A pore network model for simulating non-ideal gas flow in micro- and nano-porous materials

Jingsheng Ma, Juan Pablo Sanchez, Kejian Wu, Gary D. Couples, Zeyun Jiang

Research output: Contribution to journalArticle

95 Citations (Scopus)

Abstract

The capability to simulate real gas flow in porous materials with micro- and nano-meter-scale pores is of importance in many applications, such as gas extraction from shale reservoirs, and the design of gasbased fuel cells. A node-bond pore-network flow model (PNFM) has been developed for gas flow where it is the only fluid phase. The flow conductance equation includes the usual Darcy flow terms, and additional terms that capture the contributions from slip flow to Knudsen diffusion. With respect to the case for a non-ideal gas, the extra contributions, which are necessary, to the coefficients of the Darcy and Knudsen terms, are expressed in terms of reduced temperature and pressure, using van der Waals’s
two-parameter principle of corresponding states. Analysis on cylindrical pores shows that the coefficient deviates from that of the non-ideal gas case by more than 80% in the Darcy term, while between 80% and 150% in the Knudsen term, when the physical states approach to the critical state of the fluid. Although the deviations become smaller when the states are away from the critical state, they remain relatively large even at conditions relevant to practical applications. The model was applied to a pore network of a realistic 3D shale model to show slippage and Knudsen effects on the predicted permeability and the sensitivity to pore sizes. Simulations were carried out for methane under the operational conditions of typical shale-gas reservoirs, and nitrogen under the conditions of laboratory experiments. The results show that the ratio of gas and Darcy permeability correlates positively and strongly with the pore size but inversely with the gas pressure and Tangential Momentum Accommodation Coefficient (TMAC) in the slip term, which can impact gas permeability disproportionally. The results are in favour of controlling the rate of gas depressurisation to avoid early depletion in shale gas production. The methane permeability is shown to be 30% greater, relatively, than that when the ideal gas law is applied, even under normal field operational conditions, while the nitrogen permeability can only approximate the methane permeability within a certain range of field operational conditions when the slip flow is not dominating.
Original languageEnglish
Pages (from-to)498-508
Number of pages11
JournalFuel
Volume116
Early online date29 Aug 2013
DOIs
Publication statusPublished - 15 Jan 2014

Fingerprint

Flow of gases
Porous materials
Gases
Methane
Shale
Pore size
Nitrogen
Gas permeability
Fluids
Fuel cells
Momentum
Experiments
Temperature

Keywords

  • Gas transport
  • Slip flow
  • Knudsen diffusion
  • Micro/nanoporous media
  • Shale gas reservoir

Cite this

A pore network model for simulating non-ideal gas flow in micro- and nano-porous materials. / Ma, Jingsheng ; Sanchez, Juan Pablo ; Wu, Kejian; Couples, Gary D. ; Jiang, Zeyun.

In: Fuel, Vol. 116, 15.01.2014, p. 498-508.

Research output: Contribution to journalArticle

Ma, Jingsheng ; Sanchez, Juan Pablo ; Wu, Kejian ; Couples, Gary D. ; Jiang, Zeyun. / A pore network model for simulating non-ideal gas flow in micro- and nano-porous materials. In: Fuel. 2014 ; Vol. 116. pp. 498-508.
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abstract = "The capability to simulate real gas flow in porous materials with micro- and nano-meter-scale pores is of importance in many applications, such as gas extraction from shale reservoirs, and the design of gasbased fuel cells. A node-bond pore-network flow model (PNFM) has been developed for gas flow where it is the only fluid phase. The flow conductance equation includes the usual Darcy flow terms, and additional terms that capture the contributions from slip flow to Knudsen diffusion. With respect to the case for a non-ideal gas, the extra contributions, which are necessary, to the coefficients of the Darcy and Knudsen terms, are expressed in terms of reduced temperature and pressure, using van der Waals’stwo-parameter principle of corresponding states. Analysis on cylindrical pores shows that the coefficient deviates from that of the non-ideal gas case by more than 80{\%} in the Darcy term, while between 80{\%} and 150{\%} in the Knudsen term, when the physical states approach to the critical state of the fluid. Although the deviations become smaller when the states are away from the critical state, they remain relatively large even at conditions relevant to practical applications. The model was applied to a pore network of a realistic 3D shale model to show slippage and Knudsen effects on the predicted permeability and the sensitivity to pore sizes. Simulations were carried out for methane under the operational conditions of typical shale-gas reservoirs, and nitrogen under the conditions of laboratory experiments. The results show that the ratio of gas and Darcy permeability correlates positively and strongly with the pore size but inversely with the gas pressure and Tangential Momentum Accommodation Coefficient (TMAC) in the slip term, which can impact gas permeability disproportionally. The results are in favour of controlling the rate of gas depressurisation to avoid early depletion in shale gas production. The methane permeability is shown to be 30{\%} greater, relatively, than that when the ideal gas law is applied, even under normal field operational conditions, while the nitrogen permeability can only approximate the methane permeability within a certain range of field operational conditions when the slip flow is not dominating.",
keywords = "Gas transport , Slip flow , Knudsen diffusion , Micro/nanoporous media , Shale gas reservoir",
author = "Jingsheng Ma and Sanchez, {Juan Pablo} and Kejian Wu and Couples, {Gary D.} and Zeyun Jiang",
note = "The authors wish to thank G. Desbois, RWTH Aachen University, Germany, for providing the shale SEM images that were used in this work to construct the gas shale model. The authors wish to thank X. Zhang, School of Engineering, University of Liverpool, S.D. McDougall and M.I.J. van Dijke, Institute of Petroleum Engineering, Heriot-Watt University, UK, for constructive discussions in relation to this work.",
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AU - Ma, Jingsheng

AU - Sanchez, Juan Pablo

AU - Wu, Kejian

AU - Couples, Gary D.

AU - Jiang, Zeyun

N1 - The authors wish to thank G. Desbois, RWTH Aachen University, Germany, for providing the shale SEM images that were used in this work to construct the gas shale model. The authors wish to thank X. Zhang, School of Engineering, University of Liverpool, S.D. McDougall and M.I.J. van Dijke, Institute of Petroleum Engineering, Heriot-Watt University, UK, for constructive discussions in relation to this work.

PY - 2014/1/15

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N2 - The capability to simulate real gas flow in porous materials with micro- and nano-meter-scale pores is of importance in many applications, such as gas extraction from shale reservoirs, and the design of gasbased fuel cells. A node-bond pore-network flow model (PNFM) has been developed for gas flow where it is the only fluid phase. The flow conductance equation includes the usual Darcy flow terms, and additional terms that capture the contributions from slip flow to Knudsen diffusion. With respect to the case for a non-ideal gas, the extra contributions, which are necessary, to the coefficients of the Darcy and Knudsen terms, are expressed in terms of reduced temperature and pressure, using van der Waals’stwo-parameter principle of corresponding states. Analysis on cylindrical pores shows that the coefficient deviates from that of the non-ideal gas case by more than 80% in the Darcy term, while between 80% and 150% in the Knudsen term, when the physical states approach to the critical state of the fluid. Although the deviations become smaller when the states are away from the critical state, they remain relatively large even at conditions relevant to practical applications. The model was applied to a pore network of a realistic 3D shale model to show slippage and Knudsen effects on the predicted permeability and the sensitivity to pore sizes. Simulations were carried out for methane under the operational conditions of typical shale-gas reservoirs, and nitrogen under the conditions of laboratory experiments. The results show that the ratio of gas and Darcy permeability correlates positively and strongly with the pore size but inversely with the gas pressure and Tangential Momentum Accommodation Coefficient (TMAC) in the slip term, which can impact gas permeability disproportionally. The results are in favour of controlling the rate of gas depressurisation to avoid early depletion in shale gas production. The methane permeability is shown to be 30% greater, relatively, than that when the ideal gas law is applied, even under normal field operational conditions, while the nitrogen permeability can only approximate the methane permeability within a certain range of field operational conditions when the slip flow is not dominating.

AB - The capability to simulate real gas flow in porous materials with micro- and nano-meter-scale pores is of importance in many applications, such as gas extraction from shale reservoirs, and the design of gasbased fuel cells. A node-bond pore-network flow model (PNFM) has been developed for gas flow where it is the only fluid phase. The flow conductance equation includes the usual Darcy flow terms, and additional terms that capture the contributions from slip flow to Knudsen diffusion. With respect to the case for a non-ideal gas, the extra contributions, which are necessary, to the coefficients of the Darcy and Knudsen terms, are expressed in terms of reduced temperature and pressure, using van der Waals’stwo-parameter principle of corresponding states. Analysis on cylindrical pores shows that the coefficient deviates from that of the non-ideal gas case by more than 80% in the Darcy term, while between 80% and 150% in the Knudsen term, when the physical states approach to the critical state of the fluid. Although the deviations become smaller when the states are away from the critical state, they remain relatively large even at conditions relevant to practical applications. The model was applied to a pore network of a realistic 3D shale model to show slippage and Knudsen effects on the predicted permeability and the sensitivity to pore sizes. Simulations were carried out for methane under the operational conditions of typical shale-gas reservoirs, and nitrogen under the conditions of laboratory experiments. The results show that the ratio of gas and Darcy permeability correlates positively and strongly with the pore size but inversely with the gas pressure and Tangential Momentum Accommodation Coefficient (TMAC) in the slip term, which can impact gas permeability disproportionally. The results are in favour of controlling the rate of gas depressurisation to avoid early depletion in shale gas production. The methane permeability is shown to be 30% greater, relatively, than that when the ideal gas law is applied, even under normal field operational conditions, while the nitrogen permeability can only approximate the methane permeability within a certain range of field operational conditions when the slip flow is not dominating.

KW - Gas transport

KW - Slip flow

KW - Knudsen diffusion

KW - Micro/nanoporous media

KW - Shale gas reservoir

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SN - 0016-2361

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