Establishment of a new slip permeability model of gas flow in shale nanopores based on experimental and molecular dynamics simulations studies

Duan, Xianggang; Hu, Zhiming; Shao, Nan; Li, Wuguang; Li, Yaxiong; Chang, Jin; Shen, Rui

doi:10.1016/j.petrol.2020.107365

Cited by 24 publications

(9 citation statements)

References 30 publications

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“…It is found that the permeabilities decrease rapidly with the increasing pressure for pressure less than 10 MPa, while they decrease slowly for pressure higher than 10 MPa. The trend is consistent with those in previous studies. − Figure demonstrates the variations in the apparent permeabilities with free gas density. The relations between the apparent permeabilities and the reciprocal of free gas density are found to be approximately linear.…”

Section: Resultssupporting

confidence: 91%

Apparent Permeability Coupling of Adsorbed and Free Gases for Deep Shale: Theoretical Model and Measurements

Ning

et al. 2022

Energy Fuels

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Understanding the percolation behavior of deep shale gas is of great significance for efficient development. This paper aims to propose an analytical model coupling adsorbed and free gases for the permeability of deep shale gas. By correcting gas slippage with the properties of adsorbed gas and applying the Navier−Stokes equations, flow models for a single cylinder and slit pore are established respectively. The model fits the flow velocities from the molecular simulations well. A permeability model for shale is further established with the capillary bundle model. The permeabilities of shale cores are measured under average gas pressure up to 50 MPa and the temperature of 140 °C with nitrogen. The model and experiments prove a linear relationship between the apparent permeability and the reciprocal of free gas density for the flow coupling adsorbed and free gases. The calculated results of the permeability model under the condition of deep reservoirs indicate that (1) the apparent permeability of shale tends to a limit higher than the intrinsic permeability at high pressure; this limit decreases with the increase in tangential momentum accommodation coefficient (TMAC) of the pore wall and pore size;(2) ignoring gas adsorption overestimates apparent permeability, especially for low pressure, small TMAC, and small pore size; and(3) the gas usually flowing in the shale is mainly free gas, and the adsorbed gas in the shale with cylinder pores is more flowable than that with slit pores; for smaller pore size, smaller TMAC, and lower pressure, the adsorbed gas contributes more to the gas flow, while the flow of adsorbed gas can be completely ignored for the shale mainly with macropores.

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Section: Resultssupporting

confidence: 91%

Apparent Permeability Coupling of Adsorbed and Free Gases for Deep Shale: Theoretical Model and Measurements

Ning

et al. 2022

Energy Fuels

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“…Duan et al [65] The velocity profile is plunger-like, and the velocity of gas molecules at the wall is consistent with that of free gas molecules.…”

Section: Flow Velocitymentioning

confidence: 70%

“…Slip phenomenon occurs when gas flows through porous media, especially in unconventional reservoirs [64]. Duan et al [65] proposed an apparent permeability model to describe the gas flow in tight pores considering the boundary layer. The result shows that the velocity profile is plungerlike, and the velocity of gas molecules at the wall is consistent with that of free phase gas molecules (see Figure 13).…”

Section: Geofluidsmentioning

confidence: 99%

“…Guo [63] The slip length of n-pentane flowing in quartz pores increases with the increase of driving force, and decreases firstly and then tends to be stable as the pore width increases. Duan et al [65] The slippage phenomenon disappears gradually as the pressure increases.…”

Section: Slipmentioning

confidence: 99%

“…Simulation results of velocity profiles for 5 nm slit under different pressures[65]. Extraction results of C 10 molecules with different depressurization rate[68].…”

mentioning

confidence: 99%

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Review on Phase Behavior in Tight Porous Media and Microscopic Flow Mechanism of CO2 Huff-n-Puff in Tight Oil Reservoirs

Tang

Liu

et al. 2020

Geofluids

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The successful development of tight oil reservoirs in the U.S. shows the bright future of unconventional reservoirs. Tight oil reservoirs will be the main target of exploration and development in the future, and CO2 huff-n-puff is one of the most important methods to enhance oil recovery factor of tight oil reservoirs in North America. To improve the performance of CO2 huff-n-puff, injection and production parameters need to be optimized through numerical simulation. The phase behavior and microscopic flow mechanism of CO2 huff-n-puff in porous media need to be further investigated. This paper presents a detailed review of phase behavior and microscopic flow mechanism in tight porous media by CO2 huff-n-puff. Phase behavior in tight porous media is different from that in a PVT cylinder since the capillary pressure in tight porous media reduces the bubble point pressure and increases the miscibility pressure and critical temperature. The condensate pressure in tight porous media and nonequilibrium phase behavior need to be further investigated. The microscopic flow mechanism during CO2 huff-n-puff in tight porous media is complicated, and the impact of molecular diffusion, gas-liquid interaction, and fluid-rock interaction on multiphase flow is significant especially in tight porous media. Nuclear magnetic resonance (NMR) and molecular simulation are efficient methods to describe the microscopic flow in tight oil reservoirs, while the NMR is not cost-effective and molecular simulation needs to be improved to better characterize and model the feature of porous media. The improved molecular simulation is still a feasible method to understand the microscopic flow mechanism of CO2 huff-n-puff in tight oil reservoirs in the near future. The microscopic flow model in micropore network based on digital core is worth to be established, and phase behavior needs to be further incorporated into the microscopic flow model of CO2 huff-n-puff in tight porous media.

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Research on multi‐mechanism synergistic effects of gas cross‐scale percolation in tight gas reservoirs of Yanchang oilfield

Gao,

Bai,

Qiao

et al. 2024

Can J Chem Eng

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Revealing the gas transport patterns at the microscale and nanoscale is of great scientific and engineering significance for unconventional oil and gas exploration and development. This paper first systematically analyzes the properties of gas transport mechanism under different Knudsen number conditions. Second, the coupling modes of the cross‐scale multi‐drive mechanism are systematically categorized, and three typical coupling calculation methods are pointed out. Again, the rationality of the cross‐scale multi‐agency coupling is quantitatively calculated. The results show that (a) Under the influence of Fick's diffusion equation, when Knr > 0, the coupled ‘slip flow–Fick diffusion–Knudsen diffusion’ equation does not converge to the Knudson diffusion equation. (b) The ‘Fick diffusion–Knudsen diffusion’ coupled equation is calculated to be more than 102 times as large as the Knudsen diffusion equation.

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Establishment of a new slip permeability model of gas flow in shale nanopores based on experimental and molecular dynamics simulations studies

Cited by 24 publications

References 30 publications

Apparent Permeability Coupling of Adsorbed and Free Gases for Deep Shale: Theoretical Model and Measurements

Apparent Permeability Coupling of Adsorbed and Free Gases for Deep Shale: Theoretical Model and Measurements

Review on Phase Behavior in Tight Porous Media and Microscopic Flow Mechanism of CO2 Huff-n-Puff in Tight Oil Reservoirs

Research on multi‐mechanism synergistic effects of gas cross‐scale percolation in tight gas reservoirs of Yanchang oilfield

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