Frequency-varying filtering of simultaneous source seismic data

摘要

Seismic data acquired by independent simultaneous sweeping (ISS®) techniques are processed is to attenuate random uncompressed cross-talk signals and improve the resolution of the pre-stack migrated time image. A frequency-varying mean filter is applied on cross-spread offset-azimuth gathers of the data. The frequency-space domain filter may vary its window size according to the characteristics of the cross-talk.

主权项

1. A method of seismic surveying and attenuating crosstalk in seismic traces resulting from the seismic survey, comprising the steps of:
locating a plurality of swept frequency vibratory seismic energy sources in a seismic spread over a subsurface area of interest; the sources being located at assigned separate sectors in the seismic spread; locating a plurality of seismic energy receivers in assigned separate sectors over the subsurface area of interest; simultaneously emitting seismic energy at the plurality of swept frequency vibratory seismic energy sources; the seismic energy sources operating at different frequency sweeps of different time length while emitting the seismic energy to travel through the earth; the simultaneously emitted seismic energy traveling through the earth for reception by the plurality of seismic energy receivers; concurrently receiving the seismic energy from the simultaneous emissions as time-variant seismic traces at the plurality of seismic energy receivers after travel of the seismic energy through the earth; assembling in a computer the time-variant seismic traces received at the receivers into common offset gathers in a time-distance domain; transforming the common offset gathers in the time-distance domain with the computer into a frequency-space domain; forming cross-spread azimuth-offset gathers of the assembled common offset gathers in the frequency-space domain; determining median trace amplitude for selected frequency slices of interest for the cross-spread azimuth-offset gathers in the frequency-space domain; normalizing the amplitudes in individual ones of the traces in the selected frequency slices of interest for the cross-spread azimuth-offset gathers in the frequency-space domain based on the determined median trace amplitude; applying a variable-frequency mean filter to each of the traces of the selected frequency slices of interest to form attenuated crosstalk seismic traces; storing the attenuated crosstalk traces from the variable-frequency mean filtered traces of the selected frequency slices of interest; and forming an output record of the attenuated crosstalk traces from the variable-frequency mean filtered traces of the selected frequency slices of interest.