The potential of digital seismic recordings for multichannel processing

The availability of seismic digital field recording equipment has made possible new processing techniques which achieve significant reflection data enhancement. Typical of the processes that are now used routinely are deconvolution, autocorrelation and crosscorrelation, Fourier transformation, and spectral alteration. A recording fidelity that reduces errors to 1 part in 10,000 has provided the motive for developing and using these techniques.An additional capability of digital field equipment is the recording of amplifier gain information to a precision of 0.1 percent. This appears to provide a motive for developing multichannel processes which expand further our processing capabilities beyond the essentially single channel ones now in use. The present study evaluates the multichannel processing potential afforded by present day seismic digital field recording systems. The evaluation is based on measurement and computation of the effects of channel performance deviations. Each component of the field recording system (geophone, cable, amplifier, filters, sampling skew) separately, and the system as a whole, are evaluated in this context.Results of the study indicate that whereas any given channel possesses a dynamic range of 80 db, channel-to-channel variations establish a dynamic range of only 15 db. The 15 db range sets a serious limit on the performance of multichannel processes and points up the need for additional improvements in field hardware capabilities.