oa Feasibility of the application of borehole seismology for hard rock exploration

Mineralisation of economic importance typically occurs in hard rock environments that tests the resolution limits of surface seismic techniques. Complex geology, steeply dipping structures and thick highly heterogeneous regolith cover hinder collection, processing and interpretation of seismic data. Hard rock units in contact often exhibit similar elastic properties with small velocity and density contrasts. In addition, reactivated, altered and highly fractured zones cause significant scattering of seismic energy. All these factors can combine to make it very difficult to produce interpretable images from seismic reflection surveys. Borehole seismic methods reduce the effects of wavefield scattering by placing either the receiver or source within the bedrock. The result is higher signal to noise ratios, higher frequency content and greater accuracy in velocity observations, ultimately giving higher resolution images.

To test the viability of borehole seismology in typical hard rock exploration environments we have conducted a number of modelling tests. These tests are aimed to demonstrate the potential of recording and producing high resolution images from borehole seismic measurements. We also offer potential Vertical Seismic Profile (VSP) methodologies to assist in hard rock seismic exploration.