Two years out of college, Leah Sanders was making as much as $19,000 a month servicing oil wells in Kuwait. After getting laid off in May by oil-field services giant Schlumberger Ltd., she’s back with her parents in Tennessee, earning $15 an hour helping out at her father’s construction business. She recently began considering switching careers and going to law school.

“I don’t think it’s going to recover as fast as I hoped it would,” said Ms. Sanders, 24. “Do you want to wait and go back to something that you spent two years…