Bright reflections in high-resolution seismic recordings

Amplitudes of high-resolution seismic reflections are reduced to within the dynamic range of facsimile profile recording by linear time-varied gain followed by 10:1 logarithmic compression so that relative amplitudes can be distinguished. The asymmetric pulse of the high-resolution Bogmer enables the polarity of isolated reflections to be determined. Seismic systems have been calibrated so that measurements of peak reflection amplitudes could be interpreted, yielding reflection coefficients of -50 to -80% in cases where no deeper penetration was observed. Presumed reduction of acoustic impedance by gas has been confirmed by samples containing gas and decomposing biologic material. These improvements to amplitude and polarity display and calibration help interpretation of biologic zones and limits to penetration on seismic profiles.