Apparent permeability model for real gas transport through shale gas reservoirs considering water distribution characteristic

Sun, Zheng; Li, Xiangfang; Shi, Juntai; Zhang, Tao; Sun, Fengrui

doi:10.1016/j.ijheatmasstransfer.2017.07.123

Cited by 152 publications

(58 citation statements)

References 38 publications

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“…More importantly, in the shale gas/oil industry, abundant nanoscale pores are observed and discovered through advanced approaches. [22][23][24] Notably, during the long geological evolution process of shale gas/oil reservoirs, it can be demonstrated that regular circular nanopores are hardly existed in realistic shale matrix. [25][26][27] Unfortunately, a commonly used assumption is made in almost all the current research about shale gas/oil reservoirs, that is, pore shape in shale matrix is regarded as circles, which is inconsistent with the real situation and will result in a dramatic discrepancy.…”

Section: Introductionmentioning

confidence: 99%

Effect of pore geometry on nanoconfined water transport behavior

Sun

Shi

et al. 2019

AIChE Journal

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Different pore shapes correspond to different interaction strengths between pore surface and molecules, which will result in discrepancy of nanoconfined water transport capacity. In this article, complex nanoscale pore shapes are represented by ellipses, which possess an excellent shape-variation physical property, that is, ellipses can gradually transition from circles to slit-like cross-sections by manipulating aspect ratio from 1 to maxima. Moreover, capturing water slip phenomenon and spatially variation of water viscosity, an analytical model for water transport capacity through elliptical nanopores is developed. Results show that (a) water slip effect plays a limited positive role at hydrophilic environment and a strong positive role at hydrophobic environment;(b) nanopores with more flat geometry feature will possess smaller enhance factor at hydrophilic environment; (c) spatially viscosity distribution is a negative factor when contact angle is lower than about 130 and turns to a positive factor when contact angle is higher than about 130 . K E Y W O R D Snanoconfined water flow, various pore shapes, water slip phenomenon, water viscosity

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Section: Introductionmentioning

confidence: 99%

Effect of pore geometry on nanoconfined water transport behavior

Sun

Shi

et al. 2019

AIChE Journal

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“…In its experimental test, helium and methane were used to measure shale permeability, and the basic input parameters of model verification were shown in Table 1. Since gas viscosity is a function of pressure, the widely used formula is adopted to calculate, namely [47][48][49][50] (47) where γ g is gas molar weight, kg/mol. Since shale has no adsorption effect on helium gas, the effect of surface diffusion on apparent permeability is not considered when calculating the apparent permeability of helium gas.…”

Section: Model Validationmentioning

confidence: 99%

Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

Wang

Zhao

et al. 2019

Energies

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Based on fractal geometry theory, the Hagen–Poiseuille law, and the Langmuir adsorption law, this paper established a mathematical model of gas flow in nano-pores of shale, and deduced a new shale apparent permeability model. This model considers such flow mechanisms as pore size distribution, tortuosity, slippage effect, Knudsen diffusion, and surface extension of shale matrix. This model is closely related to the pore structure and size parameters of shale, and can better reflect the distribution characteristics of nano-pores in shale. The correctness of the model is verified by comparison with the classical experimental data. Finally, the influences of pressure, temperature, integral shape dimension of pore surface and tortuous fractal dimension on apparent permeability, slip flow, Knudsen diffusion and surface diffusion of shale gas transport mechanism on shale gas transport capacity are analyzed, and gas transport behaviors and rules in multi-scale shale pores are revealed. The proposed model is conducive to a more profound and clear understanding of the flow mechanism of shale gas nanopores.

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“…The permeability plays an important role in gas flow transport in shale gas reservoirs (Sun et al 2017;Tokunaga et al 2017). In the study, four cases of different permeability values from 1.0 × 10 −12 to 1.0 × 10 −21 m 2 are selected to study the effects of methane diffusion and adsorption in shale rocks, as shown in Fig.…”

Section: Effect Of Permeabilitymentioning

confidence: 99%

Methane Diffusion and Adsorption in Shale Rocks: A Numerical Study Using the Dusty Gas Model in TOUGH2/EOS7C-ECBM

et al. 2018

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Gas production from shale gas reservoirs plays a significant role in satisfying increasing energy demands. Compared with conventional sandstone and carbonate reservoirs, shale gas reservoirs are characterized by extremely low porosity, ultra-low permeability and high clay content. Slip flow, diffusion, adsorption and desorption are the primary gas transport processes in shale matrix, while Darcy flow is restricted to fractures. Understanding methane diffusion and adsorption, and gas flow and equilibrium in the low-permeability matrix of shale is crucial for shale formation evaluation and for predicting gas production. Modeling of diffusion in low-permeability shale rocks requires use of the Dusty gas model (DGM) rather than Fick's law. The DGM is incorporated in the TOUGH2 module EOS7C-ECBM, a modified version of EOS7C that simulates multicomponent gas mixture transport in porous media. Also included in EOS7C-ECBM is the extended Langmuir model for adsorption and desorption of gases. In this study, a column shale model was constructed to simulate methane diffusion and adsorption through shale rocks. The process of binary CH 4 −N 2 diffusion and adsorption was analyzed. A sensitivity study was performed to investigate the effects of pressure, temperature and permeability on diffusion and adsorption in shale rocks. The results show that methane gas diffusion and adsorption in shale is a slow process of dynamic equilibrium, which can be illustrated by the slope of a curve in CH 4 mass variation. The amount of adsorption increases with the pressure increase at the low pressure, and the mass change by gas diffusion will decrease due to the decrease in the compressibility factor of the gas. With the elevated temperature, the gas molecules move faster and then the greater gas diffusion rates make the process duration shorter. The gas diffusion rate decreases with the permeability decrease, and there is a limit of gas diffusion if the permeability is less than 1.0 × 10 −15 m 2 . The results can provide insights for a better understanding of methane diffusion and adsorption in the shale rocks so as to optimize gas production performance of shale gas reservoirs.

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Apparent permeability model for real gas transport through shale gas reservoirs considering water distribution characteristic

Cited by 152 publications

References 38 publications

Effect of pore geometry on nanoconfined water transport behavior

Effect of pore geometry on nanoconfined water transport behavior

Multiscale Apparent Permeability Model of Shale Nanopores Based on Fractal Theory

Methane Diffusion and Adsorption in Shale Rocks: A Numerical Study Using the Dusty Gas Model in TOUGH2/EOS7C-ECBM

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