Comparison between core log and hydraulic and geophysical measurements in boreholes

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Authors:Magnusson, Kurt-Åke; Duran, O.
Author Affiliations:Primary:
Sver. Geol., Uppsala, Sweden
Volume Title:Geoexploration
Source:Geoexploration, 22(3-4), p.169-186. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0016-7142
Publication Date:1984
Note:In English. 14 refs.Special issue; nuclear fuel waste management; illus. incl. sketch map
Summary:The fractures and microfractures in crystalline rock constitute the main transport paths for both ground water and electric currents. They will therefore govern both the permeability and the resistivity of the rock. A detailed comparison has been made between the hydraulic conductivity and resistivity, respectively, and the character of fractures in the core and the borehole wall. The fractures show very large variations in hydraulic conductivity. Microfractures and most of the thin fractures have no measurable hydraulic conductivity, while test sections which contain a single isolated fracture can have no measurable to rather high hydraulic conductivities (> 10-7 ms-1). Wide fracture zones often have hydraulic conductivities which vary from very low (less than 2 . 10 -9 m s-1) to high values (10-5 m s-1). This indicates that the hydraulic conductivity is governed by a few discrete fractures. The resistivity shows a continuous variation in the range 1,000-100,000 ohm-m and a relatively poor correlation with hydraulic conductivities. The observed difference is considered to be the effect of restriction of water flow on a few channels, while electric surface conduction makes current transport possible through fractures with very small apertures. Modified journal abstract.
Subjects:Boreholes; Cores; Cracks; Crystalline rocks; Electrical logging; Engineering geology; Fractures; Ground water; Histograms; Hydraulic conductivity; Interpretation; Microcracks; Permeability; Radioactive waste; Resistivity; Statistical analysis; Transmissivity; Waste disposal; Well-logging; Europe; Scandinavia; Sweden; Western Europe; Krakemala
Record ID:1985012060
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute.
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