Surface Consistent Amplitude Correction
Unbiased Surface Consistent Amplitude Correction AVO Compliant Processing
Preservation of relative amplitude information is critical for many downstream applications such as AVO/LMR analysis and AVAZ/VVAZ inversion.
TGS’ AVO compliant processing flow contains a strong suite of tools from linear noise attenuation through to prestack migration which collectively
provide robust noise attenuation and good imaging without distortion of primary reflection energy.
The industry-standard technique for surface-consistent scaling bases its amplitude estimates on the RMS amplitude of prestack traces. This RMS amplitude is always biased by the energy level of random noise and its use in the computation of surface-consistent scalars causes the amplitudes of the stack to be too low in noisy parts of a survey. In order to overcome this problem, TGS has developed a new technique called SCORE (Surface Consistent Correlation Stack Equalization) which computes prestack amplitudes from the zero-lag of the cross-correlations between each prestack trace and its CDP stack trace. Such a crosscorrelation can provide unbiased prestack amplitudes which are independent of time variations in the structure. The shot and receiver consistent averages can then be computed to obtain the scalars in a surface-consistent manner. The technique has proven to be highly effective at overcoming scaling problems in areas where the noise and signal are both surface-consistent.
More detail can be found in the paper titled “Unbiased surface-consistent scalar estimation by crosscorrelation” By N. Nagarajappa and P. Cary, presented at the 2015 GeoConvention.