CRIEPI’s Fractured Rock Studies (C-FRS)

CRIEPI has conducted a number of tests for the demonstration of acoustic tomography as a methodology for fracture characterisation. The acquired tomographic images of seismic velocities and attenuation have been used to illustrate to image potential hydraulic interconnections between borehole pairs.

Acoustic tomography performed at the GTS and its results.

CRIEPI’s Fractured Rock Studies - C-FRS

CRIEPI has performed several conservative tracer tests to characterise the target fractures at depth. Newly developed equipment which can treat both sorbing and conservative tracers was demonstrated at the C-FRS site. A highly viscous fluid was injected to obtain more information about the flow dimension and aperture of the target fractures.

Equipment and tracer samples for in-situ tracer testing. Photo comet.

CRIEPI’s Fractured Rock Studies - C-FRS

The radon concentration has been determined several times for groundwater samples collected in sampling campaigns in a growing number of C-FRS borehole intervals. The purpose is to demonstrate the application of radon concentration measurements for fracture characterisation. The equipment and methodology have also been tested with repeated calibration measurements.

Principle for the in-situ measurement of radon concentration.

Groundwater sampling for the measurement of dissolved radon. Photo: comet.

CRIEPI’s Fractured Rock Studies - C-FRS

Borehole wall images have been recorded with a high-resolution camera in selected, newly drilled boreholes and target intervals of specific interest. These optical images have been used mostly to assess the position and orientation of geological structures in the boreholes. They also allow the detailed mapping of fracture aperture near the borehole wall.

High-resolution camera equipment. Photo: comet.

Sample images of the FZ2 target fracture. Image: CRIEPI.

CRIEPI’s Fractured Rock Studies - C-FRS