Datum tab

The Datum tab has two major functions: selecting a reference datum at the beginning of a project, and selecting the reference datum for new data imports.

The Map Projection Datum tab

Project Datum Reference - This dropdown sets the project’s reference datum, which is critical to correctly projecting all well, seismic, and overlay data.  After changing the datum, it’s necessary to select a coordinate system in order to save any changes.  

It’s important to note that changing the project’s datum here does not reproject the entire project.  Really, the only time to use this option on the Datum tab is when setting up the project’s map projection before importing any data.  To change the datum of the project, select the Advanced tab on the Map Projection Settings box.

Datum for Data Imports - This dropdown automatically recalculates the imported data’s latitude and longitude to match the project’s reference datum.  In the example below, the incoming well data’s LatLons are based on the NAD27 reference datum, while the project is based on the NAD83 datum.  

Project Area - This option sets the list of available reference datums.  The “Contiguous US” option lists only the datums relevant to the US, while the “International” option shows all available datums.