The energy landscape in US has changed a lot in the last decade or so. Petroleum is still the forerunner in the energy market and might remain the same for next few decades. However, looking at the great deal of research that is being carried in the alternative energy field, you would really wanna rethink your career. Moreover, a chemical engineering degree will still allow you to work upstream in petroleum industries (most of the processing works are done by chemes)  and very often with the experience you can go downstream if you want. I think chemical engineering is a more versatile degree than any other discipline. Unless you have a penchant for drilling and can't see yourself in any other discipline, I suggest you to go chemical.