Scanning Seismic Data - SN Evaluation and AUTO Quality

This section describes an automatic process used to evaluate the signal-to-noise (SN) ratio of each record in a seismic data file
[*(SR)*.dat].  Definition of SN ratio is based on the five attributes of an overtone record (processed from each seismic record) as
outlined in the
overview; Pattern, Coherency, Definition, Amplitude, and Energy.  The evaluation results can be used to
infer the overall "quality" of original seismic field records.  In consequence, they can also be used to evaluate the relative
confidence level of the final velocity (Vs) cross section by considering the record range that was responsible for specific lateral
area in the cross section.  Range of SN values and corresponding quality descriptions are presented in the table below:
SN (%)
Quality Description
Best quality for AUTO process.  Highly reliable results are expected
Good candidate for AUTO process.  Reliable results are expected
Marginal quality for AUTO process.  Results should be used with caution.
Lowest quality for AUTO process.  Results should be used with caution.
Bad (Unusable)
Data should not be used for AUTO process.  
Table 1: Description of SN evaluated and corresponding attributes.
Scanning Seismic Data for SN Evaluation

To scan a seismic data for SN evaluation, select items as shown below from the main menu:
Or, from the tool panel, select the button as shown below:
If the file was previously processed in AUTO mode, then the program will detect it and try to utilize the previous results.
Select a seismic data file previously prepared that has source/receiver (SR) setup encoded [*(SR)*.dat].
Otherwise, the program will run the scanning again without referring to the previous results as shown below:
The final scanning results will be displayed in a chart as shown below:
The scanning results shown above indicate that the velocity (Vs) results in 2D cross section corresponding to record numbers
approximately in 80-130 are more reliable in comparison to other areas.  The relationship between record number of seismic
data and lateral distances in the cross section can be found by displaying the table of SR setup from a seismic data display (a
button in "View" tab).  
Park Seismic LLC, Shelton, Connecticut, Tel: 347-860-1223, Fax: 203-513-2056, Email: