Numerical Simulation of Multiphase Flow in Nanoporous Organic Matter With Application to Coal and Gas Shale Systems

Wenhui Song, Jun Yao, Jingsheng Ma, Hai Sun, Yang Li, Yongfei Yang, Lei Zhang

Research output: Contribution to journalArticle

20 Citations (Scopus)
25 Downloads (Pure)

Abstract

Fluid flow in nanoscale organic pores is known to be affected by fluid transport mechanisms and properties within confined pore space. The flow of gas and water shows notably different characteristics compared with conventional continuum modeling approach. A pore network flow model is developed and implemented in this work. A 3-D organic pore network model is constructed from 3-D image that is reconstructed from 2-D shale SEM image of organic-rich sample. The 3-D pore network model is assumed to be gas-wet and to contain initially gas-filled pores only, and the flow model is concerned with drainage process. Gas flow considers a full range of gas transport mechanisms, including viscous flow, Knudsen diffusion, surface diffusion, ad/desorption, and gas PVT and viscosity using a modified van der Waals' EoS and a correlation for natural gas, respectively. The influences of slip length, contact angle, and gas adsorption layer on water flow are considered. Surface tension considers the pore size and temperature effects. Invasion percolation is applied to calculate gas-water relative permeability. The results indicate that the influences of pore pressure and temperature on water phase relative permeabilities are negligible while gas phase relative permeabilities are relatively larger in higher temperatures and lower pore pressures. Gas phase relative permeability increases while water phase relative permeability decreases with the shrinkage of pore size. This can be attributed to the fact that gas adsorption layer decreases the effective flow area of the water phase and surface diffusion capacity for adsorbed gas is enhanced in small pore size.

Original languageEnglish
Pages (from-to)1077-1092
Number of pages16
JournalWater Resources Research
Volume54
Issue number2
Early online date8 Feb 2018
DOIs
Publication statusPublished - Feb 2018

Keywords

  • coal and gas shale
  • multiphase flow
  • nanoporous organic matter
  • pore network model
  • relative permeability
  • transport mechanisms

ASJC Scopus subject areas

  • Water Science and Technology

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