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AUTOMATIC EDITING OF NOISY SEISMIC DATA1
- Source: Geophysical Prospecting, Volume 37, Issue 8, Nov 1989, p. 875 - 892
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- 27 Apr 2006
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Abstract
Seismic data often contain traces that are dominated by noise; these traces should be removed (edited) before multichannel filtering or stacking. Noise bursts and spikes should be edited before single channel filtering. Spikes can be edited using a running median filter with a threshold; noise bursts can be edited by comparing the amplitudes of each trace to those of traces that are nearby in offset‐common midpoint space. Relative amplitude decay rates of traces are diagnostic of their signal‐to‐noise (S/N) ratios and can be used to define trace editing criteria. The relative amplitude decay rate is calculated by comparing the time‐gated trace amplitudes to a control function that is the median trace amplitude as a function of time, offset, and common midpoint. The editing threshold is set using a data‐adaptive procedure that analyses a histogram of the amplitude decay rates.
A performance evaluation shows that the algorithm makes slightly fewer incorrect trace editing decisions than human editors. The procedure for threshold setting achieves a good balance between preserving the fold of the data and removing the noisiest traces. Tests using a synthetic seismic line show that the relative amplitude decay rates are diagnostic of the traces’S/N ratios. However, the S/N ratios cannot be accurately usefully estimated at the start of processing, where noisy‐trace editing is most needed; this is the fundamental limit to the accuracy of noisy trace editing.
When trace equalization is omitted from the processing flow (as in amplitude‐versus‐offset analysis), precise noisy‐trace editing is critical. The S/N ratio of the stack is more sensitive to type 2 errors (failing to reject noisy traces) than it is to type 1 errors (rejecting good traces). However, as the fold of the data decreases, the S/N ratio of the stack becomes increasingly sensitive to type 1 errors.