Local television stations aired images of a towering plume of smoke billowing over the port city of Concon. But ENAP says the Tuesday morning blaze at a unit of the Aconcagua refinery is now under control.
ENAP says contractors Sebastian González and Pedro Alvarez are being treated for minor injuries at a local hospital.
Aconcagua is one of Chile's top oil refineries along with the Bio Bio refinery, also owned by ENAP.
The Aconcagua refinery has started an investigation into the accident.
Chile imports most of its fossil fuels and depends largely on hydropower for electricity.