I only have 2D data, why do I need to set up as if I have a 3D survey?

Because OpendTect works in a 3D space. Just to be able to have some ‘work space’, an initial work wireframe - some kind of 3D raster must be set up. It defines the boundaries and granularity of the elements in space. You can use ‘Set for 2D only’ which fills everything with sensible numbers.

I have a 2D line only. Why doesn’t ‘Scan SEG-Y file’ set up the survey?

Because 2D lines have insufficient information to set up a 3D survey working cube. Just scan the file for coordinate ranges and average trace distance, then use ‘Set for 2D only’ to set up your survey.

My SEG-Y scan says: ‘one in-line only’ (or invalid coordinates, or …).

Scan only works if the SEG-Y file has the correct info in the trace headers. Your SEG-Y file may not have the data required to set up the survey. Per trace, a coordinate and an inline/crossline. If you select the wrong locations or if the data is bad, you get this sort of problems. Remember: you do not *have* to use a SEG-Y file scan to set up your survey. You can do it ‘by hand’, and later import the cube with only inline/crossline or only coordinates from the headers. See the following resources for further help:

I would like to locate the OpendTect survey bounding box and wells correctly in Google Earth. How do I go about that?

The workflow for this is described in detail in the following PDF file: