Interviewed with three members from a team in the structuring department. Three quant analysts and one manager. The questions are not hard, and are relatively easy compared with those financial companies.

Submitted application, two weeks later had a call with the hiring manager going over basic stuff about my resume, why I wanted to work there (and in energy more broadly), details about the job, plus some brainteasers. Three weeks later, got a call back to schedule some interviews over video chat - two half-hour interviews with various parts of the team focusing on behavioral stuff and some light math, then an hour long interview dealing with more typical quant questions. Called back with an offer later that day (I had other offers on the table and told them about that). Be sure to ask about work/life balance and make sure that fits with your expectations. Bonus structure can be a little interesting, so if you get to an offer you may need to ask for clarification about it.

The interview lasted most of the day. Mainly met with pairs of interviewers but the higher level folks were one on one. Mainly brainteasers and "how would you approach this problem" type questions. Lunch was provided.