What's the minimum age to work in the oilfield?

Most oilfield field roles set a minimum age of 18, and many employers effectively require 21 or older. Two things push the practical floor up: a commercial driver's license for interstate hauling requires being at least 21 under federal rules (intrastate-only CDL holders can be 18–20 in many states), and insurance requirements for operating heavy equipment often set a higher minimum than the law does. Hazardous, safety-sensitive field work is also restricted to adult workers under federal child-labor rules, so this isn't an oilfield-specific quirk. If you're 18–20, the roles most open to you are non-driving field positions — roustabout, floorhand, shop and yard work — with driving roles becoming realistic at 21. The exact floor for a given job is set by that employer and the role's licensing and insurance requirements.