Wavefield Signal Apparition, Part I - Theory

A new method for discrete sampling of signals with applications to separation of interfering wavefields is presented. By utilizing a periodic sequence of source signatures along one source line, the wavefield becomes separately visible in different parts of the spectral domain where it can be isolated from interfering signals, processed, and subtracted from the original recordings, thereby separating the wavefields from each other. The concept is referred to as signal apparition which we suggest refers to "the act of becoming visible". We anticipate a broad range of applications of the new sampling approach including simultaneous source separation, seismic interference cancellation, residual shot noise attenuation, modeling of wavefields and source-side deghosting. We illustrate the concept of seismic apparition on 2D finite-difference modeled data to remove the source ghost. In a companion paper (Sjøen Pedersen, Å., Amundsen, T., and Robertsson, J. O. A., 2016, Wavefield signal apparition, Part II: Application to simultaneous sources and their separation: Expanded abstract submitted to the EAGE annual meeting) we discuss the application of seismic apparition to simultaneous source acquisition to increase productivity and/or obtain a better source-side sampling of the seismic data.