They want candidates that desire hands on work and aren't afraid to get dirty. It goes without saying that this isn't a job for everyone, and if you're not willing to put in the hours, get dirty, and work in remote locations, this is not the job for you. If you make it clear that you fit these criteria through the the first interview processes, you have a decent chance of getting to the second interview.
The second interview is onsite as functions more as an tour. You see some of the technology, the office, some current field engineers, and possibly visit a field site. Then, you tell them your choice. Having seen the technology, and the location, do you still want to work for Halliburton? In what product service line are you interested in? Other than that, depending on your panel, you might receive some technical questions. This is really a dummy check more than anything, and if you paid any attention in school you should be able to figure out most of them.