Geosond SA have over 25 years’ experience in the field of specialist construction with expertise in geotechnical and hydrogeological studies. Amongst their specialties is the execution of geotechnical, geological and hydrogeological drilling.
The Bicaz lake is an artificial reservoir created to support the Bizac dam and Stejaru Hydroelectric Power Plant. The hydro system in Bicaz-Stejaru has been active for over 50 years and the dam is 127m high with a length of 435m. The Stejaru hydro power plant, which includes four turbines of 27.5 MW and two turbines of 50 MW, has been undergoing a programme of upgrades.
RGS supplied the 3-Arm Caliper Probe and High-Resolution Acoustic Televiewer (HRAT)® to detect fractures within the formation, to provide data to assist with the determination of a suitable location to place a hydroelectric pump/turbine station.
The main challenge was to collect borehole wall images from the borehole through PVC pipe, which would require fine tuning of the HRAT®. The borehole was logged in sections with the parameters being changed for each run to obtain the clearest images. Natural gamma data was used to ensure the individual runs were correctly spliced together to give a continuous profile.
The highly experienced engineers were able to fine-tune the HRAT® settings for each run eventually resulting in a high quality amplitude log from which bedding and fractures could be readily picked. From the picks, the dip azimuths and directions were calculated and then aggregated into Wulff plots, Rose diagrams and a 3D core plot.
