Interpretation of multi tracer tests in single fractures

Characterization of fractures in granite is important for the assessment of rocks in nuclear waste repositories. Basically information is obtained from single or doublet boreholes, in which tracer tests (either dilution or borehole to borehole) are performed. To get more information we changed the type of tracer using beside solute tracers particle tracers, injecting air to create an unsaturated zone and finally injecting differently soluble gases into that unsaturated zone to characterize its air volume and water content. While solute tracers alone did not allow to separate model hypotheses made on the fracture, the gas tracer tests are conclusive for moderately heterogeneous media. The fractures in the Grimsel are fault gouge filled fractures with variable gouge permeability. The air is distributed in fine streaks causing the total air volume to be very small. The Corey-Brooks law is better able to describe this behaviour than the van Genuchten law.

Main publications

Lunati, I., W. Kinzelbach, I. Sorensen, 2003. Effects of pore volume-transmissivity correlation on transport phenomena, JCH, Chen, Q. Kinzelbach, W., 2002. An NMR study of single- and two-phase flow in fault gouge filled fractures. J. of Hydrology, 259, p. 236-245

Contacts

W. Kinzelbach

Agency/Funding

NAGRA/146 kCHF

Partners

UPC Barcelona, ANDRA, France

Status

Finished in 2003

See other past research projects