The water retention curve and relative permeability for gas production from hydrate-bearing sediments: pore-network model simulation

Nariman Mahabadi Mahabad, Sheng Dai, Yongkoo Seol, Tae Sup Yun, Jaewon Jang

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

The water retention curve and relative permeability are critical to predict gas and water production from hydrate-bearing sediments. However, values for key parameters that characterize gas and water flows during hydrate dissociation have not been identified due to experimental challenges. This study utilizes the combined techniques of micro-focus X-ray computed tomography (CT) and pore-network model simulation to identify proper values for those key parameters, such as gas entry pressure, residual water saturation, and curve fitting values. Hydrates with various saturation and morphology are realized in the pore-network that was extracted from micron-resolution CT images of sediments recovered from the hydrate deposit at the Mallik site, and then the processes of gas invasion, hydrate dissociation, gas expansion, and gas and water permeability are simulated. Results show that greater hydrate saturation in sediments lead to higher gas entry pressure, higher residual water saturation, and steeper water retention curve. An increase in hydrate saturation decreases gas permeability but has marginal effects on water permeability in sediments with uniformly distributed hydrate. Hydrate morphology has more significant impacts than hydrate saturation on relative permeability. Sediments with heterogeneously distributed hydrate tend to result in lower residual water saturation and higher gas and water permeability. In this sense, the Brooks-Corey model that uses two fitting parameters individually for gas and water permeability properly capture the effect of hydrate saturation and morphology on gas and water flows in hydrate-bearing sediments.

Original languageEnglish (US)
Pages (from-to)3099-3110
Number of pages12
JournalGeochemistry, Geophysics, Geosystems
Volume17
Issue number8
DOIs
StatePublished - Aug 1 2016

Keywords

  • Brooks-Corey model
  • hydrate-bearing sediments
  • pore-network model
  • relative permeability
  • van Genuchten model
  • water retention curve

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Fingerprint Dive into the research topics of 'The water retention curve and relative permeability for gas production from hydrate-bearing sediments: pore-network model simulation'. Together they form a unique fingerprint.

  • Cite this