From noise to signal - Harnessing harmonics for imaging

Summary Harmonics within vibrator data have long been seen as unwanted noise distortions to be attenuated from seismic data. Indeed, methods have been developed to eliminate harmonic “contamination” in the acquisition and processing phases of seismic exploration as well as from the vibrator mechanical and hydraulic system itself. In this paper, however, we propose that these harmonics and their associated higher frequency content can be harnessed for seismic imaging of shallow thin reflectors. Through high sampling of the wave field, harmonic decomposition of recorded sweeps through the use of the Gabor transform, and surprisingly simple processing, we show that thin shallow reflectors are brought into focus from the blur of the near surface.