Have you worked in the oil and gas industry? You sound like you have, but you also make it sound like all fun and games, which leads me to believe that maybe you've just heard slick presenters talk about how awesome it is.
The other side of it is: get ready to:
Work 60,70,80 hrs a week when you're really busy.
Get ready to be away from your family a LOT when you have to travel.
Possibly have to live offshore. Fun for about a week. Then SUCKS.
Have to travel to, and live in, some REMOTE areas.
Work for a huge corporation and deal with all the bullshit attached to that.
I worked as a refinery engineer for a year before grad school, so I dealt with refining, and knew lots of people in upstream. It has its ups and its downs. Represent them accurately.
As for OP. You can be a project manager with just about any Engineering degree, except for Industrial. You can't do shit of value with an industrial degree, but also don't think you're going to start out as a manager. That is a common misconception amongst engineers. You still have to work for the positions you want. It's just that it will seem like nothing compared to what you dealt with in school.
Getting an engineering degree is a huge investment in your future, and will literally prepare you to do just about anything. There is a reason that, even in a tough economy, I have 1 job offer and am talking to 3 other companies. I worked realy hard, and so should you.
All that said, I would go Mechanical.