Import IP Data from Instrumentation GDD Format File

Use the Import Instrumentation GDD File dialog to import IP data from an Instrumentation GDD file.

Import Instrumentation GDD File dialog options

Instrumentation GDD file

The name of the Instrumentation GDD file. Multiple files can be selected. Script Parameter: IP.GDDFILE

Application Notes

The GDD file format is similar to the IPDATA format with some variations. The GDD files start with four header lines, followed by the data:

• Line1 - Version descriptor
• Line 2 - Project descriptor
• Line 3 - Configuration descriptor
• Line 4 - Channel Header descriptor

Subsequent lines have an equal number of fields as defined by Line 4.

The GDD dump file format supported by this import contains the version descriptor “PPC.”

The supported array types along with their file acronyms are listed below:

Dipole-Dipole	Pole-Dipole	Pole-Pole	Schlumberger	Wenner	Gradient
DP-DP	P-DP	P-P	SCHL	WEN	GRAD

Any other acronym will trigger an error.

Lines are split based on changes in the “LineRx” data column. Separate versions of the same line are created if the array type changes, but the “LineRx” value remains the same. This is because the Oasis montaj IP system supports only a single type of array per database line.

You cannot produce pseudo-sections of the Schlumberger, Wenner, Gradient configurations. These configurations are absent in Setup database for IP. To apply Setup database for IP to such GDD data, treat them more generally as a 3D Dipole-Dipole configuration.

Although the GDD format contains the N value, the IP extension does not import it as this is a channel that is calculated internally.

The “Sym(%)” channel is imported as “Sym.”

All the “M##” data is imported to a single “IP” array channel.

In that case the “/” is ignored, “Time” is imported as “Hour”, “El-array” is recognized as “Array”, and the Tx and Rx values are recognized as Tx1, Tx2, Rx1, Rx2

the “/”, if present in the header line 4, is ignored.

9999999.00 is recognized as Tx and Rx dummy locations.

999999.99 is recognized as the dummy Rho value.

“------“ is also recognized as a dummy value.

Blank lines are skipped.

The line number is created using the value of “LineRx” (Receiver line).

The “LineTx” is imported, but not used for anything in particular.

The line direction (N-S or E-W) is included in the import data.

Some files bearing the “gdd” file type are actually Geosoft IPDATA format files, and if you receive an error message such as “Error importing Instrumentation GDD file “YourFile.gdd”, the file does not appear to be a valid GDD file. Expected 'Version PPC:' on the first line”, then visual inspection of the file text may reveal it to be Geosoft IPDATA format, and it is recommended you try that import instead.

Imports of surveys where the Tx and Rx locations are on separate lines (and hence the “LineTx” and “LineRx” values are different) are not supported; currently all Tx and Rx locations are imported to the same “LineRx” value.