First you are invited for an Assessment, the assessment consists of English, Math, Engineering, and pattern recognition questions.. 50+ candidates take the same assessment at the same time and the highest scorers advance to the interview.
For the interview, you had a choice between 5 different departments to interview for and if you wanted to you can interview for all. the departments were Coiled tubing, cementing, slickline, well testing, and Drilling (workshop maintenance only for drilling).
The interview itself is not very difficult, just the assessment.