Amplitude Corrections
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Source Amplitude Solution 3D survey, dual source Early QC checks compute RMS amplitude statistics for each sail line compute RMS amplitude statistics on shot and channel basis analyse frequency spectra of selected shots mplitude of the t!o sources seen to vary considerably across the survey "ne source consistently stron#er than the other Differences in frequency content apparent bet!een the t!o sources Si#nature Deconvolution Source !avelet matched to a user$defined !avelet Deconvolution performed separately for each #un and matched to a common !avelet %o need to determine !hich #un has correct spectrum Deconvolution filters derived for each shot from runnin# avera#e acro &' field records at a time Deconvolution filters applied on shot$by$shot basis mplitude and frequency discrepancy bet!een sources is si#nificantly reduce the application of si#nature deconvolution Equalisation of the amplitudes is clearly visible on RMS displays, shot plo near traces Survey$!ide variation in source amplitude is eliminated Surface Consistent Scaling mplitude variations !ill e(ist !ithin data volumes on many levels Channel, shot, #un, cable, line, receiver etc )he measured amplitude responses in the data are modelled usin# a series of terms *also includin# CM+ offset terms- )he model is estimated in a least squares sense, !ith the terms bein# compu iteratively in a user specified order. Corrections can be computed on individual lines or on a number of lines simultaneously. Line to Line Corrections (Common Offsets) /ine to line amplitude variations can be effectively safely removed after normalisation. mplitudes e(tracted on common time slices for each common offset. Median amplitude responses analysed and corrections applied to correct ra! amplitudes to these median values. )ime dependent scalars *ie filterin# can be easily controlled if nece throu#h tar#et hori0ons-
description
Amplitude Corrections
Transcript of Amplitude Corrections
Source Amplitude Solution
Source Amplitude Solution 3D survey, dual source
Early QC checks
compute RMS amplitude statistics for each sail line
compute RMS amplitude statistics on shot and channel basis
analyse frequency spectra of selected shots
Amplitude of the two sources seen to vary considerably across the survey
One source consistently stronger than the other
Differences in frequency content apparent between the two sources Signature Deconvolution
Source wavelet matched to a user-defined wavelet
Deconvolution performed separately for each gun and matched to a common wavelet
No need to determine which gun has correct spectrum
Deconvolution filters derived for each shot from running average across 50 field records at a time
Deconvolution filters applied on shot-by-shot basis
Amplitude and frequency discrepancy between sources is significantly reduced by the application of signature deconvolution
Equalisation of the amplitudes is clearly visible on RMS displays, shot plots and near traces
Survey-wide variation in source amplitude is eliminated
Surface Consistent Scaling Amplitude variations will exist within data volumes on many levels
Channel, shot, gun, cable, line, receiver etc
The measured amplitude responses in the data are modelled using a series of such terms (also including CMP & offset terms)
The model is estimated in a least squares sense, with the terms being computed iteratively in a user specified order.
Corrections can be computed on individual lines or on a number of lines simultaneously.
Line to Line Corrections (Common Offsets)
Line to line amplitude variations can be effectively & safely removed after fold normalisation.
Amplitudes extracted on common time slices for each common offset.
Median amplitude responses analysed and corrections applied to correct raw amplitudes to these median values.
Time dependent scalars (ie filtering can be easily controlled if necessary through target horizons)
