We have a really big area rug, and it keeps getting these huge...fold crease bulges in the same exact area...how the heck do you get rid of these for good?
Do you have a thick carpet pad beneath it? A good carpet pad will prevent a rug from creeping and creasing. Rotating the rug periodically will also help.
Use carpet tape, even if you have a rug pad beneath it. The tape is double sided and will secure the rug to the pad so it won't shift. You can also secure it with the tape on the border of your rug to prevent shifting.