Tl;dr it's easy if you speak accurately about what you've done and what you know and don't make things up. It's only tiring because it's all day. Based on a university job fair, my first initial on-campus interview was difficult. My interviewer was inscrutable and I couldn't tell if I was doing well or poorly. We went through basically everything I had on my resume and she asked some detailed questions. I thought I didn't do well after leaving the interview, but I must have done better than I thought because I was offered a second-round two-day interview in Houston, TX. They flew me there. First afternoon/evening was largely informational, we got to talk to current employees presenting on their research. Some of these employees would later be interviewers (though we didn't know that at the time). The next day we had interviews and at one point had to present for 10 minutes on a technical project we were in charge of. SLB employees in attendance asked some pretty detailed and difficult questions, so I highly suggest presenting on something you know very well. It was really clear when people gave bad answers and were lying or making things up. The rest of the interviews were okay, it was just tiring. Every single thing on my resume was something I reviewed probably multiple times across the four or five conversations. They felt more like placement interviews than weeder interviews, though there were technical questions about my ability to read drawings. Some of the drawings weren't really detailed enough--maybe the interviewers weren't prepared--but this was really only the case for 1 out of all of them. They gave good feedback.

I applied for an internship position through my university portal and got an email from slb to schedule an interview. They conducted the interview online and it took roughly 30 minutes