Earlier this year, Phillip Whalen packed his bags, left his home in Louisiana and set up shop in western Pennsylvania. The 15-year oil and gas industry veteran said work has dried up around the Gulf of Mexico, in part because of the fallout from the BP PLC oil spill last year. In what has become a kind of reverse national oil rush, Mr. Whalen said, his motivation for heading north to this small community 20 miles south of Pittsburgh was simple. “I’m doing what I have to do to keep a roof over the head and pay the bills,” the...