Hyperalkaline Plume in Fractured Rock (HPF) - Preliminary Results

The results so far suggest that the shear zone was gradually blocked and increasingly fewer of the smaller fractures contributed to the flow field. Originally, the breakthrough curve was quite diffuse, due to transport in a wide range of water conducting features. The more recent breakthrough curves obtained show a much better defined peak and faster breakthrough times, suggesting focussing of the transport into a few larger fractures.


Graph of uranine (sodium fluoroscene dye) breakthrough since start of continuous high pH fluid injection

The evolution of injection pressure at constant rate pumping of 1 mL/min records a steady increase after the initial injection of high pH fluid. This pressure increase is a result of a gradual decrease in the overall transmissivity of the shear zone, presumably due to blocking of the smaller fractures (as noted above). A corresponding decrease in the passive outflow rate can be observed at the extraction site.

 

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.