Determination of the hydraulic conductivities of a sandstone using an air permeameter

The objective of the current study is to determine hydraulic conductivities of a sandstone matrix and a single fracture using a portable air permeameter. For this purpose, the fluvial-aeolian Bebertal sandstone from the Upper Rotliegend in Saxony-Anhalt is investigated. Matrix permeabilities of the different facies and hydraulic apertures along a bedding joint are determined. The estimated hydraulic conductivities of the sandstone matrix range between 1.0 center dot 10(-7) and 9.2 center dot 10(-10) m/s, but only 3 out of 298 measurement points show K values of > 7.4 center dot 10(-8) m/s or permeabilities of > 10 mD. These belong to the more homogeneous and higher permeable aeolian facies. The estimated mean hydraulic fracture aperture is 82 +/- 12 mu m. Using both hydraulic parameters, the effective hydraulic conductivity of the studied sandstone can be determined. Our results illustrate the practical and robust applicability of the air permeameter for determining hydraulic conductivities of sandstones in the laboratory and in the field.