10.1016/j.petrol.2015.06.008

Cited by 41 publications

(25 citation statements)

References 17 publications

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“…Kim et al . (2015) presented that the Fick diffusion coefficient remains 5.068 × 10 −4 cm 2 /s and is independent of the pore radius31. Therefore, in this study, the range of diffusion coefficient is determined from 1 × 10 −2 to 1 × 10 −4 cm 2 /s.…”

Section: Resultsmentioning

confidence: 68%

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

Yang

Huang

et al. 2016

Sci Rep

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A complex fracture network is generally generated during the hydraulic fracturing treatment in shale gas reservoirs. Numerous efforts have been made to model the flow behavior of such fracture networks. However, it is still challenging to predict the impacts of various gas transport mechanisms on well performance with arbitrary fracture geometry in a computationally efficient manner. We develop a robust and comprehensive model for real gas transport in shales with complex non-planar fracture network. Contributions of gas transport mechanisms and fracture complexity to well productivity and rate transient behavior are systematically analyzed. The major findings are: simple planar fracture can overestimate gas production than non-planar fracture due to less fracture interference. A “hump” that occurs in the transition period and formation linear flow with a slope less than 1/2 can infer the appearance of natural fractures. The sharpness of the “hump” can indicate the complexity and irregularity of the fracture networks. Gas flow mechanisms can extend the transition flow period. The gas desorption could make the “hump” more profound. The Knudsen diffusion and slippage effect play a dominant role in the later production time. Maximizing the fracture complexity through generating large connected networks is an effective way to increase shale gas production.

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Section: Resultsmentioning

confidence: 68%

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

Yang

Huang

et al. 2016

Sci Rep

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“…Therefore, the Darcy law reflecting continuum flow is no longer applicable for shale gas due to the significant influence of molecular diffusion and gas slippage. To date, it has been generally accepted that gas flow regimes can be subdivided into continuum flow (K n < 0.001), slip flow (0.001 < K n < 0.1), transition flow (0.1 < K n < 10) and free molecular flow (K n > 10) based on the Knudsen number (K n , i.e., the ratio of the mean free path of molecule to pore diameter) Kim et al, 2015;Kazemi and Takbiri-Borujeni, 2015), as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Insights on the gas permeability change in porous shale

Chen

Xu³

et al. 2017

Adv. Geo-Energ. Res.

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Due to abundant nanoscale pores developed in shale, gas flow in shale presents a complex dynamic process. This paper summarized the effects from effective stress increase, shale matrix shrinkage, gas slippage and Knudsen diffusion on the gas permeability change in shale during shale gas recovery. With the reduce in gas pressure, effective stress increase leads to the decline of the permeability in an exponential form; the permeability increases due to the shale matrix shrinkage induced by gas desorption; appearances of gas slippage and Knudsen diffusion cause an additional increase in the gas permeability particularly in small pores at low pressures. In addition, some reported models evaluating the shale permeability were reviewed preliminarily. Models considering these four effects may be potentially effective to evaluate the gas permeability change in shale.

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“…When K n > 10, the diffusion resistance is quite small, the CH 4 molecule can freely vibrate in compliance with the Fick diffusion law ( Figure 5 ). Thus, the Fick self-diffusivity D F is defined as follows 59 where u̅ A is the mean square velocity of the CH 4 molecule, m/s, which can be described as in which, M is the mean square velocity of the CH 4 molecule, 16.043 kg/mol. 6 demonstrate that the Fick self-diffusivity D F of CH 4 is mainly affected by the ambient temperature and the pressure of adsorption.…”

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Mechanism of CH₄ Diffusion Inhibition by Low Temperature in Anthracite Microcrystallites

Wang

et al. 2020

ACS Omega

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Understanding the adsorption/diffusion characteristics of CH 4 at low temperatures (<273.15 K) is of great significance not only for coal bed methane estimation but also for gas disaster prevention and methane storage in deep coal beds. In this work, the adsorption configurations of anthracite macromolecules were constructed with Materials Studio, and then, the adsorption and diffusion behaviors of CH 4 at 233.15–363.15 K were simulated, respectively, using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) algorithms. The results show that the absolute adsorption capacities of CH 4 at low temperatures are substantially larger than those at high temperatures, and the adsorption amount further increases with the continued cooling at a given sorption pressure. The isosteric heat of CH 4 adsorption ranges from 8.715 to 11.746 kJ/mol, belonging to a spontaneous physical adsorption. The self-diffusivity D s of CH 4 at low temperatures is substantially smaller than that at high temperatures and further decreases with cooling. The most probable velocity of CH 4 molecules ( v p ) greatly decreases, and the number of gas molecules with a higher energy is significantly reduced by a low temperature, resulting in the diffusion inhibition of CH 4 .

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Experimental investigation on the characteristics of gas diffusion in shale gas reservoir using porosity and permeability of nanopore scale

Cited by 41 publications

References 17 publications

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

Insights on the gas permeability change in porous shale

Molecular Dynamics Mechanism of CH₄ Diffusion Inhibition by Low Temperature in Anthracite Microcrystallites

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Experimental investigation on the characteristics of gas diffusion in shale gas reservoir using porosity and permeability of nanopore scale

Cited by 41 publications

References 17 publications

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

A Comprehensive Model for Real Gas Transport in Shale Formations with Complex Non-planar Fracture Networks

Insights on the gas permeability change in porous shale

Molecular Dynamics Mechanism of CH4 Diffusion Inhibition by Low Temperature in Anthracite Microcrystallites

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Molecular Dynamics Mechanism of CH₄ Diffusion Inhibition by Low Temperature in Anthracite Microcrystallites