Enrollment in U.S. petroleum engineering degree programs fell for the first time in 13 years this fall, as an oil industry slump makes college students wary of entering the boom and bust world of oil and gas. The drop, revealed this week in annual data provided by the country's 21 petroleum engineering departments and made available to Reuters, is modest - the number of enrollments dipped just 1 percent from a record high of 11,332 hit last year when oil was around $100 a barrel.