I've never worked the rigs, but I worked around them quite a bit when I lived in Wyoming and Colorado. Very hard, Very dirty, VERY dangerous work. Pays relatively well, especially once you work your way up the ladder. (IIRC, it's roughneck, wormhand, grease hand (or oiler) deck hand, drill hand, driller or something along those lines) At the bottom of the food chain, work is nasty, nasty, nasty...pay is ok, but not great...you'll work your ass off 7 days a week, 12 hours a day, sometimes 14 0n, 14 off, other times, on different schedules...most companies work similar schedules however, and may include rotating shifts.
This is not something you want to just jump into. Not exactly like working at your local Best Buy or McD's...Usually, you are on that job with no transportation of your own from whatever man-camp they have set up. You can't quit, because if you do, you can't stay at the man-camp if you're not an employee, but you can't leave, because you have no way home...and they're usually WAAAAAAAAY out in BFE somewhere...