Databank

Workreport 2007-16

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Name:

Difference Flow and Electric Conductivity Measurements at the Olkiluoto Site in Eurajoki, Boreholes KR25, KR25B and KR31

Writer:

Väisäsvaara, J. & Pöllänen, J.

Language:

English

Page count:

129

Summary:

The Posiva Flow Log/Difference flow method can be used for a relatively fast determination of water conductivity and hydraulic head in fractures/fractured zones in cored boreholes. In this method, a flow meter utilizing flow guide is used. This report presents the principles and the results of the measurements carried out in boreholes KR25, KR25B and KR31 at the Olkiluoto investigation site between April 2006 and August 2006.

The measuring program varied only slightly between the boreholes. The section length of the flow guide was 2 m and 0.5 m. The flow into the borehole or from the borehole to the bedrock was measured within the section lengths. This was carried out both in pumped and in natural (un-pumped) conditions. The transmissivity (T) and the hydraulic head of the zones are calculated in the results, if a measurement in natural conditions was performed.

The device that was used also includes a sensor for single point resistance (SPR). SPR was always measured in connection with flow measurements, and it was registered when the tool was moving.

The electric conductivity of fracture-specific water (EC) was measured in chosen fractures in some of the boreholes. The fractures were chosen on the basis of the measured flow from the fracture to the borehole. The EC of the borehole water was also measured.

Keywords:

Groundwater, flow, measurement, bedrock, borehole, electric conductivity, Posiva Flow Log

File(s):

Difference Flow and Electric Conductivity Measurements at the Olkiluoto Site in Eurajoki, Boreholes KR25, KR25B and KR31 (pdf) (11 MB)


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