The well at Seoul seem to be one way for certain people.  I can use a well to get to Seoul but I can't use Seoul's well to go somewhere else.

To recreate: 

1. go to Velia well

2. use it to go to Seoul by paying 5 mil

3. jump in well and pop up in Seoul

4. when at Seoul use that well to go back to Velia by paying 5 mil

5. jump in well and fall down to your death

It doesn't work for either my under lvl 49 or over lvl 49 toons.  It seems to work for some but it didn't work for me and another person that I asked.  Of note, I have not done the Seoul quests or any of Loml.

*update: it seems to work after I went into Magnus and spent energy to "learn" about the Seoul portal.

Thanks for the updated info, I went and did that first : )

I thought if someone jumped into an unopened well that it would just spit them back out.  I don't think I ever tried that.