Workreport 2009-81

Difference Flow and Electrical Conductivity Measurements at the Olkiluoto Site in Eurajoki, Drillholes OL-KR44, OL-KR44B, OL-KR45, OL-KR45B, OL-KR46, OL-KR47 and OL-KR48, Part 2

Pöllänen, J.

English

366

The Posiva Flow Log, Difference flow method (PFL DIFF) uses a flowmeter that incorporates a flow guide and can be used for relatively quick determinations of hydraulic conductivity and hydraulic head in fractures/fractured zones in cored drillholes. This report presents the principles of the method and the results of measurements carried out in drillholes OL-KR44, OL-KR44B, OL-KR45, OL-KR45B, OL-KR46, OL-KR47 and OL-KR48 at the Olkiluoto investigation site between July 2007 and March 2008.

The measuring programme employed varied only slightly between drillholes. The section length of the flow guide was either 2 m or 0.5 m. Flow into the drillhole or from the drillhole to the bedrock was measured within the section lengths and carried out in both pumped and natural (i.e. un-pumped) conditions. Calculations of the transmissivity (T) and the hydraulic head (h) of the zones are shown in the results.

The device used includes a sensor for single point resistance (SPR). SPR was measured in connection with flow measurements.

The electrical conductivity (EC) of fracture-specific water was measured in chosen fractures in some of the drillholes. Fractures were selected on the basis of the measured flow from fracture to drillhole. The EC of the drillhole water was also measured.

Groundwater, flow, measurement, bedrock, drillhole, electrical conductivity, Posiva Flow Log

Difference Flow and Electrical Conductivity Measurements at the Olkiluoto Site in Eurajoki, Drillholes OL-KR44, OL-KR44B, OL-KR45, OL-KR45B, OL-KR46, OL-KR47 and OL-KR48, Part2 (pdf) (33.4 MB)