The SEG-Y Scanner

Scanning seismics

Before performing a full import it can be a good idea to scan the seismic SEG-Y file to learn its properties. Some of these properties will be transferred to the SEG-Y import tool.

The scanner allows you to:

• Visually inspect the file headers for useful metadata

• Inspect any trace header to learn properties like byte positions to be set during import

• See file statistics

• Preview the navigation in the map directly from the SEG-Y file

• Preview SEG-Y file amplitudes

• Import only navigation

• Generate rasters (JPEG, PNG or TIF) from amplitudes

Using the SEG-Y scanner

1. In the Ground Model toolbar, click the button SEG-Y Scanner. The scanner window will open.

2. In the scanner window click Browse to select the SEG-Y file. The scanner supports both 2D and 3D seismics.

3. The File Headers tab in the scanner window will show the contents of the textual and binary headers. Click a row in the binary header table to view any extended information for that entry.

4. The Trace Header tab show the contents of the trace headers. A SEG-Y file is mostly comprised of so-called traces, where a trace contains a header along with sample data. To see extended information for a trace header click on the corresponding row in the trace header table on the left. Use the play-button to navigate trace-by-trace in the file. The trace table on the tab to the right will show trace header values for several traces at once, whereas the trace header table on the left tab will only show the current trace. To select which headers to display in the trace table check or uncheck the corresponding field in the trace header table. The corresponding column will appear or disappear in the trace table on the tab to the right.

5. The scanner makes it possible to preview the seismic navigation in the map before performing a full import. Visually verifying that the navigation ends up in the right place can be a useful QC tool. The preview works by reading the navigation coordinates directly from the SEG-Y file and displaying them in the map. To preview the navigation:

• In the Coordinate Settings section (under the Trace Headers tab), select byte positions to read for trace index, and X/Y coordinates positions. Tick of Coordinate Scalar Override if necessary

• Is the seismic of interest 3D also select byte positions for in- and crosslines.

• Choose the coordinate system that applies to the SEG-Y file.

• If the coordinates in the file are given as seconds of arc, tick of Convert from seconds of arc.

• In the Map Preview section, select the traces to be visualized. Also select if the navigation should be displayed as points or lines (Geometry Type).

• Hit View to display the navigation in the map.

6. In the Header Statistics tab, the file can be scanned for file statistics. For example, x/y coordinates equal to zero can be detected, or consecutive ensemble number values can be checked to see that the increment is 1 throughout the file.

7. Previewing the seismic amplitudes can be done by loading the samples in the viewer in the Samples tab. To display the file as desired it is possible to zoom in/out, fit preview to viewer, se full size and pick color table. Use the sliders in the statistics tab to adjust the displayed data range. In the coordinates tab set the domain and unit, set delay recording time and apply scalar. When Apply Scalar is checked a scalar multiplication to some of the fields in the trace header will be applied. This is for display purposes only, but gives an indication of the final values that will be used during import. The scalar itself is a number that is used as a multiplier (> 1) or divisor (< -1) to a header value to arrive at the final value. Examples of scalar are:

   • Coordinate scalar

   • Elevation scalar

   • Shotpoint scalar

10. The seismic navigation can be imported as features, with or without accompanied amplitudes as rasters (TIF, PNG or JPEG). This is done under the scanner Import tab. If not already done, browse in the SEG-Y file of interest. If only navigation is needed, select Import navigation as features. Select Import samples as raster(s) if needed, either with or without the navigation features. Select the target feature class for the navigation and target folder for the raster(s). The data range from the samples viewer will be applied when generating the sample raster(s) if the Use current clip range from samples viewer in the options section is ticked off. Click the Import button. The navigation feature and raster(s) will be written to their respective targets.