Hydraulic versus pneumatic measurements of fractured sandstone permeability

Salima Baraka-Lokmane

Research output: Contribution to journalArticle

Abstract

This paper investigates the issue of ascertaining whether gas can replace water for determining the flow parameters in fractured porous media. This is accomplished by the determination of the hydraulic parameters using brine, the pneumatic parameters using air, and the study of the correlation between these two parameters. The measurements are obtained for fractured sandstone cores from the middle Stubensandstein unit in the Southwest German Trias. In most cases, the intrinsic liquid permeability is lower than the intrinsic gas permeability. Intrinsic gas permeability (kg) ranged from 32 to 159 md, while intrinsic liquid permeability (kl) ranged from 12 to 47 md. The ratio of intrinsic gas permeability to intrinsic liquid permeability (kg/kl) shows two subgroups: (1) ratios ranging from 1 to 2 (62.5% of samples) and (2) ratios ranging from 4 to 5 (37.5% of samples). The reduction in the intrinsic liquid permeability is governed by three phenomena: physicochemically, by the migration of the clay particles which clog the pores, mechanically, by the breakdown of original fabrics caused by the passage of wetting fronts across relatively delicate clay mineral complexes, and experimentally, by the undersaturation of samples during liquid permeability measurements. This study concludes that gas permeability is more accurate than liquid permeability because it measures more closely intrinsic permeability especially for clay-rich rocks. In addition, because gas experiments can be conducted much faster than liquid flow experiments, gas is a desirable replacement fluid.
Original languageEnglish
Pages (from-to)183-192
Number of pages10
JournalJournal of Petroleum Science and Engineering
Volume36
Publication statusPublished - 30 Sep 2002

Keywords

  • Fractured sandstone
  • liquid permeability
  • gas permeability
  • laboratory study

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