I submitted an abstract to AAPG expo in Houston, TX and I was contacted prior to the expo for an interview. The interview was friendly and not terribly formal; it was a conversation.

First contact was through a career fair in OK. Had first interview one on one for about a 1/2 hour. Got a call back a few weeks later for a formal interview at CHK campus. Flew in night before on their dime. Interview process took ~ 6 hours including a lunch. Went through 4-5 interviews with 2-5 CHK people at a time.