GerryWright: The fields I am talking about are not magically locked doors. They occur in doorways with no doors. When I look at them, they are identified as electric fields. Anyway, after additional exploration in the basement of the cyclops castle, I found that there was a switch behind a secret door that shut off the fields blocking the doors. So, I guess those barriers weren't meant to be dispelled by magic, after all.
Ohhh, electric fields, not energy fields.
Gotcha. Yup, those are switch-activated fields. Even if you cast dispel, they'll persist b/c electricity continues to supply them. You gotta cut off the electricity via a switch, which are sometimes really far away, or hidden behind an object that needs to be moved.
Those are in a few other places, like Covetous/Wrong and I think the Gargoyle Tombs. Super annoying when you're in an area with a buttload of switches, and you have to figure out which switches correspond to certain electric fields.