AGC / RMS / Absorption Processing

On the Application toolbar, select | Seismic Processing Functions. View image

Either scale can be selected by clicking the AGC Scale, One-Gate RMS Scale, or Gas Absorption Ratio radio button.

Select the lines and/or areas that you wish to apply the scaling to by either clicking on them, or using the pull down options provided. Choose the version of SEGY data that will be processed into a new version.

AGC - You will have to define a window length in milliseconds, as well as the application point and level to max value. Click < Execute> to begin processing.
One-Gate RMS - You will have to define a Window Start and End in milliseconds, as well as a Level to Max Value. Click Execute to begin processing.
Energy Absorption Ratio - A new seismic trace attribute that shows the instantaneous ratio of energy above an below any single trace sample.

The ratio is created by computing the RMS amplitude in a narrow time window above and below each trace sample. The RMS amplitude immediately above the data sample is divided by the RMS amplitude immediately below the data sample.

This ratio is output and replaces the original data sample. The ratio is computed for every sample on each trace and a new seismic line is output.

Instantaneous Energy is decreasing downwards when the ratio is greater than one, while instantaneous energy increases downwards when the ratio is less than one. The ratio will always have positive values.

This trace attribute can highlight gas filled reservoirs. Depending upon the processing parameters and the rock properties the ratio may be larger or smaller than one, but in gas filled reservoirs it frequently highlights anomalous gas filled zones.

Definitions

AGC Application Point % - This value determines which sample the AGC window applies the computed scalier to. The default is 50%, or the middle of the window.
Percent RMS/AVG Level to Max Value - This is the level to which the data is scaled to, and is specified as a percentage of the Max Value. For 16 bit integer, the Max Value is 32767 which means with the default scale level of 16% of Max Value, it is equal to 5243. At this level the max amplitude on normal data will stay around 32767. If the data appears to be clipped, you may wish to decrease this value.

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