being a petroleum engineer is a huge time commitment. they work long hours and have to wake up pretty early. sometimes when you are joining to the petroleum engineering jobs, then you might be going to the places inside the sea shore far way from your family.
the main reasons are:
lack of supply- there are only a handful of petroleum engineering department in the nation also petroleum engineering is one of the few fields where there really is a wave of retirees who are leaving the field and salaries for experienced petroleum engineers are so high that it's almost impossible for schools to attract faculty to start new departments.
working conditions- many petroleum engineers spend the first few years of their careers working in the field for 12-18 hours a day, 6 or 7 days a week with very little vacation.