Downhole seismic imaging of a massive sulfide orebody with mode-converted waves, Halfmile Lake, New Brunswick, Canada

Multioffset, multiazimuth downhole seismic data were acquired at Halfmile Lake, New Brunswick, to image known massive sulfide lenses and to investigate the potential existence of a steeply dipping mineralized zone connecting them. The massive sulfide lenses, which have significantly higher elastic impedances than host rocks, produce strong scattering. The downhole seismic data show prominent scattered (P-P and S-S) and mode-converted (P-S and S-P) waves originating from the deposit. Such complex scattering from massive sulfide ore was not observed previously in vertical seismic profiling data. Migration of the scattered and mode-converted waves from several shot points imaged different parts of the deepest lens. The scattered S-waves and mode-converted waves provide additional imaging capabilities that should be considered when selecting downhole seismic methods for mining exploration.