Hydraulic versus pneumatic measurements of fractured sandstone permeability

Baraka-Lokmane, Salima (2002) Hydraulic versus pneumatic measurements of fractured sandstone permeability Journal of Petroleum Science and Engineering, 36. pp. 183-192. ISSN 0920-4105

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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.

Item Type: Journal article
Uncontrolled Keywords: Fractured sandstone; liquid permeability; gas permeability; laboratory study
Subjects: F000 Physical Sciences > F800 Physical Geography and Environmental Sciences > F840 Physical Geography
F000 Physical Sciences > F600 Geology
Faculties: Faculty of Science and Engineering > School of Environment and Technology > Applied Geosciences
Faculty of Science and Engineering > School of Environment and Technology
Depositing User: editor environment
Date Deposited: 21 Jan 2008
Last Modified: 04 Apr 2014 09:36
URI: http://eprints.brighton.ac.uk/id/eprint/2155

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