Structural Mapping for Uranium Exploration by Borehole Seismic

The McArthur River mine has become a testing ground for seismic techniques, as a part of Cameco’s innovative and integrated multidisciplinary approach to exploration. Downhole side-scan seismic surveys were performed in boreholes MC-269 and MC-204 to a depth of 570m, using a tool consisting of a piezoelectric, swept-impact source and a string of 24 hydrophones. The main objectives of the survey were to detect uranium ore and structural ore controls. Downhole seismic profiling offers the possibility of mapping seismic reflectors and diffractors up to 200m away from the drill hole using high frequency seismic waves. Two parallel lines of processing were used, one aimed at imaging steeply dipping reflectors, the other at emphasizing point diffractors. Strong reflections associated with known structures were observed, which matched well the drill core logs The survey at McArthur River was successful in achieving its goals, by detecting diffraction and reflection patterns consistent with probable locations of mineralization. The survey also showed that delineation of fault zones, e.g. the P2 zone, is possible.