Hey man, I did the Skype interview last week. it was pretty short, I think 10 mins max. He asked simple questions such as name a time you worked with numerical data to achieve results, why Exxon, something along the lines of having a tough conversation and how you felt, worked with people who did not cooperate or were difficult to work. I think there were a couple more but I can't remember, but they were all very easy, as long as you have a few examples to show basic competencies it doesn't really require any prep. They got back to me in 3 days and called me for an in person interview.